ISIS PHARMACEUTICALS INC
8-K, 1999-05-03
PHARMACEUTICAL PREPARATIONS
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<PAGE>   1

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT
                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


        Date of Report (Date of earliest event reported): APRIL 20, 1999




                           ISIS PHARMACEUTICALS, INC.
             (Exact name of registrant as specified in its charter)



                                    DELAWARE
                 (State or other jurisdiction of incorporation)



    000-19125                                             33-0336973
(Commission File No.)                          (IRS Employer Identification No.)

                               2292 FARADAY AVENUE
                           CARLSBAD, CALIFORNIA 92008
              (Address of principal executive offices and zip code)

                                 (760) 931-9200
              (Registrant's telephone number, including area code)

<PAGE>   2

ITEM 2.   ACQUISITION OR DISPOSITION OF ASSETS.

On April 20, 1999, Isis Pharmaceuticals, Inc., a Delaware corporation ("Isis" or
the "Company") and Elan Corporation, plc ("Elan") formed a joint venture to
develop technology for the formulation of oral oligonucleotide drugs. The joint
venture, Orasense Ltd. ("Orasense"), a Bermuda limited company, is initially
owned 80.1% by the Company and 19.9% by Elan. Isis and Elan each contributed
rights certain to oral drug delivery technology to the joint venture. In
addition, Isis contributed rights to a proprietary oligonucleotide, which will
be the first candidate for oral formulation by Orasense. Isis and Elan will
provide development and manufacturing services to Orasense and will be entitled
to royalties on milestone payments and royalties received by Orasense for
development of orally formulated oligonucleotide drugs. In the event that Isis
enters into an agreement with Orasense for oral formulation of any Isis
oligonucleotide drug, Isis will pay Orasense royalties and a portion of certain
third party milestone payments with respect to the drug.

In connection with the joint venture, Elan International Services, Ltd. ("EIS")
purchased $15 million of Common Stock of Isis at a premium. Isis also issued a
warrant to EIS to purchase 215,000 shares of Isis Common Stock at $24.00 per
share. EIS also purchased $12 million of Preferred Stock of Isis, which bears a
5% dividend payable in Preferred Stock and is convertible into Isis Common Stock
at a specified premium or exchangeable for 30.1% ownership of Orasense. Isis
contributed a portion of the funding to Orasense to pay license fees to Elan for
certain of the technology contributed to the joint venture.

Until March 31, 2002, EIS will, at Isis' request, purchase convertible debt of
Isis in an amount equal to Isis' share of budgeted funding for Orasense. The
convertible debt will have a term of six years, bear interest at the rate of 12%
and be convertible into Isis Common Stock at a premium. Isis may prepay the
convertible debt in cash or Isis Common Stock. Isis will use the proceeds of the
sale of the convertible debt to provide additional development funding to
Orasense.

EIS will have certain registration rights with respect to the Isis Common Stock
and the Isis Common Stock issuable upon conversion of the Preferred Stock, the
warrant and the convertible debt.

As part of the transaction, the parties entered into several agreements,
including a Subscription, Joint Development and Operating Agreement, Securities
Purchase Agreement, Convertible Promissory Note, Registration Rights Agreements,
Warrant and License Agreements, a copy of each of which is attached hereto as an
exhibit and incorporated herein by reference.


                                       2.
<PAGE>   3

ITEM 7.   FINANCIAL STATEMENTS AND EXHIBITS.

        (a)   Financial Statements of Businesses Acquired.

        Not applicable.

        (b)   Pro Forma Financial Information.

        Not applicable.

        (c)   Exhibits.

<TABLE>
<CAPTION>
        Exhibit No.   Description 
        -----------   -----------
<S>                   <C>
               10.1*  Subscription, Joint Development and Operating Agreement,
                      dated April 20, 1999, by and among Registrant, Elan
                      Corporation, plc ("Elan"), Elan International Services,
                      Ltd. ("EIS"), and Orasense, Ltd. ("Orasense").

               10.2   Securities Purchase Agreement, dated April 20, 1999, by
                      and between Registrant and EIS.

               10.3   Convertible Promissory Note, dated April 20, 1999, by and
                      between Registrant and EIS.

               10.4   Warrant to Purchase Shares of Common Stock, dated April
                      20, 1999, by and between Registrant and EIS.

               10.5   Registration Rights Agreement, dated April 20, 1999, by
                      and between Registrant and EIS.

               10.6   Registration Rights Agreement, dated April 20, 1999, by
                      and among Registrant, EIS and Orasense.

               10.7*  License Agreement, dated April 20, 1999, by and between
                      Elan and Orasense.

               10.8*  License Agreement, dated April 20, 1999, by and between
                      Registrant and Orasense.
</TABLE>

- --------
    * Confidential treatment has been requested with respect to certain portions
of this exhibit. Omitted portions have been filed separately with the Securities
and Exchange Commission.


                                       3.
<PAGE>   4

                           ISIS PHARMACEUTICALS, INC.
                                   SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                              ISIS PHARMACEUTICALS, INC.
                                          (Registrant)


Date:05/03/99                   By:  /s/ Stanley T. Crooke
                                    --------------------------------------------
                                    Stanley T. Crooke, M.D., Ph.D.
                                    Chairman of the Board and Chief Executive
                                    Officer (Principal Executive Officer)


Date:05/03/99                   By:  /s/ B. Lynne Parshall
                                    --------------------------------------------
                                    B. Lynne Parshall
                                    Executive Vice President and Chief Financial
                                    Officer (Principal Financial Officer)


                                       4.
<PAGE>   5

                                INDEX TO EXHIBITS

<TABLE>
<S>            <C>
        10.1*  Subscription, Joint Development and Operating Agreement, dated
               April 20, 1999, by and among Registrant, Elan Corporation, plc
               ("Elan"), Elan International Services, Ltd. ("EIS"), and
               Orasense, Ltd. ("Orasense").
        
        10.2   Securities Purchase Agreement, dated April 20, 1999, by and
               between Registrant and EIS.

        10.3   Convertible Promissory Note, dated April 20, 1999, by and between
               Registrant and EIS.

        10.4   Warrant to Purchase Shares of Common Stock, dated April 20, 1999,
               by and between Registrant and EIS.

        10.5   Registration Rights Agreement, dated April 20, 1999, by and
               between Registrant and EIS.

        10.6   Registration Rights Agreement, dated April 20, 1999, by and among
               Registrant, EIS and Orasense.

        10.7*  License Agreement, dated April 20, 1999, by and between Elan and
               Orasense.

        10.8*  License Agreement, dated April 20, 1999, by and between
               Registrant and Orasense.
</TABLE>

- ----------
    * Confidential treatment has been requested with respect to certain portions
of this exhibit. Omitted portions have been filed separately with the Securities
and Exchange Commission.

<PAGE>   1
                                                                    EXHIBIT 10.1

                                            ***TEXT OMITTED AND FILED SEPARATELY
                                                CONFIDENTIAL TREATMENT REQUESTED
                                          UNDER 17 C.F.R. SECTIONS 200.80(B)(4),
                                                            200.83 AND 240.24B-2




             SUBSCRIPTION, JOINT DEVELOPMENT AND OPERATING AGREEMENT



                              ELAN CORPORATION, PLC



                        ELAN INTERNATIONAL SERVICES, LTD.



                                       AND



                           ISIS PHARMACEUTICALS, INC.



                                       AND



                                  ORASENSE LTD.


                                       
<PAGE>   2

                                      INDEX


<TABLE>
<S>          <C>           
CLAUSE 1     DEFINITIONS
             
CLAUSE 2     NEWCO'S BUSINESS
             
CLAUSE 3     REPRESENTATIONS AND WARRANTIES
             
CLAUSE 4     AUTHORIZATION AND CLOSING
             
CLAUSE 5     CERTAIN ASSIGNMENT RIGHTS
             
CLAUSE 6     NONCOMPETITION
             
CLAUSE 7     DIRECTORS; MANAGEMENT AND R&D COMMITTEES
             
CLAUSE 8     THE BUSINESS PLAN AND REVIEWS
             
CLAUSE 9     RESEARCH AND DEVELOPMENT WORK
             
CLAUSE 10    INTELLECTUAL PROPERTY RIGHTS
             
CLAUSE 11    EXPLOITATION OF PRODUCTS OUTSIDE THE FIELD
             
CLAUSE 12    COMMERCIALIZATION
             
CLAUSE 13    MANUFACTURING
             
CLAUSE 14    TECHNICAL SERVICES AND ASSISTANCE
             
CLAUSE 15    AUDITORS, BANKERS, REGISTERED OFFICE, ACCOUNTING REFERENCE DATE; 
             SECRETARY; COUNSEL
             
CLAUSE 16    REGULATORY
             
CLAUSE 17    TRANSFERS OF SHARES; RIGHT OF FIRST OFFER; TAG ALONG RIGHTS
             
CLAUSE 18    MATTERS REQUIRING PARTICIPANTS' APPROVAL
             
CLAUSE 19    DISPUTES
             
CLAUSE 20    CERTAIN CHANGES OF CONTROL
             
CLAUSE 21    TERMINATION
</TABLE>


                                       i
<PAGE>   3

<TABLE>
<S>          <C>           
CLAUSE 22    CONFIDENTIALITY
             
CLAUSE 23    COSTS
             
CLAUSE 24    GENERAL
</TABLE>
             
             
                                       ii
<PAGE>   4
             
           
THIS SUBSCRIPTION, JOINT DEVELOPMENT AND OPERATING AGREEMENT made this 20th day
of April, 1999,

AMONG:

(1)     ELAN CORPORATION, PLC, a public limited company incorporated under the
        laws of Ireland, and having its registered office at Lincoln House,
        Lincoln Place, Dublin 2, Ireland ("ELAN");

(2)     ELAN INTERNATIONAL SERVICES, LTD., a private limited company
        incorporated under the laws of Bermuda, and having its registered office
        at Clarendon House, 2 Church St., Hamilton, Bermuda ("EIS");

(3)     ISIS PHARMACEUTICALS, INC., a corporation incorporated under the laws of
        Delaware and having its principal place of business at 2292 Faraday
        Avenue, Carlsbad, CA 92008, United States of America ("ISIS"); and

(4)     ORASENSE LTD., a private limited company incorporated under the laws of
        Bermuda, and having its registered office at Clarendon House, 2 Church
        St., Hamilton, Bermuda ("NEWCO").


RECITALS:


A.      Newco desires to issue and sell to the Participants (as defined below),
        and the Participants desire to purchase from Newco, for aggregate
        consideration of $15,000,000, apportioned between them as set forth
        herein, 12,000 shares of Newco's common stock, par value $1.00 per share
        (the "COMMON STOCK"), allocated 9,612 shares to Isis and 2,388 shares to
        EIS.

B.      Elan is beneficially entitled to the use of certain patents which have
        been granted or are pending in relation to drug delivery including
        modification of the solubility, intrinsic dissolution, stability and/or
        permeability of an active agent, improved dosage form processing,
        modification of the surface of particles, and in vivo, in situ, and in
        vitro cell tissue and animal models for drug absorption.

C.      Isis is beneficially entitled to the use of certain patents that have
        been granted or are pending in relation to metabolism and transport
        inhibitors and methods of identifying the same and in vivo, in situ, and
        in vitro cell tissue and animal models for drug absorption.

D.      As of the date hereof, Elan Pharmaceutical Technologies, a division of
        Elan ("EPT"), has entered into a license agreement with Newco, and Isis
        has entered 


                                       7.
<PAGE>   5

        into a license agreement with Newco, in connection with the license to
        Newco of the Elan Intellectual Property and the Isis Intellectual
        Property, respectively (each as defined below).

E.      Elan and Isis have agreed to co-operate in the establishment and
        management of a business for the research, development and
        commercialization of the Products (as defined below) based on their
        respective technologies.

F.      Elan and Isis have agreed to enter into this Agreement for the purpose
        of recording the terms and conditions of the joint venture and of
        regulating their relationship with each other and certain aspects of the
        affairs of and their dealings with Newco.


NOW IT IS HEREBY AGREED AS FOLLOWS:

                                    CLAUSE 1

                                   DEFINITIONS

1.1     In this Agreement, the following terms shall, where not inconsistent
        with the context, have the following meanings respectively.

        "AFFILIATE" of any Person (in the case of a legal entity) shall mean any
        other Person controlling, controlled or under the common control of such
        first Person, as the case may be. For the purposes of this definition,
        "control" shall mean direct or indirect ownership of greater than fifty
        percent (50%) of the stock or shares entitled to vote for the election
        of directors or capital interests representing more than fifty percent
        (50%) of the equity thereof and "controlling" and "controlled" shall be
        construed accordingly. Notwithstanding the foregoing, Newco shall not be
        construed to be an Affiliate, as defined herein, of Elan or EIS.

        "AGREEMENT" means this agreement (which expression shall be deemed to
        include the Recitals and the Schedules hereto).

        "BUSINESS" means the business of Newco as described in Clause 2 and as
        more particularly specified in the Business Plan and such other business
        as the Participants may agree from time to time in writing (each in its
        sole discretion) should be carried on by Newco.

        "BUSINESS PLAN" shall mean the business plan and program of development
        to be agreed by Elan and Isis within 60 days of the Closing Date, with
        respect to the research, development, and commercialization of the
        Products, which shall be reviewed and updated by Elan and Isis on an
        annual basis, upon mutual written agreement.


                                       2.
<PAGE>   6

        "CHANGE OF CONTROL" shall mean, with respect to a Party, the acquisition
        of [...***...] or more of its voting securities, the ability, by
        contract or otherwise, to control the board of directors or management
        of any such entity, or a sale of all or substantially all of the
        business of such Party to which the Transaction Documents relate,
        whether by merger, sale of stock, sale of assets or otherwise.

         "CLOSING DATE" shall mean the date upon which the Transaction Documents
        are executed and delivered by the Parties and the transactions effected
        thereby are closed.

        "COMMERCIALIZATION" shall mean the manufacture, promotion, distribution,
        marketing and sale of the Products and the Development Product.

        "COMMON STOCK EQUIVALENTS" means any options, warrants, rights or any
        other securities convertible, exercisable or exchangeable, in whole or
        in part, for or into Common Stock.

        "CONTROL" shall mean, with respect to a drug, the ability to grant a
        license or sublicense as contemplated herein without violating the terms
        of any agreement with any third party.

        "CONVERTIBLE NOTE" means that certain convertible promissory note, of
        even date herewith, by and between Isis and EIS.

        "DEVELOPMENT CANDIDATE" shall mean a [...***...] antisense inhibitor of
        TNF-(alpha), as more specifically detailed in the License Agreements.

        "DEVELOPMENT PRODUCT" shall mean any product containing as an active
        ingredient the Development Candidate (or a Substituted Development
        Candidate) in an Oral formulation for humans.

        "DIRECTORS" means, at any time, the directors of Newco.

        "EIS DIRECTOR" has the meaning set forth in Clause 7.

        "EIS EXCHANGE RIGHT" has the meaning assigned to such term in the Isis
        Securities Purchase Agreement.

        "ELAN IMPROVEMENTS" has the meaning assigned thereto in the Elan License
        Agreement.

        "ELAN INTELLECTUAL PROPERTY" has the meaning assigned thereto in the
        Elan License Agreement.

                                              * CONFIDENTIAL TREATMENT REQUESTED

                                       3.

<PAGE>   7

        "ELAN KNOW-HOW" has the meaning assigned thereto in the Elan License
        Agreement.

        "ELAN LICENSE" has the meaning assigned thereto in the Elan License
        Agreement.

        "ELAN LICENSE AGREEMENT" means the license agreement between Elan and
        Newco, of even date herewith, attached hereto in Schedule 1.

        "ELAN PATENT RIGHTS" has the meaning assigned thereto in the Elan
        License Agreement.

        "ELAN PROGRAM TECHNOLOGY" shall mean all Program Technology solely
        conceived or made by Elan and/or its agents.

        "ENCUMBRANCE" means any liens, charges, encumbrances, equities, claims,
        options, proxies, pledges, security interests, or other similar rights
        of any nature.

        "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.

        "FIELD" shall mean the research, development and Commercialization of an
        Oral Platform for delivery of Oligonucleotide Drugs.

        "FINANCIAL YEAR" means each year commencing on January 1 (or in the case
        of the first Financial Year, the date hereof) and expiring on December
        31 of each year.

        "FULLY DILUTED COMMON STOCK" means all of the issued and outstanding
        Common Stock, assuming the conversion, exercise or exchange of all
        outstanding Common Stock Equivalents.

        "FUNDING AGREEMENT" shall mean the Funding Agreement, dated as of the
        date hereof, between Elan, EIS and Isis.

        "INDEPENDENT THIRD PARTY" shall mean any person other than Newco, Isis,
        Elan or any of their respective Affiliates.

        "ISIS DELIVERY KNOW-HOW" shall have the meaning given to such term in
        the Isis License Agreement.

        "ISIS DELIVERY PATENTS" shall have the meaning given to such term in the
        Isis License Agreement.

        "ISIS DELIVERY TECHNOLOGY" shall have the meaning given to such term in
        the Isis License Agreement.

        "ISIS DEVELOPMENT CANDIDATE KNOW-HOW" shall have the meaning given to
        such term in the Isis License Agreement.


                                       4.
<PAGE>   8
        "ISIS DEVELOPMENT CANDIDATE PATENTS" shall have the meaning given to 
        such term in the Isis License Agreement.

        "ISIS DEVELOPMENT CANDIDATE TECHNOLOGY" shall have the meaning given to
        such term in the Isis License Agreement.

        "ISIS DIRECTORS" has the meaning set forth in Clause 7.

        "ISIS IMPROVEMENTS" shall have the meaning given to such term in the
        Isis License Agreement.

        "ISIS INTELLECTUAL PROPERTY" shall have the meaning given to such term
        in the Isis License Agreement.

        "ISIS LICENSE" shall have the meaning given to such term in the Isis
        License Agreement.

        "ISIS LICENSE AGREEMENT" shall mean the license agreement between Isis
        and Newco, of even date herewith, attached hereto as Schedule 2

        "ISIS OLIGONUCLEOTIDE DRUG" shall mean any Oligonucleotide Drug
        Controlled by Isis other than the Development Candidate.

        "ISIS PRODUCTS" shall mean Products for Oral delivery based upon Isis
        Oligonucleotide Drugs that are made, designed, or otherwise created by
        or on behalf of Isis or any of its Affiliates after the date hereof
        pursuant to the Project using the Newco Technology and/or the Licensed
        Technologies.

        "ISIS PROGRAM TECHNOLOGY" shall mean all Program Technology solely
        conceived or made by Isis and/or its agents.

        "ISIS SECURITIES PURCHASE AGREEMENT" means that certain securities
        purchase agreement, of even date herewith, by and between Isis and EIS.

        "LICENSE AGREEMENTS" means the Elan License Agreement and the Isis
        License Agreement.

        "LICENSED TECHNOLOGIES" means, together, the Elan Intellectual Property
        and the Isis Intellectual Property.

        "NEWCO MEMORANDUM OF ASSOCIATION AND BYE-LAWS" shall mean the Memorandum
        of Association and Bye-Laws of Newco.

        "NEWCO PATENTS" shall mean any and all patents and patent applications
        Controlled by Newco, existing and/or pending as of the Effective Date or
        hereafter filed or obtained by Newco, other than Elan Patent Rights,
        Isis Delivery


                                       5.
<PAGE>   9

        Patent Rights and Isis Development Candidate License Rights. Newco
        Patent Rights shall also include all extensions, continuations,
        continuations-in-part, divisionals, patents-of-additions,
        re-examinations, re-issues, supplementary protection certificates and
        foreign counterparts of such patents and patent applications and any
        patents issuing thereon and extensions of any patents licensed
        hereunder.

        "NEWCO PROGRAM TECHNOLOGY" shall mean all Program Technology other than
        Elan Program Technology and Isis Program Technology.

        "NEWCO TECHNOLOGY" shall mean all Program Technology and all technology
        licensed or acquired by Newco or developed by Newco whether or not
        pursuant to the Research and Development Program, excluding, however,
        Isis Intellectual Property and Elan
        Intellectual Property.

        "OLIGONUCLEOTIDE DRUG" shall mean any single stranded, [...***...]
        oligonucleotide including those [...***...] used as a human therapeutic
        and/or prophylactic compound containing between [...***...] nucleotides
        and/or nucleosides including oligonucleotide analogs which may include
        [...***...]. For purposes of this Agreement, Oligonucleotide Drug shall
        specifically exclude oligonucleotides used in gene therapy except
        [...***...] an oligonucleotide, oligonucleotides used as [...***...] or
        oligonucleotides used as adjuvants. Oligonucleotide Drug shall also
        specifically exclude polymers in which the linkages are amide based,
        such as peptides and proteins but shall not exclude [...***...]. Should
        Isis develop [...***...] oligonucleotides or should Elan independently
        discover drug delivery technology it believes to be potentially
        applicable to [...***...] oligonucleotides, then the Participants shall
        discuss in good faith whether such oligonucleotides can be formulated
        for Oral delivery using the Oral Platform, and whether such formulation
        appears feasible without requiring a significant further investment in
        developing or enhancing the Oral Platform; if such formulation appears
        feasible, the Participants shall discuss in good faith the inclusion of
        such oligonucleotides as Oligonucleotide Drugs.

        "ORAL" shall mean administration by way of the mouth for the purpose of
        topical or systemic delivery by way of the alimentary canal.

        "ORAL DELIVERY DEVICES" shall mean devices for delivering an active
        agent orally such as those employing [...***...] technologies.


                                               *CONFIDENTIAL TREATMENT REQUESTED
                                       6.
<PAGE>   10

        "ORAL PLATFORM" shall mean formulation and excipient systems and
        technologies including [...***...] and further including the use of
        [...***...], which can be employed to develop dosage forms of
        Oligonucleotide Drugs, deliver said dosage forms to the alimentary canal
        and facilitate and/or promote the Oral systemic and topical delivery of
        Oligonucleotide Drugs.

        "PARTICIPANT" means Isis or Elan, as the case may be, and "Participants"
        means both of the Participants together.

        "PARTY" means Elan, Isis, or Newco, as the case may be, and "Parties"
        means all three together.

        "PERSON" means an individual, partnership, corporation, limited
        liability company, business trust, joint stock company, trust,
        unincorporated association, joint venture, governmental entity or
        authority or other entity of whatever nature.

        "PERMITTED TRANSFEREE" means any Affiliate or subsidiary of Elan, EIS or
        Isis, to whom this Agreement may be assigned, in whole or in part,
        pursuant to the terms hereof or in the case of Elan/EIS, an off-balance
        sheet special purpose entity created by Elan or EIS.

        "PRIMARY TECHNOLOGICAL COMPETITOR OF ELAN" shall mean those entities
        listed on Schedule 2A to the Elan License Agreement.

        "PRODUCT" shall mean any Oligonucleotide Drug under development or
        developed by or on behalf of Newco in an Oral formulation for
        administration to humans.

        "PROGRAM TECHNOLOGY" shall mean all technology developed by or on behalf
        of Newco, whether by Elan, Isis, a third party or jointly by any
        combination thereof, pursuant to the Research and Development Program.

        "PROJECT" shall mean all activity as undertaken by or on behalf of Newco
        in order to develop the Products in accordance with the Business Plan.

        "REGISTRATION RIGHTS AGREEMENTS" means the Registration Rights
        Agreements of even date herewith relating to securities of Isis and
        Newco, respectively.

        "REGULATORY APPLICATION" means any regulatory application or any other
        application for marketing approval for a Product, which Newco will file
        in any country of the Territory, including any supplements or amendments
        thereto.

        "REGULATORY APPROVAL" means the final approval to market a Product in
        any country of the Territory, and any other approval which is required
        to launch the Product in the normal course of business.


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       7.
<PAGE>   11

        "RESEARCH TERM" shall mean the period commencing on the Closing Date and
        continuing for a period of [...***...] thereafter, unless extended by
        the mutual written agreement of Elan and Isis; provided, however, that
        if a Participant shall be prevented by (i) events beyond the
        Participant's control, or (ii) by such Participant's delay or negligent
        act or omission, from performing its obligations under the Transaction
        Documents within said [...***...] period, then the other Participant at
        its option, may extend the duration of the Research Term by a term equal
        in length to the period during which the first Participant was unable to
        perform its obligations hereunder.

        "RHA" means any relevant government health authority (or successor
        agency thereof) in any country of the Territory whose approval is
        necessary to market a Product in the relevant country of the Territory.

        "SECURITIES ACT" means the Securities Act of 1933, as amended.

        "SHARES" means the shares of Common Stock of Newco.

        "STOCKHOLDER" means any of EIS, Isis, any Permitted Transferee or any
        other Person who subsequently becomes bound by this Agreement as a
        holder of the Shares, and "STOCKHOLDERS" means all of the Stockholders
        together.

        "SUBSIDIARY" means any company that is a subsidiary of Newco within the
        meaning of applicable laws.

        "SUBSTITUTED DEVELOPMENT CANDIDATE" shall mean an Isis Oligonucleotide
        Drug licensed to Newco by Isis for development by Newco in replacement
        of the Development Candidate pursuant to the Isis License Agreement.

        "TECHNOLOGICAL COMPETITOR OF ELAN" shall mean any entity which has a
        significant program for the development of drug delivery systems and
        which is active in promoting and contracting the use of such drug
        delivery systems to third parties, a listing of which is contained on
        Schedule 2B to the Elan License Agreement, as the same shall be updated
        and revised on an annual basis by mutual consent of the Parties.

        "TECHNOLOGICAL COMPETITOR OF ISIS" shall mean any entity which has a
        significant program for the discovery and development of antisense
        drugs, a listing of which is contained on Schedule 3 to the Elan License
        Agreement, as the same shall be updated and revised on an annual basis
        by mutual consent of the Parties.

        "TERM" means the term of this Agreement.

        "TERRITORY" means all of the countries of the world.


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       8.
<PAGE>   12

        "THIRD PARTY OLIGONUCLEOTIDE DRUG" shall mean any Oligonucleotide Drugs
        Controlled by an Independent Third Party, other than an Isis
        Oligonucleotide Drug.

        "THIRD PARTY PRODUCT" shall mean Products based upon Third Party
        Oligonucleotide Drug that are made, designed, or otherwise created by or
        on behalf of an Independent Third Party after the date hereof pursuant
        to the Project using the Newco Technology and/or the Licensed
        Technologies. For avoidance of doubt, any Product based upon an
        Oligonucleotide Drug jointly developed by an Independent Third Party and
        Isis other than pursuant of the Program shall be deemed to be an Isis
        Product.

        "TRANSACTION DOCUMENTS" means this Agreement, the Funding Agreement, the
        Elan License Agreement, the Isis License Agreement, the Convertible
        Note, the Isis Securities Purchase Agreement, the Registration Rights
        Agreements and associated documentation of even date herewith, by and
        between Isis, Elan, EIS and Newco, as applicable.

        "UNITED STATES DOLLAR" and "US$" and "$" means the lawful currency of
        the United States of America.

1.2     In addition, the following definitions have the meanings in the Clauses
        corresponding thereto, as set forth below.

<TABLE>
<CAPTION>
        DEFINITION                             CLAUSE
<S>                                            <C> 
        "Buyout Option"                        20.1
        "Closing"                              4.2
        "Common Stock"                         Recital
        "Confidential Information"             22.1
        "Co-sale Notice"                       17.3
        "Elan"                                 Recital
        "Elan Valuation"                       20.2
        "EIS"                                  Recital
        "EPT"                                  Recital
        "Isis"                                 Recital
        "Isis Valuation"                       20.2
        "Management Committee"                 7.2.1
        "Newco"                                Recital
        "Notice of Exercise"                   17.2
        "Notice of Intention"                  17.2
        "Offered Shares"                       17.2
        "Offering Price"                       17.2
        "Presiding Justice"                    20.2
        "Purchase Price"                       20.2
        "R&D Committee"                        7.2.2
        "Remaining Stockholders"               17.3
</TABLE>


                                       9.
<PAGE>   13

<TABLE>
<S>                                            <C> 
        "Relevant Event"                       21.2
        "Research and Development Program"     9.1
        "Selling Stockholder"                  17.2
        "Tag-Along Right"                      17.3
        "Transaction Proposal"                 17.2
        "Transfer"                             17.1
        "Transferee Terms"                     17.3
        "Transferring Stockholders"            17.3
</TABLE>

1.3     Words importing the singular shall include the plural and vice versa.

1.4     Unless the context otherwise requires, reference to a recital, article,
        paragraph, provision, clause or schedule is to a recital, article,
        paragraph, provision, clause or schedule of or to this Agreement.

1.5     Reference to a statute or statutory provision includes a reference to it
        as from time to time amended, extended or re-enacted.

1.6     The headings in this Agreement are inserted for convenience only and do
        not affect its construction.

1.7     Unless the context or subject otherwise requires, references to words in
        one gender include references to the other genders.

1.8     Capitalized terms used but not defined herein shall have the meanings
        ascribed in the Transaction Documents, if defined therein.

                                    CLAUSE 2

                                NEWCO'S BUSINESS

2.1     The primary objective of Newco and any Subsidiaries is to carry on the
        business of the development, testing, registration, manufacture,
        commercialization and licensing of Products in the Territory and to
        achieve the objectives set out in this Agreement. The focus of the
        collaborative venture will be to develop the Products using the Elan
        Intellectual Property, the Isis Intellectual Property and the Newco
        Technology to agreed-upon specifications and timelines.

2.2     Except as the Participants otherwise agree in writing and except as may
        be provided in this Agreement, the Business Plan or the License
        Agreements, the Participants shall exercise their respective powers in
        relation to Newco so as to ensure that the Business is carried on in a
        proper and prudent manner.

2.3     Each Participant shall use all commercially reasonable and proper means
        at its disposal and within its power to maintain, extend and improve the
        Business of 


                                      10.
<PAGE>   14

        Newco, within the limits of this Agreement, and to further the
        reputation and interests of Newco.

2.4     The central management and control of Newco shall be exercised in
        Bermuda and shall be vested in the Directors and such Persons as they
        may delegate the exercise of their powers in accordance with the Newco
        Memorandum of Association and Bye-Laws. The Participants shall use their
        best endeavors to ensure that to the extent required pursuant to the
        laws of Bermuda, and to ensure the sole residence of Newco in Bermuda,
        all meetings of the Directors are held in Bermuda or other jurisdictions
        outside the United States and generally to ensure that Newco is treated
        as resident for taxation purposes in Bermuda.

                                    CLAUSE 3

                         REPRESENTATIONS AND WARRANTIES

3.1     REPRESENTATIONS AND WARRANTIES OF NEWCO: Newco hereby represents and
        warrants to each of the Stockholders as follows, as of the date hereof:

        3.1.1  ORGANIZATION: Newco is an exempted company duly organized,
               validly existing and in good standing under the laws of Bermuda,
               and has all the requisite corporate power and authority to own
               and lease its properties, to carry on its business as presently
               conducted and as proposed to be conducted, to execute this
               Agreement, which has been duly authorized and is enforceable
               against Newco in accordance with its terms, and to carry out the
               transactions contemplated hereby.

        3.1.2  CAPITALIZATION: As of the date hereof, the authorized capital
               stock of Newco consists of 12,000 shares of Common Stock. Prior
               to the date hereof, no shares of capital stock of Newco have been
               issued.

        3.1.3  AUTHORIZATION: The execution, delivery and performance by Newco
               of this Agreement, including the issuance of the Shares, have
               been duly authorized by all requisite corporate actions; this
               Agreement has been duly executed and delivered by Newco and is
               the valid and binding obligation of Newco, enforceable against it
               in accordance with its terms, except as limited by applicable
               bankruptcy, insolvency, reorganization, moratorium and other laws
               of general application affecting the enforcement of creditors'
               rights generally, and by general equity principles and
               limitations on the availability of equitable relief, including
               specific performance. The Shares, when issued as contemplated
               hereby, will be validly issued and outstanding, fully paid and
               non-assessable and not subject to preemptive or any other similar
               rights of the Stockholders or others.


                                      11.
<PAGE>   15

        3.1.4  NO CONFLICTS: The execution, delivery and performance by Newco of
               this Agreement, the issuance, sale and delivery of the Shares,
               and compliance with the provisions hereof by Newco, will not:

               (i)       violate any provision of applicable law, statute, rule
                         or regulation applicable to Newco or any ruling, writ,
                         injunction, order, judgment or decree of any court,
                         arbitrator, administrative agency or other governmental
                         body applicable to Newco or any of its properties or
                         assets;

               (ii)      conflict with or result in any breach of any of the
                         terms, conditions or provisions of, or constitute (with
                         notice or lapse of time or both) a default (or give
                         rise to any right of termination, cancellation or
                         acceleration) under its charter or organizational
                         documents or any material contract to which Newco is a
                         party, except where such violation, conflict or breach
                         would not, individually or in the aggregate, have a
                         material adverse effect on Newco; or

               (iii)     result in the creation of, any Encumbrance upon any of
                         the properties or assets of Newco, except as
                         contemplated by the Transaction Documents.

        3.1.5  APPROVALS: As of the date hereof, no permit, authorization,
               consent or approval of or by, or any notification of or filing
               with, any Person is required in connection with the execution,
               delivery or performance of this Agreement by Newco. Newco has
               full authority to conduct its business as contemplated in the
               Business Plan and the Transaction Documents.

        3.1.6  DISCLOSURE: This Agreement does not contain any untrue statement
               of a material fact or omit to state any material fact necessary
               to make the statements contained herein not misleading. Newco is
               not aware of any material contingency, event or circumstance
               relating to its business or prospects, which could have a
               material adverse effect thereon, in order for the disclosure
               herein relating to Newco not to be misleading in any material
               respect.

        3.1.7  NO BUSINESS; NO LIABILITIES: Newco has not conducted any business
               or incurred any liabilities or obligations prior to the date
               hereof, except solely in connection with its organization and
               formation.

3.2     REPRESENTATIONS AND WARRANTIES OF THE STOCKHOLDERS: Each of the
        Stockholders hereby severally represents and warrants to Newco as
        follows as of the date hereof:

        3.2.1  ORGANIZATION: Such Stockholder is a corporation duly organized
               and validly existing under the laws of its jurisdiction of
               organization and has


                                      12.
<PAGE>   16

               all the requisite corporate power and authority to own and lease
               its respective properties, to carry on its respective business as
               presently conducted and as proposed to be conducted and to carry
               out the transactions contemplated hereby.

        3.2.2  AUTHORITY: Such Stockholder has full corporate power and
               authority to enter into this Agreement and to perform its
               obligations hereunder, which have been duly authorized by all
               requisite corporate action of such Stockholder. This Agreement is
               the valid and binding obligation of such Stockholder, enforceable
               against it in accordance with its terms, except as limited by
               applicable bankruptcy, insolvency, reorganization, moratorium and
               other laws of general application affecting the enforcement of
               creditors' rights generally, and by general equity principles and
               limitations on the availability of equitable relief, including
               specific performance.

        3.2.3  NO CONFLICTS: The execution, delivery and performance by such
               Stockholder of this Agreement, purchase of the Shares, and
               compliance with the provisions hereof by such Stockholder will
               not:

               (i)       violate any provision of applicable law, statute, rule
                         or regulation known by and applicable to such
                         Stockholder or any ruling, writ, injunction, order,
                         judgment or decree of any court, arbitrator,
                         administrative agency or other governmental body
                         applicable to such Stockholder or any of its properties
                         or assets;

               (ii)      conflict with or result in any breach of any of the
                         terms, conditions or provisions of, or constitute (with
                         notice or lapse of time or both) a default (or give
                         rise to any right of termination, cancellation or
                         acceleration) under the charter or organizational
                         documents of such Stockholder or any material contract
                         to which such Stockholder is a party, except where such
                         violation, conflict or breach would not, individually
                         or in the aggregate, have a material adverse effect on
                         such Stockholder; or

               (iii)     result in the creation of, any Encumbrance upon any of
                         the properties or assets of such Stockholder, except as
                         contemplated by the Transaction Documents.

        3.2.4  APPROVALS: As of the date hereof, no material permit,
               authorization, consent or approval of or by, or any notification
               of or filing with, any Person is required in connection with the
               execution, delivery or performance of this Agreement by such
               Stockholder.

        3.2.5  INVESTMENT REPRESENTATIONS: Such Stockholder is capable of
               evaluating the merits and risks of its investment in Newco. Such
               Stockholder has not been formed solely for the purpose of making
               this investment and such 


                                      13.
<PAGE>   17

               Stockholder is acquiring the Common Stock for investment for its
               own account, not as a nominee or agent, and not with the view to,
               or for resale in connection with, any distribution of any part
               thereof. Such Stockholder understands that the Shares have not
               been registered under the Securities Act or applicable state and
               foreign securities laws by reason of a specific exemption from
               the registration provisions of the Securities Act and applicable
               state and foreign securities laws, the availability of which
               depends upon, among other things, the bona fide nature of the
               investment intent and the accuracy of such Stockholders'
               representations as expressed herein. Such Stockholder understands
               that no public market now exists for any of the Shares and that
               there is no assurance that a public market will ever exist for
               such Shares.

3.3     SURVIVAL: The representations and warranties in this Clause 3 shall
        survive for a period of two years from and after the date hereof.

                                    CLAUSE 4

                            AUTHORIZATION AND CLOSING

4.1     Newco has authorized the issuance to (i) EIS of 2,388 shares of Common
        Stock and (ii) Isis of 9,612 shares of Common Stock, issuable as
        provided in Clause 4.3 hereof.

4.2     The closing (the "CLOSING") shall take place at the offices of Brock
        Silverstein LLC at 153 East 53rd Street, New York, New York 10022 on the
        date hereof or such other place if any, as the Parties may agree and
        shall occur contemporaneously with the closing under the Isis Securities
        Purchase Agreement.

4.3     At the Closing,

        4.3.1  Newco shall issue and sell to EIS, and EIS shall purchase from
               Newco, upon the terms and subject to the conditions set forth
               herein, 2,388 shares of Common Stock for an aggregate purchase
               price of $2,985,000. Newco shall issue and sell to Isis, and Isis
               shall purchase from Newco, upon the terms and conditions set
               forth herein, 9,612 shares of Common Stock for an aggregate
               purchase price of $12,015,000.

        4.3.2  The Parties shall execute and deliver to each other, as
               applicable, certificates in respect of the Common Stock described
               above and any other certificates, resolutions or documents which
               the Parties shall reasonably require.


                                      14.
<PAGE>   18

4.4     EXEMPTION FROM REGISTRATION:

        The Shares will be issued under an exemption or exemptions from
        registration under the Securities Act. Accordingly, the certificates
        evidencing the Shares shall, upon issuance, contain the following
        legend:

         THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT UNDER ANY CIRCUMSTANCES
         BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF WITHOUT AN EFFECTIVE
         REGISTRATION STATEMENT FOR SUCH SECURITIES UNDER THE SECURITIES ACT OF
         1933, AS AMENDED, AND ANY APPLICABLE STATE SECURITIES LAWS OR AN
         OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT REGISTRATION IS NOT
         REQUIRED UNDER SUCH ACT OR APPLICABLE STATE SECURITIES LAWS.

         THE TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS ALSO
         SUBJECT TO THE RESTRICTIONS CONTAINED IN THAT CERTAIN SUBSCRIPTION,
         JOINT DEVELOPMENT AND OPERATING AGREEMENT, DATED APRIL 20, 1999, BY AND
         AMONG ELAN CORPORATION, PLC, ELAN INTERNATIONAL SERVICES, INC., ISIS
         PHARMACEUTICALS, INC. AND ORASENSE LTD.

                                    CLAUSE 5

                            CERTAIN ASSIGNMENT RIGHTS

5.1     At any time after exercise of the EIS Exchange Right and upon 1 month's
        prior notice in writing from Elan to Newco and Isis, Newco shall assign
        the Newco Intellectual Property from Newco to a wholly-owned subsidiary
        of Newco to be incorporated in Ireland, which company shall be newly
        incorporated by Elan to facilitate such assignment.

                                    CLAUSE 6

                                 NON-COMPETITION

6.1     The Parties acknowledge and agree to be bound by the provisions of
        Clause 11 of the Elan License Agreement and the provisions of Clause 11
        of the Isis License Agreement which set forth the agreement between the
        parties thereto in relation to the non-competition obligations of Elan
        and Isis, respectively.


                                      15.
<PAGE>   19

                                    CLAUSE 7

                    DIRECTORS; MANAGEMENT AND R&D COMMITTEES

7.1.    DIRECTORS:

        Prior to the exercise of the EIS Exchange Right, the Board of Directors
        of Newco shall be composed of four Directors. Isis shall have the right
        to nominate three directors of Newco ("ISIS DIRECTORS"), provided that
        one such director is a resident of Bermuda, and EIS shall have the right
        to nominate one Director of Newco ("EIS DIRECTOR"). Isis may appoint one
        of the Isis Directors to be the chairman of Newco. Each Participant
        agrees to vote its shares of Common Stock in favor of the election of
        the nominees of the other Participant to the Board of Directors.

        7.1.1  If the chairman is unable to attend any meeting of the Board, the
               Isis Directors shall be entitled to appoint another Director to
               act as chairman in his place at the meeting.

        7.1.2  If EIS removes the EIS Director, or Isis removes any of the Isis
               Directors, EIS or Isis, as the case may be, shall indemnify the
               other Stockholder against any claim by such removed Director
               arising from such removal.

        7.1.3  The Directors shall meet not less than three times in each
               Financial Year and all Directors' meetings shall be held in
               Bermuda to the extent required pursuant to the laws of Bermuda or
               to ensure the sole residence of Newco in Bermuda.

        7.1.4  At any such meeting, the presence of the EIS Director and one of
               the Isis Directors shall be required to constitute a quorum and,
               subject to Clause 18 hereof, the affirmative vote of a majority
               of the Directors present at a meeting at which such a quorum is
               present shall constitute an action of the Directors. In the event
               of any meeting being inquorate, the meeting shall be adjourned
               for a period of seven days. A notice shall be sent to the EIS
               Director and the Isis Directors specifying the date, time and
               place where such adjourned meeting is to be held and reconvened.


        7.1.5  The chairman of Newco shall hold office until the first meeting
               of the Directors after the exercise by EIS of the EIS Exchange
               Right. In the event that the EIS Exchange Right is exercised at
               any time by EIS, each of Isis, and EIS shall cause the board of
               Directors of Newco to be reconfigured so that an equal number of
               Directors are designated by EIS and Isis. Thereafter, each of EIS
               and Isis, beginning with EIS, shall have the right, exercisable
               alternatively, of nominating one Director to be chairman of Newco
               for a term of one year. If the chairman of Newco is unable to
               attend any meeting of the Directors, the Directors shall be


                                      16.
<PAGE>   20

               entitled to appoint another Director to act as chairman of Newco
               in his place at the meeting.

        7.1.6  In case of an equality of votes at a meeting of the board of
               Directors of Newco, the chairman of Newco shall not be entitled
               to a second or casting vote. In the event of continued deadlock,
               the board of Directors shall resolve the deadlock pursuant to the
               provisions set forth in Clause 19.

7.2  MANAGEMENT AND R&D COMMITTEES:

        7.2.1  The Directors shall appoint a management committee (the
               "MANAGEMENT COMMITTEE") to perform certain operational functions,
               such delegation to be consistent with the Directors' right to
               delegate powers pursuant to the Newco Memorandum of Association
               of Bye-Laws. The Management Committee shall initially consist of
               four members, two of whom will be nominated by EIS and two of
               whom will be nominated by Isis, and each of whom shall be
               entitled to one vote, whether or not present at any Management
               Committee meeting during which such operational functions are
               discussed. Except as otherwise provided herein or in the License
               Agreements, decisions of the Management Committee shall require
               approval by at least one EIS nominee on the Management Committee
               and one Isis nominee on the Management Committee. Each of EIS and
               Isis shall be entitled to remove any of their nominees to the
               Management Committee and appoint a replacement in place of any
               nominees so removed.

        7.2.2  The Management Committee shall appoint a research and development
               committee (the "R&D COMMITTEE") which shall initially be
               comprised of four members, two of whom will be nominated by Elan
               and two of whom will be nominated by Isis, and each of whom shall
               have one vote, whether or not present at an R&D Committee meeting
               during which research and development issues are discussed.
               Decisions of the R&D Committee shall require approval by at least
               one Elan nominee on the R&D Committee and one Isis nominee on the
               R&D Committee. Each of Elan and Isis shall be entitled to remove
               any of their nominees to the R&D Committee and appoint a
               replacement in place of any nominees so removed.

        7.2.3  The Management Committee shall be responsible for, inter alia,
               devising, implementing and reviewing strategy for the business of
               Newco, and the operation of Newco, and in particular, devising
               Newco's strategy for research and development and to monitor and
               supervise the implementation of Newco's strategy for research and
               development.

        7.2.4  The R&D Committee shall be responsible for:

               7.2.4.1   designing that portion of the Business Plan that
                         relates to the Project for consideration by the
                         Management Committee;


                                      17.
<PAGE>   21

               7.2.4.2   establishing a joint Project team consisting of an
                         equal number of team members from Elan and Isis,
                         including one Project leader from each of Elan and
                         Isis; and

               7.2.4.3   implementing such portion of the Business Plan that
                         relates to the Project, as approved by the Management
                         Committee.

        7.2.5  In the event of any dispute amongst the R&D Committee, the R&D
               Committee shall refer such dispute to the Management Committee
               whose decision on the dispute shall be binding on the R&D
               Committee. If the Management Committee cannot resolve the matter,
               the dispute will be referred to the President of EPT and the
               Chief Executive Officer of Isis pursuant to Clause 19 hereof.

        7.2.6  On not more than two times in each Financial Year, Elan and Isis
               shall permit Newco or its duly authorized representative on
               reasonable notice and at any reasonable time during normal
               business hours to have access to inspect and audit the accounts
               and records of Elan or Isis and any other book, record, voucher,
               receipt or invoice relating to the calculation or the cost of the
               Research and Development Program and to the accuracy of the
               reports which accompanied them. Any such inspection of Elan's or
               Isis's records, as the case may be, shall be at the expense of
               Newco, except that if such inspection reveals an overpayment in
               the amount paid to Elan or Isis, as the case may be, for the
               Research and Development Program hereunder in any Financial Year
               of 5% or more of the amount due to Elan or Isis, as the case may
               be, then the expense of such inspection shall be borne solely by
               Elan or Isis, as the case may be, instead of by Newco. Any
               surplus over the sum properly payable by Newco to Elan or Isis,
               as the case may be, shall be paid promptly by Elan or Isis, as
               the case may be, to Newco. If such inspection reveals a deficit
               in the amount of the sum properly payable to Elan or Isis, as the
               case may be, by Newco, Newco shall pay the deficit to Elan or
               Isis, as the case may be.

                                    CLAUSE 8

                          THE BUSINESS PLAN AND REVIEWS

8.1     The Directors shall meet as soon as reasonably practicable after the
        Closing Date hereof and shall agree upon and approve the Business Plan
        for the current Financial Year within 60 days of the date hereof. The
        research and development budget contained in the Business Plan shall
        provide for the supply of the Development Candidate and the [...***...]
        and [...***...] compounds by Isis to Newco at [...***...]. In subsequent
        Financial Years, the Directors shall meet prior to the accounting
        reference date specified in Clause 15 and agree upon and approve the
        Business Plan for


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      18.
<PAGE>   22
        the following Financial Year, or any amendment or modification to the
        Business Plan.

8.2     The Participants agree that the Management Committee shall submit to the
        Directors on February 15th, May 15th, August 15th, and November 15th or
        as soon as reasonably practicable thereafter in each Financial Year a
        report on the performance of the Business and research and development
        activities of Newco, and the Directors shall hold such meeting as may be
        necessary to review the performance of Newco against the Business Plan
        for the relevant year.

                                    CLAUSE 9

                          RESEARCH AND DEVELOPMENT WORK

9.1     During the Research Term, Newco will diligently pursue the research and
        development of the Elan Intellectual Property, Isis Intellectual
        Property and Newco Technology in accordance with the Research and
        Development Program. The "RESEARCH AND DEVELOPMENT PROGRAM" will be the
        program for (a) the development of the Oral Platform, and (b) the
        development of the Development Product in the Field, including without
        limitation, screening, in-vitro pharmacology, toxicology, stability,
        prototype dosage form development, formulation, optimization, clinical
        and regulatory activities. Such work shall be agreed to and conducted by
        Elan and/or Isis under contract with Newco as provided in the Business
        Plan.

9.2     Isis and Elan shall provide such research and development services as
        may be reasonably required by Newco in accordance with the provisions in
        the License Agreements. Newco shall pay Isis and Elan for any research
        and development work carried out by them on behalf of Newco at the end
        of each month during the Research and Development Program, subject to
        the proper vouching of research and development work and expenses. An
        invoice shall be issued to Newco by Isis or Elan, as applicable, by the
        15th day of the month following the month in which work was performed.
        The payments by Newco to Isis or Elan, as the case may be, shall be at
        the rates prescribed in the respective License Agreement. Research and
        development activities that are outsourced to third party providers
        shall be charged to Newco at [...***...].

9.3     In the event the Management Committee, by unanimous vote of its members,
        shall determine that preclinical toxicology or pharmacology studies
        indicate that clinical trials of the Development Candidate should not be
        undertaken, or the Management Committee determines that development of
        the Development Candidate is not economically viable, Isis in good faith
        shall offer, and the Management Committee, by unanimous vote of its
        members shall approve, an Isis Oligonucleotide Drug in pre-clinical
        development that it deems economically viable as a Substituted
        Development Candidate, subject to the agreement of the


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      19.
<PAGE>   23

        Participants, negotiating in good faith, to changes concerning the
        budget, Business Plan and funding of Newco.

9.4     Except as otherwise provided herein and as provided in the Isis License
        Agreement, upon designation of an Isis Oligonucleotide as a Substituted
        Development Candidate, (i) all rights to the Development Candidate shall
        revert to Isis and (ii) all provisions contained herein and in the Isis
        License Agreement other than in the preceding clause (i) relating to the
        Development Candidate shall be deemed to apply to the Substituted
        Development Candidate as if it were the Development Candidate.

                                    CLAUSE 10

                          INTELLECTUAL PROPERTY RIGHTS

10.1    Title and all other ownership rights, including patent rights, relating
        to the Elan Intellectual Property shall belong to Elan. Title and all
        other ownership rights, including patent rights relating to the Isis
        Intellectual Property shall belong to Isis. Title and all other
        ownership rights, including patent rights, relating to the Newco
        Technology shall belong to Newco.

10.2    The Participants shall discuss in good faith all material issues
        relating to filing, prosecution and maintenance of Elan Patents, Isis
        Development Candidate Patents and Isis Delivery Patents insofar as such
        patent rights are of relevance to the License Agreements and any
        patentable inventions and discoveries within the Elan Intellectual
        Property, Isis Intellectual Property and Newco Technology that relate to
        the License Agreements and any patentable improvements thereto. Subject
        to mutual agreement to the contrary by Isis and Elan the following
        provisions shall apply:

        10.2.1 Elan, at its expense, shall make a good faith effort (i) to
               secure the grant of any material patent applications within the
               Elan Patents that relate to the Field; (ii) to file and prosecute
               patent applications on material patentable inventions and
               discoveries within the Elan Improvements that relate to the
               Field; (iii) to defend all such applications against third party
               oppositions; and (iv) to maintain in force any material issued
               letters patent within the Elan Patents that relate to the Field
               (including any letters patent that may issue covering any such
               Elan Improvements that relate to the Field). Elan shall have the
               right in its discretion to control such filing, prosecution,
               defense and maintenance provided that Newco and Isis at their
               request shall be provided with copies of all documents relating
               to such filing, prosecution, defense and maintenance in
               sufficient time to review such documents and comment thereon
               prior to filing.

        10.2.2 Isis, at its expense, shall make a good faith effort (i) to
               secure the grant of any material patent applications within the
               Isis Delivery Patents that relate


                                      20.
<PAGE>   24

               to the Field and the Isis Development Candidate Patents; (ii) to
               file and prosecute patent applications on material patentable
               inventions and discoveries within the Isis Improvements that
               relate to the Field and the Development Candidate; (iii) to
               defend all such applications against third party oppositions; and
               (iv) to maintain in force any material issued letters patent
               within the Isis Delivery Patents that relate to the Field and the
               Isis Development Candidate Patents (including any letters patent
               that may issue covering any such Isis Improvements that relate to
               the Field). Isis shall have the right in its discretion to
               control such filing, prosecution, defense and maintenance
               provided that Elan and Newco at their request shall be provided
               with copies of all documents relating to such filing,
               prosecution, defense and maintenance in sufficient time to review
               such documents and comment thereon prior to filing.

        10.2.3 In the event that a Participant informs the other Participant
               that it does not intend to file patent applications on patentable
               inventions and discoveries within the Isis Intellectual Property
               or Elan Intellectual Property as the case may be that relate to
               the Field in one or more countries in the Territory or fails to
               file such an application within a reasonable period of time,
               Newco shall have the option at its expense to file and prosecute
               such patent application(s) in the joint names of Newco and the
               Participant not intending or failing to so file (or, if required
               by law, on behalf of the inventors and assignable to Newco and
               the Participant). Upon written request from Newco, such
               Participant shall execute all documents, forms and declarations
               and to do all things as shall be reasonably necessary to enable
               Newco to exercise such option.

        10.2.4 Elan and Isis, at their joint expense on behalf of Newco, shall
               (i) file and prosecute patent applications on patentable
               inventions and discoveries within the Newco Technology; (ii)
               defend all such applications against third party oppositions; and
               (iii) maintain in force any issued letters patent within the
               Newco Patents (including any patents that issue on patentable
               inventions and discoveries within the Newco Technology). Elan and
               Isis, directly or through the Management Committee, shall control
               such filing, prosecution, defense and maintenance. Elan and Isis
               agree to negotiate in good faith on the course of action to be
               taken with respect to Newco Technology.

        10.2.5 Newco, Elan and Isis shall promptly inform each other in writing
               of any alleged infringement of any patents within the Elan
               Patents, the Isis Delivery Patents, the Isis Development
               Candidate Patents or the Newco Patents or any alleged
               misappropriation of trade secrets within the Elan Intellectual
               Property, the Isis Intellectual Property or the Newco Technology
               by a third party of which it becomes aware and provide the others
               with any available evidence of such infringement or


                                      21.
<PAGE>   25

               misappropriation insofar as such infringements or
               misappropriation relate solely to the Field.

        10.2.6 Newco shall have the right to prosecute at its own expense and
               for its own benefit any infringements of the Elan Patents, the
               Isis Delivery Patents and the Isis Development Candidate Patents
               or misappropriation of the Elan Intellectual Property and the
               Isis Intellectual Property, insofar as such infringements or
               misappropriation relate solely to the Field. In the event that
               Newco takes such action, Newco shall do so at its own cost and
               expense. At Newco's request, the Participants shall cooperate
               with such action. Any recovery remaining after the deduction by
               Newco of the reasonable expenses (including attorney's fees and
               expenses) incurred in relation to such infringement proceeding
               shall belong to Newco. Should Newco decide not to pursue such
               infringers, within a reasonable period but in any event within
               twenty (20) days after receiving written notice of such alleged
               infringement or misappropriation each of the Participants may in
               its discretion initiate such proceedings in its own name, at its
               expense and for its own benefit, and at such Participant's
               request, Newco shall cooperate with such action. Alternatively,
               the Participants may agree to institute such proceedings in their
               joint names and shall reach agreement as to the proportion in
               which they shall share the proceeds of any such proceedings, and
               the expense of any costs not recovered, or the costs or damages
               payable to the third party. If the infringement of the Elan
               Patents, the Isis Delivery Patents or the Isis Development
               Candidate Patents affects both the Field as well as other
               products being developed or commercialized by Isis or Elan or its
               commercial partners outside the Field, Isis or Elan shall
               endeavor to agree as to the manner in which the proceedings
               should be instituted and as to the proportion in which they shall
               share the proceeds of any such proceedings, and the expense of
               any costs not recovered, or the costs or damages payable to the
               third party.

        10.2.7 Newco shall have the first right but not the obligation to bring
               suit or otherwise take action against any alleged infringement of
               the Newco Patents or alleged misappropriation of the Newco
               Technology. If any such alleged infringement or misappropriation
               occurs that gives rise to a cause of action both inside and
               outside the Field, Newco, in consultation with the Participants,
               shall determine the cause of action to be taken. In the event
               that Newco takes such action, Newco shall do so at its own cost
               and expense and all damages and monetary award recovered in or
               with respect to such action shall be the property of Newco. Newco
               shall keep Elan and Isis informed of any action in a timely
               manner so as to enable Isis and Elan to provide input in any such
               action and Newco shall reasonably take into consideration any
               such input. At Newco's request, the Participants shall cooperate
               with any such action at Newco's cost and expense.


                                      22.
<PAGE>   26

        10.2.8  In the event that Newco does not bring suit or otherwise take
                action against all infringement of the Newco Patents or
                misappropriation of the Newco Technology, then (i) if only one
                Participant determines to pursue such suit or take such action
                at its own cost and expense, it shall be entitled to all damages
                and monetary award recovered in or with respect to such action
                and (ii) if the Participants pursue such suit or action outside
                of Newco, they shall negotiate in good faith an appropriate
                allocation of costs, expenses and recovery amounts.

        10.2.9  In the event that a claim is, or proceedings are, brought
                against Newco by a third party alleging that the sale,
                distribution or use of a Product in the Territory or use of the
                Elan Intellectual Property or the Isis Intellectual Property, as
                the case may be, infringes the intellectual property rights of
                such party, Newco shall promptly advise the other Participants
                of such threat or suit.

        10.2.10 Newco shall indemnify, defend and hold harmless Elan or Isis, as
                the case may be, against all actions, losses, claims, demands,
                damages, costs and liabilities (including reasonable attorneys
                fees) relating directly or indirectly to all such claims or
                proceedings referred to herein, provided that Elan or Isis, as
                the case may be, shall not acknowledge to the third party or to
                any other person the validity of any claims of such a third
                party, and shall not compromise or settle any claim or
                proceedings relating thereto without the prior written consent
                to Newco, not to be unreasonably withheld or delayed. At its
                option, Elan or Isis, as the case may be, may elect to take over
                the conduct of such proceedings from Newco provided that Newco's
                indemnification obligations shall continue; the costs of
                defending such claim shall be borne by Elan or Isis, as the case
                may be and such Participant shall not compromise or settle any
                such claim or proceeding without the prior written consent of
                Newco, such consent not to be unreasonably withheld or delayed.

10.3    Newco shall not encumber any of its rights under the Licenses or the
        Newco Technology without the prior written consent of Elan and Isis.
        Newco shall not be permitted to assign or sublicense any of its rights
        under the Licenses or the Program Technology without the prior written
        consent of Elan and Isis, respectively, which may be withheld in Elan's
        or Isis' sole discretion, as the case may be. Any permitted agreement
        between Newco and any permitted third party for the development or
        exploitation of the Elan Intellectual Property and/or Isis Intellectual
        Property in the Field shall require such third party to maintain the
        confidentiality of all information concerning the Elan Intellectual
        Property and the Isis Intellectual Property and shall provide that any
        improvements to the Elan Intellectual Property shall belong to Elan and
        any improvements to the Isis Intellectual Property shall belong to Isis.


                                      23.
<PAGE>   27

                                    CLAUSE 11

                   EXPLOITATION OF PRODUCTS OUTSIDE THE FIELD

11.1    LICENSES TO ELAN PROGRAM TECHNOLOGY AND ISIS PROGRAM TECHNOLOGY. Subject
        to the provisions of the License Agreements, Newco shall grant to Elan a
        perpetual, exclusive, royalty free and sublicensable license in the
        Territory to Elan Program Technology outside of the Field, and to Isis a
        perpetual, exclusive, royalty free and sublicensable license in the
        Territory to the Isis Program Technology outside of the Field.

11.2    LICENSES FOR NEWCO PROGRAM TECHNOLOGY. Newco shall grant (i) to Isis an
        exclusive license of Newco Program Technology outside the Field in the
        Territory solely for use in connection with Isis proprietary drug
        products (including drug products discovered or developed in
        collaborative partnerships) and (ii) to Elan an exclusive license in the
        Territory for the use of Newco Program Technology in all fields other
        than the Field or in connection with Isis proprietary drug products. All
        such licenses shall contain such customary provisions as are contained
        in similar licenses in the industry, as agreed to by the licensee and
        the unanimous decision of the Management Committee, acting in good
        faith. (including all material provisions thereof). The financial terms
        of the said license agreement shall have regard, inter alia, to:

        11.1.1 the amount of monies expended by Newco in developing the licensed
               Newco Program Technology;

        11.1.2 the materiality of the contribution of the Newco Intellectual
               Property by comparison to the further research and development
               work to be conducted, and of the Elan Intellectual Property and
               Isis Intellectual Property;

        11.1.3 the financial return likely to be earned by Isis or Elan, as the
               case may be, from the proposed exploitation outside the Field;
               and

        11.1.4 the impact of the proposed exploitation of the Newco Program
               Technology outside the Field on the exploitation of the Newco
               Program Technology within the Field.


                                    CLAUSE 12

                                COMMERCIALIZATION

12.1    The Participants shall assist Newco in diligently pursuing the research,
        development, prosecution and commercialization of Products in accordance
        with the Business Plan. During the Research Term, Elan and Isis shall
        meet to discuss the commercial strategy for Newco, Commercialization of
        the Development


                                      24.
<PAGE>   28

        Product and the further exploitation of the Newco Technology. For
        example, Isis and Elan shall discuss strategy and terms relating to
        product and clinical development, corporate partnering, licensing and
        supply agreements. It is contemplated that Isis, either as agent for
        Newco or through its representatives on the Management Committee, shall
        locate and negotiate with Independent Third Party marketing partners for
        the Development Product. In the course of such representation, Isis
        shall keep Newco and Elan fully informed of its efforts and progress
        with respect to the foregoing.

12.2    In the event Isis shall propose to Newco the development of one or more
        Isis Products, the Management Committee, by unanimous decision, shall
        determine whether or not to develop any such Isis Product. It is
        contemplated that Isis shall locate and negotiate with Independent Third
        Party marketing partners for Isis Products. Isis shall keep Newco and
        Elan apprised of its efforts and progress with respect to the foregoing;
        provided, however, that any such information shall be kept confidential
        and shall not be disclosed to EPT (excluding senior executive personnel
        of Elan).

12.3    The Business Plan shall be reviewed and mutually agreed to by Isis and
        Elan on an annual basis.

12.4    If Isis wishes to research, develop, and/or Commercialize one or more
        Isis Oligonucleotide Drugs other than the Development Candidate, Newco
        shall have an option to negotiate in good faith the terms of the
        formulation research, development, and/or Commercialization of any such
        Isis Oligonucleotide Drugs. Provided Newco has the capability and
        technology to substantially perform the services sought by Isis with
        respect to such Isis Oligonucleotide Drugs, Isis will not offer such
        arrangement to Newco on terms less favorable than those it offers to
        Independent Third Parties and Newco shall not offer such arrangement to
        Isis on terms less favorable than those it offers to Independent Third
        Parties.

12.5    In the event an Independent Third Party shall propose to Newco the
        development of Third Party Products, the Management Committee, by
        unanimous decision, shall determine whether or not to develop any such
        Third Party Product. Newco shall be responsible for negotiating with any
        Independent Third Parties commercially reasonable terms (e.g.,
        royalties, milestones, development fees, manufacturing rights) for
        developing and licensing Third Party Products. It is contemplated that
        Elan, either as agent for Newco or through its representatives on the
        Management Committee, shall locate and negotiate Independent Third Party
        marketing partners for Third Party Products. In the course of such
        representation, Elan shall keep Newco and Elan fully informed of its
        efforts and their progress with respect to the foregoing.

12.6    Notwithstanding anything set forth herein, at such time as Newco intends
        to Commercialize the Development Product, Elan shall have the right of
        first negotiation with respect to the world-wide commercialization of
        the Development Product in accordance with the terms of the Elan License
        Agreement.


                                      25.
<PAGE>   29

12.7    Subject to the rights of Elan with respect to the Development Product,
        Newco shall not be permitted to contract the Commercialization of the
        Development Product or any other Product without the prior written
        consent of Elan and Isis, which consent will not be unreasonably
        withheld or delayed; provided that such reasonableness standard, in the
        case of Elan, shall not be applicable in the case of a proposed
        sublicense to any Technological Competitor of Elan and in the case of
        Isis, shall not be applicable in the case of a proposed sublicense to
        any Technological Competitor of Isis.


                                    CLAUSE 13

                                  MANUFACTURING

13.1    Elan shall have a first right of negotiation for the commercial
        production of the Development Product on behalf of Newco, in accordance
        with the provisions of section 2.13 of the Elan License Agreement.
        Subject to the foregoing rights of Elan with respect to the Development
        Product, Newco shall not be permitted to contract the manufacture of the
        Development Product or any other Product without the prior written
        consent of Elan and Isis, which consent will not be unreasonably
        withheld or delayed; provided that such reasonableness standard, in the
        case of Elan, shall not be applicable in the case of a proposed
        sublicense to any Technological Competitor of Elan and in the case of
        Isis, shall not be applicable in the case of a proposed sublicense to
        any Technological Competitor of Isis.

                                    CLAUSE 14

                        TECHNICAL SERVICES AND ASSISTANCE

14.1    Whenever commercially and technically feasible, Newco shall contract
        with Isis or Elan, as the case may be, to perform such other services as
        Newco may require, other than those specifically dealt with hereunder or
        in the License Agreements. In determining which Party should provide
        such services, the Management Committee shall take into account the
        respective infrastructure, capabilities and experience of Elan and Isis.

14.2    Newco shall, if appropriate, conclude an administrative support
        agreement with Elan and/or Isis on such terms as the Parties thereto
        shall in good faith negotiate. The administrative services shall include
        one or more of the following administrative services as requested by
        Newco:

        14.2.1 accounting, financial and other services;

        14.2.2 tax services;


                                      26.
<PAGE>   30

        14.2.3 insurance services;

        14.2.4 human resources services;

        14.2.5 legal and company secretarial services;

        14.2.6 patent and related intellectual property services; and

        14.2.7 all such other services consistent with and of the same type as
               those services to be provided pursuant to this Agreement, as may
               be required.

        The foregoing list of services shall not be deemed exhaustive and may be
        changed from time to time upon written request by Newco.

14.3.   The Parties agree that each Party shall effect and maintain
        comprehensive general liability insurance in respect of all clinical
        trials and other activities performed by them on behalf of Newco. The
        Stockholders and Newco shall ensure that the industry standard insurance
        policies shall be in place for all activities to be carried out by
        Newco.

14.4    If Elan or Isis so requires, Isis or Elan, as the case may be, shall
        receive, at times and for periods mutually acceptable to the Parties,
        employees of the other Party (such employees to be acceptable to the
        receiving Party in the matter of qualification and competence) for
        instruction in respect of the Elan Intellectual Property or the Isis
        Intellectual Property, as the case may be, as necessary to further the
        Project.

14.5    The employees received by Elan or Isis, as the case may be, shall be
        subject to obligations of confidentiality no less stringent than those
        set out in Clause 22 and such employees shall observe the rules,
        regulations and systems adopted by the Party receiving the said
        employees for its own employees or visitors.

                                    CLAUSE 15

                      AUDITORS, BANKERS, REGISTERED OFFICE,
                  ACCOUNTING REFERENCE DATE; SECRETARY; COUNSEL

Unless otherwise agreed by the Stockholders and save as may be provided to the
contrary herein:

15.1    the auditors of Newco shall be Ernst & Young;

15.2    the bankers of Newco shall be Bank of Bermuda or such other bank as may
        be mutually agreed from time to time;


                                      27.
<PAGE>   31

15.3    the accounting reference date of Newco shall be December 31st in each
        Financial Year; and

15.4    the secretary of Newco shall be Diana Martin or such other Person as may
        be appointed by the Directors from time to time.


                                    CLAUSE 16

                                   REGULATORY

16.1    Newco shall keep the other Parties promptly and fully advised of Newco's
        regulatory activities, progress and procedures. Newco shall inform the
        other Parties of any dealings it shall have with an RHA, and shall
        furnish the other Parties with copies of all correspondence relating to
        the Products. The Parties shall collaborate to obtain any required
        regulatory approval of the RHA to market the Products.

16.2    Newco shall, at its own cost, file, prosecute and maintain any and all
        Regulatory Applications for the Products in the Territory in accordance
        with the Business Plan.

16.3    Any and all Regulatory Approvals obtained hereunder for any Product
        shall remain the property of Newco, provided that Newco shall allow Elan
        and Isis access thereto to enable Elan and Isis to fulfill their
        respective obligations and exercise their respective rights under this
        Agreement. Newco shall maintain such Regulatory Approvals at its own
        cost.

16.4    It is hereby acknowledged that there are inherent uncertainties involved
        in the registration of pharmaceutical products with the RHAs insofar as
        obtaining approval is concerned and such uncertainties form part of the
        business risk involved in undertaking the form of commercial
        collaboration as set forth in this Agreement. Therefore, except for
        liabilities resulting from failure to use reasonable efforts, none of
        Elan, EIS or Isis shall have any liability to Newco solely as a result
        of any failure of a Product to achieve the approval of any RHA.

                                    CLAUSE 17

                              TRANSFERS OF SHARES;
                     RIGHT OF FIRST OFFER; TAG ALONG RIGHTS

17.1    GENERAL:

        No Stockholder shall, directly or indirectly, sell or otherwise transfer
        (each, a "TRANSFER") any Shares held by it except in accordance with
        this Agreement. Newco shall not, and shall not permit any transfer agent
        or registrar for any Shares to, transfer upon the books of Newco any
        Shares from any Stockholder to 


                                      28.
<PAGE>   32

        any transferee, in any manner, except in accordance with this Agreement,
        and any purported transfer not in compliance with this Agreement shall
        be void.

17.2    RIGHTS OF FIRST OFFER:

        If at any time after the end of the Term, a Stockholder shall desire to
        Transfer any Shares owned by it (a "SELLING STOCKHOLDER"), in any
        transaction or series of related transactions other than a Transfer to
        an Affiliate or subsidiary or in the case of EIS to an off-balance sheet
        special purpose entity established by EIS, then such Selling Stockholder
        shall deliver prior written notice of its desire to Transfer (a "NOTICE
        OF INTENTION") (i) to Newco and (ii) to the Stockholders who are not the
        Selling Stockholder (and any transferee thereof permitted hereunder, if
        any), as applicable, setting forth such Selling Stockholder's desire to
        make such Transfer, the number of Shares proposed to be transferred (the
        "OFFERED SHARES") and the proposed form of transaction (the "TRANSACTION
        PROPOSAL"), together with any available documentation relating thereto
        and the price at which such Selling Stockholder proposes to Transfer the
        Offered Shares (the "OFFER PRICE"). The "Right of First Offer" provided
        for in this Clause 17 shall be subject to any "Tag Along Right"
        benefiting a Stockholder which may be provided for by Clause 17, subject
        to the exceptions set forth therein.

        Upon receipt of the Notice of Intention, the Stockholders who are not
        the Selling Stockholder shall have the right to purchase at the Offer
        Price the Offered Shares, exercisable by the delivery of notice to the
        Selling Stockholder (the "NOTICE OF EXERCISE"), with a copy to Newco,
        within 10 business days from the date of receipt of the Notice of
        Intention. If no such Notice of Exercise has been delivered by the
        Stockholders who are not the Selling Stockholder within such 10-business
        day period, or such Notice of Exercise does not relate to all of the
        Offered Shares covered by the Notice of Intention, then the Selling
        Stockholder shall be entitled to Transfer all of the Offered Shares to
        the intended transferee. In the event that all of the Offered Shares are
        not purchased by the non-selling Stockholders, the Selling Stockholder
        shall sell the available Offered Shares within 30 days after the
        delivery of such Notice of Intention on terms no more favorable to a
        third party than those presented to the non-selling Stockholders. If
        such sale does not occur, the Offered Shares shall again be subject to
        the Right of First Offer set forth in Clause 17.2.

        In the event that any of the Stockholders who are not the Selling
        Stockholder exercises their right to purchase all of the Offered Shares
        (in accordance with this Clause 17), then the Selling Stockholder shall
        sell all of the Offered Shares to such Stockholder(s), in the amounts
        set forth in the Notice of Intention, after not less than 10 business
        days and not more than 25 business days from the date of the delivery of
        the Notice of Exercise. In the event that more than one of the
        Stockholders who are not the Selling Stockholders wish to purchase the
        Offered Shares, the Offered Shares shall be allocated to such
        Stockholders on the basis of their pro rata equity interests in Newco.


                                      29.
<PAGE>   33

        The rights and obligations of each of the Stockholders pursuant to the
        Right of First Offer provided herein shall terminate upon the date that
        the Common Stock is registered under Section 12(b) or 12(g) of the
        Exchange Act.

        At the closing of the purchase of all of the Offered Shares by the
        Stockholders who are not the Selling Stockholder (scheduled in
        accordance with Clause 17), the Selling Stockholder shall deliver
        certificates evidencing the Offered Shares being sold, duly endorsed, or
        accompanied by written instruments of transfer in form reasonably
        satisfactory to the Stockholders who are not the Selling Stockholder,
        duly executed by the Selling Stockholder, free and clear of any adverse
        claims, against payment of the purchase price therefor in cash, and such
        other customary documents as shall be necessary in connection therewith.

        Notwithstanding any other provision of this Clause 17.2, a Change in
        Control of any Stockholder shall not trigger a "Right of First Offer" in
        favor of any other Stockholder.

17.3    TAG ALONG RIGHTS:

        Subject to Clause 17.2, a Stockholder (the "TRANSFERRING STOCKHOLDER")
        shall not Transfer (either directly or indirectly), in any one
        transaction or series of related transactions, to any Person or group of
        Persons, any Shares, unless the terms and conditions of such Transfer
        shall include an offer to the other Stockholders (the "REMAINING
        STOCKHOLDERS"), to sell Shares at the same price and on the same terms
        and conditions as the Transferring Stockholder has agreed to sell its
        Shares (the "TAG ALONG RIGHT").

        In the event a Transferring Stockholder proposes to Transfer any Shares
        in a transaction subject to this Clause 17.3, it shall notify, or cause
        to be notified, the Remaining Stockholders in writing of each such
        proposed Transfer. Such notice shall set forth: (i) the name of the
        transferee and the amount of Shares proposed to be transferred, (ii) the
        proposed amount and form of consideration and terms and conditions of
        payment offered by the transferee (the "TRANSFEREE TERMS") and (iii)
        that the transferee has been informed of the Tag Along Right provided
        for in this Clause 17, if such right is applicable, and the total number
        of Shares the transferee has agreed to purchase from the Stockholders in
        accordance with the terms hereof.

        The Tag Along Right may be exercised by each of the Remaining
        Stockholders by delivery of a written notice to the Transferring
        Stockholder (the "CO-SALE NOTICE") within 10 business days following
        receipt of the notice specified in the preceding subsection. The Co-sale
        Notice shall state the number of Shares owned by such Remaining
        Stockholder which the Remaining Stockholder wishes to include in such
        Transfer; provided, however, that without the written consent of the
        Transferring Stockholder, the amount of such securities belonging to the


                                      30.
<PAGE>   34

        Remaining Stockholder included in such Transfer may not be greater than
        such Remaining Stockholder's percentage beneficial ownership of Fully
        Diluted Common Stock multiplied by the total number of shares of Fully
        Diluted Common Stock to be sold by both the Transferring Stockholder and
        all Remaining Stockholders. Upon receipt of a Co-sale Notice, the
        Transferring Stockholder shall be obligated to transfer at least the
        entire number of Shares set forth in the Co-sale Notice to the
        transferee on the Transferee Terms; provided, however, that the
        Transferring Stockholder shall not consummate the purchase and sale of
        any Shares hereunder if the transferee does not purchase all such Shares
        specified in all Co-sale Notices. If no Co-sale Notice has been
        delivered to the Transferring Stockholder prior to the expiration of the
        10 business day period referred to above and if the provisions of this
        Section have been complied with in all respects, the Transferring
        Stockholder shall have the right for a 45 day calendar day period to
        Transfer Shares to the transferee on the Transferee Terms without
        further notice to any other party, but after such 45-day period, no such
        Transfer may be made without again giving notice to the Remaining
        Stockholders of the proposed Transfer and complying with the
        requirements of this Clause 17.

        At the closing of any Transfer of Shares subject to this Clause 17, the
        Transferring Stockholder, and the Remaining Stockholder, in the event
        such Tag Along Right is exercised, shall deliver certificates evidencing
        such securities as have been Transferred by each, duly endorsed, or
        accompanied by written instruments of transfer in form reasonably
        satisfactory to the transferee, free and clear of any adverse claim,
        against payment of the purchase price therefor.

        Notwithstanding the foregoing, this Clause 17 shall not apply to any
        sale of Common Stock pursuant to an effective registration statement
        under the Securities Act in a bona fide public offering.

        The rights and obligations of each of the Stockholders pursuant to the
        "Tag Along Right" provided herein shall terminate upon the date that the
        Common Stock is registered under Section 12(b) or 12(g) of the Exchange
        Act.

        Notwithstanding any other provision of this Clause 17.3, a Change in
        Control of any Stockholder shall not trigger a "Tag Along Right" in
        favor of any other Stockholder.

                                    CLAUSE 18

                    MATTERS REQUIRING PARTICIPANTS' APPROVAL

18.1    In consideration of Isis and Elan agreeing to enter into the License
        Agreements, the Parties hereby agree that Newco shall not without the
        prior approval of the EIS Director and at least two of the Isis
        Directors:

        18.1.1.  engage in any activity other than the Business;


                                      31.
<PAGE>   35

        18.1.2.  acquire or dispose of assets of a value in excess of $25,000 or
                 sell the principal assets, undertaking or Business of Newco;

        18.1.3.  create any fixed or floating charge, lien (other than a lien
                 arising by operation of law) or other encumbrance over the
                 whole or any part of the undertaking, property or assets of
                 Newco or of any Subsidiary;

        18.1.4.  borrow any sum in excess of a maximum aggregate sum outstanding
                 at any time of US $25,000;

        18.1.5.  make any loan or advance or give any credit (other than normal
                 trade credit) in excess of US$25,000 to any Person;

        18.1.6.  give any guarantee or indemnity to secure the liabilities or
                 obligations of any Party other than those which it is usual to
                 give in the ordinary course of a business similar to the
                 Business;

        18.1.7.  enter into any contract, arrangement or commitment involving
                 expenditure on capital account or the realization of capital
                 assets if the amount or the aggregate amount of such
                 expenditure or realization by Newco would exceed US$50,000 in
                 any one year or in relation to any one project, and for the
                 purpose of this paragraph the aggregate amount payable under
                 any agreement for hire, hire purchase or purchase on credit
                 sale or conditional sale terms shall be deemed to be capital
                 expenditure incurred in the year in which such agreement is
                 entered into;

        18.1.8.  issue any unissued Shares or create or issue any new shares;

        18.1.9.  alter any rights attaching to any class of share in the capital
                 of Newco or alter the Newco Memorandum of Association and
                 Bye-Laws;

        18.1.10. consolidate, sub-divide or convert any of Newco's share capital
                 or in any way alter the rights attaching thereto;

        18.1.11. dispose of Newco or of any shares in Newco;

        18.1.12. enter into any partnership or profit sharing agreement with any
                 Person other than arrangements with trade representatives and
                 similar Persons in the ordinary course of business;

        18.1.13. do or permit or suffer to be done any act or thing whereby
                 Newco may be wound up (whether voluntarily or compulsorily),
                 save as otherwise expressly provided for in this Agreement;


                                      32.
<PAGE>   36

        18.1.14. issue any debentures or other securities convertible into
                 shares or debentures or any share warrants or any options in
                 respect of shares in Newco;

        18.1.15. enter into any contract or transaction except in the ordinary
                 and proper course of the Business on arm's length terms;

        18.1.16. acquire, purchase or subscribe for any shares, debentures,
                 mortgages or securities (or any interest therein) in any
                 company, trust or other Person;

        18.1.17. adopt any employee benefit program or incentive schemes;

        18.1.18. engage any new employee at remuneration of greater than
                 US$60,000 per annum;

        18.1.19. pay any remuneration to the Directors by virtue of holding such
                 office other than Directors who hold executive office;

        18.1.20. license or sub-license any of the Elan Intellectual Property,
                 Isis Intellectual Property, or Newco Technology;

        18.1.21. amend or vary the terms of the Isis License Agreement or the
                 Elan License Agreement;

        18.1.22. permit a person other than Newco to own a regulatory approval
                 relating to the Product(s);

        18.1.23. change the authorized signatories on Newco bank accounts;

        18.1.24. amend or vary the Business Plan or agree the Budget;

        18.1.25. alter the number of Directors;

        18.1.26. pay dividends or distributions in respect of, or redeem or
                 repurchase, the equity of Newco;

        18.1.27. enter into joint venture agreements or any similar arrangements
                 with any Person; or

        18.1.28. create, acquire or dispose of any Subsidiary or of any shares
                 in any Subsidiary.


                                      33.
<PAGE>   37

                                    CLAUSE 19

                                    DISPUTES

19.1    Should any dispute or difference arise between Elan and Isis, or between
        Elan or Isis and Newco, during the period that this Agreement is in
        force, other than a dispute or difference relating to (i) the
        interpretation of any provision of this Agreement, (ii) the
        interpretation or application of law, or (iii) the ownership of any
        intellectual property, then any Party may forthwith give notice to the
        other Parties that it wishes such dispute or difference to be referred
        to the Chief Executive Officer of Isis and the President of EPT.

19.2    In any event of a notice being served in accordance with Clause 19.1,
        each of the Participants shall within 14 days of the service of such
        notice prepare and circulate to the Chief Executive Officer of Isis and
        the President of EPT a memorandum or other form of statement setting out
        its position on the matter in dispute and its reasons for adopting that
        position. Each memorandum or statement shall be considered by the Chief
        Executive Officer of Isis and the President of EPT who shall endeavor to
        resolve the dispute. If the chief executive officers of the Participants
        agree upon a resolution or disposition of the matter, they shall each
        sign a statement which sets out the terms of their agreement. The
        Participants agree that they shall exercise the voting rights and other
        powers available to them in relation to Newco to procure that the agreed
        terms are fully and promptly carried into effect.

                                    CLAUSE 20

                           CERTAIN CHANGES OF CONTROL

20.1    [...***...].

20.2    In the event that [...***...] pursuant to Clause 20.1 above, the
        Participants shall jointly select a nationally recognized investment
        banking firm as arbitrator to make such determination. In the event the
        Participants do not agree upon the selection of such investment banking
        firm, Elan may contact the presiding justice of the Supreme Court of the
        State of New York sitting in the City, County, and State of


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      34.
<PAGE>   38

        New York (the "PRESIDING JUSTICE") and request that an independent
        US-based nationally recognized investment banking firm which is
        knowledgeable of the pharmaceutical/biotechnology industry be appointed
        within 10 Business Days. The Presiding Justice shall endeavor to select
        an investment banking firm as arbitrator which is technically
        knowledgeable in the pharmaceutical/biotechnology industry (and which
        directly and through its Affiliates, has no business relationship with,
        or shareholding in, either of the Participants). Promptly upon being
        notified of the arbitrator's appointment, the Participants shall submit
        to the arbitrator details of their assessment of [...***...] together
        with such information as they think necessary to validate their
        assessment. The arbitrator shall notify Isis of [...***...] and shall
        notify Elan of [...***...]. The Participants shall then be entitled to
        make further submissions to the arbitrator within five Business Days
        explaining why [...***...], as the case may be, are unjustified. The
        arbitrator shall thereafter meet with Isis and Elan and shall thereafter
        choose either [...***...] on the basis of [...***...]. The arbitrator
        shall use its best efforts to determine [...***...] within 30 Business
        Days of his appointment. The Participants shall bear the costs of the
        arbitrator equally provided that the arbitrator may, in its discretion,
        allocate all or a portion of such costs to one Party. Any decision of
        the arbitrator shall be final and binding.

20.3    Elan shall purchase the Shares beneficially owned by Isis by delivery of
        the Purchase Price in cash no later than the 15th Business Day following
        determination of the Purchase Price by the arbitrator.

20.4    The Shares so transferred shall be sold by Isis with effect from the
        date of such transfer free from any lien, charge or encumbrance, but
        with all rights and restrictions attaching thereto.

20.5    If Elan exercises the Buyout Option, Newco shall continue to develop
        Isis Products on terms which are substantially the same as those which
        would be provided to an Independent Third Party negotiating on an arm's
        length basis.

20.6    If Elan exercises the Buyout Option, both parties will negotiate in good
        faith to agree to additional reasonable provisions and/or amendments to
        the License Agreements to protect the intellectual property rights of
        the Participants.

20.7    If Elan exercises the Buyout Option, the provisions of Clauses 1, 3,
        11.1, 17, 20.7, 21.4, 22, 23 and 24 shall survive the termination of
        this Agreement under this Clause 20.7; all other terms and provisions of
        this Agreement shall cease to have effect and be null and void.


                                               *CONFIDENTIAL TREATMENT REQUESTED


                                      35.
<PAGE>   39

                                    CLAUSE 21

                                   TERMINATION

21.1    This Agreement shall govern the operation and existence of Newco until
        (i) terminated by written agreement of all Parties hereto or (ii)
        otherwise terminated in accordance with this Clause 21.

21.2    For the purpose of this Clause 21, a "RELEVANT EVENT" is committed or
        suffered by a Participant if:

        21.2.1 it commits a material breach of its obligations under this
               Agreement or the applicable License, which breach remains uncured
               60 days after written notice thereof; provided, however, that (x)
               if the breaching Participant has proposed a course of action to
               rectify the breach and is acting in good faith to rectify same
               but has not cured the breach by the 60th day, such period shall
               be extended by such period as is reasonably necessary to permit
               the breach to be rectified and (y) if a default involves a good
               faith dispute regarding the amount of any required payment,
               provided any undisputed amount is paid, such default shall be
               stayed and the remainder may be withheld for a reasonable period
               during which a good faith resolution of the amount owed is being
               pursued;

        21.2.2 a distress, execution, sequestration or other process is levied
               or enforced upon or sued out against a material part of its
               property which is not discharged or challenged within 30 days;

        21.2.3 it is unable to pay its debts in the normal course of business;

        21.2.4 it ceases wholly or substantially to carry on its business,
               otherwise than for the purpose of a reconstruction or
               amalgamation, without the prior written consent of the other
               Participant (such consent not to be unreasonably withheld);

        21.2.5 the appointment of a liquidator, receiver, administrator,
               examiner, trustee or similar officer of such Participant or over
               all or substantially all of its assets under the law of any
               applicable jurisdiction, including without limitation, the United
               States of America, Bermuda or Ireland;

        21.2.6 an application or petition for bankruptcy, corporate
               re-organization, composition, administration, examination,
               arrangement or any other procedure similar to any of the
               foregoing under the law of any applicable jurisdiction, including
               without limitation, the United States of America, Bermuda or
               Ireland, is filed, and is not discharged within 60 days, or a
               Participant applies for or consents to the appointment of a
               receiver, administrator, examiner or similar officer of it or of
               all or a material part 


                                      36.
<PAGE>   40

               of its assets, rights or revenues or the assets and/or the
               business of a Participant are for any reason seized, confiscated
               or condemned.

21.3    If either Participant commits a Relevant Event, the other Stockholder
        shall have in addition to all other legal and equitable rights and
        remedies hereunder, the right to terminate this Agreement upon 30 days'
        written notice.

21.4    In the event of a termination of the Elan License Agreement and/or the
        Isis License Agreement, both parties will negotiate in good faith to
        determine whether this Agreement should be terminated and if so, which
        provisions should survive termination.

21.5    The provisions of Clauses 1, 3, 7.1, 11.1, 17, 21.4, 21.5, 22, 23 and 24
        shall survive the termination of this Agreement under Clause 21.3 or by
        mutual consent pursuant to Clause 21.1 in accordance with their terms;
        all other terms and provisions of this Agreement shall cease to have
        effect and be null and void upon the termination of this Agreement under
        Clause 21.3 or by mutual consent pursuant to Clause 21.1.

                                    CLAUSE 22

                                 CONFIDENTIALITY

22.1    The Parties and/or Newco acknowledge and agree that it may be necessary,
        from time to time, to disclose to each other confidential and/or
        proprietary information, including without limitation, inventions, works
        of authorship, trade secrets, specifications, designs, data, know-how
        and other information, relating to the Field, the Products, present or
        future products, the Newco Technology, the Elan Intellectual Property or
        the Isis Intellectual Property, as the case may be, methods, compounds,
        research projects, work in process, services, sales suppliers,
        customers, employees and/or business of the disclosing Party, whether in
        oral, written, graphic or electronic form (collectively "CONFIDENTIAL
        INFORMATION").

22.2    Any Confidential Information revealed by a Party to another Party shall
        be maintained as confidential and shall be used by the receiving Party
        exclusively for the purposes of fulfilling the receiving Party's rights
        and obligations under this Agreement, and for no other purpose.
        Confidential Information shall not include:

        22.2.1 information that is generally available to the public;

        22.2.2 information that is made public by the disclosing Party;

        22.2.3 information that is independently developed by the receiving
               Party, as evidenced by such Party's written records, without the
               aid, application or use of the disclosing Party's Confidential
               Information;


                                      37.
<PAGE>   41

        22.2.4 information that is published or otherwise becomes part of the
               public domain without any disclosure by the receiving Party, or
               on the part of the receiving Party's directors, officers, agents,
               representatives or employees;

        22.2.5 information that becomes available to the receiving Party on a
               non-confidential basis, whether directly or indirectly, from a
               source other than the disclosing Party, which source did not
               acquire this information on a confidential basis;

        22.2.6 information which the receiving Party is required to disclose
pursuant to:

               (i)       a valid order of a court or other governmental body or
                         any political subdivision thereof or as otherwise
                         required by law, rule or regulation; or

               (ii)      other requirement of law; provided, however, that if
                         the receiving Party becomes legally required to
                         disclose any Confidential Information, the receiving
                         Party shall give the disclosing Party prompt notice of
                         such fact so that the disclosing Party may obtain a
                         protective order or seek confidential treatment or
                         other appropriate remedy concerning any such
                         disclosure. The receiving Party shall fully co-operate
                         with the disclosing Party in connection with the
                         disclosing Party's efforts to obtain any such order or
                         other remedy. If any such order or other remedy does
                         not fully preclude disclosure, the receiving Party
                         shall make such disclosure only to the extent that such
                         disclosure is legally required;

        22.2.7 information which was already in the possession of the receiving
               Party at the time of receiving such information, as evidenced by
               its written records, provided such information was not previously
               provided to the receiving Party from a source which was under an
               obligation to keep such information confidential; or

        22.2.8 information that is the subject of a written permission to
               disclose, without restriction or limitation, by the disclosing
               Party.

22.3    Each Party agrees to disclose Confidential Information of another Party
        only to those employees, representatives and agents requiring knowledge
        thereof in connection with their duties directly related to the
        fulfilling of the Party's obligations under this Agreement, so long as
        such persons are under an obligation of confidentiality no less
        stringent than as set forth herein. Each Party further agrees to inform
        all such employees, representatives and agents of the terms and
        provisions of the Transaction Documents and their duties hereunder and
        to obtain their consent hereto as a condition of receiving Confidential
        Information. Each Party agrees that it will exercise the same degree of
        care and protection to preserve the proprietary and confidential nature
        of the Confidential Information 


                                      38.
<PAGE>   42

        disclosed by a Party, as the receiving Party would exercise to preserve
        its own Confidential Information. Each Party agrees that it will, upon
        request of another Party, return all documents and any copies thereof
        containing Confidential Information belonging to or disclosed by such
        other Party. Each Party shall promptly notify the other Parties upon
        discovery of any unauthorized use or disclosure of the other Parties'
        Confidential Information.

22.4    Notwithstanding the above, each Party may use or disclose Confidential
        Information disclosed to it by another Party to the extent such use or
        disclosure is reasonably necessary in filing or prosecuting patent
        applications, prosecuting or defending litigation, complying with patent
        applications, prosecuting or defending litigation, complying with
        applicable governmental regulations or otherwise submitting information
        to tax or other governmental authorities, conducting clinical trials, or
        granting a permitted sub-license or otherwise exercising its rights
        hereunder; provided, that if a Party is required to make any such
        disclosure of the other Party's Confidential Information, other than
        pursuant to a confidentiality agreement, such Party shall inform the
        third party recipient of the terms and provisions of this Agreement and
        their duties hereunder and shall obtain their consent hereto as a
        condition of releasing to the third party recipient the Confidential
        Information.

22.5    Nothing contained herein shall obligate or restrict any Party from
        utilizing public, non-proprietary information which is not subject to
        the protection of applicable patent laws.

22.6    Any breach of this Clause 22 by any employee, representative or agent of
        a Party shall be considered a breach by the Party itself.

22.7    The provisions relating to confidentiality in this Clause 22 shall
        remain in effect during the Term and for a period of seven years
        following the termination of this Agreement.

22.8    The Parties agree that the obligations of this Clause 22 are necessary
        and reasonable in order to protect the Parties' respective businesses,
        and each Party expressly agrees that monetary damages would be
        inadequate to compensate a Party for any breach by the other Party of
        its covenants and agreements set forth herein. Accordingly, the Parties
        agree and acknowledge that any such violation or threatened violation
        will cause irreparable injury to a Party and that, in addition to any
        other remedies that may be available, in law or in equity or otherwise,
        any Party shall be entitled to obtain injunctive relief against the
        threatened breach of the provisions of this Clause 22, or a continuation
        of any such breach by the other Party, specific performance and other
        equitable relief to redress such breach together with its damages and
        reasonable counsel fees and expenses to enforce its rights hereunder,
        without the necessity of proving actual or express damages.


                                      39.
<PAGE>   43

                                    CLAUSE 23

                                      COSTS

23.1    Each Stockholder shall bear its own legal and other costs incurred in
        relation to preparing and concluding this Agreement and the other
        Transaction Documents.

23.2    All other costs, legal fees, registration fees and other expenses
        relating to the transactions contemplated hereby, including the costs
        and expenses incurred in relation to the incorporation of Newco, shall
        be borne by Newco.

                                    CLAUSE 24

                                     GENERAL

24.1    GOOD FAITH:

        Each of the Parties hereto undertakes with the others to do all things
        reasonably within its power that are necessary or desirable to give
        effect to the spirit and intent of this Agreement.

24.2    FURTHER ASSURANCE:

        At the request of any of the Parties, the other Party or Parties shall
        (and shall use reasonable efforts to procure that any other necessary
        parties shall) execute and perform all such documents, acts and things
        as may reasonably be required subsequent to the signing of this
        Agreement for assuring to or vesting in the requesting Party the full
        benefit of the terms hereof.

24.3    RELIANCE ON REPRESENTATION AND WARRANTIES:

        Each of the Parties hereto hereby acknowledges that in entering into
        this Agreement it has not relied on any representation or warranty
        except as expressly set forth herein or in any document referred to
        herein.

24.4    FORCE MAJEURE:

        Neither Party to this Agreement shall be liable for delay in the
        performance of any of its obligations hereunder if such delay is caused
        by or results from causes beyond its reasonable control, including
        without limitation, acts of God, fires, strikes, acts of war (whether
        war be declared or not), insurrections, riots, civil commotions,
        strikes, lockouts or other labor disturbances or intervention of any
        relevant government authority, but any such delay or failure shall be
        remedied by such Party as soon as practicable.


                                      40.
<PAGE>   44

24.5    RELATIONSHIP OF THE PARTIES:

        Nothing contained in this Agreement is intended or is to be construed to
        constitute Elan/EIS and Isis as partners, or Elan/EIS as an employee or
        agent of Isis, or Isis as an employee or agent of Elan/EIS.

        No Party hereto shall have any express or implied right or authority to
        assume or create any obligations on behalf of or in the name of another
        Party or to bind another Party to any contract, agreement or undertaking
        with any third Party.

24.6    COUNTERPARTS:

        This Agreement may be executed in any number of counterparts, each of
        which when so executed shall be deemed to be an original and all of
        which when taken together shall constitute this Agreement.

24.7    NOTICES:

        Any notice to be given under this Agreement shall be sent in writing by
        registered or recorded delivery post or reputable overnight courier such
        as Federal Express or telecopied to:

        Elan at:

        Lincoln House, Lincoln Place, Dublin 2
        Ireland
        Attention:  Vice President & General Counsel,
        Elan Pharmaceutical Technologies,
        a division of Elan Corporation, plc
        Telephone:    353-1-709-4000
        Fax:          353-1-709-4124

        with a copy to:

        Brock Silverstein LLC
        One Citicorp Center, 56th Floor
        New York, NY 10022
        Attention:  David Robbins, Esq.
        Telephone:    212-371-2000
        Fax:          212-371-5500

        EIS at:

        Elan International Services, Ltd.
        102 St. James Court
        Flatts, Smiths Parish FL04


                                      41.
<PAGE>   45

        Bermuda
        Attention:  President
        Telephone:    441-292-9169
        Fax:          441-292-2224

        with a copy to:

        Brock Silverstein LLC
        One Citicorp Center, 56th Floor
        New York, NY 10022
        Attention:  David Robbins, Esq.
        Telephone:    212-371-2000
        Fax:          212-371-5500

        Isis at:

        2292 Faraday Avenue
        Carlsbad, CA 92008
        Attention:  B. Lynne Parshall
        Telephone:    760-603-2460
        Fax:          760-931-9639

        with a copy to:

        Cooley Godward LLP
        4365 Executive Drive
        San Diego, CA 92121
        Attention: L. Kay Chandler, Esq.
        Telephone:    619-550-6000
        Fax:          619-453-3555

        Newco at:

        Orasense Ltd.
        c/o Appleby, Spurling & Kempe
        Cedar House, 41 Cedar Avenue
        P.O. Box HM 1179
        Hamilton, Bermuda HM EX
        Attention:   Timothy Faries
        Telephone:    441-295-2244
        Fax:          441-295-7768

        with a copy to each of Isis, EIS and their respective counsel at the
        addresses indicated above;


                                      42.
<PAGE>   46

        or to such other address(es) as may from time to time be notified by any
        Party to the others hereunder.

        Any notice sent by mail shall be deemed to have been delivered within
        three Business Days after dispatch or delivery to the relevant courier
        and any notice sent by telecopy shall be deemed to have been delivered
        upon confirmation of receipt by telephone. Notices of change of address
        shall be effective upon receipt.

24.8    GOVERNING LAW

        This Agreement shall be governed by and construed in accordance with the
        laws of the State of New York without giving effect to any choice or
        conflict or law provision or rule.

24.9    ARBITRATION

        (a)    Any dispute under this Agreement or the other Transaction
               Documents which is not settled by mutual consent (whether
               pursuant to the provisions in Clause 19 hereof or otherwise)
               shall be finally settled by binding arbitration, conducted in
               accordance with the Commercial Arbitration Rules of the American
               Arbitration Association by one (1) arbitrator appointed in
               accordance with said rules. Such arbitrator shall be reasonably
               satisfactory to each of the Parties; provided, that if the
               Parties are unable to agree upon the identity of such arbitrator
               within 15 days of demand by either Party, then either Party shall
               have the right to petition the Presiding Justice to appoint an
               arbitrator.

               The arbitration shall be held in New York, New York and the
               arbitrator shall be an independent expert in pharmaceutical
               product development and marketing (including clinical development
               and regulatory affairs).

        (b)    The arbitrator shall determine what discovery will be permitted,
               consistent with the goal of limiting the cost and time which the
               Parties must expend for discovery; provided the arbitrator shall
               permit such discovery as they deem necessary to permit an
               equitable resolution of the dispute.

               Any written evidence originally in a language other than English
               shall be submitted in English translation accompanied by the
               original or a true copy thereof.

               The costs of the arbitration, including administrative and
               arbitrators' fees, shall be shared equally by the Parties and
               each Party shall bear its own costs and attorneys' and witness'
               fees incurred in connection with the arbitration.


                                      43.
<PAGE>   47

        (c)    In rendering judgment, the arbitrator shall be instructed by the
               Parties that he shall be permitted to select solely from between
               the proposals for resolution of the relevant issue presented by
               each Party, and not any other proposal.

               A disputed performance or suspended performances pending the
               resolution of the arbitration must be completed within thirty
               (30) days following the final decision of the arbitrators or such
               other reasonable period as the arbitrators determine in a written
               opinion.

        (d)    Any arbitration under the Transaction Documents shall be
               completed within one year from the filing of notice of a request
               for such arbitration.

               The arbitration proceedings and the decision shall not be made
               public without the joint consent of the Parties and each Party
               shall maintain the confidentiality of such proceedings and
               decision unless otherwise permitted by the other Party.

        (e)    The Parties agree that the decision shall be the sole, exclusive
               and binding remedy between them regarding any and all disputes,
               controversies, claims and counterclaims presented to the
               arbitrators. Application may be made to any court having
               jurisdiction over the Party (or its assets) against whom the
               decision is rendered for a judicial recognition of the decision
               and an order of enforcement.

24.10   SEVERABILITY:

        If any provision in this Agreement is agreed by the Parties to be,
        deemed to be or becomes invalid, illegal, void or unenforceable under
        any law that is applicable hereto, such provision will be deemed amended
        to conform to applicable laws so as to be valid and enforceable or, if
        it cannot be so amended without materially altering the intention of the
        Parties, it will be deleted, with effect from the date of such agreement
        or such earlier date as the Parties may agree, and the validity,
        legality and enforceability of the remaining provisions of this
        Agreement shall not be impaired or affected in any way.

24.11   AMENDMENTS:

        No amendment, modification or addition hereto shall be effective or
        binding on any Party unless set forth in writing and executed by a duly
        authorized representative of all Parties.

24.12   WAIVER:

        No waiver of any right under this Agreement shall be deemed effective
        unless contained in a written document signed by the Party charged with
        such waiver,


                                      44.
<PAGE>   48

        and no waiver of any breach or failure to perform shall be deemed to be
        a waiver of any future breach or failure to perform or of any other
        right arising under this Agreement.

24.13   ASSIGNMENT:

        None of the Parties shall be permitted to assign its rights or
        obligations hereunder without the prior written consent of the other
        Parties except as follows:

        24.13.1 Elan, EIS and/or Isis shall have the right to assign their
                rights and obligations hereunder to their Affiliates provided,
                however, that such assignment does not result in adverse tax
                consequences for any other Parties.

        24.13.2 Elan and EIS shall have the right to assign their rights and
                obligations hereunder to an off-balance sheet special purpose
                entity established by Elan or EIS.

        24.13.3 Elan, EIS and/or Isis shall have the right to assign or
                otherwise transfer their rights and obligations hereunder in
                connection with a sale of all or substantially all of the
                business of such Party to which the transaction Documents
                relate, whether by merger, sale of stock, sale of assets or
                otherwise, subject, however, to the Elan's right to exercise the
                Buyout Option pursuant to the provisions of Clause 20 hereof in
                the event of a Change of Control of Isis and/or Newco.

24.14   WHOLE AGREEMENT/NO EFFECT ON OTHER AGREEMENTS:

        This Agreement (including the Schedules attached hereto) and the other
        Transaction Documents set forth all of the agreements and understandings
        between the Parties with respect to the subject matter hereof, and
        supersedes and terminates all prior agreements and understandings
        between the Parties with respect to the subject matter hereof. There are
        no agreements or understandings with respect to the subject matter
        hereof, either oral or written, between the Parties other than as set
        forth in this Agreement and the other Transaction Documents.

        In the event of any ambiguity or conflict arising between the terms of
        this Agreement and those of the Newco Memorandum of Association and
        Bye-Laws, the terms of this Agreement shall prevail.

        No provision of this Agreement shall be construed so as to negate,
        modify or affect in any way the provisions of any other agreement
        between any of the Parties unless specifically referred to, and solely
        to the extent provided herein. In the event of a conflict between the
        provisions of this Agreement and the


                                      45.
<PAGE>   49

        provisions of the License Agreements, the terms of this Agreement shall
        prevail unless this Agreement specifically provide otherwise.

24.15   SUCCESSORS:

        This Agreement shall be binding upon and inure to the benefit of the
        Parties hereto, their successors and permitted assigns.

                            [Signature Page Follows]



























                                      46.
<PAGE>   50

               IN WITNESS WHEREOF, the Parties hereto have executed this
Agreement on the day first set forth above.

                                               SIGNED

                                               BY:_______________________

                                               for and on behalf of
                                               ELAN CORPORATION, PLC

in the presence of:__________________


                                               SIGNED

                                               BY:_______________________

                                               for and on behalf of
                                               ELAN INTERNATIONAL SERVICES, LTD.

in the presence of:__________________


                                               SIGNED

                                               BY:_______________________

                                               for and on behalf of
                                               ISIS PHARMACEUTICALS, INC.

in the presence of:__________________


                                               SIGNED

                                               BY:_______________________

                                               for and on behalf of
                                               ORASENSE LTD.

in the presence of:__________________



<PAGE>   1
                                                                    EXHIBIT 10.2

                          SECURITIES PURCHASE AGREEMENT

               SECURITIES PURCHASE AGREEMENT (this "Agreement"), dated as of
April 20, 1999, between ISIS PHARMACEUTICALS, INC., a Delaware corporation (the
"Company"), and ELAN INTERNATIONAL SERVICES, LTD., a Bermuda private limited
company ("EIS").

                                R E C I T A L S:

               A. The Company desires to issue and sell to EIS, and EIS desires
to purchase from the Company, (i) 120,150 shares of a newly-created series of
the Company's Preferred Stock, par value $.001 per share, captioned "Series A
Convertible Preferred Stock" (the "Series A Preferred Stock"), (ii) 910,844
shares of the Company's Common Stock, par value $.001 per share (the "Common
Stock") ((i) and (ii) together, the "Shares"), and (iii) a warrant (the
"Warrant") to purchase up to 215,000 shares of Common Stock as provided for
therein. In addition, EIS has agreed to lend certain funds to the Company
pursuant to a convertible promissory note in the form attached hereto as Exhibit
A (as amended at any time, the "Note" and, together with the Series A Preferred
Stock, the Common Stock, and the Warrant, the "Securities"), with a maximum
aggregate principal amount of U.S.$18,400,000, amounts in respect of which shall
be disbursed in accordance with its terms and subject to the conditions
contained herein and therein. The rights, preferences and privileges of the
Series A Preferred Stock are as set forth in the Certificate of Designations,
Preferences and Rights (the "Certificate of Designations"), the form of which is
attached hereto as Exhibit B.

               B. The Company and EIS have previously caused to be formed
Orasense Ltd., a Bermuda private limited company ("Newco"), and pursuant to the
terms of a Subscription, Joint Development and Operating Agreement, dated as of
the date hereof (as amended at any time, the "JDOA"), simultaneously with the
transactions contemplated by this Agreement, (i) the Company shall acquire 9,612
common shares of Newco, par value U.S.$1.00 per share (the "Newco Common
Stock"), and (ii) EIS shall acquire 2,388 shares of Newco Common Stock.
Additionally, as of the date hereof, Newco has entered into license agreements
with (i) ELAN CORPORATION, PLC, an Irish public limited company and parent
corporation of EIS ("Elan;" such agreement, as amended at any time, the "Elan
License Agreement"), and (ii) the Company (such agreement, as amended at any
time, the "Newco License Agreement" and, together with the Elan License
Agreement, the "License Agreements").

               C. The Company and EIS are executing and delivering on the date
hereof a Registration Rights Agreement, in the form attached hereto as Exhibit C
(as amended at any time, the "Registration Rights Agreement"), in respect of the
Common Stock issued or issuable upon conversion of the Series A Preferred Stock
and the Note and exercise of the Warrant, the Common Stock being purchased
hereunder, and any other Common Stock issued to EIS or any of its affiliates or
permitted transferees upon any stock split, stock dividend, recapitalization or
similar event affecting the Securities. The Company, EIS and Newco are also
executing and delivering on the date hereof a Registration Rights Agreement in
the form attached hereto as 


<PAGE>   2

Exhibit D (as amended at any time, the "Newco Registration Rights Agreement").
Additionally, the Company and EIS are executing and delivering on the date
hereof a Funding Agreement in the form attached hereto as Exhibit E (the
"Funding Agreement;" and, together with this Agreement, the Certificate of
Designations, the JDOA, the Registration Rights Agreement, the Newco
Registration Rights Agreement, the License Agreements and each other document or
instrument executed and delivered in connection with the transactions
contemplated hereby and by the JDOA, the "Transaction Documents").

                               A G R E E M E N T:

               The parties hereto agree as follows:

               SECTION 1.  Closing.

               (a)  Time and Place. The closing of the transactions contemplated
hereby (the "Closing") shall occur on the date hereof (the "Closing Date"), at
the offices of Brock Silverstein LLC, One Citicorp Center, 56th Floor, New York,
NY 10022.

               (b)  Issuance of Securities. At the Closing, the Company shall
issue and sell to EIS, and EIS shall purchase from the Company: (i) 120,150
shares of Series A Preferred Stock, (ii) 910,844 shares of Common Stock, (iii)
the Warrant, and (iv) the Note, the principal amount of which shall be disbursed
by EIS subsequent to the Closing in accordance with its terms.

               (c)  Purchase Price. The purchase price (the "Purchase Price")
shall be the sum of (i) U.S.$12,015,000, the purchase price for the Series A
Preferred Stock, and (ii) U.S.$15,000,000, the purchase price for the Common
Stock.

               (d)  Delivery. At the Closing:

                    (i)       EIS shall pay the Purchase Price by wire transfer
        to an account designated by the Company and the parties hereto shall
        execute and deliver to each other, as applicable: (A) a certificate or
        certificates for the Series A Preferred Stock and the Common Stock; (B)
        the Note; (C) the Warrant; (D) the Registration Rights Agreement; (E)
        the Newco Registration Rights Agreement; (F) the JDOA; (G) the
        Certificate of Designations, as filed with the Secretary of State of the
        State of Delaware; (H) the License Agreements; (I) the Funding
        Agreement; (J) certificates as to the incumbency of the officers of the
        Company executing any of the Transaction Documents; and (K) any other
        documents or instruments reasonably requested by a party hereto; and

                    (ii)      The Company shall cause to be delivered to EIS an
        opinion of counsel in the form attached hereto as Exhibit C to the
        Letter Agreement, dated March 31, 1998, by and among Elan, EIS and the
        Company (the "Letter Agreement").


                                       2
<PAGE>   3

               (e)  Exemption from Registration. The Securities and any
underlying shares of Common Stock will be issued under an exemption or
exemptions from registration under the Securities Act of 1933, as amended (the
"Securities Act"). Accordingly, the certificates evidencing the Series A
Preferred Stock and the Common Stock, the Warrant, the Note and any shares of
Common Stock or other securities issuable upon the exercise, conversion or
exchange of any of the Securities shall, upon issuance, contain a legend,
substantially in the form as follows:

               THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER
               THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT UNDER ANY
               CIRCUMSTANCES BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF
               WITHOUT AN EFFECTIVE REGISTRATION STATEMENT FOR SUCH SECURITIES
               UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE
               STATE SECURITIES LAWS OR AN OPINION OF COUNSEL SATISFACTORY TO
               THE COMPANY THAT REGISTRATION IS NOT REQUIRED UNDER SUCH ACT OR
               APPLICABLE STATE SECURITIES LAWS.

               THE TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS
               ALSO SUBJECT TO THE RESTRICTIONS CONTAINED IN THAT CERTAIN
               SECURITIES PURCHASE AGREEMENT, DATED APRIL 20, 1999, BY AND
               BETWEEN ISIS PHARMACEUTICALS, INC. AND ELAN INTERNATIONAL
               SERVICES, LTD.

               SECTION 2. Representations and Warranties of the Company. The
Company hereby represents and warrants to EIS, as of the date hereof, as
follows:

               (a) Organization. The Company is duly organized, validly existing
and in good standing under the laws of the State of Delaware and has all
requisite corporate power and authority to own and lease its properties, to
carry on its business as presently conducted and as proposed to be conducted and
to consummate the transactions contemplated hereby. The Company is duly
qualified as a foreign corporation and in good standing to do business in each
jurisdiction in which the nature of the business conducted or the property owned
by it requires such qualification, except where the failure to be so qualified
would not, individually or in the aggregate, have a material adverse effect on
the business, assets, liabilities (contingent or otherwise), operations,
condition (financial or otherwise), or prospects of the Company (a "Company
Material Adverse Effect").

               (b) Capitalization. As of the Closing Date, the Company has
reserved a sufficient number of shares of Common Stock (i) for issuance upon
conversion of the Series A 


                                       3
<PAGE>   4

Preferred Stock being purchased hereunder by EIS (including dividends in-kind
thereon), (ii) for issuance upon exercise of the Warrant, and (iii) for issuance
upon conversion of the Note (including interest payable thereon). The Shares,
when issued against payment therefor in accordance with this Agreement, will be
duly and validly issued, fully paid and nonassessable, will not be issued in
violation of any preemptive or similar rights. The shares of Common Stock
underlying the Series A Preferred Stock, the Note and the Warrant (the
"Underlying Shares"), when issued upon conversion or exercise in accordance with
the terms thereof, will be duly and validly issued, fully paid and
nonassessable, will not be issued in violation of any preemptive or similar
rights.

               (c)  Authorization of Transaction Documents. The Company has full
corporate power and authority to execute and deliver this Agreement and each of
the other Transaction Documents to which it is a party, and to perform its
obligations hereunder and thereunder. The execution, delivery and performance by
the Company of this Agreement and each of the other Transaction Documents to
which it is a party, including the issuance and sale of the Securities, have
been duly authorized by all requisite corporate action by the Company and, when
executed and delivered by the Company, this Agreement and each of the other
Transaction Documents to which it is a party will be the valid and binding
obligations of the Company, enforceable against the Company in accordance with
their respective terms, except (A) that enforcement may be limited by (i)
applicable bankruptcy, insolvency, reorganization, arrangement, moratorium or
other similar laws affecting creditors' rights, and (ii) general equity
principles and limitations on the availability of equitable relief, including
specific performance, and (B) that any rights to indemnity or contribution
hereunder or thereunder may be limited by state and federal securities laws and
by public policy considerations.

               (d)  No Violation. The execution, delivery and performance by the
Company of this Agreement and each other Transaction Document to which it is a
party, including the issuance and sale of the Securities, and compliance with
the provisions hereof and thereof by the Company, does not conflict with or
constitute or result in a breach of or default under (or an event which with
notice or passage of time or both would constitute a default) or give rise to
any right of termination, cancellation or acceleration under (i) the Certificate
of Incorporation, as amended, or by-laws, of the Company, (ii) applicable law,
statute, rule or regulation, or any ruling, writ, injunction, order, judgment or
decree of any court, arbitrator, administrative agency or other governmental
body applicable to the Company or any of its properties or assets, or (iii) any
contract filed as an exhibit to the Company's Annual Report on Form 10-K for the
year ended December 31, 1998 (the "1998 Form 10-K"), except where such breach,
default, termination, cancellation or acceleration would not, individually or in
the aggregate, have a Company Material Adverse Effect.

               (e)  Approvals. No material permit, authorization, consent,
approval, or order of or by, or any notification of or filing with, any person
or entity (governmental or otherwise) is required in connection with the
execution, delivery or performance of this Agreement or the Transaction
Documents, including the issuance and sale of the Securities, by the Company,
other 


                                       4
<PAGE>   5

than the filing of a Form D by the Company pursuant to Regulation D under the
Securities Act ("Regulation D").

               (f)  SEC Filings. The Company has filed with the Securities and
Exchange Commission (the "SEC") all forms, reports, schedules, statements,
exhibits and other documents (collectively, the "SEC Filings") required to be
filed by the Company on or before the date hereof. At the time filed, the SEC
Filings, including without limitation, any financial statements, exhibits and
schedules included therein or documents incorporated therein by reference (i)
did not contain any untrue statement of a material fact or omit to state a
material fact required to be stated therein or necessary in order to make the
statements therein, in light of the circumstances under which they were made,
not misleading and (ii) complied in all material respects with the applicable
requirements of the Securities Act or the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), as the case may be.

               (g)  Financial Statements. The audited balance sheets of the
Company at December 31, 1997 and 1998, together with the related statements of
operations, stockholders' equity (deficit) and cash flows for each of the three
years ended December 31, 1998, together with the reports and opinions thereon of
Ernst & Young LLP, contained in the 1998 Form 10-K, comply as to form in all
material respects with applicable accounting requirements and the published
rules and regulation of the SEC with respect thereto, and fairly present, in all
material respects, the financial position of the Company and the results of its
operations and its cash flows at such dates and for the years then ended and
were prepared in conformity in all material respects with generally accepted
accounting principles applied on a consistent basis.

               (h)  Litigation. Except as disclosed in the 1998 Form 10-K, there
is no legal, administrative, arbitration or other action or proceeding or
governmental investigation pending, or to the Company's knowledge, threatened
against the Company, or any director, officer or employee of the Company that
challenges the validity or performance of this Agreement or the other
Transaction Documents to which the Company is a party.

               (i)  Absence of Certain Events. Since March 31, 1998, except as
contemplated by the Transaction Documents, (A) the Company has not (i) made,
paid or declared any dividend or distribution to any equity holder (in such
capacity) or redeemed any of its capital stock, (ii) varied its business plan or
practices, in any material respect, from past practices, (iii) entered into any
financing, joint venture, license or similar arrangement that would limit or
restrict its ability to perform its obligations hereunder and under each of the
other Transaction Documents to which it is a party, or (iv) suffered or
permitted to be incurred any liability or obligation or any lien or encumbrance
against any of its properties or assets that would limit or restrict its ability
to perform its obligations hereunder and under each of the other Transaction
Documents to which it is a party, and (B) there has not been any change or
development which has had, or in the Company's reasonable judgment is likely to
have, a Company Material Adverse Effect.


                                       5
<PAGE>   6

               (j) Brokers or Finders. The Company has not retained any
investment banker, broker, finder or person or entity acting in a similar
capacity, and is not liable for any fee or payment to any such person, in
connection with the transactions contemplated by the Transaction Documents.

               SECTION 3. Representation and Warranties of EIS. EIS hereby
represents and warrants to the Company, as of the date hereof, as follows:

               (a) Organization. EIS is duly organized, validly existing and in
good standing under the laws of Bermuda and has all requisite corporate power
and authority to own and lease its properties, to carry on its business as
presently conducted and as proposed to be conducted and to consummate the
transactions contemplated hereby. EIS is duly qualified as a foreign corporation
and in good standing to do business in each jurisdiction in which the nature of
the business conducted or the property owned by it requires such qualification,
except where the failure to be so qualified would not, individually or in the
aggregate, have a material adverse effect on the business, assets, liabilities
(contingent or otherwise), operations, condition (financial or otherwise), or
prospects of EIS (an "EIS Material Adverse Effect").

               (b) Authorization of Transaction Documents. EIS has full
corporate power and authority to execute and deliver this Agreement and each of
the other Transaction Documents to which it is a party, and to perform its
obligations hereunder and thereunder. The execution, delivery, and performance
by EIS of this Agreement and each other Transaction Document to which it is a
party, including the purchase and acceptance of the Securities, have been duly
authorized by all requisite corporate action by EIS and, when executed and
delivered by EIS, this Agreement and each of the other Transaction Document to
which it is a party, will be the valid and binding obligations of EIS,
enforceable against it in accordance with their respective terms, except (A)
that enforcement may be limited by (i) applicable bankruptcy, insolvency,
reorganization, arrangement, moratorium or other similar laws affecting
creditors' rights, and (ii) general equity principles and limitations on the
availability of equitable relief, including specific performance, and (B) that
any rights to indemnity or contribution hereunder or thereunder may be limited
by state and federal securities laws and by public policy considerations.

               (c) No Violation. The execution, delivery and performance by EIS
of this Agreement and each other Transaction Document to which it is a party,
including the purchase and acceptance of the Securities, and compliance with
provisions hereof and thereof by EIS, will not conflict with or constitute or
result in a breach of or default under (or an event which with notice or passage
of time or both would constitute a default) or give rise to any right of
termination, cancellation or acceleration under (i) the Memorandum and Articles
of Association of EIS, (ii) applicable law, statute, rule or regulation, or any
ruling, writ, injunction, order, judgment or decree of any court, arbitrator,
administrative agency or other governmental body applicable to EIS or any of its
properties or assets, or (iii) any material contract to which EIS is party,
except where such breach, default, termination, cancellation or acceleration
would not, individually or in the aggregate, have an EIS Material Adverse
Effect.


                                       6
<PAGE>   7

               (d)  Approvals. No material permit, authorization, consent,
approval or order of or by, or any notification of or filing with, any person or
entity (governmental or otherwise) is required in connection with the execution,
delivery or performance of this Agreement or the Transaction Documents by EIS.

               (e)  Investment Representations.

                    (i)       EIS is sophisticated in transactions of this type 
        and capable of evaluating the merits and risks of the transactions
        described herein and in the other Transaction Documents to which it is a
        party, and has the capacity to protect its own interests. EIS has not
        been formed solely for the purpose of entering into the transactions
        described herein and therein and is acquiring the Securities (and the
        Underlying Shares) for investment for its own account, not as a nominee
        or agent, and not with the view to, or for resale, distribution or
        fractionalization thereof, in whole or in part, and no other person
        (other than Elan) has a direct or indirect interest, beneficial or
        otherwise in the Securities (or the Underlying Shares); provided,
        however, that EIS shall be permitted to convert or exchange such
        Securities in accordance with their terms.

                    (ii)      EIS has not and does not intend to enter into any
        contract, undertaking, agreement or arrangement with any person or
        entity to sell, transfer or pledge the Securities (or the Underlying
        Shares).

                    (iii)     EIS acknowledges its understanding that the 
        private placement and sale of the Securities (and the Underlying Shares)
        is exempt from registration under the Securities Act by virtue of the
        provisions of Regulation D. In furtherance thereof, EIS represents and
        warrants that it is an "accredited investor" as that term is defined in
        Regulation D, has the financial ability to bear the economic risk of its
        investment, has adequate means for providing for its current needs and
        personal contingencies and has no need for liquidity with respect to its
        investment in the Company.

                    (iv)      EIS agrees that it shall not sell or otherwise 
        transfer any of the Securities (or the Underlying Shares) without
        registration under the Securities Act or pursuant to an opinion of
        counsel reasonably satisfactory to the Company that an exemption from
        registration is available, and fully understands and agrees that it must
        bear the total economic risk of its purchase for an indefinite period of
        time because, among other reasons, none of the Securities (or the
        Underlying Shares) have been registered under the Securities Act or
        under the securities laws of any applicable state or other jurisdiction
        and, therefore, cannot be resold, pledged, assigned or otherwise
        disposed of unless subsequently registered under the Securities Act and
        under the applicable securities laws of such states or jurisdictions or
        an exemption from such registration is available. EIS understands that
        the Company is under no obligation to register the Securities (or the
        Underlying Shares) on its behalf with the exception of certain
        registration rights with respect to certain of the Securities (and the
        Underlying 


                                       7
<PAGE>   8

        Shares), as provided in the Registration Rights Agreement. EIS
        understands the lack of liquidity and restrictions on transfer of the
        Securities (and the Underlying Shares) and that this investment is
        suitable only for a person or entity of adequate financial means that
        has no need for liquidity of this investment and that can afford a total
        loss of its investment.

               (f) Litigation. There is no legal, administrative, arbitration or
other action or proceeding or governmental investigation pending, or to EIS's
knowledge threatened, against EIS that challenges the validity or performance of
this Agreement or the other Transaction Documents to which EIS is a party.

               (g) Brokers or Finders. EIS has not retained any investment
banker, broker, finder or person or entity acting in a similar capacity, and is
not liable for any fee or payment to any such person, in connection with the
transactions contemplated by the Transaction Documents.

               SECTION 4.  Covenants of the Parties.

               (a) Operating Covenants. From and after the Closing Date and
until the earlier to occur of the exercise or expiration of the EIS Exchange
Right (as such term is defined in Section 6 hereof), the Company shall not
without the prior written consent of EIS: (i) encumber, pledge or otherwise
affect, in any respect, (A) any shares of Newco Common Stock owned by the
Company, including, without limitation, those shares of Newco Common Stock
transferable to EIS upon exercise by EIS of the EIS Exchange Right, or (B) its
ability to permit EIS to exercise the EIS Exchange Right in full, as provided
herein, or (ii) enter into any Significant Transaction (as such term is defined
in the Letter Agreement) with a director, officer or more than 20% beneficial
owner of Common Stock on other than an arm's length basis. From and after the
Closing Date and until the earlier to occur of the exercise or expiration of the
EIS Exchange Right, EIS shall not without the prior written consent of the
Company encumber, pledge or otherwise affect, in any respect, any shares of
Newco Common Stock owned by EIS.

               (b) Fully-diluted Stock Ownership. Notwithstanding any other
provision of this Agreement, in the event that EIS shall have determined that at
any time it (together with its affiliates, if applicable) holds or has the right
to receive Common Stock (or securities or rights, options or warrants
exercisable, exchangeable or convertible for or into Common Stock) representing
in the aggregate in excess of 19.9% of the Company's outstanding Common Stock on
a fully diluted basis (assuming the exercise, exchange or conversion of such
securities beneficially owned by EIS or its affiliates, but not the exercise,
exchange or conversion of any other similar securities), EIS shall have the
right, in its sole discretion, rather than acquiring such securities from the
Company, to exchange such number of securities, as are necessary to bring its
holdings to below 19.9% of the voting securities of the Company, for non-voting,
convertible liquidation preferred stock of the Company (which shall be
reasonably satisfactory to each of the Company and EIS), which equity securities
shall be entitled to all of the other rights and benefits of the Common Stock.
In the event that EIS shall undertake to exercise such right, EIS shall 


                                       8
<PAGE>   9

retain the additional right to exchange such new class of equity security for
Common Stock, in its discretion at any time. Each of the Company and EIS shall
use commercially reasonable effort to effect such transactions and any required
subsequent conversions or adjustments to such securities, on a quarterly basis,
within 10 business days of the end of each of EIS' fiscal quarter.

               (c)  Use of Proceeds. The Company shall use the proceeds of (i)
the issuance and sale of the Series A Preferred Stock solely to meet its initial
capitalization obligations to Newco as described in the JDOA, and (ii) the
issuance and funding of the Note solely to meet its developmental funding
obligations to Newco, as described in the Funding Agreement.

               (d)  Confidentiality; Non-Disclosure.

                    (i)       Subject to clauses (ii) and (iii) below, from and
        after the date hereof, neither the Company nor EIS (nor their respective
        affiliates) shall disclose to any person or entity this Agreement or the
        other Transaction Documents or the contents thereof or the parties
        thereto, except that such parties may make such disclosure (x) to their
        directors, officers, employees and advisors, so long as they shall have
        advised such persons of the obligation of confidentiality herein and for
        whose breach or default the disclosing party shall be responsible, or
        (y) as required by applicable law, rule, regulation or judicial or
        administrative process, provided that the disclosing party uses
        reasonable efforts to obtain an order or ruling protecting the
        confidentiality of confidential information of the other party contained
        herein or therein. The parties shall be entitled to seek injunctive or
        other equitable relief in respect of any breach or threatened breach of
        the foregoing covenant without the requirement of posting a bond or
        other collateral.

                    (ii)      Prior to issuing any press release or public 
        disclosure in respect of this Agreement or the transactions contemplated
        hereby, the party proposing such issuance shall obtain the consent of
        the other party to the contents thereof, which consent shall not be
        unreasonably withheld or delayed; it being understood that if such
        second party shall not have responded to such consent request within
        five business days, such consent shall be deemed given.

                    (iii)     This Section 4(d) shall not be construed to 
        prohibit disclosure by the receiving party of any information which has
        not been previously determined to be confidential by the disclosing
        party, or which shall have become publicly disclosed (other than by
        breach of the receiving party's obligations hereunder).

               (e)  Further Assurances. From and after the date hereof, each of
the parties hereto agree to do or cause to be done such further acts and things
and deliver or cause to be delivered to each other such additional assignments,
agreements, powers and instruments, as each may reasonably require or deem
advisable to carry into effect the purposes of this Agreement and the other
Transaction Documents.

               SECTION 5.  Standstill.


                                       9
<PAGE>   10

               (a) Provided that nothing contained herein will prevent or
prohibit EIS from purchasing Voting Stock (as defined below) of the Company
pursuant to subsection 5(b) or from acquiring Voting Stock pursuant to the
conversion of the Series A Preferred Stock or the Note or the exercise of the
Warrant in accordance with their respective terms, EIS will not, directly or
indirectly, without the prior consent of a majority of the Board of Directors of
the Company (the "Board"), (i) acquire (or offer or agree to acquire) any Voting
Stock if, as a result, EIS would beneficially own more than 20% of the then
outstanding Voting Stock; (ii) directly or indirectly solicit proxies or
consents or become a participant in a solicitation (as such terms are defined in
Regulation 14A under the Exchange Act) in opposition to the recommendation of
the majority of the Board for a Takeover Event (as defined below); or (iii)
transfer to any third party, other than its "affiliates," "associates" (as such
terms are defined in Rule 12b-2 under the Exchange Act), officers, directors or
employees, the right to vote any Voting Stock except in connection with the
transfer of ownership of such Voting Stock for fair value. EIS also agrees that
it will not advise, assist or encourage any third party to do any of the
foregoing. Notwithstanding the foregoing, EIS will not be obligated to dispose
of any Voting Stock it owns if its percentage ownership is increased as a result
of a decrease in the number of shares of Voting Stock outstanding.

               (b) The provisions of this Section 5 will terminate: (i) if EIS
owns less than 2% of Voting Stock; (ii) if EIS makes a tender offer to purchase
100% of the then outstanding Voting Stock and such offer is accepted by the
holders of more than 50% of the Voting Stock not owned directly or indirectly by
EIS (which tender offer, if it contains such acceptance as a condition to
consummation, will not be a violation of subsection 5(a)); (iii) if any person
or group, excluding EIS, makes a bona fide offer to acquire Voting Stock which
would, if successful, result in the bidder's beneficial ownership of at least
15% of the then outstanding Voting Stock; or (iv) upon the third anniversary of
the date of this Agreement. For purposes of clause (iii), the provisions of this
Section 5 will not terminate until such time as such offer is rejected or
revoked, however, EIS will not have to dispose of any Voting Stock acquired by
it before such offer is rejected or revoked, and EIS will be permitted to
consummate pending transactions which are not cancelable without a penalty.

               (c) The Company will give EIS prompt notice of the receipt by the
Company of any written notice couched in such terms as to put the Company
reasonably on notice of the likelihood that a person or group has acquired or is
proposing to acquire an aggregate position of at least 5% of the Voting Stock,
the Company's receiving any bona fide offer to purchase or acquire 15% or more
of the Voting Stock or all or substantially all of the assets of the Company,
and any Board determination to seek an acquiror for in excess of 50% of the
Voting Stock.

               (d) EIS will cause its affiliates and associates to comply with
the provisions of this Section 5, whether directly or indirectly, individually
or as part of a "group" (as such term is defined in Rule 13d-5 under the
Exchange Act). When used in this Section 5, the term EIS includes EIS together
with its affiliates and associates.


                                       10
<PAGE>   11

               (e) For purposes of this Section 5, the term "Takeover Event"
means any proposal for any merger or business combination involving the Company
or any of its subsidiaries, the purchase or sale of any assets of the Company or
any of its subsidiaries, or the purchase of any of the Voting Stock, by tender
offer or otherwise (except pursuant to the exercise of rights, warrants, options
or similar securities distributed by the Company to holders of Voting Stock
generally), and the term "Voting Stock" means the Common Stock and any preferred
stock of the Company possessing voting rights and eligible to participate in
votes of all of the Company's stockholders pursuant to the Company's Certificate
of Incorporation and Delaware law, and includes any options, convertible
securities or other rights to acquire such stock.

               SECTION 6. Conversion and Exchange Rights. The Certificate of
Designations sets forth certain rights of the holders of shares of Series A
Preferred Stock to convert such shares of preferred stock into newly issued
shares of Common Stock, or to exchange such shares of Series A Preferred Stock
into certain shares of Newco Common Stock owned by the Company (the "EIS
Exchange Right"), both on the terms and conditions set forth therein.

               SECTION 7. Survival Period. The representations and warranties of
the Company and EIS contained herein shall survive for a period of two years
from and after the date hereof.

               SECTION 8. Notices. All notices, demands and requests of any kind
to be delivered to any party in connection with this Agreement shall be in
writing and shall be deemed to have been duly given if personally or hand
delivered or if sent by an internationally-recognized overnight delivery or by
registered or certified mail, return receipt requested and postage prepaid, or
by facsimile transmission (with receipt confirmed by telephone) addressed as
follows:

                      (i) if to the Company, to:

                      Isis Pharmaceuticals, Inc.
                      2292 Faraday Avenue
                      Carlsbad, CA 92008
                      Attn:  B. Lynne Parshall
                      Tel.: 760-603-2460
                      Fax:  760-931-9639

                      with a copy to:
                      Cooley Godward LLP
                      4365 Executive Drive
                      San Diego, CA 92121
                      Attn:  L. Kay Chandler, Esq.
                      Tel.:  619-550-6000
                      Fax:  619-453-3555


                                       11
<PAGE>   12

                      (ii) if to EIS, to:

                      Elan International Services, Ltd.
                      Flatts, Smiths Parish
                      Bermuda, FL 04
                      Attention: Director
                      Tel.:  441-292-9169
                      Fax:  441-292-2224

                      with a copy to:

                      Brock Silverstein LLC
                      153 East 53rd Street , 56th Floor
                      New York, New York 10022
                      Attention: David Robbins, Esq.
                      Tel.: 212-371-2000
                      Fax:  212-371-5500

or to such other address as the party to whom notice is to be given may have
furnished to the other party hereto in writing in accordance with provisions of
this Section 8. Any such notice or communication shall be deemed to have been
effectively given (i) in the case of personal or hand delivery, on the date of
such delivery, (ii) in the case of an internationally-recognized overnight
delivery service, on the second business day after the date when sent, (iii) in
the case of mailing, on the fifth business day following that day on which the
piece of mail containing such communication is posted, and (iv) in the case of
facsimile transmission, on the date of telephone confirmation of receipt.

               SECTION 9. Entire Agreement. This Agreement and the other
Transaction Documents contain the entire understanding of the parties with
respect to the subject matter hereof and thereof and supersede all prior
agreements and understandings among the parties with respect thereto.

               SECTION 10. Amendments. This Agreement may not be modified or
amended, or any of the provisions hereof waived, except by written agreement of
the Company and EIS.

               SECTION 11. Counterparts and Facsimile. The Transaction Documents
may be executed in any number of counterparts, and each such counterpart hereof
shall be deemed to be an original instrument, but all such counterparts together
shall constitute one agreement. Each of the Transaction Documents may be signed
and delivered to the other party by facsimile transmission; such transmission
shall be deemed a valid signature.

               SECTION 12. Headings. The section and paragraph headings
contained in this Agreement are for reference purposes only and shall not affect
in any way the meaning or interpretation of the Agreement.


                                       12
<PAGE>   13

               SECTION 13. Governing Law. This Agreement shall be governed by
and construed in accordance with the laws of the State of New York, without
giving effect to principles thereof relating to conflicts of laws, except that
all issues concerning the relative rights of the Company and its stockholders
shall be governed by the Delaware General Corporation Law, without giving effect
to the principles thereof relating to conflicts of laws.

               SECTION 14.  Arbitration.

               (a) Any dispute under the Transaction Documents which is not
settled by mutual consent shall be finally settled by binding arbitration,
conducted in accordance with the Commercial Arbitration Rules of the American
Arbitration Association by one arbitrator appointed in accordance with said
rules. Such arbitrator shall be reasonably satisfactory to each of the parties;
provided, that if the parties are unable to agree upon the identity of such
arbitrator within 15 days of demand by either party, then either party shall
have the right to petition a presiding justice of the Supreme Court of New York,
New York County, to appoint an arbitrator. The arbitration shall be held in New
York, New York and the arbitrator shall be an independent expert in
pharmaceutical product development and marketing (including clinical development
and regulatory affairs).

               (b) The arbitrator shall determine what discovery will be
permitted, consistent with the goal of limiting the cost and time which the
parties must expend for discovery; provided the arbitrator shall permit such
discovery as they deem necessary to permit an equitable resolution of the
dispute. Any written evidence originally in a language other than English shall
be submitted in English translation accompanied by the original or a true copy
thereof. The costs of the arbitration, including administrative and arbitrators'
fees, shall be shared equally by the parties and each party shall bear its own
costs and attorneys' and witness' fees incurred in connection with the
arbitration.

               (c) In rendering judgment, the arbitrator shall be instructed by
the parties that he shall be permitted to select solely from between the
proposals for resolution of the relevant issue presented by each party, and not
any other proposal. A disputed performance or suspended performances pending the
resolution of the arbitration must be completed within 30 days following the
final decision of the arbitrators or such other reasonable period as the
arbitrators determine in a written opinion.

               (d) Any arbitration under the Transaction Documents shall be
completed within one year from the filing of notice of a request for such
arbitration. The arbitration proceedings and the decision shall not be made
public without the joint consent of the parties and each party shall maintain
the confidentiality of such proceedings and decision unless otherwise permitted
by the other party.

               (e) The parties agree that the decision shall be the sole,
exclusive and binding remedy between them regarding any and all disputes,
controversies, claims and counterclaims 


                                       13
<PAGE>   14

presented to the arbitrators. Application may be made to any court having
jurisdiction over the party (or its assets) against whom the decision is
rendered for a judicial recognition of the decision and an order of enforcement.

               SECTION 15. Expenses. Each of the parties shall be responsible
for its own costs and expenses incurred in connection with the transactions
contemplated hereby and by the other Transaction Documents.

               SECTION 16. Schedules, etc. All statements contained in any
exhibit or schedule delivered by the parties hereto, or in connection with the
transactions contemplated hereby, are an integral part of this Agreement and
shall be deemed representations and warranties hereunder.

               SECTION 17. Assignments and Transfers. This Agreement and all of
the provisions hereof shall be binding upon and inure to the benefit of the
parties hereto and their respective successors and permitted assigns. This
Agreement, the shares of Series A Preferred Stock and Common Stock being
purchased hereunder by EIS, the Note, the Warrant, and the shares of Common
Stock underlying the Series A Preferred Stock, the Note and the Warrant may be
transferred by EIS to its affiliates and subsidiaries, as well as any
off-balance sheet special purpose entity established by EIS, provided, however,
that EIS shall remain liable for its obligations hereunder after any such
assignment. Other than as set forth above, no party shall transfer or assign
this Agreement, the shares of Series A Preferred Stock and Common Stock being
purchased hereunder by EIS, the Note, the Warrant, and the shares of Common
Stock underlying the Series A Preferred Stock, the Note and the Warrant, or any
interest therein, without the prior written consent of the other party;
provided, however, that no consent shall be required in connection with any such
transfer or assignment by a party pursuant to a sale of all or substantially all
of the business of such party to which the Transaction Documents relate, whether
by merger, sale of stock, sale of assets or otherwise.

               SECTION 18. Severability. In case any provision of this Agreement
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not be in any way affected or
impaired thereby.

                            [Signature Page Follows.]


                                       14
<PAGE>   15

               IN WITNESS WHEREOF, each of the undersigned has duly executed
this Agreement as of the date first written above.

                                       ISIS PHARMACEUTICALS, INC.



                                       By:   /s/ B. Lynne Parshall
                                            ------------------------------------
                                            B. Lynne Parshall
                                            Executive Vice President


                                       ELAN INTERNATIONAL SERVICES, LTD.


                                       By:  /s/ Kevin Insley
                                            ------------------------------------
                                            Kevin Insley
                                            President

<PAGE>   1
                                                                    EXHIBIT 10.3

THIS CONVERTIBLE PROMISSORY NOTE AND THE SHARES OF COMMON STOCK ISSUABLE UPON
CONVERSION HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, AND MAY NOT UNDER ANY CIRCUMSTANCES BE SOLD, TRANSFERRED OR OTHERWISE
DISPOSED OF WITHOUT AN EFFECTIVE REGISTRATION STATEMENT FOR SUCH SECURITIES
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE STATE
SECURITIES LAWS OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT
REGISTRATION IS NOT REQUIRED UNDER SUCH ACT OR APPLICABLE STATE SECURITIES LAWS.

THE TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS ALSO SUBJECT
TO THE RESTRICTIONS CONTAINED IN THAT CERTAIN SECURITIES PURCHASE AGREEMENT,
DATED APRIL 20, 1999, BY AND BETWEEN ISIS PHARMACEUTICALS, INC. AND ELAN
INTERNATIONAL SERVICES, LTD.


                           ISIS PHARMACEUTICALS, INC.
                           CONVERTIBLE PROMISSORY NOTE


U.S. $18,400,000                                           APRIL 20, 1999
                                                           NEW YORK, NEW YORK

               The undersigned, ISIS PHARMACEUTICALS, INC., a Delaware
corporation with offices at 2292 Faraday Avenue, Carlsbad, California 92008 (the
"Company"), unconditionally promises to pay to ELAN INTERNATIONAL SERVICES,
LTD., a Bermuda private limited company ("EIS"), or its permitted assigns,
transferees and successors as provided herein (collectively, the "Holder"), on
April 19, 2005 (the "Maturity Date"), at such place as may be designated by the
Holder to the Company, the principal amount outstanding hereunder (not to exceed
U.S.$18,400,000), together with interest thereon accrued at a rate per annum
equal to 12.0%, from and after the date of the initial disbursement of funds
hereunder (the "Original Issue Date"), compounded on a semi-annual basis, the
initial such compounding to commence on the date that is six months from and
after the Original Issue Date (each such date, a "Compounding Date").

        SECTION 1.  SECURITIES PURCHASE AGREEMENT AND FUNDING AGREEMENT.

               This Note is issued pursuant to a Securities Purchase Agreement
dated as of the date hereof, by and between the Company and EIS (as amended at
any time, the "Securities Purchase Agreement"), and is intended to be afforded
the benefits thereof, including the representations and warranties set forth
therein. The Company shall use the proceeds of the


<PAGE>   2

issuance and sale of this Note solely in accordance with the provisions set
forth therein and in a certain Funding Agreement, dated as of the date hereof
(as amended at any time, the "Funding Agreement"), by and among Elan
Corporation, plc, an Irish public limited company and the parent corporation of
EIS, EIS and the Company, and as described in Section 6 below. Capitalized terms
used but not otherwise defined herein shall have the meanings given such terms
in the Securities Purchase Agreement.

        SECTION 2.  DISBURSEMENTS.

        (a)    From and after the date that is 10 days after the approval of
Newco's budget and until March 31, 2002, disbursements shall be made by the
Holder to the Company hereunder in minimum increments of U.S.$250,000 (except in
the event that an amount less than U.S.$250,000 shall be remaining and available
for funding hereunder, in which case such lesser amount may be funded
hereunder); provided, that the Company shall deliver notice of a request
therefor to the Holder in the form attached hereto as Exhibit A (the
"Disbursement Notice"), together with an Officer's Certificate confirming that
as of such date no Event of Default exists hereunder; the Holder shall, subject
to the terms and conditions hereof, fund such amount within 10 business days of
the receipt of the Disbursement Notice, subject to the receipt by the Holder of
any required approvals under the Mergers and Takeovers (Control) Acts 1978-1996.
A "business day" is any day that commercial banks are open for the transaction
of business in the City of New York.

        (b)    The Holder shall not be required to disburse more than a maximum
principal amount of U.S.$18,400,000.

        SECTION 3.  PAYMENTS AND COVENANTS.

        (a)    Unless earlier converted in accordance with the terms of Section 
4 below, or prepaid in accordance with the terms hereof, the entire outstanding
principal amount of this Note, together with any accrued and unpaid interest
thereon, shall be due and payable on the Maturity Date.

        (b)    Accrued interest hereon shall not be paid in cash, but shall be
capitalized and added to principal amount outstanding hereunder on each
Compounding Date.

        (c)    This Note may be prepaid by the Company, in whole or in part,

               (i)       in cash, upon not less than 30 days' prior written 
        notice to EIS; or

               (ii)      in shares of the Company's Common Stock, par value 
        $.001 per share (the "Common Stock"), at any time, at a price equal to
        the average of the closing price of the Common Stock for the 60 trading
        days ending two business days prior to the date of repayment.


                                       2
<PAGE>   3

        SECTION 4.  CONVERSION. 

        (a)    Conversion Right.

               (i)       From and after the Original Issue Date and until this 
        Note is repaid in full, the Holder shall have the right from time to
        time, in its sole discretion, to convert the outstanding principal
        amount and accrued and unpaid interest then-outstanding hereunder, on a
        per tranche basis (each, a "Conversion Right"), into such number of
        shares of Common Stock that shall be obtained by dividing the sum of the
        outstanding principal amount of such tranche and all accrued and unpaid
        interest thereon by a per share price calculated as 150% of the average
        of the closing price of the Common Stock for the 60 trading days ending
        two business days prior to the date of disbursement of such tranche
        (each, a "Conversion Price").

               (ii)      The Holder shall be entitled to exercise a Conversion 
        Right upon at least five days' prior written notice to the Company, such
        notice to be in the form attached hereto as Exhibit B. Within 10 days of
        the conversion date specified in such notice, the Company shall issue
        stock certificates to EIS representing the aggregate number of shares of
        Common Stock due to EIS as a result of such conversion.

        (b)    Reclassification, Etc. In case of (i) any reclassification,
reorganization, change or conversion of securities of the class issuable upon
conversion of the outstanding principal amount and accrued and unpaid interest
then-outstanding hereunder (other than a change in par value, or from par value
to no par value), or (ii) any consolidation of the Company with or into another
entity (other than a merger or consolidation with another entity in which the
Company is the surviving entity and that does not result in any reclassification
or change of the class of securities issuable upon the conversion of the
outstanding principal amount and accrued and unpaid interest then-outstanding
hereunder), or (iii) any sale of all or substantially all the assets of the
Company (excluding the transactions contemplated by the Transaction Documents),
then the Company, or such successor or purchasing entity, as the case may be,
shall duly execute and deliver to the Holder a new Note or a supplement hereto
(in form and substance reasonably satisfactory to the Holder of this Note), so
that the Holder shall have the right to receive, at a total purchase price not
to exceed the outstanding principal amount and accrued and unpaid interest
then-outstanding hereunder, and in lieu of the shares of Common Stock
theretofore issuable upon the conversion of such outstanding principal amount
and accrued and unpaid interest then-outstanding hereunder, the kind and amount
of shares of stock and other securities, money and property receivable upon such
reclassification, reorganization, change, merger, consolidation or conversion by
a holder of the number of shares of Common Stock then issuable under this Note.
Such new Note shall provide for adjustments that shall be as nearly equivalent
as may be practicable to the adjustments provided for in this Section 4. The
provisions of this Section 4(b) shall similarly attach to successive
reclassifications, reorganizations, changes, mergers, consolidations, transfers
or conversions.

        (c)    No Impairment. The Company will not, by amendment of its 
Certificate of Incorporation or by-laws or through any reorganization,
recapitalization, transfer of assets, 


                                       3
<PAGE>   4

consolidation, merger, dissolution, issue or sale of securities or any other
voluntary action, avoid or seek to avoid the observance or performance of any of
the terms to be observed or performed hereunder by the Company, but will at all
times in good faith assist in the carrying out of all the provisions of this
Section 4 and in the taking of all such action as may be necessary or
appropriate in order to protect the rights of EIS against impairment. This
provision shall not restrict the Company from otherwise amending and/or
restating its Certificate of Incorporation in accordance with Delaware General
Corporation Law.

        (d)    Notice of Adjustments. Whenever the consideration issuable upon a
conversion hereunder shall be changed pursuant to this Section 4, the Company
shall prepare a certificate setting forth, in reasonable detail, the event
requiring the change and the kind and amount of shares of stock and other
securities, money and property subsequently issuable upon a conversion hereof.
Such certificate shall be signed by its chief financial officer and shall be
delivered to EIS.

        (e)    Fractional Shares; Rounding. No fractional shares of Common Stock
will be issued in connection with any exercise hereunder, but in lieu of such
fractional shares the Company shall make a cash payment therefor based on the
applicable Conversion Price. All calculations under this Section 4 shall be made
to the nearest cent or to the nearest one-hundredth of a share, as the case may
be.

        SECTION 5.  EXCHANGE RIGHT.

        (a)    In the event that EIS shall exercise the EIS Exchange Right, a
principal amount outstanding hereunder equal to 30.1% of the total amount of
development funding expenditures to date provided by each of the parties to
Newco, in accordance with the terms of the Funding Agreement, together with all
accrued interest thereon, shall be canceled upon the closing of such exchange.

        (b)    In no event shall the amount determined in accordance with
subsection (a) above exceed the aggregate principal amount issued hereunder and
accrued interest thereon.

        SECTION 6.  USE OF PROCEEDS.

               The Company shall use the proceeds of this Note solely for
developmental funding of Newco, provided that the Board of Directors of Newco
has determined that such developmental funding is necessary (which shall include
the consent of at least one of the Company's directors and the EIS director).

        SECTION 7.  EVENTS OF DEFAULT.

               The occurrence of any of the following events shall constitute an
event of default (an "Event of Default"):


                                       4
<PAGE>   5

        (a)    a default in the payment of the principal amount of this Note, 
when and as the same shall become due and payable;

        (b)    a default in the payment of any accrued and unpaid interest on 
this Note, when and as the same shall become due and payable;

        (b)    a material breach by the Company of its obligations under the 
JDOA or the Isis License Agreement, which breach remains uncured 60 days after
written notice thereof by EIS; provided, however, that (x) if the Company has
proposed a course of action to rectify the breach and is acting in good faith to
rectify same but has not cured the breach by the 60th day, such period shall be
extended by such period as is reasonably necessary to permit the breach to be
rectified and (y) if such default involves a good faith dispute regarding the
amount of any required payment, provided any undisputed amount is paid, such
default shall be stayed and the remainder may be withheld for a reasonable
period during which a good faith resolution of the amount owed is being pursued;

        (c)    a distress, execution, sequestration or other process is levied 
or enforced upon the Company or sued out against a material part of its property
which is not discharged or challenged within 30 days;

        (d)    the Company is unable to pay its debts in the normal course of
business;

        (e)    the Company ceases wholly or substantially to carry on its 
business, otherwise than for the purpose of a reconstruction or amalgamation,
without the prior written consent of the EIS (such consent not to be
unreasonably withheld);

        (f)    the appointment of a liquidator, receiver, administrator, 
examiner, trustee or similar officer of the Company or over all or substantially
all of its assets under the law; or

        (g)    any other termination of the JDOA.

        SECTION 8.  REMEDIES IN THE EVENT OF DEFAULT.

        (a)    In the case of any Event of Default by the Company, the Holder, 
may in its sole discretion, demand that the aggregate amount of funds advanced
to the Company under this Note and outstanding hereunder and accrued and unpaid
interest thereon shall, in addition to all other rights and remedies of the
Holder hereunder and under applicable law, be and become immediately due and
payable upon written notice delivered by the Holder to the Company.
Notwithstanding the preceding sentence, the rights of the Holder as set forth in
Section 4 hereunder shall survive any such acceleration and payment. If the
Holder shall accelerate and be paid and then elect to exercise the Conversion
Right, the Holder shall pay the Company for shares of Common Stock issued under
such Conversion Right.

        (b)    The Company hereby waives demand and presentment for payment, 
notice of nonpayment, protest and notice of protest, diligence, filing suit, and
all other notice and promises


                                       5
<PAGE>   6

to pay the Holder its costs of collection of all amounts due hereunder,
including reasonable attorneys' fees.

        (c) In the case of any Event of Default under this Note by the Company
this Note shall continue to bear interest after such default at the interest
rate otherwise in effect hereunder plus 3% per annum (but in any event not in
excess of the maximum rate of interest permitted by applicable law).

        SECTION 9.  VOTING RIGHTS.

               This Note shall not entitle the holder hereof to any voting
rights or other rights as a stockholder of the Company prior to its conversion.

        SECTION 10.  SENIORITY.

        (a)    The Holder acknowledges and agrees that the obligations evidenced
hereby are subordinate in right to payment in full of interest and principal
relating to the Company's 14% Senior Subordinated Discount Notes due November
2007 (the "Discount Notes") and therefore the obligations evidenced hereby are
"Subordinated Indebtedness" as defined in that certain Purchase Agreement, dated
October 24, 1997, between the Company and the purchasers listed on Schedule I
thereto (the "Purchase Agreement"); it being understood that in the event there
is any event of default in respect of the Purchase Agreement, the Company shall
not pay to the Holder hereof in cash any amounts due hereunder until such event
of default is cured or waived pursuant to the terms of such indenture.

        (b)    The Company shall not incur any indebtedness for money borrowed
which shall rank senior to this Note without the prior written consent of the
Holder; provided, however, that the Company may incur additional indebtedness
which ranks pari passu with the obligations evidenced hereby.

        SECTION 11.  MISCELLANEOUS.

        (a)    EIS may assign this Note to its affiliates and subsidiaries, as 
well as any off-balance sheet special purpose entity established by EIS. This
Note and all of the provisions hereof shall be binding upon and inure to the
benefit of the parties hereto and their respective successors and permitted
assigns; provided, however, that EIS and the Company shall remain liable for
their respective obligations hereunder after any such assignment.

        (b)    All notices, demands and requests of any kind to be delivered to 
any party in connection with this Agreement shall be in writing and shall be
deemed to have been duly given if personally delivered or if sent by
nationally-recognized overnight courier or by registered or certified mail,
return receipt requested and postage prepaid, or by facsimile transmission,
addressed as follows:


                                       6
<PAGE>   7

                             (i) if to the Company:

                             Isis Pharmaceuticals, Inc.
                             2292 Faraday Avenue
                             Carlsbad, CA 92008
                             Attn: B. Lynne Parshall
                             Tel.: 760-603-2460
                             Fax:  760-931-9639

                             with a copy to:

                             Cooley Godward LLP
                             4365 Executive Drive
                             San Diego, CA 92121
                             Attention: L. Kay Chandler, Esq.
                             Tel:  619-550-6000
                             Fax:  619-453-3555

                             (ii) if to EIS, to:

                             Elan International Services, Ltd.
                             102 St. James Court
                             Flatts, Smiths Parish
                             Bermuda  SL04
                             Attention: President
                             Tel:  441-292-9169
                             Fax:  441-292-2224

                             with a copy to:

                             Brock Silverstein LLC
                             153 East 53rd Street
                             New York, New York 10022
                             Attention: David Robbins, Esq.
                             Tel:  212-371-2000
                             Fax:  212-371-5500

Each party, by written notice given to the other in accordance with this Section
11(b) may change the address to which notices, other communication or documents
are to be sent to such party. All notices, other communications or documents
shall be deemed to have been duly given when received. Any such notice or
communication shall be deemed to have been effectively given, (a) in the case of
personal delivery, on the date of such delivery, (b) in the case of
nationally-recognized overnight courier, on the second business day after the
date when sent, (c) in the case of mailing, on the fifth business day following
that day on which the piece of mail 


                                       7
<PAGE>   8

containing such communication is posted, and (d) in the case of facsimile
transmission, on the date of telephone conformation of receipt.

        (c)    This Note may not be modified or amended, or any of the 
provisions hereof waived, except by written agreement of the Company and EIS.

        (d)    This Note shall be governed by and construed in accordance with 
the laws of the State of New York, without giving effect to principles thereof
relating to conflicts of laws, except that all issues concerning the relative
rights of the Company and its stockholders shall be governed by the Delaware
General Corporation Law, without giving effect to the principles thereof
relating to conflicts of laws.

        (e)    This Note may be executed in any number of counterparts, and each
such counterpart hereof shall be deemed to be an original instrument, but all
such counterparts together shall constitute one note. The Note may be signed and
delivered to the other party by a facsimile transmission; such transmission
shall be deemed a valid signature.

        (f)    Each of the parties shall be responsible for its own costs and
expenses incurred in connection with the transactions contemplated hereby.


                            [Signature page follows]


                                       8
<PAGE>   9

               IN WITNESS WHEREOF, the Company and EIS have executed this Note
on the date first above written.

                                            ISIS PHARMACEUTICALS, INC.


                                            By: /s/ B. Lynne Parshall
                                                ----------------------------
                                                B. Lynne Parshall
                                                Executive Vice President


                                            ELAN INTERNATIONAL SERVICES, LTD.


                                            By: /s/ Kevin Insley
                                                ----------------------------
                                                Kevin Insley
                                                President

                                       9
<PAGE>   10

                                    EXHIBIT A

                       NOTICE OF REQUEST FOR DISBURSEMENT

Date:

To:     Elan International Services, Ltd.

From:   Isis Pharmaceuticals, Inc.

Re:     Disbursement Request

- --------------------------------------------------------------------------------


        Pursuant to the terms of the Convertible Promissory Note (the "Note")
issued by Isis Pharmaceuticals, Inc. (the "Company") to Elan International
Services, Ltd. ("EIS"), dated April 20, 1999, the Company hereby notifies EIS of
its request for a disbursement thereunder in the amount of $_________. Please
provide funding in the requested amount to the Company in accordance with the
following wire instructions

                      [




                                                                 ]




                                            Sincerely,

                                            ISIS PHARMACEUTICALS, INC.


                                            By: ___________________________
                                                Name:
                                                Title:


<PAGE>   11

                                    EXHIBIT B

                NOTICE OF ELECTION TO EXERCISE A CONVERSION RIGHT


Date:

To:     Isis Pharmaceuticals, Inc.

From:   Elan International Services, Ltd.

Re:     Exercise of a Conversion Right

- --------------------------------------------------------------------------------

        Pursuant to the terms of the Convertible Promissory Note (the "Note")
issued by Isis Pharmaceuticals, Inc. (the "Company") to Elan International
Services, Ltd. ("EIS"), dated April 20, 1999, specifically Section 4 thereof,
EIS hereby notifies the Company of its intention to exercise a right of
conversion.

        Pursuant to Section 4 of the Note, EIS hereby elects to convert
[$__________]* in aggregate principal amount and all accrued and unpaid interest
thereon for shares of the Company's Common Stock, par value $.001 per share,
effective [__________, ____]

        We have instructed our attorneys to contact the Company to discuss the
timing and documentation of the conversion.


                                            Sincerely,

                                            ELAN INTERNATIONAL SERVICES, LTD.


                                            By: ___________________________
                                                Name:
                                                Title:

- --------
* Amount must represent one or more tranches drawn down by the Company under the
  Note.

<PAGE>   1
                                                                    EXHIBIT 10.4

THIS WARRANT AND THE SHARES OF COMMON STOCK ISSUABLE UPON EXERCISE HEREOF HAVE
NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT
UNDER ANY CIRCUMSTANCES BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF WITHOUT AN
EFFECTIVE REGISTRATION STATEMENT FOR SUCH SECURITIES UNDER THE SECURITIES ACT OF
1933, AS AMENDED, AND ANY APPLICABLE STATE SECURITIES LAWS OR AN OPINION OF
COUNSEL SATISFACTORY TO THE COMPANY THAT REGISTRATION IS NOT REQUIRED UNDER SUCH
ACT OR APPLICABLE STATE SECURITIES LAWS.

THE TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS ALSO SUBJECT
TO THE RESTRICTIONS CONTAINED IN THAT CERTAIN SECURITIES PURCHASE AGREEMENT,
DATED APRIL 20, 1999, BY AND BETWEEN ISIS PHARMACEUTICALS, INC. AND ELAN
INTERNATIONAL SERVICES, LTD.

                                                                  APRIL 20, 1999

                           ISIS PHARMACEUTICALS, INC.

                           WARRANT TO PURCHASE SHARES
                                 OF COMMON STOCK

        THIS CERTIFIES THAT for value received, Elan International Services,
Ltd., a Bermuda corporation ("EIS"), or its permitted transferees and successors
as provided herein (each, a "Holder"), is entitled to subscribe for and purchase
up to 215,000 shares, as adjusted pursuant to Section 4 (the "Shares"), of the
fully paid and nonassessable common stock, par value $.001 per share (the
"Common Stock"), of Isis Pharmaceuticals, Inc., a Delaware corporation (the
"Company"), with offices located at 2292 Faraday Avenue, Carlsbad, CA 92008, at
the price of U.S.$24.00 per share (such price, and such other prices that shall
result from time to time, from the adjustments specified in Section 4, the
"Warrant Price"), subject to the provisions and upon the terms and conditions
hereinafter set forth.

        1.     Term. The purchase right represented by this Warrant is 
exercisable, in whole or in part, at any time, and from time to time, from and
after the date hereof and until 5:00 p.m. Eastern Standard Time on April 19,
2004. To the extent not exercised at 5:00 p.m. Eastern Standard Time on April
19, 2004, this Warrant shall completely and automatically terminate and expire,
and thereafter it shall be of no force or effect.

        2.     Method of Exercise; Payment; Issuance of New Warrant.

               (a)  The purchase right represented by this Warrant may be
exercised by the Holder, in whole or in part and from time to time, by the
surrender of this Warrant (with the notice of exercise form attached hereto as
Annex A duly executed) at the principal office of the 


<PAGE>   2

Company and by the payment to the Company of an amount, in cash or other
immediately available funds, equal to the then-applicable Warrant Price per
Share multiplied by the number of Shares then being purchased or pursuant to the
cashless exercise procedure described below.

               (b)  In lieu of delivering cash or other immediately available
funds, the Holder may instruct the Company in writing to deduct from the number
of Shares that would otherwise be issued upon such exercise, a number of shares
of Common Stock equal to the quotient obtained from dividing (x) the product
obtained by multiplying (A) the number of Shares for which the Warrant is being
exercised and (B) the Warrant Price then in effect by (y) a price equal to the
average of the closing price of the Common Stock for the 60 trading days ending
two business days prior to the date of exercise.

               (c)  The persons or entities in whose name(s) any certificate(s)
representing Shares shall be issuable upon exercise of this Warrant shall be
deemed to have become the holder(s) of record of, and shall be treated for all
purposes as the record holder(s) of, the Shares represented thereby (and such
Shares shall be deemed to have been issued) immediately prior to the close of
business on the date or dates upon which this Warrant is properly exercised and
full payment for the Shares acquired pursuant to such exercise is made. Upon any
exercise of the rights represented by this Warrant, certificates for the Shares
purchased shall be delivered to the Holder hereof as soon as possible and in any
event within 15 days of receipt of such notice and payment, and unless this
Warrant has been fully exercised or expired, a new Warrant representing the
portion of Shares, if any, with respect to which this Warrant shall not then
have been exercised shall also be issued to the Holder hereof as soon as
possible and in any event within such 15-day period.

        3.     Stock Fully Paid, Reservation of Shares. All Shares that may be
issued upon the exercise of this Warrant, when issued upon exercise in
accordance with the terms hereof, will be duly and validly issued, fully paid
and nonassessable, will not be issued in violation of any preemptive or similar
rights. During the period within which this Warrant may be exercised, the
Company will at all times have authorized and reserved for the purpose of the
issue upon the exercise of the purchase rights evidenced by this Warrant a
sufficient number of shares of its Common Stock to provide for the exercise of
the rights represented by this Warrant.

        4.     Adjustment of Warrant Price and Number of Shares. The number and 
kind of securities purchasable upon the exercise of this Warrant and the Warrant
Price shall be subject to the adjustment from time to time upon the occurrence
of certain events, as follows:

               (a)  Reclassification, Etc. In case of (i) any reclassification,
reorganization, change or conversion of securities of the class issuable upon
exercise of this Warrant (other than a change in par value, or from par value to
no par value), or (ii) any consolidation of the Company with or into another
entity (other than a merger or consolidation with another entity in which the
Company is the surviving entity and that does not result in any reclassification
or change of outstanding securities issuable upon exercise of this Warrant), or
(iii) any sale of all or substantially all the assets of the Company, then the
Company, or such successor or purchasing entity, as the case may be, shall duly
execute and deliver to the Holder of this Warrant a new Warrant or a supplement
hereto (in form and substance reasonably satisfactory to the Holder of 


                                       2
<PAGE>   3

this Warrant), so that the Holder shall have the right to receive, at a total
purchase price not to exceed that payable upon the exercise of the unexercised
portion of this Warrant, and in lieu of the shares of Common Stock theretofore
issuable upon the exercise of this Warrant, the kind and amount of shares of
stock and other securities, receivable upon such reclassification,
reorganization, change or conversion by a holder of the number of shares of
Common Stock then purchasable under this Warrant. Such new Warrant shall provide
for adjustments that shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Section 4. The provisions of this Section 4(a)
shall similarly attach to successive reclassifications, reorganizations,
changes, and conversions.

               (b)  Subdivision or Combination of Shares. If the Company at any
time during which this Warrant remains outstanding and unexpired shall subdivide
or combine its Common Stock, (i) in the case of a subdivision, the Warrant Price
shall be proportionately decreased and the number of Shares purchasable
hereunder shall be proportionately increased, and (ii) in the case of a
combination, the Warrant Price shall be proportionately increased and the number
of Shares purchasable hereunder shall be proportionately decreased.

               (c)  No Impairment. The Company will not, by amendment of its
Certificate of Incorporation or by-laws or through any reorganization,
recapitalization, transfer of assets, consolidation, merger, dissolution, issue
or sale of securities or any other voluntary action, avoid or seek to avoid the
observance or performance of any of the terms to be observed or performed
hereunder by the Company, but will at all times in good faith assist in the
carrying out of all the provisions of this Section 4 and in the taking of all
such action as may be necessary or appropriate in order to protect the rights of
the Holder against impairment.

               (d)  Notice of Adjustments. Whenever the Warrant Price or the
number of Shares purchasable hereunder shall be adjusted pursuant to this
Section 4, the Company shall prepare a certificate setting forth, in reasonable
detail, the event requiring the adjustment, the amount of the adjustment, the
method by which such adjustment was calculated. Such certificate shall be signed
by its chief financial officer and shall be delivered to the Holder.

               (e)  Fractional Shares. No fractional shares of Common Stock will
be issued in connection with any exercise hereunder, but in lieu of such
fractional shares the Company shall make a cash payment therefor based on the
average of the closing price of the Common Stock for the 60 trading days ending
two business days prior to date of exercise.

               (f)  Cumulative Adjustments. No adjustment in the Warrant Price 
or the number of Shares purchasable hereunder shall be required under this
Section 4 until cumulative adjustments result in a concomitant change of 1% or
more of the Warrant Price or in the number of Shares purchasable upon exercise
of this Warrant as in effect prior to the last such adjustment; provided,
however, that any adjustment that by reason of this Section 4 are not required
to be made shall be carried forward and taken into account in any subsequent
adjustment. All calculations under this Section 4 shall be made to the nearest
cent or to the nearest one-hundredth of a share, as the case may be.


                                       3
<PAGE>   4

        5.     Compliance with Securities Act; Disposition of Warrant or Shares 
of Common Stock.

               (a)  The Holder, by acceptance hereof, confirms the investment
representations made in the Securities Purchase Agreement, dated April 20, 1999,
by and between the Company and EIS, with regard to this Warrant and the Shares
to be issued upon exercise hereof and, without limiting the foregoing, agrees
that this Warrant and the Shares to be issued upon exercise hereof are being
acquired for investment and that such Holder will not offer, sell or otherwise
dispose of this Warrant or any Shares to be issued upon exercise hereof except
under circumstances which will not result in a violation of applicable
securities laws. Upon exercise of this Warrant, unless the Shares being acquired
are registered under the Securities Act, or an exemption from the registration
requirements of the Securities Act is available, the Holder shall confirm in
writing, by executing an instrument in form reasonably satisfactory to the
Company, that the Shares so purchased are being acquired for investment and not
with a view toward distribution or resale. This Warrant and all Shares issued
upon exercise of this Warrant (unless registered under the Securities Act) shall
be stamped or imprinted with a legend in substantially the following form:

               THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER
               THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT UNDER ANY
               CIRCUMSTANCES BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF
               WITHOUT AN EFFECTIVE REGISTRATION STATEMENT FOR SUCH SECURITIES
               UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE
               STATE SECURITIES LAWS OR AN OPINION OF COUNSEL SATISFACTORY TO
               THE COMPANY THAT REGISTRATION IS NOT REQUIRED UNDER SUCH ACT OR
               APPLICABLE STATE SECURITIES LAWS.

               THE TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS
               ALSO SUBJECT TO THE RESTRICTIONS CONTAINED IN THAT CERTAIN
               SECURITIES PURCHASE AGREEMENT, DATED APRIL 20, 1999, BY AND
               BETWEEN ISIS PHARMACEUTICALS, INC. AND ELAN INTERNATIONAL
               SERVICES, LTD.

               (b)  (i) This Warrant may be transferred or assigned, in whole or
in part, by EIS to its affiliates and/or subsidiaries, as well as any
off-balance sheet special purpose entity established by EIS; provided, that the
transferor shall continue to be liable and obligated for its obligations
hereunder. Subject to the foregoing, this Warrant and all of the provisions
hereof shall be binding upon and inure to the benefit of the parties hereto and
their respective successors and permitted assigns. Other than as set forth
above, this Warrant may not be transferred or assigned by either party without
the prior written consent of the other; provided, however, that no consent shall
be required in connection with any transfer or assignment by a party pursuant to
a sale of all or substantially all of 


                                       4
<PAGE>   5

        the business of such party to which the Transaction Documents relate,
        whether by merger, sale of stock, sale of assets or otherwise.

               (ii)      With respect to any offer, sale or other disposition of
        this Warrant or any Shares acquired pursuant to the exercise of this
        Warrant prior to registration of such Shares, the Holder shall give
        written notice to the Company prior thereto, describing briefly the
        manner thereof, together with a written opinion of such Holder's
        counsel, if requested by the Company, to the effect that such offer,
        sale or other disposition may be effected without registration or
        qualification (under the Securities Act as then in effect or any other
        applicable federal or state securities law then in effect) of this
        Warrant or such Shares and indicating whether or not under the
        Securities Act certificates for this Warrant or such Shares to be sold
        or otherwise disposed of require any restrictive legend as to applicable
        restrictions on transferability in order to ensure compliance with the
        Securities Act. Promptly upon receiving such written notice and
        reasonably satisfactory opinion, if so requested, the Company, as
        promptly as practicable, shall notify such Holder that such Holder may
        sell or otherwise dispose of this Warrant or such Shares, all in
        accordance with the terms of the notice delivered to the Company. Each
        certificate representing this Warrant or the Shares thus transferred
        shall bear a legend as to the applicable restrictions on transferability
        in order to insure compliance with the Securities Act, unless in the
        aforesaid opinion of counsel for the Holder such legend is not required
        in order to insure compliance with the Securities Act. The Company may
        issue stop transfer instructions to its transfer agent in connection
        with such restrictions.

               (iii)     The shares of Common Stock underlying this Warrant are
        entitled to the benefit of certain registration rights as set forth in a
        Registration Rights Agreement dated as of the date hereof between the
        Company and the initial Holder named herein.

        6.     Rights as Shareholders. No Holder, as such, shall be entitled to 
vote or receive dividends or be deemed the holder of Shares or any other
securities of the Company which may at any time be issuable upon the exercise
hereof for any purpose, nor shall anything contained herein be construed to
confer upon the Holder, as such, any right to vote for the election of directors
or upon any matter submitted to shareholders at any meeting thereof, or to
receive notice of meetings, or to receive dividends or subscription rights or
otherwise until this Warrant is exercised and the Shares purchasable upon the
exercise hereof shall have become deliverable, as provided herein.

        7.     Miscellaneous.

               (a)  This Warrant may not be modified or amended, or any
provisions hereof waived, except by written agreement of the Company and the
Holder.

               (b)  Any notice, request or other document required or permitted
to be given or delivered to the Holder or the Company shall (i) be in writing,
(ii) be delivered personally or sent by mail or overnight courier to the
intended recipient to Holder at 102 St. James Court, Flatts, Smiths Parish,
Bermuda FL 04, Attn: President, or to the Company at the address indicated on
the first page of this Warrant, unless the recipient has given notice of another
address in 


                                       5
<PAGE>   6

accordance with this paragraph, and (iii) be effective on receipt if delivered
personally, two business days after dispatch if mailed, and one business day
after dispatch if sent by overnight courier service.

               (c)  The Company covenants to the Holder that upon receipt of
evidence reasonably satisfactory to the Company of the loss, theft, destruction
or mutilation of this Warrant and, in the case of any such loss, theft or
destruction, upon receipt of a bond or indemnity reasonably satisfactory to the
Company, or in the case of any such mutilation upon surrender and cancellation
of such Warrant, the Company will prepare and deliver a new Warrant, of like
tenor, in lieu of the lost, stolen, destroyed or mutilated Warrant.

               (d)  The descriptive headings of the several sections and
paragraphs of this Warrant are inserted for convenience only and do not
constitute a part of this Warrant.

               (e)  This Warrant shall be governed by and construed in 
accordance with the laws of the State of New York without giving effect to the
principles thereof relating to conflicts of laws, except that all issues
concerning the relative rights of the Company and its stockholders shall be
governed by the Delaware General Corporation Law, without giving effect to the
principles thereof relating to conflicts of laws.

               (f)  This Warrant may be executed in any number of counterparts,
and each such counterpart hereof shall be deemed to be an original instrument,
but all such counterparts together shall constitute one Warrant.

               (g)  Each of the parties shall be responsible for its own costs
and expenses incurred in connection with the transactions contemplated hereby.

                            [Signature page follows]


                                       6
<PAGE>   7


               IN WITNESS WHEREOF, Isis Pharmaceuticals, Inc. has caused this
Warrant to be executed and delivered by its duly authorized corporate officers
on the date first above written.


                                               ISIS PHARMACEUTICALS, INC.


                                               By: /s/ B. Lynne Parshall
                                                   --------------------------
                                                   B. Lynne Parshall
                                                   Executive Vice President


Attest:


By: /s/ Debbie Jo Blank
    ---------------------------
    Debbie Jo Blank


Agreed and accepted by:

ELAN INTERNATIONAL SERVICES, LTD.


By: /s/ Kevin Insley
    ---------------------------
    Kevin Insley
    President


<PAGE>   8

                                                                         ANNEX A

                               NOTICE OF EXERCISE


To:     Isis Pharmaceuticals, Inc.

1.      The undersigned hereby elects to purchase __________ shares of Common
        Stock of Isis Pharmaceuticals, Inc. pursuant to the terms of the
        attached Warrant, and

               [ ]  (a)  tenders herewith full payment of the purchase price of 
                         such shares, in cash or other immediately available 
                         funds.

               [ ]  (b)  instructs and agrees that pursuant to paragraph 2(b) of
                         the attached Warrant, __________ shares of Common Stock
                         be withheld in payment therefor.

2.      Please issue a certificate or certificates representing said shares in
        the name of the undersigned or in such other name or names as are
        specified below:



_____________________________________(Name)

_____________________________________(Address)


3.      The undersigned represents that the aforesaid shares are being acquired
        for the account of the undersigned for investment and not with a view
        to, or for resale in connection with, the distribution thereof and that
        the undersigned has no present intention of distributing or reselling
        such shares and otherwise confirms the investment representations made
        in Section 5 of the Warrant with regard to the shares of Common Stock
        being acquired.


Signature:__________________________

Name:_______________________________

Address:____________________________

Social Security or taxpayer identification 
number:

____________________________________

<PAGE>   1
                                                                    EXHIBIT 10.5

                           ISIS PHARMACEUTICALS, INC.
                          REGISTRATION RIGHTS AGREEMENT

               THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made as
of April 20, 1999 by and among ISIS PHARMACEUTICALS, INC., a Delaware
corporation (the "Company"), and ELAN INTERNATIONAL SERVICES, LTD., a Bermuda
corporation ("EIS").

                                R E C I T A L S:

               A. Pursuant to a securities purchase agreement dated as of the
date hereof by and between the Company and EIS (the "Purchase Agreement"), EIS
has acquired certain shares of common stock of the Company (the "Common Stock"),
Series A Convertible Preferred Stock of the Company (the "Series A Convertible
Preferred Stock"), a convertible promissory note (the "Note"), which Series A
Convertible Preferred Stock and Note are convertible into shares of Common
Stock, and a warrant (the "Warrant") to purchase shares of Common Stock.

               B. The execution of the Purchase Agreement has occurred on the
date hereof and it is a condition to the closing of the transactions
contemplated thereby that the parties execute and deliver this Agreement.

               C. The parties desire to set forth herein their agreement on the
terms and subject to the conditions set forth herein related to the granting of
certain registration rights to the Holders (as defined below) relating to the
Common Stock held by such Holders and the Common Stock underlying the Series A
Convertible Preferred Stock, the Note and the Warrant.

                               A G R E E M E N T:

               The parties hereto agree as follows:

               1.   Certain Definitions.  As used in this Agreement, the 
following terms shall have the following respective meanings:

               "Commission" shall mean the U.S. Securities and Exchange
Commission.

               "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect from time to time.

               "Holders" or "Holders of Registrable Securities" shall mean EIS
and any Person who shall have acquired Registrable Securities from EIS as
permitted herein, either individually or jointly, as the case may be, in a
transaction pursuant to which registration rights are transferred pursuant to
Section 10 hereof.


<PAGE>   2

               "Person" shall mean an individual, a partnership, a company, an
association, a joint stock company, a trust, a joint venture, an unincorporated
organization and a governmental or quasi-governmental entity, or any department,
agency or political subdivision thereof.

               "Registrable Securities" means (i) any shares of Common Stock
purchased pursuant to the Purchase Agreement, any shares of Common Stock issued
or issuable upon conversion of shares of Series A Convertible Preferred Stock
(or issued as dividends thereon) or the Note, and any shares of Common Stock
issued or issuable upon exercise of the Warrant, and (ii) any Common Stock
issued or issuable in respect of the securities referred to in clause (i) above
upon any stock split, stock dividend, recapitalization or similar event;
excluding in all cases, however, any Registrable Securities sold by a Person in
a transaction (including a transaction pursuant to a registration statement
under this Agreement and a transaction pursuant to Rule 144 promulgated under
the Securities Act) in which registration rights are not transferred pursuant to
Section 10 hereof.

               The terms "register," "registered" and "registration" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or order of the
effectiveness of such registration statement.

               "Registration Expenses" shall mean all expenses, other than
Selling Expenses, incurred by the Company in complying with Sections 2 or 3
hereof, including without limitation, all registration, qualification and filing
fees, exchange listing fees, printing expenses, escrow fees, fees and
disbursements of counsel for the Company, blue sky fees and expenses, the
expense of any special audits incident to or required by any such registration
and the reasonable fees and disbursements, not to exceed $10,000, of one counsel
for the Holders, such counsel to be selected by Holders holding a majority of
the Registrable Securities included in such registration.

               "Securities Act" shall mean the Securities Act of 1933, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect from time to time.

               "Selling Expenses" shall mean all underwriting discounts, selling
commissions and stock transfer taxes applicable to the securities registered by
the Holders and the costs of any accountants or other experts retained by the
Holders.

               2.  Demand Registration.

               (a) Requests for Registration. From and after the date hereof
until the date of filing of the Shelf Registration Statement (as defined
herein), any Holder or Holders who collectively hold Registrable Securities
representing at least 50% of the Registrable Securities then outstanding shall
have the right at any time from time to time, to request one registration under
the Securities Act of a minimum of 400,000 shares of Common Stock (as adjusted
for any combinations, consolidations, stock distributions, stock dividends or
other recapitalizations with respect to such shares) on Form S-1, S-2 or S-3 (if
available) or any similar registration statement (a "Demand Registration"), such
form to be selected by the Company as appropriate. The request for the Demand
Registration shall specify the approximate number of Registrable 


                                       2
<PAGE>   3

Securities requested to be registered. Within 20 days after receipt of any such
request, the Company will give written notice of such requested registration to
all other Holders of Registrable Securities. The Company shall include such
other Holders' Registrable Securities in such offering if they have responded
affirmatively within 20 days after the receipt of the Company's notice. The
Holders in aggregate will be entitled to request only one Demand Registration
hereunder. A registration will not count as the permitted Demand Registration
until it has become effective (unless such Demand Registration has not become
effective due solely to the fault of the Holders requesting such registration,
including a request by such Holders that such registration be withdrawn). The
Company shall pay all Registration Expenses in connection with any Demand
Registration whether or not such Demand Registration has become effective.

               (b) Priority on Demand Registration. If a Demand Registration is
an underwritten offering and the managing underwriters advise the Company in
writing that in their opinion the number of Registrable Securities requested to
be included in such offering exceeds the number of Registrable Securities which
can be sold in such offering without adversely affecting the marketability of
the offering, the Company will include in such registration such number of
Registrable Securities allocated pro rata among the Holders thereof based upon
the number of Registrable Securities owned by each such Holder. No securities
other than Registrable Securities hereunder shall be included in such Demand
Registration without the prior written consent of Holders who collectively hold
Registrable Securities representing at least 50% of the Registrable Securities
then outstanding.

               (c) Restrictions on Demand Registration. The Company may postpone
the filing or the effectiveness of a registration statement for a Demand
Registration if the Company determines in good faith that such Demand
Registration would reasonably be expected to have a material adverse effect on
any proposal or plan by the Company to engage in any financing, acquisition or
disposition of assets (other than in the ordinary course of business) or any
merger, consolidation, tender offer or similar transaction or would require
disclosure of any information that the board of directors of the Company
determines in good faith the disclosure of which would be detrimental to the
Company; provided, however, that in such event, the Holders initially requesting
such Demand Registration will be entitled to withdraw such request and, if such
request is withdrawn, such Demand Registration will not count as the permitted
Demand Registration hereunder and the Company will pay any Registration Expenses
in connection with such registration.

               (d) Selection of Underwriters. The Holders will have the right to
select the investment banker(s) and manager(s) to administer an offering
pursuant to the Demand Registration, subject to the Company's prior written
approval, which will not be unreasonably withheld or delayed.

               (e) Other Registration Rights. Except as provided in this
Agreement, so long as any Holder owns any Registrable Securities, the Company
will not grant to any Persons the right to request the Company to register any
equity securities of the Company, or any securities convertible or exchangeable
into or exercisable for such securities, which conflicts with the


                                       3
<PAGE>   4

rights granted to the Holders hereunder, without the prior written consent of
the Holders of at least 50% of the Registrable Securities.

               3. Shelf Registration Statement.

               (a)  The Company will cause, by May 30, 2002, to be prepared and
filed, and will use commercially reasonable to have declared effective with the
Commission within 60 days after filing, a Registration Statement on Form S-3 (or
such other form of registration statement that the Company shall determine and
that is reasonably satisfactory to the Holders) for an offering to be made on a
continuous basis pursuant to Rule 415 (or any similar rule that may be adopted
by the Commission) under the Securities Act covering the Registrable Securities
(the "Shelf Registration Statement"); provided, however, that if the Company
shall furnish to the Holders a certificate signed by any executive officer of
the Company stating that in the good faith judgment of the Board of Directors of
the Company it would be seriously detrimental to the Company to file the Shelf
Registration Statement at such time and it is therefore essential to defer the
filing of the Shelf Registration Statement, the Company shall have the right to
defer such filing for a reasonable period, not to exceed 60 days. The Shelf
Registration Statement may be terminated (and the Company shall have no
obligation to update the Shelf Registration Statement and may suspend sales
thereunder) at such time as all Registrable Securities can be sold by their
Holders within a three-month period without compliance with the registration
requirements of the Securities Act pursuant to Rule 144 (including Rule 144(k))
promulgated thereunder (the "Termination Date"). The Holder shall furnish to the
Company such information regarding themselves, the Registrable Securities held
by them, and the intended method of distribution of such securities as shall be
required to effect the Shelf Registration Statement. In that connection, each
Holder shall be required to represent that all such information which is given
is both complete and accurate in all material respects.

               (b)  So long as the Shelf Registration Statement is effective, 
the Company will furnish to the Purchaser as soon as practicable after available
(but in the case of the Company's Annual Report to Stockholders, within 120 days
after the end of each fiscal year of the Company), (i) one copy of (A) its
Annual Report to Stockholders (which Annual Report shall contain financial
statements audited in accordance with generally accepted auditing standards
certified by a national firm of certified public accountants), (B) if not
included in substance in the Annual Report to Stockholders, its Annual Report on
Form 10-K, (C) if not included in substance in its Quarterly Reports to
Stockholders, its quarterly reports on Form 10-Q, and (D) a full copy of the
particular Registration Statement covering the Registrable Securities (the
foregoing, in each case, excluding exhibits), (ii) upon the reasonable request
of any Holder, all exhibits excluded by the parenthetical in clause (i) of this
paragraph, in the form generally available to the public, and (c) upon the
reasonable request of any Holder, an adequate number of copies of the
prospectuses and supplements to supply to any other party requiring such
prospectuses.

               4. Expenses of Registration. Except as otherwise provided herein,
all Registration Expenses incurred in connection with all registrations pursuant
to Sections 2 and 3 shall be borne by the Company. All Selling Expenses relating
to securities registered on behalf of the Holders of Registrable Securities
shall be borne by such Holders.


                                       4
<PAGE>   5

               5.  Holdback Agreements.

               (a) The Company agrees (i) not to effect any public sale or
distribution of its equity securities, or any securities convertible into or
exchangeable or exercisable for such securities, for its own account during the
seven days prior to and during the 90-day period beginning on the effective date
of any underwritten Demand Registration (except (A) as part of such underwritten
registration, (B) pursuant to registration statements on Form S-4 or Form S-8 or
any successor form, (C) pursuant to a registration statement then in effect or
(D) as required under any existing contractual obligation of the Company),
unless the underwriters managing the registered public offering otherwise agree,
and (ii) to use reasonable efforts to cause each holder of at least 5% (on a
fully-diluted basis) of its outstanding Common Stock, or any securities
convertible into or exchangeable or exercisable for Common Stock, purchased from
the Company at any time after the date of this Agreement (other than in a
registered public offering) to agree not to effect any public sale or
distribution (including sales pursuant to Rule 144) of any such securities
during such periods (except as part of such underwritten registration, if
otherwise permitted), unless the underwriters managing the registered public
offering otherwise agree.

               (b) Each Holder agrees, if requested by the managing underwriter
or underwriters in an underwritten offering of securities of the Company, not to
effect any offer, sale, distribution or transfer, including a sale pursuant to
Rule 144 (or any similar provision then effect) under the Securities Act (except
as part of such underwritten registration), during the seven-day period prior
to, and during the 180-day period (or such shorter period as may be agreed to in
writing by the Company and the Holders of at least 50% of the Registrable
Securities) following the effective date of such Registration Statement to the
extent timely notified in writing by the managing underwriter or underwriters.

               6. Registration Procedures. Whenever the Company is under the
obligation to register Registrable Securities hereunder, the Company will use
all reasonable efforts to effect the registration and the sale of such
Registrable Securities, and pursuant thereto the Company will as expeditiously
as possible:

               (a) subject to Section 2(c) and 3(a) hereof, prepare and file
with the Commission a registration statement on any form for which the Company
qualifies with respect to such Registrable Securities and use all reasonable
efforts to cause such registration statement to become effective (provided that
before filing a registration statement or prospectus or any amendments or
supplements thereto, the Company will (i) furnish to the counsel selected by the
Holders copies of all such documents proposed to be filed, which documents will
be subject to the review of such counsel, and (ii) notify each Holder of
Registrable Securities covered by such registration of any stop order issued or
threatened by the Commission);

               (b) subject to Section 2(c), 3(b) and 6(e) hereof, prepare and
file with the Commission such amendments and supplements to such registration
statement and the prospectus used in connection therewith as may be necessary to
keep such registration statement effective for, in the case of a Demand
Registration, a period equal to the shorter of (i) six months and (ii) the time
by which all securities covered by such registration statement have been sold,


                                       5
<PAGE>   6

and in the case of the Shelf Registration Statement, until the Termination Date,
and comply with the provisions of the Securities Act with respect to the
disposition of all securities covered by such registration statement during such
period in accordance with the intended methods of disposition by the sellers
thereof set forth in such registration statement;

               (c) furnish to each seller of Registrable Securities such number
of copies of such registration statement, each amendment and supplement thereto,
the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such seller may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such seller;

               (d) use all reasonable efforts to register or qualify such
Registrable Securities under the securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable
Securities owned by such seller (provided that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this Section 6(d), (ii) subject itself
to taxation in any jurisdiction, or (iii) consent to general service of process
in any such jurisdiction);

               (e) notify each seller of such Registrable Securities, at any
time when a prospectus relating thereto is required to be delivered under the
Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading, and, at the request of any such seller, the Company will prepare
a supplement or amendment to such prospectus so that, as thereafter delivered to
the purchasers of such Registrable Securities, such prospectus will not contain
an untrue statement of a material fact or omit to state any fact necessary to
make the statements therein not misleading; provided, however, that the Company
shall not be required to amend the registration statement or supplement the
Prospectus for a period of up to six months if the board of directors determines
in good faith that to do so would reasonably be expected to have a material
adverse effect on any proposal or plan by the Company to engage in any
financing, acquisition or disposition of assets (other than in the ordinary
course of business) or any merger, consolidation, tender offer or similar
transaction or would require the disclosure of any information that the board of
directors determines in good faith the disclosure of which would be detrimental
to the Company, it being understood that the period for which the Company is
obligated to keep the Registration Statement effective shall be extended for a
number of days equal to the number of days the Company delays amendments or
supplements pursuant to this provision. Upon receipt of any notice pursuant to
this Section 6(e), the Holders shall suspend all offers and sales of securities
of the Company and all use of any prospectus until advised by the Company that
offers and sales may resume, and shall keep confidential the fact and content of
any notice given by the Company pursuant to this Section 6(e);

               (f) cause all such Registrable Securities to be listed on each
securities exchange on which similar securities issued by the Company are then
listed;


                                       6
<PAGE>   7

               (g) provide a transfer agent and registrar for all such
Registrable Securities not later than the effective date of such registration
statement;

               (h) enter into such customary agreements (including underwriting
agreements in customary form) and take all such other actions as the Holders of
a majority of the Registrable Securities being sold or the underwriters, if any,
reasonably request in order to expedite or facilitate the disposition of such
Registrable Securities;

               (i) make available for inspection by a representative of the
Holders of Registrable Securities included in the registration statement, any
underwriter participating in any disposition pursuant to such registration
statement and any attorney, accountant or other agent retained by any such
seller or underwriter, all pertinent financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers, directors, employees and independent accountants to supply all
information reasonably requested by any such seller, underwriter, attorney,
accountant or agent in connection with such registration statement;

               (j) otherwise use its reasonable efforts to comply with all
applicable rules and regulations of the Commission, and make available to its
security holders, as soon as reasonably practicable, an earnings statement
covering the period of at least 12 months beginning with the first day of the
Company's first full calendar quarter after the effective date of the
registration statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 thereunder;

               (k) in the event of the issuance of any stop order suspending the
effectiveness of a registration statement, or of any order suspending or
preventing the use of any related prospectus or suspending the qualification of
any Common Stock included in such registration statement for sale in any
jurisdiction, use all reasonable efforts promptly to obtain the withdrawal of
such order; and

               (l) if the registration is an underwritten offering, use all
reasonable efforts to obtain a so-called "cold comfort" letter from the
Company's independent public accountants in customary form and covering such
matters of the type customarily covered by cold comfort letters.

               7. Obligations of Holders. Whenever the Holders of Registrable
Securities sell any Registrable Securities pursuant to a Demand Registration or
the Shelf Registration Statement, such Holders shall be obligated to comply with
the applicable provisions of the Securities Act, including the prospectus
delivery requirements thereunder, and any applicable state securities or blue
sky laws.

               8. Indemnification. (a) In connection with any registration
statement for a Demand Registration or any Shelf Registration Statement in which
a Holder of Registrable Securities is participating, the Company agrees to
indemnify, to the fullest extent permitted by applicable law, each such Holder
of Registrable Securities, its officers and directors and each Person who
controls such Holder (within the meaning of the Securities Act) against all
losses, 


                                       7
<PAGE>   8

claims, damages, liabilities, expenses or any amounts paid in settlement
of any litigation, investigation or proceeding commenced or threatened to which
each such indemnified party may become subject under the Securities Act
(collectively, "Claims") insofar as such Claim arose out of (i) any untrue or
alleged untrue statement of material fact contained, on the effective date
thereof, in any such registration statement, prospectus or preliminary
prospectus or any amendment thereof or supplement thereto or (ii) any omission
or alleged omission to state therein a material fact required to be stated
therein or necessary to make the statements therein not misleading, except
insofar as the same are caused by or contained in any information furnished in
writing to the Company by such Holder expressly for use therein or by such
Holder's failure to deliver a copy of the registration statement or prospectus
or any amendments or supplements thereto after the Company has furnished such
Holder with a sufficient number of copies of the same. In connection with an
underwritten offering, the Company will indemnify the underwriters, their
officers and directors and each Person who controls the underwriters (within the
meaning of the Securities Act) to the same extent as provided above with respect
to the indemnification of the Holders of Registrable Securities.

               (b) In connection with any registration statements for a Demand
Registration or any Shelf Registration Statement in which a Holder of
Registrable Securities is participating, each such Holder will furnish to the
Company in writing such customary information as the Company reasonably requests
for use in connection with any such registration statement or prospectus (the
"Seller's Information") and, to the fullest extent permitted by applicable law,
will indemnify the Company, its directors and officers and each Person who
controls the Company (within the meaning of the Securities Act) against any and
all Claims to which each such indemnified party may become subject under the
Securities Act insofar as such Claim arose out of (i) any untrue or alleged
untrue statement of material fact contained, on the effective date thereof, in
any such registration statement, prospectus or preliminary prospectus or any
amendment thereof or supplement thereto or (ii) any omission or alleged omission
to state therein a material fact required to be stated therein or necessary to
make the statements therein not misleading; provided that with respect to a
Claim arising pursuant to clause (i) or (ii) above, the material misstatement or
omission is contained in such Seller's Information; provided, further, that the
obligation to indemnify will be individual to each Holder and will be limited to
the amount of proceeds received by such Holder from the sale of Registrable
Securities pursuant to such registration statement.

               (c) Any Person entitled to indemnification hereunder will (i)
give prompt written notice to the indemnifying party of any claim with respect
to which it seeks indemnification (but the failure to provide such notice shall
not release the indemnifying party of its obligation under paragraphs (a) and
(b), unless and then only to the extent that, the indemnifying party has been
prejudiced by such failure to provide such notice) and (ii) unless in such
indemnified party's reasonable judgment a conflict of interest between such
indemnified and indemnifying parties may exist with respect to such claim,
permit such indemnifying party to assume the defense of such claim with counsel
reasonably satisfactory to the indemnified party. An indemnifying party who is
not entitled to, or elects not to, assume the defense of a claim will not be
obligated to pay the fees and expenses of more than one counsel for all parties
indemnified by such indemnifying party with respect to such claim, unless in the
reasonable judgment of any indemnified party a 


                                       8
<PAGE>   9

conflict of interest may exist between such indemnified party and any other of
such indemnified parties with respect to such claim.

               (d) The indemnifying party shall not be liable to indemnify an
indemnified party for any settlement, or consent to judgment of any such action
effected without the indemnifying party's consent (but such consent will not be
unreasonably withheld). Furthermore, the indemnifying party shall not, except
with the prior written approval of each indemnified party, consent to entry of
any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to each
indemnified party of a release from all liability in respect of such claim or
litigation without any payment or consideration provided by each such
indemnified party.

               (e) If the indemnification provided for in this Section 8 is
unavailable to an indemnified party under clauses (a) and (b) above in respect
of any losses, claims, damages or liabilities referred to therein, then each
indemnifying party, in lieu of indemnifying such indemnified party, shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages or liabilities in such proportion as is
appropriate to reflect not only the relative benefits received by the Company
(if any), the underwriters, the sellers of Registrable Securities and any other
sellers participating in the registration statement from the sale of shares
pursuant to the registered offering of securities for which indemnity is sought
but also the relative fault of the Company, the underwriters, the sellers of
Registrable Securities and any other sellers participating in the registration
statement in connection with the statement or omission which resulted in such
losses, claims, damages or liabilities, as well as any other relevant equitable
considerations. The relative benefits received by the Company (if any), the
underwriters, the sellers of Registrable Securities and any other sellers
participating in the registration statement shall be deemed to be based on the
relative relationship of the total net proceeds from the offering (before
deducting expenses) to the Company (if any), the total underwriting commissions
and fees from the offering (before deducting expenses) to the underwriters and
the total net proceeds from the offering (before deducting expenses) to the
sellers of Registrable Securities and any other sellers participating in the
registration statement. The relative fault of the Company, the underwriters, the
sellers of Registrable Securities and any other sellers participating in the
registration statement shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or the
omission or alleged omission to state a material fact relates to information
supplied by the Company or by the sellers of Registrable Securities and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such statement or omission.

               (f) The indemnification provided for under this Agreement will
remain in full force and effect regardless of any investigation made by or on
behalf of the indemnified party or any officer, director or controlling person
of such indemnified party and will survive the transfer of the Registrable
Securities.

               9. Participation in Underwritten Registrations. No Holder may
participate in any registration hereunder which is underwritten unless such
Holder (a) agrees to sell such Holder's securities on the basis provided in any
underwriting arrangements approved by the Holder or Holders entitled hereunder
to approve such arrangements, (b) as expeditiously as possible 


                                       9
<PAGE>   10

notifies the Company of the occurrence of any event as a result of which any
prospectus contains an untrue statement of material fact or omits to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading and (c) completes and executes all questionnaires, powers
of attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements.

               10. Transfer of Registration Rights. The rights granted to any
Holder under this Agreement may be assigned to any permitted transferee of
Registrable Securities, in connection with any transfer or assignment of
Registrable Securities by a Holder; provided, however, that: (a) such transfer
is otherwise effected in accordance with applicable securities laws, (b) if not
already a party hereto, the assignee or transferee agrees in writing prior to
such transfer to be bound by the provisions of this Agreement applicable to the
transferor, (c) such transferee shall own Registrable Securities representing at
least 200,000 shares of Common Stock (as adjusted for any combinations,
consolidations, stock distributions, stock dividends or other recapitalizations
with respect to such shares), and (d) EIS shall act as agent and representative
for such Holder for the giving and receiving of notices hereunder.

               11. Information by Holder. Each Holder shall furnish to the
Company such written information regarding such Holder and any distribution
proposed by such Holder as the Company may reasonably request in writing and as
shall be reasonably required in connection with any registration, qualification
or compliance referred to in this Agreement and shall promptly notify the
Company of any changes in such information.

               12. Exchange Act Compliance. The Company shall comply with all of
the reporting requirements of the Exchange Act then applicable to it and shall
comply with all other public information reporting requirements of the
Commission which are conditions to the availability of Rule 144 for the sale of
the Registrable Securities. The Company shall cooperate with each Holder in
supplying such information as may be necessary for such Holder to complete and
file any information reporting forms presently or hereafter required by the
Commission as a condition to the availability of Rule 144.

               13. Termination of Registration Rights. All registration rights
granted under this Agreement shall terminate and be of no further force and
effect, as to any particular Holder, at such time as all Registrable Securities
held by such Holder can be sold within a three-month period without compliance
with the registration requirements of the Securities Act pursuant to Rule 144
(including Rule 144(k)) promulgated thereunder or have been resold pursuant to a
Demand Registration or the Shelf Registration Statement.

               14.  Miscellaneous.

               (a) No Inconsistent Agreements. The Company will not hereafter
enter into any agreement with respect to its securities which is inconsistent
with or violates the rights granted to the Holders of Registrable Securities in
this Agreement without the prior written consent of a majority in interest of
such Registrable Securities.


                                       10
<PAGE>   11

               (b) Remedies. Any Person having rights under any provision of
this Agreement will be entitled to enforce such rights specifically to recover
damages caused by reason of any breach of any provision of this Agreement and to
exercise all other rights granted by law. The parties hereto agree and
acknowledge that money damages may not be an adequate remedy for any breach of
the provisions of this Agreement and that any party may in its sole discretion
apply to any court of law or equity of competent jurisdiction (without posting
any bond or other security) for specific performance and for other injunctive
relief in order to enforce or prevent violation of the provisions of this
Agreement; provided, however, that in no event shall any Holder have the right
to enjoin, delay or interfere with any offering of securities by the Company.

               (c) Amendments and Waivers. Except as otherwise provided herein,
the provisions of this Agreement may be amended or waived only with the prior
written consent of the Company and Holders of at least 50% of the Registrable
Securities; provided, however, that without the prior written consent of all the
Holders, no such amendment or waiver shall reduce the foregoing percentage
required to amend or waive any provision of this Agreement.

               (d) Successors and Assigns. All covenants and agreements in this
Agreement by or on behalf of any of the parties hereto will bind and inure to
the benefit of the respective successors and assigns of the parties hereto, and
shall inure to the benefit and be enforceable by each Holder of Registrable
Securities from time to time. In addition, whether or not any express assignment
has been made, the provisions of this Agreement which are for the benefit of
Holders of Registrable Securities are also for the benefit of, and enforceable
by, any permitted transferee of Registrable Securities in accordance with
Section 10 hereof.

               (e) Severability. Whenever possible, each provision of this
Agreement will be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Agreement is held to be prohibited
by or invalid under applicable law, such provision will be ineffective only to
the extent of such prohibition or invalidity, without invalidating the remainder
of this Agreement.

               (f) Counterparts. This Agreement may be executed simultaneously
in two or more counterparts, any one of which need not contain the signatures of
more than one party, but all such counterparts taken together will constitute
one and the same Agreement.

               (g) Descriptive Headings. The descriptive headings of this
Agreement are inserted for convenience only and do not constitute a part of this
Agreement.

               (h) Governing Law. All questions concerning the construction,
validity and interpretation of this Agreement will be governed by the laws of
the State of New York without regard to principles of conflicts of laws, except
that all issues concerning the relative rights of the Company and its
stockholders shall be governed by the Delaware General Corporation Law, without
giving effect to the principles thereof relating to conflicts of laws.

               (i) Notices. All notices, demands and requests of any kind to be
delivered to any party in connection with this Agreement shall be in writing and
shall be deemed to have been 


                                       11
<PAGE>   12

duly given if personally delivered or if sent by nationally-recognized overnight
courier or by registered or certified airmail, return receipt requested and
postage prepaid or by facsimile transmission (with receipt confirmed by
telephone), addressed as follows:

                      (i) if to the Company, to:

                      Isis Pharmaceuticals, Inc.
                      2292 Faraday Avenue
                      Carlsbad, CA 92008
                      Facsimile:  (760) 931-9639
                        telephone confirmation required at (760) 603-2460
                      Attention:  B. Lynne Parshall

                      with a copy to:

                      Cooley Godward LLP
                      4365 Executive Drive
                      San Diego, CA 92121
                      Facsimile:  (619) 453-3555
                        telephone confirmation required at (619) 550-6000
                      Attention:  L. Kay Chandler, Esq.

                      (ii) if to EIS, to:

                      Elan International Services, Ltd.
                      Flatts, Smiths Parish
                      Bermuda, FL 04
                      Facsimile:  (441) 292-2224
                        telephone confirmation required at (441) 292-9169
                      Attention:   President

                      with a copy to:

                      Brock Silverstein LLC
                      153 East 53rd Street, 56th Floor
                      New York, New York 10022
                      Facsimile:  (212) 371-5500
                        telephone confirmation required at (212) 371-2000
                      Attention:  David Robbins, Esq.

               (j) Entire Agreement. This Agreement constitutes the full and
entire understanding and agreement between the parties with regard to the
subject matter hereof.

                            [Signature page follows]


                                       12
<PAGE>   13

               IN WITNESS WHEREOF, the parties have executed this Registration
Rights Agreement as of the date first written above.



                                  ISIS PHARMACEUTICALS, INC.



                                  By:  /s/ B. LYNNE PARSHALL
                                       ---------------------------------
                                       B. Lynne Parshall
                                       Executive Vice President


                                  ELAN INTERNATIONAL SERVICES, LTD.



                                  By:  /s/ KEVIN INSLEY
                                       ---------------------------------
                                       Kevin Insley
                                       President



<PAGE>   1
                                                                    EXHIBIT 10.6

                                  ORASENSE LTD.
                          REGISTRATION RIGHTS AGREEMENT

               THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made as
of April 20, 1999 by and among ORASENSE LTD., a Bermuda corporation (the
"Company"), ISIS PHARMACEUTICALS, INC., a Delaware corporation ("Isis"), and
ELAN INTERNATIONAL SERVICES, Ltd., a Bermuda corporation ("EIS").

                                R E C I T A L S:

               A.   Pursuant to a joint development and operating agreement 
dated as of the date hereof by and among the Company, Isis, ELAN CORPORATION,
PLC, an Irish public limited company and EIS (the "JDOA"), Isis and EIS have
acquired certain common shares, par value $1.00 per share (the "Common Shares"),
of the Company.

               B.   The execution of the JDOA has occurred on the date hereof 
and it is a condition to the closing of the transactions contemplated thereby
that the parties execute and deliver this Agreement.

               C.   The parties desire to set forth herein their agreement on 
the terms and subject to the conditions set forth herein related to the granting
of certain registration rights to the Holders (as defined below) relating to the
Common Shares held by such Holders.

                               A G R E E M E N T:

               The parties hereto agree as follows:

               1.   Certain Definitions.  As used in this Agreement, the 
following terms shall have the following respective meanings:

               "Commission" shall mean the U.S. Securities and Exchange
Commission.

               "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect from time to time.

               "Holders" or "Holders of Registrable Securities" shall mean Isis,
EIS and any Person who shall have acquired Registrable Securities from either
Isis or EIS as permitted herein, either individually or jointly, as the case may
be, in a transaction pursuant to which registration rights are transferred
pursuant to Section 10 hereof.


<PAGE>   2

               "Person" shall mean an individual, a partnership, a company, an
association, a joint stock company, a trust, a joint venture, an unincorporated
organization and a governmental or quasi-governmental entity, or any department,
agency or political subdivision thereof.

               "Registrable Securities" means (i) any Common Shares subscribed
for pursuant to the JDOA and (ii) any Common Shares issued or issuable in
respect of the securities referred to in clause (i) above upon any stock split,
stock dividend, recapitalization or similar event; excluding in all cases,
however, any Registrable Securities sold by a Person in a transaction (including
a transaction pursuant to a registration statement under this Agreement and a
transaction pursuant to Rule 144 promulgated under the Securities Act) in which
registration rights are not transferred pursuant to Section 10 hereof.

               The terms "register," "registered" and "registration" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or order of the
effectiveness of such registration statement.

               "Registration Expenses" shall mean all expenses, other than
Selling Expenses, incurred by the Company in complying with Sections 2 or 3
hereof, including without limitation, all registration, qualification and filing
fees, exchange listing fees, printing expenses, escrow fees, fees and
disbursements of counsel for the Company, blue sky fees and expenses, the
expense of any special audits incident to or required by any such registration
and the reasonable fees and disbursements, not to exceed $10,000, of one counsel
for the Holders, such counsel to be selected by Holders holding a majority of
the Registrable Securities included in such registration.

               "Securities Act" shall mean the Securities Act of 1933, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect from time to time.

               "Selling Expenses" shall mean all underwriting discounts, selling
commissions and stock transfer taxes applicable to the securities registered by
the Holders and the costs of any accountants or other experts retained by the
Holders.

               2.     Demand Registrations.

               (a) Requests for Registration. From and after the occurrence of
the initial public offering of the Company's Common Shares under the Securities
Act, any Holder or Holders who collectively hold Registrable Securities
representing at least 33% of the Registrable Securities then outstanding shall
have the right at any time from time to time, to request two registrations under
the Securities Act of all or part of their Registrable Securities on Form S-1,
S-2 or S-3 (if available) or any similar registration statement (each, a "Demand
Registration"), such form to be selected by the Company as appropriate. The
request for the Demand Registration shall specify the approximate number of
Registrable Securities requested to be registered, which must have a minimum
expected aggregate offering price to the public of at least $1,000,000. Within
20 days after receipt of any such request, the Company will give written notice
of such requested registration to all other Holders of Registrable Securities.
The Company shall include such other 


                                       2
<PAGE>   3

Holders' Registrable Securities in such offering if they have responded
affirmatively within 20 days after the receipt of the Company's notice. The
Holders in aggregate will be entitled to request only one Demand Registration
hereunder within any 12-month period. A registration will not count as a
permitted Demand Registration until it has become effective (unless such Demand
Registration has not become effective due solely to the fault of the Holders
requesting such registration, including a request by such Holders that such
registration be withdrawn). The Company shall pay all Registration Expenses in
connection with any Demand Registration whether or not such Demand Registration
has become effective.

               (b) Priority on Demand Registrations. If a Demand Registration is
an underwritten offering and the managing underwriters advise the Company in
writing that in their opinion the number of Registrable Securities and, if
permitted hereunder, other securities requested to be included in such offering,
exceeds the number of Registrable Securities and other securities, if any, which
can be sold in such offering without adversely affecting the marketability of
the offering, the Company will include in such registration:

                      (i) first, the Registrable Securities requested to be
        included in such registration by the Holders (or, if necessary, such
        Registrable Securities pro rata among the Holders thereof based upon the
        number of Registrable Securities owned by each such Holder) together
        with any securities held by third parties holding a similar, previously
        granted right to be included in such registration; and

                      (ii) thereafter, other securities requested to be included
        in such registration.

               (c) Restrictions on Demand Registration. The Company may postpone
for up to six months in any 12-month period, the filing or the effectiveness of
a registration statement for a Demand Registration if the Company determines in
good faith that such Demand Registration would reasonably be expected to have a
material adverse effect on any proposal or plan by the Company to engage in any
financing, acquisition or disposition of assets (other than in the ordinary
course of business) or any merger, consolidation, tender offer or similar
transaction or would require disclosure of any information that the board of
directors of the Company determines in good faith the disclosure of which would
be detrimental to the Company; provided, however, that in such event, the
Holders initially requesting such Demand Registration will be entitled to
withdraw such request and, if such request is withdrawn, such Demand
Registration will not count as a permitted Demand Registration hereunder and the
Company will pay any Registration Expenses in connection with such registration.

               (d) Selection of Underwriters. The Holders will have the right to
select the investment banker(s) and manager(s) to administer an offering
pursuant to the Demand Registration, subject to the Company's prior written
approval, which will not be unreasonably withheld or delayed.

               (e) Other Registration Rights. Except as provided in this
Agreement, so long as any Holder owns any Registrable Securities, the Company
will not grant to any Persons the right to request the Company to register any
equity securities of the Company, or any securities 


                                       3
<PAGE>   4

convertible or exchangeable into or exercisable for such securities, which
conflicts with the rights granted to the Holders hereunder, without the prior
written consent of the Holders of at least 50% of the Registrable Securities;
provided, however, that the Company may grant rights to other Persons to demand
and piggyback registrations so long as the Holders of Registrable Securities are
entitled to participate in any such registrations with such Persons pro rata on
the basis of the number of shares owned by each such Holder.

               3.  Piggyback Registrations.

               (a) Right to Piggyback. At any time the Company shall propose to
register Common Shares under the Securities Act (other than in a registration
statement on Form S-3 relating to sales of securities to participants in a
Company dividend reinvestment plan, or Form S-4 or S-8 or any successor form or
in connection with an acquisition or exchange offer or an offering of securities
solely to the existing shareholders or employees of the Company) (each, a
"Piggyback Registration"), the Company will give prompt written notice to all
Holders of Registrable Securities of its intention to effect such a registration
and, subject to Section 3(b) and the other terms of this Agreement, will include
in such registration all Registrable Securities which are permitted under
applicable securities laws to be included in the form of registration statement
selected by the Company and with respect to which the Company has received
written requests for inclusion therein within 20 days after the receipt of the
Company's notice.

               (b) Priority on Piggyback Registrations. If a Piggyback
Registration is to be an underwritten offering, and the managing underwriters
advise the Company in writing that in their opinion the number of securities
requested to be included in such registration exceeds the number which can be
sold in such offering without adversely affecting the marketability of the
offering, the Company will include in such registration:

                      (i) first, the securities the Company proposes to sell;

                      (ii) any securities having the right to be included in
        such registration prior to the securities of the Holders;

                      (iii) the Registrable Securities requested to be included
        in such registration by the Holders and any securities requested to be
        included in such registration by any other Person having equal priority
        to registration with the Holders, pro rata among the Holders of such
        Registrable Securities and such other Persons, on the basis of the
        number of shares owned by each of such Holders; and

                      (iv) thereafter, other securities requested to be included
        in such registration.

               The Holders of any Registrable Securities included in such an
underwritten offering must execute an underwriting agreement, in customary form
and in form and substance satisfactory to the managing underwriters.


                                       4
<PAGE>   5

               (c) Right to Terminate Registration. If, at any time after giving
written notice of its intention to register any of its securities as set forth
in Section 3(a) and prior to the effective date of the registration statement
filed in connection with such registration, the Company shall determine for any
reason not to register such securities, the Company may, at its election, give
written notice of such determination to each Holder of Registrable Securities
and thereupon be relieved of its obligation to register any Registrable
Securities in connection with such registration (but not from its obligation to
pay the Registration Expenses in connection therewith as provided herein).

               (d) Selection of Underwriters. The Company will have the right to
select the investment banker(s) and manager(s) to administer an offering
pursuant to a Piggyback Registration.

               4. Expenses of Registration. Except as otherwise provided herein
or as may otherwise be prohibited by applicable law, all Registration Expenses
incurred in connection with all registrations pursuant to Sections 2 and 3 shall
be borne by the Company. All Selling Expenses relating to securities registered
on behalf of the Holders of Registrable Securities shall be borne by such
Holders.

               5.  Holdback Agreements.

               (a) The Company agrees (i) not to effect any public sale or
distribution of its equity securities, or any securities convertible into or
exchangeable or exercisable for such securities, during the seven days prior to
and during the 180-day period beginning on the effective date of any
underwritten Demand Registration or any underwritten Piggyback Registration
(except as part of such underwritten registration or pursuant to registration
statements on Form S-4 or Form S-8 or any successor form), unless the
underwriters managing the registered public offering otherwise agree, and (ii)
to use reasonable efforts to cause each holder of at least 5% (on a
fully-diluted basis) of its outstanding Common Shares, or any securities
convertible into or exchangeable or exercisable for Common Shares, purchased
from the Company at any time after the date of this Agreement (other than in a
registered public offering) to agree not to effect any public sale or
distribution (including sales pursuant to Rule 144) of any such securities
during such periods (except as part of such underwritten registration, if
otherwise permitted), unless the underwriters managing the registered public
offering otherwise agree.

               (b) Each Holder agrees, if requested by the managing underwriter
or underwriters in an underwritten offering of securities of the Company, not to
effect any offer, sale, distribution or transfer, including a sale pursuant to
Rule 144 (or any similar provision then effect) under the Securities Act (except
as part of such underwritten registration), during the seven-day period prior
to, and during the 180-day period (or such shorter period as may be agreed to in
writing by the Company and the Holders of at least 50% of the Registrable
Securities) following the effective date of such Registration Statement to the
extent timely notified in writing by the managing underwriter or underwriters.


                                       5
<PAGE>   6

               6. Registration Procedures. Whenever the Holders of Registrable
Securities have requested that any Registrable Securities be registered pursuant
to this Agreement, the Company will use all reasonable efforts to effect the
registration and the sale of such Registrable Securities in accordance with the
intended method of distribution thereof, and pursuant thereto the Company will
as expeditiously as possible:

               (a) subject to Section 2(c) hereof, prepare and file with the
Commission a registration statement on any form for which the Company qualifies
with respect to such Registrable Securities and use all reasonable efforts to
cause such registration statement to become effective (provided that before
filing a registration statement or prospectus or any amendments or supplements
thereto, the Company will (i) furnish to the counsel selected by the Holders
copies of all such documents proposed to be filed, which documents will be
subject to the review of such counsel, and (ii) notify each Holder of
Registrable Securities covered by such registration of any stop order issued or
threatened by the Commission);

               (b) subject to Section 2(c) hereof, prepare and file with the
Commission such amendments and supplements to such registration statement and
the prospectus used in connection therewith as may be necessary to keep such
registration statement effective for a period equal to the shorter of (i) six
months and (ii) the time by which all securities covered by such registration
statement have been sold, and comply with the provisions of the Securities Act
with respect to the disposition of all securities covered by such registration
statement during such period in accordance with the intended methods of
disposition by the sellers thereof set forth in such registration statement;

               (c) furnish to each seller of Registrable Securities such number
of copies of such registration statement, each amendment and supplement thereto,
the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such seller may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such seller;

               (d) use all reasonable efforts to register or qualify such
Registrable Securities under the securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable
Securities owned by such seller (provided that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this Section 6(d), (ii) subject itself
to taxation in any jurisdiction, or (iii) consent to general service of process
in any such jurisdiction);

               (e) notify each seller of such Registrable Securities, at any
time when a prospectus relating thereto is required to be delivered under the
Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading, and, at the request of any such seller, the Company will prepare
a supplement or amendment to such prospectus so that, as thereafter delivered to
the purchasers of such Registrable Securities, such prospectus will not contain
an untrue statement of a material fact or 


                                       6
<PAGE>   7

omit to state any fact necessary to make the statements therein not misleading;
provided, however, that the Company shall not be required to amend the
registration statement or supplement the Prospectus for a period of up to six
months if the board of directors determines in good faith that to do so would
reasonably be expected to have a material adverse effect on any proposal or plan
by the Company to engage in any financing, acquisition or disposition of assets
(other than in the ordinary course of business) or any merger, consolidation,
tender offer or similar transaction or would require the disclosure of any
information that the board of directors determines in good faith the disclosure
of which would be detrimental to the Company, it being understood that the
period for which the Company is obligated to keep the Registration Statement
effective shall be extended for a number of days equal to the number of days the
Company delays amendments or supplements pursuant to this provision. Upon
receipt of any notice pursuant to this Section 6(e), the Holders shall suspend
all offers and sales of securities of the Company and all use of any prospectus
until advised by the Company that offers and sales may resume, and shall keep
confidential the fact and content of any notice given by the Company pursuant to
this Section 6(e);

               (f) cause all such Registrable Securities to be listed on each
securities exchange on which similar securities issued by the Company are then
listed;

               (g) provide a transfer agent and registrar for all such
Registrable Securities not later than the effective date of such registration
statement;

               (h) enter into such customary agreements (including underwriting
agreements in customary form) and take all such other actions as the Holders of
a majority of the Registrable Securities being sold or the underwriters, if any,
reasonably request in order to expedite or facilitate the disposition of such
Registrable Securities;

               (i) make available for inspection by a representative of the
Holders of Registrable Securities included in the registration statement, any
underwriter participating in any disposition pursuant to such registration
statement and any attorney, accountant or other agent retained by any such
seller or underwriter, all pertinent financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers, directors, employees and independent accountants to supply all
information reasonably requested by any such seller, underwriter, attorney,
accountant or agent in connection with such registration statement;

               (j) otherwise use its reasonable efforts to comply with all
applicable rules and regulations of the Commission, and make available to its
security holders, as soon as reasonably practicable, an earnings statement
covering the period of at least 12 months beginning with the first day of the
Company's first full calendar quarter after the effective date of the
registration statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 thereunder;

               (k) in the event of the issuance of any stop order suspending the
effectiveness of a registration statement, or of any order suspending or
preventing the use of any related prospectus or suspending the qualification of
any Common Shares included in such registration statement 


                                       7
<PAGE>   8

for sale in any jurisdiction, use all reasonable efforts promptly to obtain the
withdrawal of such order; and

               (l) if the registration is an underwritten offering, use all
reasonable efforts to obtain a so-called "cold comfort" letter from the
Company's independent public accountants in customary form and covering such
matters of the type customarily covered by cold comfort letters.

               7. Obligations of Holders. Whenever the Holders of Registrable
Securities sell any Registrable Securities pursuant to a Demand Registration or
a Piggyback Registration, such Holders shall be obligated to comply with the
applicable provisions of the Securities Act, including the prospectus delivery
requirements thereunder, and any applicable state securities or blue sky laws.

               8. Indemnification. (a) The Company agrees to indemnify, to the
fullest extent permitted by applicable law, each Holder of Registrable
Securities, its officers and directors and each Person who controls such Holder
(within the meaning of the Securities Act) against all losses, claims, damages,
liabilities, expenses or any amounts paid in settlement of any litigation,
investigation or proceeding commenced or threatened (collectively, "Claims") to
which each such indemnified party may become subject under the Securities Act
insofar as such Claim arose out of (i) any untrue or alleged untrue statement of
material fact contained, on the effective date thereof, in any registration
statement, prospectus or preliminary prospectus or any amendment thereof or
supplement thereto or (ii) any omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, except insofar as the same are caused by or contained in
any information furnished in writing to the Company by such Holder expressly for
use therein or by such Holder's failure to deliver a copy of the registration
statement or prospectus or any amendments or supplements thereto after the
Company has furnished such Holder with a sufficient number of copies of the
same. In connection with an underwritten offering, the Company will indemnify
the underwriters, their officers and directors and each Person who controls the
underwriters (within the meaning of the Securities Act) to the same extent as
provided above with respect to the indemnification of the Holders of Registrable
Securities.

               (b) In connection with any registration statements in which a
Holder of Registrable Securities is participating, each such Holder will furnish
to the Company in writing such customary information as the Company reasonably
requests for use in connection with any such registration statement or
prospectus (the "Seller's Information") and, to the fullest extent permitted by
applicable law, will indemnify the Company, its directors and officers and each
Person who controls the Company (within the meaning of the Securities Act)
against any and all Claims to which each such indemnified party may become
subject under the Securities Act insofar as such Claim arose out of (i) any
untrue or alleged untrue statement of material fact contained, on the effective
date thereof, in any registration statement, prospectus or preliminary
prospectus or any amendment thereof or supplement thereto or (ii) any omission
or alleged omission to state therein a material fact required to be stated
therein or necessary to make the statements therein not misleading; provided
that with respect to a Claim arising pursuant to clause (i) or (ii) above, the
material misstatement or omission is contained in such Seller's 


                                       8
<PAGE>   9

Information; provided, further, that the obligation to indemnify will be
individual to each Holder and will be limited to the amount of proceeds received
by such Holder from the sale of Registrable Securities pursuant to such
registration statement.

               (c) Any Person entitled to indemnification hereunder will (i)
give prompt written notice to the indemnifying party of any claim with respect
to which it seeks indemnification (but the failure to provide such notice shall
not release the indemnifying party of its obligation under paragraphs (a) and
(b), unless and then only to the extent that, the indemnifying party has been
prejudiced by such failure to provide such notice) and (ii) unless in such
indemnified party's reasonable judgment a conflict of interest between such
indemnified and indemnifying parties may exist with respect to such claim,
permit such indemnifying party to assume the defense of such claim with counsel
reasonably satisfactory to the indemnified party. An indemnifying party who is
not entitled to, or elects not to, assume the defense of a claim will not be
obligated to pay the fees and expenses of more than one counsel for all parties
indemnified by such indemnifying party with respect to such claim, unless in the
reasonable judgment of any indemnified party a conflict of interest may exist
between such indemnified party and any other of such indemnified parties with
respect to such claim.

               (d) The indemnifying party shall not be liable to indemnify an
indemnified party for any settlement, or consent to judgment of any such action
effected without the indemnifying party's consent (but such consent will not be
unreasonably withheld). Furthermore, the indemnifying party shall not, except
with the prior written approval of each indemnified party, consent to entry of
any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to each
indemnified party of a release from all liability in respect of such claim or
litigation without any payment or consideration provided by each such
indemnified party.

               (e) If the indemnification provided for in this Section 8 is
unavailable to an indemnified party under clauses (a) and (b) above in respect
of any losses, claims, damages or liabilities referred to therein, then each
indemnifying party, in lieu of indemnifying such indemnified party, shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages or liabilities in such proportion as is
appropriate to reflect not only the relative benefits received by the Company,
the underwriters, the sellers of Registrable Securities and any other sellers
participating in the registration statement from the sale of shares pursuant to
the registered offering of securities for which indemnity is sought but also the
relative fault of the Company, the underwriters, the sellers of Registrable
Securities and any other sellers participating in the registration statement in
connection with the statement or omission which resulted in such losses, claims,
damages or liabilities, as well as any other relevant equitable considerations.
The relative benefits received by the Company, the underwriters, the sellers of
Registrable Securities and any other sellers participating in the registration
statement shall be deemed to be based on the relative relationship of the total
net proceeds from the offering (before deducting expenses) to the Company, the
total underwriting commissions and fees from the offering (before deducting
expenses) to the underwriters and the total net proceeds from the offering
(before deducting expenses) to the sellers of Registrable Securities and any
other sellers participating in the registration statement. The relative fault of
the Company, the underwriters, the sellers of Registrable Securities and any
other sellers 


                                       9
<PAGE>   10

participating in the registration statement shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or the omission or alleged omission to state a material fact relates to
information supplied by the Company or by the sellers of Registrable Securities
and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission.

               (f) The indemnification provided for under this Agreement will
remain in full force and effect regardless of any investigation made by or on
behalf of the indemnified party or any officer, director or controlling person
of such indemnified party and will survive the transfer of the Registrable
Securities.

               9. Participation in Underwritten Registrations. No Holder may
participate in any registration hereunder which is underwritten unless such
Holder (a) agrees to sell such Holder's securities on the basis provided in any
underwriting arrangements approved by the Holder or Holders entitled hereunder
to approve such arrangements, (b) as expeditiously as possible notifies the
Company of the occurrence of any event as a result of which any prospectus
contains an untrue statement of material fact or omits to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading and (c) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements.

               10. Transfer of Registration Rights. The rights granted to any
Holder under this Agreement may be assigned to any permitted transferee of
Registrable Securities, in connection with any transfer or assignment of
Registrable Securities by a Holder; provided, however, that: (a) such transfer
is otherwise effected in accordance with applicable securities laws, (b) if not
already a party hereto, the assignee or transferee agrees in writing prior to
such transfer to be bound by the provisions of this Agreement applicable to the
transferor, (c) such transferee shall own Registrable Securities representing at
least 3,000 Common Shares (as adjusted for any combinations, consolidations,
stock distributions, stock dividends or other recapitalizations with respect to
such shares), and (d) Isis or EIS, as applicable, shall act as agent and
representative for such Holder for the giving and receiving of notices
hereunder.

               11. Information by Holder. Each Holder shall furnish to the
Company such written information regarding such Holder and any distribution
proposed by such Holder as the Company may reasonably request in writing and as
shall be reasonably required in connection with any registration, qualification
or compliance referred to in this Agreement and shall promptly notify the
Company of any changes in such information.

               12. Exchange Act Compliance. The Company shall comply with all of
the reporting requirements of the Exchange Act then applicable to it and shall
comply with all other public information reporting requirements of the
Commission which are conditions to the availability of Rule 144 for the sale of
the Registrable Securities. The Company shall cooperate with each Holder in
supplying such information as may be necessary for such Holder to complete and
file any information reporting forms presently or hereafter required by the
Commission as a condition to the availability of Rule 144.


                                       10
<PAGE>   11

               13. Termination of Registration Rights. All registration rights
granted under this Agreement shall terminate and be of no further force and
effect, as to any particular Holder, at such time as all Registrable Securities
held by such Holder can be sold within a three-month period without compliance
with the registration requirements of the Securities Act pursuant to Rule 144
(including Rule 144(k)) promulgated thereunder or have been resold pursuant to a
registration statement hereunder.

               14.  Miscellaneous.

               (a) No Inconsistent Agreements. The Company will not hereafter
enter into any agreement with respect to its securities which is inconsistent
with or violates the rights granted to the Holders of Registrable Securities in
this Agreement without the prior written consent of a majority in interest of
such Registrable Securities.

               (b) Remedies. Any Person having rights under any provision of
this Agreement will be entitled to enforce such rights specifically to recover
damages caused by reason of any breach of any provision of this Agreement and to
exercise all other rights granted by law. The parties hereto agree and
acknowledge that money damages may not be an adequate remedy for any breach of
the provisions of this Agreement and that any party may in its sole discretion
apply to any court of law or equity of competent jurisdiction (without posting
any bond or other security) for specific performance and for other injunctive
relief in order to enforce or prevent violation of the provisions of this
Agreement; provided, however, that in no event shall any Holder have the right
to enjoin, delay or interfere with any offering of securities by the Company.

               (c) Amendments and Waivers. Except as otherwise provided herein,
the provisions of this Agreement may be amended or waived only with the prior
written consent of the Company and Holders of at least 50% of the Registrable
Securities; provided, however, that without the prior written consent of all the
Holders, no such amendment or waiver shall reduce the foregoing percentage
required to amend or waive any provision of this Agreement.

               (d) Successors and Assigns. All covenants and agreements in this
Agreement by or on behalf of any of the parties hereto will bind and inure to
the benefit of the respective successors and assigns of the parties hereto, and
shall inure to the benefit and be enforceable by each Holder of Registrable
Securities from time to time. In addition, whether or not any express assignment
has been made, the provisions of this Agreement which are for the benefit of
Holders of Registrable Securities are also for the benefit of, and enforceable
by, any permitted transferee of Registrable Securities, in accordance with
Section 10 hereof.

               (e) Severability. Whenever possible, each provision of this
Agreement will be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Agreement is held to be prohibited
by or invalid under applicable law, such provision will be ineffective only to
the extent of such prohibition or invalidity, without invalidating the remainder
of this Agreement.


                                       11
<PAGE>   12

               (f) Counterparts. This Agreement may be executed simultaneously
in two or more counterparts, any one of which need not contain the signatures of
more than one party, but all such counterparts taken together will constitute
one and the same Agreement.

               (g) Descriptive Headings. The descriptive headings of this
Agreement are inserted for convenience only and do not constitute a part of this
Agreement.

               (h) Governing Law. All questions concerning the construction,
validity and interpretation of this Agreement will be governed by the laws of
the State of New York without regard to principles of conflicts of laws.

               (i) Notices. All notices, demands and requests of any kind to be
delivered to any party in connection with this Agreement shall be in writing and
shall be deemed to have been duly given if personally delivered or if sent by
nationally-recognized overnight courier or by registered or certified airmail,
return receipt requested and postage prepaid or by facsimile transmission (with
receipt confirmed by telephone), addressed as follows:

                      (i) if to the Company, to:

                      Orasense Ltd.
                      c/o Appleby, Spurling & Kempe
                      Cedar House, 41 Cedar Avenue
                      P.O. Box HM 1179
                      Hamilton, Bermuda HM EX
                      Facsimile:  (441) 295-7768
                        telephone confirmation required at (441) 295-2244
                      Attention:   Timothy Faries

                      with a copy to each of Isis, EIS and their respective
                      counsel at the addresses indicated below


                                       12
<PAGE>   13

                      (ii) if to Isis, to:

                      Isis Pharmaceuticals, Inc.
                      2292 Faraday Avenue
                      Carlsbad, CA 92008
                      Facsimile:  (760) 931-9639
                      telephone confirmation required at (760) 603-2460
                      Attention:  B. Lynne Parshall

                      with a copy to:

                      Cooley Godward LLP
                      4365 Executive Drive
                      San Diego, CA 92121
                      Facsimile:  (619) 453-3555
                      telephone confirmation required at (619) 550-6000
                      Attention:  L. Kay Chandler, Esq.

                      (iii) if to EIS, to:

                      Elan International Services, Ltd.
                      Flatts, Smiths Parish
                      Bermuda, FL 04
                      Facsimile:  (441) 292-2224
                        telephone confirmation required at (441) 292-9169
                      Attention:  President

                      with a copy to:

                      Brock Silverstein LLC
                      153 East 53rd Street, 56th Floor
                      New York, New York 10022
                      Facsimile:  (212) 371-5500
                      telephone confirmation required at (212) 371-2000
                      Attention:  David Robbins, Esq.

               (j) Entire Agreement. This Agreement constitutes the full and
entire understanding and agreement between the parties with regard to the
subject matter hereof.

                            [Signature page follows]


                                       13
<PAGE>   14

               IN WITNESS WHEREOF, the parties have executed this Registration
Rights Agreement as of the date first written above.


                                    ORASENSE LTD.



                                    By:  ________________________
                                          Name:  B. Lynne Parshall
                                          Title:  President


                                    ISIS PHARMACEUTICALS, INC.



                                    By:  ________________________
                                          Name:  B. Lynne Parshall
                                          Title:  Executive Vice President


                                    ELAN INTERNATIONAL SERVICES, LTD.



                                    By:  ________________________
                                          Name:  Kevin Insley
                                          Title:  President


<PAGE>   1
                                                                    EXHIBIT 10.7

                                            ***TEXT OMITTED AND FILED SEPARATELY
                                                CONFIDENTIAL TREATMENT REQUESTED
                                          UNDER 17 C.F.R. SECTIONS 200.80(b)(4),
                                                            200.83 AND 240.24b-2


                                LICENSE AGREEMENT




                                 BY AND BETWEEN




                                  ORASENSE LTD

                            A BERMUDA LIMITED COMPANY



                                       AND



                        ELAN PHARMACEUTICAL TECHNOLOGIES,
                       A DIVISION OF ELAN CORPORATION, PLC

                                AN IRISH COMPANY





                                 APRIL 20, 1999


<PAGE>   2

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
SECTION                                                                                   PAGE

<S>    <C>                                                                                <C>
1.      DEFINITIONS..........................................................................1

2.      GRANT OF RIGHTS......................................................................8

3.      IMPROVEMENTS AND AFTER ACQUIRED TECHNOLOGY..........................................12

4.      DEVELOPMENT OF PRODUCTS.............................................................13

5       REGULATORY APPROVALS................................................................13

6       FINANCIAL PROVISIONS................................................................14

7       CONFIDENTIAL INFORMATION............................................................18

8       WARRANTIES/INDEMNITIES..............................................................20

9.      INTELLECTUAL PROPERTY OWNERSHIP RIGHTS..............................................24

10.     RIGHTS EXPLOITATION OUTSIDE THE FIELD...............................................25

11.     NON-COMPETITION.....................................................................26

12.     TERM AND TERMINATION OF AGREEMENT...................................................26

13.     IMPOSSIBILITY OF PERFORMANCE - FORCE MAJEURE........................................29

14.     SETTLEMENT OF DISPUTES; GOVERNING LAW...............................................29

15.     ASSIGNMENT..........................................................................29

16.     NOTICES.............................................................................30

17.     MISCELLANEOUS CLAUSES...............................................................31
</TABLE>


                                       i
<PAGE>   3

LICENSE AGREEMENT dated as of March 31, 1999 between Orasense Ltd., a Bermuda
limited company, and Elan Pharmaceutical Technologies, a division of Elan
Corporation, plc, an Irish limited company.

                                    RECITALS:

A.      Contemporaneously herewith, Elan and Isis (capitalized terms used herein
        are defined below) propose to enter into the Development Agreement for
        the purpose of recording the terms and conditions of a joint venture and
        of regulating their relationship with each other and certain aspects of
        the affairs of and their dealings with Orasense.

B.      Elan is beneficially entitled to the use of certain know-how and certain
        patents that have been granted or are pending in relation to the
        development and production of various drug delivery technologies.

C.      Orasense desires to enter into this Agreement with Elan so as to permit
        Orasense to utilize the Elan Intellectual Property in the research,
        development, manufacture, distribution and sale of the Products in the
        Field and in the Territory.

D.      Elan, EIS and Isis entered into a letter agreement dated March 31, 1999
        (the "Letter Agreement") pursuant to which they agreed to enter into
        definitive documents, including this Agreement, and the Isis License
        Agreement relating to Orasense's use of the Isis Intellectual Property.

        NOW THEREFORE IT IS HEREBY AGREED AS FOLLOWS:

1.      DEFINITIONS.

        A.     In this Agreement, the following definitions shall apply:

        1.1.   "Affiliate" shall mean, with respect to Elan or Isis, any
corporation or entity other than Orasense (and entities controlled by it)
controlling, controlled or under the common control of Elan or Isis, as the case
may be, and, with respect to Orasense, any corporation or entity under control
of Orasense. A corporation or non-corporate entity shall be regarded as in
control of another corporation if it owns or directly or indirectly controls at
least fifty percent (50%) of the voting stock of the other corporation or (a) in
the absence of the ownership of at least fifty percent (50%) of the voting stock
of a corporation or (b) in the case of a non-corporate entity, the power to
direct or cause the direction of the management and policies of such corporation
or non-corporate entity, as applicable.

        1.2.   "Agreement" shall mean this agreement (which expression shall be 
deemed to include the Recitals and the Schedules hereto);

        1.3.   "cGCP", "cGLP" and "cGMP" shall mean current Good Clinical
Practices, current Good Laboratory Practices and current Good Manufacturing
Practices respectively;

        1.4.   "Commercialization" shall mean the manufacture, promotion, 
distribution, marketing and sale of the Products;


<PAGE>   4

        1.5. "Competitive Change of Control Event" shall mean that a Primary
Technological Competitor of Elan acquires directly or indirectly voting stock or
equivalent securities in Isis or Orasense representing [...***...] percent or
more of the stock which carries entitlement to vote, or a Primary Technological
Competitor of Elan acquires by all or substantially all of the business of Isis
or Orasense to which the Transaction Documents relate, whether by merger, sale
of stock, sale of assets or otherwise;

        1.6. "Control" shall mean the ability to grant a license or sublicense
as contemplated herein without violating the terms of any agreement with any
third party;

        1.7. "Cost of Living Increase" shall mean, with respect to any year of
the Term, any increase in the Consumer Price Index published by the Bureau of
Labor Statistics of the United States Department of Labor, All Urban Consumers,
United States City Average, All Items (1982/84=100);

        1.8. "Definitive Documents" shall have the same meaning as given to the
term "Transaction Documents" in the Development Agreement;

        1.9. "Development Agreement" shall mean the Joint Development and
Operating Agreement of even date entered into among Isis, Elan, EIS and
Orasense;

        1.10. "Development Candidate" shall mean a [...***...] antisense
inhibitor of TNF-(alpha), as more specifically detailed in Exhibit A hereto;

        1.11. "Development Product" shall mean any product containing as an
active ingredient the Development Candidate (or a Substituted Development
Candidate) in an Oral formulation for humans;

        1.12. "Effective Date" shall mean the date of execution and delivery of
the Definitive Documents;

        1.13. "EIS" shall mean Elan International Services, Ltd., a Bermuda
limited company;

        1.14. "Elan" shall mean Elan Pharmaceutical Technologies, a division of
Elan Corporation, plc, a public limited company incorporated under the laws of
Ireland, its, successors and permitted assigns;

        1.15. "Elan Improvements" shall mean any improvements to the Elan
Patents and Elan Know How developed by Elan (other than pursuant to the Research
and Development Program). Subject to contractual restrictions, Elan Improvements
shall be deemed part of and shall be included in the term "Elan Intellectual
Property" and shall be deemed, immediately upon development by Elan, to be
included in the license of the Elan Intellectual Property hereunder. If the
inclusion of an Elan Improvement in the license of Elan Intellectual


                                               *CONFIDENTIAL TREATMENT REQUESTED

<PAGE>   5

Property is restricted or limited by a third party agreement, Elan shall use
reasonable commercial efforts to exclude or where applicable minimize any such
restriction or limitation;

        1.16. "Elan Intellectual Property" shall mean the Elan Know-How, the
Elan Patent Rights and/or the Elan Improvements. Examples of the Elan
Intellectual Property existing as of the Effective Date include, but are not
limited to, technology related to the modification of the solubility, intrinsic
dissolution, stability and/or permeability of a drug or modification of the
surface(s) of particles, pharmaceutical formulation excipient technology,
formulation, scale-up and manufacturing know-how. Schedule 1 hereto shall
contain, by way of illustration but not limitation, examples of Elan
Intellectual Property. For the avoidance of doubt, Elan Intellectual Property
shall consist of Oral drug delivery technology Controlled by Elan doing business
as Elan Pharmaceutical Technologies and shall exclude (a) the Excluded Elan
Technology, (b) inventions, patents and know-how Controlled by all other
affiliates or subsidiaries of Elan, including, but not limited to the Elan
Pharmaceuticals division which incorporates Athena Neurosciences, Inc., Carnrick
Laboratories, Targon Corporation and Neurex Corporation and (c) inventions,
patents and know-how that are subject to contractual obligations of Elan to
third parties as of the Effective Date to the extent the licensing of such
inventions, patents and know-how is restricted or limited;

        1.17. "Elan Know-How" shall mean any and all rights Controlled by Elan
as of the Effective Date to any discovery, invention (whether or not
patentable), know-how, substances, data, techniques, processes, systems,
formulations and designs relating to Oral drug delivery;

        1.18. "Elan License" shall have the meaning set forth in Section 2.1
hereof;

        1.19. "Elan Patents" shall mean any and all patents and patent
applications Controlled by Elan, existing and/or pending as of the Effective
Date or hereafter filed or obtained relating to Oral drug delivery technology
Controlled by Elan on the Effective Date. Elan Patent Rights shall also include
all extensions, continuations, continuations-in-part, divisionals,
patents-of-additions, re-examinations, re-issues, supplementary protection
certificates and foreign counterparts of such patents and patent applications
and any patents issuing thereon and extensions of any patents licensed
hereunder;

        1.20. "Elan Program Technology" shall mean all Program Technology solely
conceived or made by Elan and/or its agents;

        1.21. "Elan Right of First Negotiation" shall have the meaning provided
in Section 2.11 hereof;

        1.22. "Elan Targeting Technology" shall mean drug targeting technology
to target a drug to a [...***...] or into a [...***...] or into a [...***...];


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        1.23. "Excluded Elan Technology" shall mean (i) Oral Delivery Devices
and (ii) Elan Targeting Technology;

        1.24. "FDA" shall mean the United States Food and Drug Administration or
any successors or agency the approval of which is necessary to market a product
in the United States of America;

        1.25. "Field" shall mean the research, development and Commercialization
of in an Oral Platform for delivery of Oligonucleotide Drugs;

        1.26. "Full Time Equivalent Rate" shall mean, for the services proposed
to be rendered by Elan, [...***...] United States dollars (US $[...***...]);

        1.27. "Independent Third Party" shall mean any person other than
Orasense, Isis, Elan or any of their respective Affiliates;

        1.28. "In market" shall mean sales of Products whether by Orasense or
its Affiliates, or where applicable by a sublicensee, to an Independent Third
Party being a wholesaler, distributor, managed care organization, hospital,
pharmacy and/or the like;

        1.29. "Isis" shall mean Isis Pharmaceuticals, Inc., a Delaware
corporation;

        1.30. "Isis Intellectual Property" shall have the meaning set forth in
the Isis License Agreement;

        1.31. "Isis License" shall have the meaning set forth in the Isis
License Agreement;

        1.34. "Isis License Agreement" shall mean that certain license
agreement, of even date herewith, entered into between Isis and Orasense;

        1.35. "Isis Oligonucleotide" shall mean any Oligonucleotide Drug
Controlled by Isis other than the Development Candidate;

        1.36. "Isis Products" shall mean Products based upon Isis
Oligonucleotides that are made, designed, or otherwise created by or on behalf
of Isis or any of its Affiliates after the date hereof pursuant to the Project
using the Orasense Technology and/or the Licensed Technologies;

        1.37. "Isis Program Technology" shall mean all Program Technology solely
conceived by Isis and/or its agents.

        1.38. "Licensed Technologies" shall mean the Elan Intellectual Property
and the Isis Intellectual Property;

        1.39.  "Licenses" shall mean the Elan License and the Isis License;


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<PAGE>   7

        1.40. "Lien" shall mean any and all liens, security interests,
restrictions, claims, encumbrances or rights of third parties of every kind and
nature;

        1.41. "Management Committee" shall have the meaning given to such term
in the Development Agreement;

        1.42. "Marketing Authorization" shall mean the procurement of
registrations and permits required by applicable government authorities in a
country in the Territory for the marketing, sale, and distribution of a Product
in such country;

        1.43. "Net Sales" shall mean the amount billed, invoiced and/or received
on sales of a Product sold by Orasense or its Affiliates or sublicensees to an
Independent Third Party, less, to the extent included in such invoice price the
total of: (1) ordinary and customary trade quantity or cash discounts and
nonaffiliated brokers' or agents' commissions actually allowed, including
government managed care and other contract rebates, pharmacy incentive programs,
including chargebacks of pharmacy or hospital performance incentive programs or
similar programs; (2) credits, rebates and returns (including, but not limited
to, wholesaler and retailer returns); (3) freight, postage and duties paid for
and separately identified on the invoice or other documentation maintained in
the ordinary course of business, and (4) import, export and sales taxes, excise
taxes, other consumption taxes, customs duties, tariffs and compulsory payments
to governmental authorities actually paid and separately identified on the
invoice or other documentation maintained in the ordinary course of business and
based on sales or turnover or delivery of the Products. Net Sales shall also
include the amount or fair market value of all other consideration received by
Orasense or its Affiliates or sublicensees in respect of Products, whether such
consideration is payment in kind, exchange or another form. If a Product is
provided to an Independent Third Party by Orasense or its Affiliates or
sublicensees without charge or provision of invoice and used by such Independent
Third Party, then Orasense or its Affiliates or sublicensees shall be treated as
having sold such Product to such Independent Third Party for an amount equal to
the fair market value of such Product. Sales between or among Orasense and its
respective Affiliates or authorized licensees shall be excluded from the
computation of Net Sales. A "sale" of a Product is deemed to occur upon the
earlier of invoicing, shipment or transfer of title in the Product to an
Independent Third Party. For avoidance of doubt, Net Sales shall include
royalties received by Orasense or its Affiliates from any Independent Third
Party in respect of Products;

        1.44. "Oligonucleotide Drug" shall mean any single stranded, [...***...]
oligonucleotide including those [...***...] used as a human therapeutic and/or
prophylactic compound containing between [...***...] nucleotides and/or
nucleosides including oligonucleotide analogs which may include [...***...]. For
purposes of this agreement, Oligonucleotide Drug shall specifically exclude
oligonucleotides used in [...***...], oligonucleotides used as [...***...] an
oligonucleotide,


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<PAGE>   8

oligonucleotides used as [...***...] or oligonucleotides used as [...***...].
Oligonucleotide Drug shall also specifically exclude polymers in which the
[...***...]but shall not exclude [...***...]. Should Isis develop [...***...]
oligonucleotides or should Elan independently discover drug delivery technology
it believes to be potentially applicable to [...***...] oligonucleotides, then
the Participants shall discuss in good faith whether such oligonucleotides can
be formulated for Oral delivery using the Oral Platform, and whether such
formulation appears feasible without requiring a significant further investment
in developing or enhancing the Oral Platform; if such formulation appears
feasible, the Participants shall discuss in good faith the inclusion of such
oligonucleotides as Oligonucleotide Drugs;

        1.45. "Oral" shall mean administration by way of the mouth for the
purpose of topical or systemic delivery by way of the alimentary canal;

        1.46. "Oral Delivery Devices" shall mean devices for delivering an
active agent orally such as those employing [...***...] technologies;

        1.47. "Oral Platform" shall mean formulation and excipient systems and
technologies including [...***...] and including the use of [...***...], which
can be employed to develop dosage forms of Oligonucleotide Drugs, deliver said
dosage forms to the alimentary canal and facilitate and promote the systemic and
topical delivery of Oligonucleotide Drugs;

        1.48. "Orasense" shall mean Orasense, Ltd., a Bermuda limited company;

        1.49. "Orasense Program Technology" shall mean all Program Technology
other than Elan Program Technology and Isis Program Technology;

        1.50. "Orasense Technology" shall mean all Program Technology and all
technology licensed or acquired by Orasense or developed by Orasense whether or
not pursuant to the Research and Development Program, excluding, however, Isis
Intellectual Property and Elan Intellectual Property;

        1.51. "Participant" shall mean Elan or Isis, as the case may be.
"Participants" shall mean both Elan and Isis;

        1.52.  "Parties" shall mean Elan and Orasense;

        1.53. "Person" shall mean an individual, partnership, corporation,
limited liability company, business trust, joint stock company, trust,
unincorporated association, joint venture, or other entity of whatever nature;


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<PAGE>   9

        1.54. "Plan" shall mean the business plan and program of development
agreed to by Elan and Isis within sixty (60) days of the date hereof, with
respect to the research, development, prosecution and commercialization of the
Products, which Plan shall be reviewed and mutually agreed to in writing by Elan
and Isis on an annual basis;

        1.54. "Primary Technological Competitor of Elan" shall mean those
entities listed on Schedule 2A hereto.

        1.55. "Project" shall mean all activity as undertaken by Elan, Isis and
Orasense to develop the Products in accordance with the Plan;

        1.56. "Product" shall mean any Oligonucleotide Drug under development or
developed by or on behalf of Orasense in an Oral formulation for administration
to humans;

        1.59. "Program Technology" shall mean all technology developed by or on
behalf of Orasense, whether by Elan, Isis, a third party or jointly by any
combination thereof, pursuant to the Research and Development Program;

        1.60. "Regulatory Authority" shall mean any regulatory authority outside
the United States of America, the approval of which is necessary to market a
Product;

        1.61. "Research and Development Program" shall have the same meaning
given to such term in the Development Agreement;

        1.62. "Research Term" shall mean the period commencing on the Effective
Date and continuing for a period of [...***...] thereafter, unless extended by
the mutual written agreement of Elan and Isis; provided, however, that if a
Participant shall be prevented by (i) events beyond the Participants' control,
or (ii) by such Participant's delay or negligent act or omission, from
performing its obligations under the Definitive Documents within said
[...***...] period, then the other Participant at its option, may extend the
duration of the Research Term by a term equal in length to the period during
which the first Participant was unable to perform its obligations hereunder;

        1.63. "Technological Competitor of Elan" shall mean any entity listed on
Schedule 2B hereto, subject to amendment from time to time upon mutual written
agreement of Orasense, Isis and Elan;

        1.64. "Technological Competitor of Isis" shall have the meaning given to
such term in the Isis License Agreement, as the same shall be amended from time
to time in accordance with such agreement;

        1.65.  "Term" shall have the meaning given to it in Clause 12 below;

        1.66.  "Territory" shall mean all the countries of the world;


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<PAGE>   10

        1.67. "Third Party Oligonucleotide Drug" shall mean any Oligonucleotide
Drug Controlled by an Independent Third Party, other than an Isis
Oligonucleotide Drug;

        1.68. "Third Party Product" shall mean Products based upon Third Party
Oligonucleotide Drug that are made, designed, or otherwise created by or on
behalf of an Independent Third Party after the date hereof pursuant to the
Project using the Orasense Technology and/or the Licensed Technologies. For
avoidance of doubt, any Product based upon an Oligonucleotide Drug jointly
developed by an Independent Third Party and Isis other than pursuant of the
Program shall be deemed to be an Isis Product;

        1.69. "Trademark" shall mean the trademark(s) belonging to Elan as may
be selected by Orasense or its permitted sub-licensees, with Elan's consent, for
use in connection with the Products. By way of example, the Trademarks include,
but are not limited to, [...***...].

        1.70. "United States Dollar" and "US$" shall mean the lawful currency
for the time being of the United States of America;

        B. Interpretation.  In this Agreement the following shall apply:

        1.1 The singular includes the plural and vice versa, the masculine
includes the feminine and vice versa.

        1.2. Any reference to a Clause or Schedule shall, unless otherwise
specifically provided, be to a Clause or Schedule of this Agreement.

        1.3. The headings of this Agreement are for ease of reference only and
shall not affect its construction or interpretation.

2.      GRANT OF RIGHTS

        2.1. Subject to the terms and conditions contained herein and, in
consideration of the payments specified in Clause 6.1(i), Elan hereby grants to
Orasense for the Term a non-exclusive license, including the limited right to
grant sublicenses pursuant to Clause 2.6 hereof, of the Elan Intellectual
Property within the Field for the Territory, solely to research, develop,
manufacture, have manufactured, and Commercialize the Products in the Territory,
subject to any contractual obligations of Elan to Independent Third Parties as
of the Effective Date and, unless prohibited by the paragraph below titled Non
Competition, contractual obligations to Independent Third Parties that Elan may
enter into after the Effective Date (the "Elan License").

        2.2. Elan hereby grants an option, to be exercised upon written notice
to Elan by Orasense and payment of an option price of [...***...], to Elan
patents and know-how related to Oral delivery systems held by Elan Transdermal
Technologies, Inc. (formerly


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<PAGE>   11

Sano Corporation) and Elan Pharmaceutical International Ltd. (but only to the
extent such technology consists of NanoCrystal(TM) technology formerly held by
NanoSystems, a division of the Eastman Kodak Company). Upon exercise of such
option by Orasense, such technology, shall, subject to any contractual
obligations to Independent Third Parties that Elan may have as of the date of
exercise of the such option, and, unless prohibited by the paragraph below
titled Non Competition, contractual obligations to Independent Third Parties
that Elan may enter into after the exercise of such option, be deemed included
within the Elan License, the Elan Intellectual Property, the Elan Patents, and
the Elan Know-How, as appropriate, and subject to the provisions hereof with
respect thereto.

        2.3. In the event, as of the Effective Date, the Elan License granted to
Orasense hereunder is restricted or limited by any contractual obligations of
Elan to Independent Third Parties, then Elan shall use reasonable commercial
efforts to exclude or, where applicable, to minimize any such restriction or
limitation. Except as expressly provided herein, all proprietary rights and
rights of ownership with respect to the Elan Intellectual Property shall at all
times remain solely with Elan. Elan shall disclose to Orasense inventions made
by or on behalf of Elan in connection with the performance of the Project, any
patentable inventions and discoveries within the Elan Intellectual Property that
relate to the Field and any patentable Elan Improvements developed by or on
behalf of Elan.

        2.4. To the extent royalty or other compensation obligations to
Independent Third Parties that are payable with respect to Elan Intellectual
Property would be triggered by a proposed use of Elan Intellectual Property in
connection with the Project, Elan will inform Orasense and Isis of such royalty
or compensation obligation. If Orasense decides to utilize such Elan
Intellectual Property in connection with the Project, Orasense will be
responsible for the payment of such royalty or other compensation obligations
relating thereto.

        2.5. Notwithstanding anything contained in this Agreement to the
contrary, Elan shall have the right, and subject to the paragraph below titled
Non-Competition, to fully exploit and grant licenses and sublicenses with
respect to the Elan Intellectual Property. Elan's rights to exploit and grant
licenses referred to in the immediately preceding sentence shall include the
right to research, develop, manufacture, license or Commercialize products.

        2.6. Orasense shall not be permitted to (a) encumber any of its rights
under the Licenses or the Orasense Technology without the prior written consent
of Elan; (b) assign or sublicense any of its rights under the licenses for the
Licensed Technologies and the Orasense Technology without the prior written
consent of Elan, which consent may be withheld in Elan's sole discretion. Any
agreement between Orasense and any permitted third party for the development or
exploitation of the Elan Intellectual Property shall require such third party to
maintain the confidentiality of all information concerning the Elan Intellectual
Property and shall provide that any Elan Improvements shall belong to Elan and
shall permit an assignment of rights by Orasense to Elan in accordance with the
terms of this Agreement. Orasense shall remain responsible for all acts and
omissions of any sub-licensee, as if they were acts and omissions by Orasense.
Rights of permitted third party sublicensees in and to the Elan Intellectual
Property shall survive the termination of the license and sublicense



                                       9
<PAGE>   12

agreements granting said intellectual property rights to Orasense; and Orasense
and Elan shall in good faith agree upon the form most advantageous to Elan in
which the rights of the sublicensor under any such sublicenses are to be held
(which form may include continuation of Orasense solely as the holder of such
licenses or assignment of such rights to a third party or parties, including an
assignment to Elan).

        2.7. Orasense will use its reasonable commercial endeavours to exploit
the Elan Intellectual Property, the Isis Intellectual Property and Orasense
Technology in accordance with this Agreement, the Isis License Agreement and the
Plan. Orasense shall employ diligent efforts to research, develop, register, and
Commercialize the Products in the Territory. Orasense shall employ or have
employed on its behalf a level of advertising, sales, marketing, and promotion
efforts in each country in the Territory where Marketing Authorization for
Product has been obtained which is: (i) commensurate with that used by other
pharmaceutical manufacturers for products of similar market potential in that
country in the Territory, and (ii) sufficient with respect to the potential for
that country to fully exploit the market potential for the Product as depicted
in the Plan and as determined by the Management Committee in accordance with the
Development Agreement.

        2.8. Orasense will be solely responsible for ensuring that it or its
sublicensees manufacture and Commercialize the Products within each country of
the Territory strictly in accordance with all the legal and regulatory
requirements of each country of the Territory.

        2.9. Upon the request of Orasense and with the consent of Elan, Elan
shall grant to Orasense during the Term a non-exclusive royalty free license in
the Territory, solely for use in connection with the sale of the Products, to
use one or more Trademark, on the following terms:

           2.9.1  Orasense shall as soon as it becomes aware of any infringement
                  give to Elan in writing full particulars of any use or
                  proposed use by any other person, firm or company of a trade
                  name or trademark or promotional or advertising activity which
                  may constitute infringement.

           2.9.2  If Orasense becomes aware that any other person, firm or
                  company alleges that such Trademark is invalid or that the use
                  of such Trademark infringes any rights of another party or
                  that the Trademark is otherwise attacked or attackable,
                  Orasense shall immediately give to Elan full particulars in
                  writing thereof and shall make no comment or admission to any
                  third party in respect thereof.



                                       10
<PAGE>   13

           2.9.3  Elan shall have the right to conduct all proceedings relating
                  to such Trademark and shall in its sole discretion decide what
                  action, if any, to take in respect of any infringement or
                  alleged infringement of such Trademark or any other claim or
                  counter-claim brought or threatened in respect of the use or
                  registration of such Trademark. Any such proceedings shall be
                  conducted at Elan's expense and for its own benefit.

           2.9.4  Nothing contained in this Agreement shall grant to Orasense
                  any right, title, or interest in or to such Trademark, whether
                  or not specifically recognized or perfected under applicable
                  laws, except for the non-exclusive license granted herein. At
                  no time during or after the term of this Agreement shall
                  Orasense challenge or assist others to challenge any such
                  Trademark or the registration thereof or attempt to register
                  any trademarks, marks, or trade names confusingly similar to
                  any such trademark. All displays of any such Trademark that
                  Orasense intends to adopt shall first be submitted to Elan for
                  approval (which shall not be unreasonably withheld) of design,
                  color, and other details, or shall be exact copies of those
                  used by Elan. In addition, Orasense shall fully comply with
                  all reasonable guidelines, if any, communicated by Elan
                  concerning the use of any such Trademark as well as all rules
                  and regulations of such use throughout the Territory.

           2.9.5  The rights granted to Orasense under this Article 2.9 shall
                  automatically terminate respect to a Product in a country in
                  the Territory upon termination of Orasense's right to market
                  such Product in any such country.

        2.10. When packaged, and to the extent permitted by law, a product label
shall include an acknowledgement that the Product is made under license from
Elan. Such acknowledgement shall take into consideration regulatory requirements
and Orasense's reasonable commercial requirements. Orasense shall wherever
possible give due acknowledgement and recognition to Elan in all printed
promotional and other material regarding the Product such as stating that the
Product is under license from Elan and that the applicable Elan Intellectual
Property has been applied to the Products. Orasense shall consult with and
obtain the written approval of Elan as to the format and content of the
promotional and other material insofar as it relates to a description of, or
other reference to, the application of the Elan Intellectual Property, such
approval not to be unreasonably withheld or delayed. The further consent of Elan
shall not be required where the format and content of such materials is
substantively similar as the materials previously furnished to and approved in
writing by Elan.

        2.11   Notwithstanding anything contained in this Agreement to the
contrary, Elan shall have [...***...]. Such [...***...] shall be exercised


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<PAGE>   14

as follows:

           2.11.1 If Orasense intends to [...***...], then Orasense immediately
           shall notify Elan in writing that Elan may elect to [...***...]
           referred to in this Article 2.11. Elan shall indicate its desire to
           [...***...] pursuant to this Article 2.11 by delivering written
           notice to Orasense within forty-five (45) days of Elan's receipt of
           the written notification from Orasense to Elan. If Elan elects to
           [...***...], the Parties shall [...***...].

           2.11.2 If, despite such good faith negotiations, Elan and Orasense do
           not [...***...] within [...***...] from the notification in writing
           by Orasense to Elan, then Orasense shall be free to [...***...],
           which [...***...], as the case may be.


        2.12. Elan shall have the first option to manufacture the Development
Product for Orasense and meet its requirements, and Orasense shall agree to
utilize Elan as its sole supplier, subject to the customary terms and conditions
contained in a supply agreement to be executed by the parties at the price set
forth in Clause 6.1.2 hereof. If, despite good faith negotiations, Elan and
Orasense do not reach agreement on the terms of such manufacturing agreement
within [...***...] from the Parties' commencement of discussion of such terms,
then Orasense shall be free to offer a third party (other than a Technological
Competitor of Elan unless consented to by Elan which consent may be withheld for
any reason, and otherwise subject to the terms and conditions of this Agreement)
terms to manufacture the Development Product in the Territory, which terms when
taken as a whole, are more favorable to Orasense than the principal terms of the
last written proposal offered to Orasense by Elan, or by Orasense to Elan, as
the case may be. Subject to the foregoing rights of Elan with respect to the
Development Product, Orasense shall not be permitted to contract the manufacture
or Commercialization of any Product without the prior written consent of Elan
and Isis, which consent will not be unreasonably withheld or delayed; provided
that such reasonableness standard, in the case of Elan, shall not be applicable
in the case of a proposed sublicense to any Technological Competitor of Elan and
in the case of Isis, shall not be applicable in the case of a proposed
sublicense to any Technological Competitor of Isis.


3.      IMPROVEMENTS AND AFTER ACQUIRED TECHNOLOGY

        3.1 Elan Improvements shall be deemed, immediately upon development, to
be


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<PAGE>   15

included in the license of the Elan Intellectual Property granted to Orasense
hereunder.

        3.2 The Elan License specifically excludes any right to use Elan
Improvements outside of the Field.

        3.3 If the inclusion of an Elan Improvement in the license of Elan
Intellectual Property granted to Orasense hereunder is restricted or limited by
a third party agreement, then Elan shall use reasonable commercial efforts to
exclude, or where applicable, to minimize any such restriction or limitation.

        3.4 All rights, title, and interest to any Elan Improvements developed
by Orasense, Isis or any third party shall be the property of Elan. Orasense,
Isis and any such third party shall execute and deliver documents, and take such
other actions as Elan may reasonably request, to effect or evidence such
ownership.

        3.5 If Elan acquires know-how or patent rights relating to the Field, or
if Elan acquires or merges with an Independent Third Party that has know-how or
patent rights relating to the Field, then Elan shall offer to license such
know-how and patent rights to Orasense (subject to existing contractual
obligations), on such terms as would be offered to an Independent Third Party
negotiating in good faith on an arms-length basis, and if the Management
Committee determines that Orasense should not acquire such license, then Elan
shall be free to fully exploit such know-how and patent rights, and to grant to
third parties licenses and sublicenses with respect thereto.


4.      DEVELOPMENT OF PRODUCTS

        4.1 During the Research Term, Orasense will diligently pursue the
research and development of the Elan Intellectual Property, Isis Intellectual
Property and Orasense Technology in accordance with the Research and Development
Program. The objectives of this initial phase of the Research and Development
Program will be (a) to develop the Oral Platform, and (b) to develop the
Development Product.

        4.2 Orasense will diligently pursue the research, development and
Commercialization of the Development Product and other Products in accordance
with the Plan, this Agreement, the Isis License Agreement and the Development
Agreement.

5       REGULATORY APPROVALS

        5.1 Orasense shall, or shall cause its sublicensees, at its or their
sole cost file and shall use its reasonable best efforts to prosecute to
approval or cause its sublicensees to prosecute to approval, the Marketing
Authorizations for the Products in the Territory in accordance with the Plan.
During any Marketing Authorization registration procedure, Orasense shall keep
Elan promptly and fully advised of Orasense's registration activities, progress
and procedures. Each Party shall inform the other Party and Isis of any dealings



                                       13
<PAGE>   16

such Party has with the FDA and any other Regulatory Authority. The Parties and
Isis shall collaborate in relation to obtaining any approval of the FDA or
Regulatory Authority for final approved labeling.

        5.2 Subject to agreement to the contrary, any and all Marketing
Authorizations filed hereunder for Products shall, to the extent owned by
Orasense, remain the property of Orasense, provided that Orasense shall allow
Elan access thereto to enable Elan to fulfill its obligations and exercise its
rights under this Agreement and the Development Agreement. Orasense shall
maintain or cause its sublicensees to maintain such Marketing Authorizations at
its or their own cost.

        5.3 Orasense shall indemnify and hold harmless Elan, its agents and
employees from and against all claims, damages, losses, liabilities and expenses
to which Elan, its agents, and employees may become subject related to or
arising out of Orasense's bad faith, negligence or intentional misconduct in
connection with the filing or maintenance of the Marketing Authorizations.

6       FINANCIAL PROVISIONS.

        6.1 In consideration of the license to the Elan Patents, Orasense shall
pay to Elan the following amounts:

          6.1.1     Up Front License Fee Payment. [...***...]United States 
        Dollars (US$[...***...]), simultaneously with the execution and delivery
        of this Agreement by both Parties; and

          6.1.2     Development Product Fees and Royalties. Payments to Elan 
        with respect to services rendered in connection with the Development
        Product shall be paid as provided below and net proceeds derived by
        Orasense from the Development Product shall be allocated as additional
        royalties in proportion to [...***...], as more particularly or as
        otherwise set forth below.

               (a)  Development Work - Research and development work performed 
        during the Research Term pursuant to the Research and Development
        Program regarding the Oral Platform and the Development Candidate
        contracted by Orasense to Elan shall be payable by Orasense to Elan
        based on fully burdened actual costs at Elan's Full Time Equivalent
        Rate, with annual Cost of Living Increases. In the event Elan is
        required to perform additional research and development work beyond that
        contemplated during the Research Term (without any extensions thereto),
        Orasense shall pay to Elan [...***...].

               (b)  Milestone Payments - If any Independent Third Party shall 
        make milestone payments (e.g., for NDA filing, approvals, etc.) to
        Orasense, Orasense shall pay to Elan and Isis an additional royalty in
        the amount of [...***...].


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       14
<PAGE>   17

               (c)  Royalties payable to Elan Upon Sales of the Development 
        Product - Elan shall receive royalties of [...***...] of the In-market
        Net Sales of Development Products by Orasense or its sublicensees.
        Notwithstanding the foregoing, in no event shall royalties payable to
        Elan with respect to sales of the Development Product [...***...].

               (d)  Manufacturing Charges. In the event Elan exercises its 
        option to manufacture the Development Products for Orasense, Orasense
        shall pay Elan a price equal to [...***...] for the manufacture of
        Development Products.

          6.1.3     Isis Product Fees and Royalties. Payments to Elan with 
        respect to services rendered in connection with Isis Products shall be
        paid as provided below and net proceeds derived by Orasense from Isis
        Products shall be allocated as additional royalties in proportion to
        [...***...], as more particularly or as otherwise set forth below.

               (a)  Development Work - Research and development work performed 
        by Elan for Orasense related to Isis Products shall be payable to Elan
        by Orasense at [...***...].

               (b)  Milestone Payments - If any Independent Third party shall 
        make milestone payments (e.g., for NDA filing, approvals, etc.) to Isis
        with respect to an Isis Product, then [...***...] of such milestone
        payment shall be paid to Orasense by Isis as an additional royalty and
        Orasense shall pay a royalty [...***...] to Elan; provided however, that
        development related milestone payments with respect to any Isis Product
        shall not be payable by Isis to Orasense or by Orasense to Elan except
        to the extent such payments exceed [...***...] with respect to such Isis
        Product (or, in the event the milestone is intended to be applied
        towards future work to be performed by Isis, in excess of [...***...].

               (c)  Elan Royalty Payments.  Orasense shall pay to Elan a royalty
        of [...***...] of In-market Net Sales of any Isis Products. Any
        marketing and/or development agreement between Orasense and Isis with
        respect to Isis Products shall provide for a royalty payment to Orasense
        of [...***...] of In-market Net Sales of the Isis Products. At such time
        as royalty payments by Isis to Orasense shall equal [...***...] for the
        particular Isis Product subject to any such agreement, the royalty
        payable by Isis to Orasense with respect to In-market Net Sales of the
        Isis Product shall be [...***...] and the royalty payable by


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       15
<PAGE>   18

        Orasense to Elan with respect to such Isis Product shall be [...***...]
        of In-market Net Sales of such Isis Product.

               (d)       Manufacturing Charges. In the event Elan agrees to 
        provide manufacturing services for Products based on Isis Products
        (other than the Development Candidate), Elan shall be paid a price equal
        to [...***...].

               6.1.4     Third Party Products. Payments to Elan with respect to
        services rendered in connection with Third Party Products shall be paid
        as provided below and net proceeds derived by Orasense from Third Party
        Products shall be allocated as additional royalties with [...***...] of
        such amount being paid to Elan and [...***...] to Isis, as more
        particularly or as otherwise set forth below set forth below; provided,
        however, that in the event [...***...] significantly contributes to the
        research and development work related to a Third Party Product, the
        Participants shall negotiate in good faith an appropriate adjustment to
        the allocation of such additional royalties to reflect their relative
        contributions to the development of such Third Party Product.

               (a)       Development Work - Research and development work 
        performed by Elan for Orasense related to Third Party Products shall be
        payable to Elan at [...***...]. Orasense shall pay to Elan an additional
        fee equal to [...***...] of all amounts paid by an Independent Third
        Parties to Orasense for development work to the extent the amounts paid
        to Orasense for such work exceeds any charges by Elan and Isis; with the
        remaining [...***...] of such excess amount being payable to Isis.

               (b)       Royalty Payments to Elan - In the event Orasense 
        contracts development work to Elan for any Third Party Product, Orasense
        shall pay Elan, a royalty equal to [...***...] of the royalties it
        receives with respect to such Product (with the remaining [...***...] of
        such royalties payable to Isis) until such time as Elan has been paid a
        sum equal to [...***...]. Thereafter, [...***...] of the royalties
        received by Orasense with respect to such Third Party Product shall be
        paid to Elan (with the balance payable to Isis).

               (c)       Milestone Payments - If any Independent Third Party 
        shall make milestone payments (e.g., for NDA filing, approvals, etc.) to
        Orasense, then [...***...] of such milestone payment shall be paid by
        Orasense to Elan as an additional royalty and [...***...] shall be paid
        by Orasense to Isis as an additional royalty to Isis.

               (d)       Manufacturing and Supply of Products - In the event 
        Orasense contracts with Elan to manufacture Third Party Products, Elan
        shall charge Orasense a price equal to [...***...].


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       16
<PAGE>   19

        Orasense shall pay to Elan an additional fee equal to [...***...] of all
        amounts paid by an Independent Third Parties to Orasense for the
        manufacture of such Third Party Products to the extent such amounts
        exceed the amount previously charged by Elan; with the remaining
        [...***...] of such excess amount being payable to Isis.

        6.2 Payment of royalties pursuant to Clauses 6.1.2-6.1.4, if any, shall
be made quarterly in arrears within forty-five (45) days after the expiry of the
calendar quarter. The method of payment shall be by wire transfer to an account
specified by Elan and shall be nonrefundable to Orasense. Each payment made to
Elan shall be accompanied by a true accounting of all Products sold by Orasense,
its Affiliates and its permitted sublicensees, if any, during such quarter. Such
accounting shall show, on a country-by-country and Product-by-Product basis, Net
Sales or royalties received by Orasense (and the calculation thereof) and each
calculation of royalties with respect thereto, including the calculation of all
adjustments and currency conversions.

        6.3 Orasense shall maintain and keep clear, detailed, complete, accurate
and separate records for a period of three (3) years following the completion of
such records so: (i) as to enable any royalties which shall have accrued
hereunder to be determined; and (ii) that any deductions made in arriving at the
Net Sales can be determined.

        6.4 All payments due hereunder shall be made in United States Dollars.
Payments due on Net Sales of any Product or royalties received by Orasense with
respect to any Product for each calendar quarter made in a currency other than
United States Dollars shall first be calculated in the foreign currency and then
converted to United States Dollars on the basis of the average exchange rate in
effect for such quarter for the purchase of United States Dollars with such
foreign currency quoted in the Wall Street Journal (or comparable publication if
not quoted in the Wall Street Journal) with respect to the currency of the
country of origin of such payment, determined by averaging the rates so quoted
on each business day of such quarter.

        6.5 If Orasense claims in good faith that one or more of its devices,
products, parts or components thereof, compounds and/or drug products does not
utilize, incorporate, apply or is not based on the Elan Intellectual Property,
the Isis Intellectual Property and/or Orasense Technology, then Orasense shall
immediately notify Elan in writing and establish same to Elan's reasonable
satisfaction.

        6.6 If, at any time, legal restrictions in the Territory prevent the
prompt payment when due of royalties or any portion thereof, the Parties shall
meet to discuss suitable and reasonable alternative methods of reimbursing Elan
the amount of such royalties. In the event that Orasense is prevented from
making any payment under this Agreement by virtue of the statutes, laws, codes
or government regulations of the country from which the payment is to be made,
then such payments may be paid by depositing them in the currency in which they
accrue to Elan's account in a bank acceptable to Elan in the country the
currency of which is involved or as otherwise agreed by the Parties.

                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       17
<PAGE>   20

        6.7    Elan and Orasense agree to co-operate in all respects necessary 
to take advantage of any double taxation agreements or similar agreements as
may, from time to time, be available.

        6.8    Any taxes payable by Elan on any payment made to Elan pursuant to
this Agreement shall be for the account of Elan. If so required by applicable
law, any payment made pursuant to this Agreement shall be made by Orasense after
deduction of the appropriate withholding tax, in which event the Parties shall
co-operate to obtain the appropriate tax clearance as soon as is practicable. On
receipt of such clearance, Orasense shall forthwith procure that the amount so
withheld is paid to Elan.

        6.9    Orasense shall, not more than once in each calendar year, permit
Elan or its duly authorized representatives upon reasonable notice and at any
reasonable time during normal business hours to have access to inspect and audit
the accounts and records of Orasense and any other book, record, voucher,
receipt or invoice relating to the calculation of the royalty payments on Net
Sales submitted to Elan. Any such inspection of Orasense's records shall be at
the expense of Elan, except that if any such inspection reveals a deficiency in
the amount of the royalty actually paid to Elan hereunder in any calendar
quarter of five percent (5%) or more of the amount of any royalty actually due
to Elan hereunder, then the expense of such inspection shall be borne solely by
Orasense. Any amount of deficiency shall be paid promptly to Elan by Orasense.
If such inspection reveals a surplus in the amount of royalties actually paid to
Elan by Orasense, Elan shall reimburse Orasense the surplus within fifteen (15)
days after determination.

        6.10   In the event of any unresolved dispute regarding any alleged
deficiency or overpayment of royalty payments hereunder, the matter will be
subject to resolution in accordance with Clause 24.9 of the Development
Agreement, which is incorporated by reference and shall for such purposes
survive termination of the Development Agreement.

7       CONFIDENTIAL INFORMATION

        7.1    The Parties acknowledge that it may be necessary, from time to 
time, to disclose to each other confidential and proprietary information,
including without limitation, inventions, works of authorship, trade secrets,
specifications, designs, data, know-how and other information relating to the
Field, the Products, Elan Intellectual Property, Isis Intellectual Property or
the Orasense Technology, as the case may be, processes, services and business of
the disclosing Party. The foregoing shall be referred to collectively as
"Confidential Information". Any Confidential Information revealed by a Party to
another Party shall be used by the receiving Party exclusively for the purposes
of fulfilling the receiving Party's obligations under this Agreement and the
Development Agreement and for no other purpose.

        7.2    Each Party agrees to disclose Confidential Information of another
Party only to those employees, representatives and agents requiring knowledge
thereof in connection with their duties directly related to the fulfilling of
the Party's obligations under this


                                       18
<PAGE>   21

Agreement. Each Party further agrees to inform all such employees,
representatives and agents of the terms and provisions of this Agreement and
their duties hereunder and to obtain their consent hereto as a condition of
receiving Confidential Information. Each Party agrees that it will exercise the
same degree of care, but in no event less than a reasonable degree, and
protection to preserve the proprietary and confidential nature of the
Confidential Information disclosed by a Party, as the receiving Party would
exercise to preserve its own proprietary and confidential information. Each
Party agrees that it will, upon request of a Party, return all documents and any
copies thereof containing Confidential Information belonging to or disclosed by,
such Party.

        7.3    Notwithstanding the above, each Party may use or disclose
Confidential Information disclosed to it by another party to the extent such use
or disclosure is reasonably necessary in filing or prosecuting patent
applications, prosecuting or defending litigation, complying with patent
applications, complying with applicable governmental regulations or otherwise
submitting information to tax or other governmental authorities, conducting
clinical trials, or making a permitted sub-license or otherwise exercising its
rights hereunder, provided that if a Party is required to make any such
disclosure of the other Party's Confidential Information, other than pursuant to
a confidentiality agreement, such Party shall inform the recipient of the terms
and provisions of this Agreement and their duties hereunder and to obtain their
consent hereto as a condition of receiving Confidential Information.

        7.4    Any breach of this Clause 7 by any of the Persons informed by one
of the Parties is considered a breach by the Party itself.

        7.5    Confidential Information shall not be deemed to include:

               (i)       information that is generally available to the public;

               (ii)      information which is made public by the disclosing 
Party;

               (iii)     information which is independently developed by a Party
as evidenced by such Party's written records, without the aid, application or
use of the disclosing Party's Confidential Information;

               (iv)      information that is published or otherwise becomes part
of the public domain without any disclosure by a Party, or on the part of a
Party's directors, officers, agents, representatives or employees;

               (v)       information that becomes available to a Party on a
non-confidential basis, whether directly or indirectly, from a source other than
a Party, which source did not acquire this information on a confidential basis;

               (vi)      information  which the receiving Party is required to 
disclose pursuant to:


                                       19
<PAGE>   22

                    (A)  a valid order of a court or other governmental body or
any political subdivision thereof or otherwise required by law; or

                    (B)  any other requirement of law;

provided that if the receiving Party becomes legally required to disclose any
Confidential Information, the receiving Party shall give the disclosing Party
prompt notice of such fact so that the disclosing Party may obtain a protective
order or other appropriate remedy concerning any such disclosure. The receiving
Party shall fully cooperate with the disclosing Party in connection with the
disclosing Party's efforts to obtain any such order or other remedy. If any such
order or other remedy does not fully preclude disclosure, the receiving Party
shall make such disclosure only to the extent that such disclosure is legally
required;

               (v)       information which was already in the possession of the
receiving Party at the time of receiving such information, as evidenced by its
written records, provided such information was not previously provided to the
receiving Party from a source which was under an obligation to keep such
information confidential; or

               (vi)      information that is the subject of a written permission
to disclose, without restriction or limitation, by the disclosing Party.

        7.6    The provisions relating to confidentiality in this Clause 7 shall
remain in effect during the term of this Agreement, and for a period of seven
(7) years following the expiration or earlier termination of this Agreement but
shall not apply to any information which a Party is required to file or
otherwise disclose in accordance with requirements which are legally binding on
it.

        7.7    The Parties agree that the obligations of this Clause 7 are
necessary and reasonable in order to protect the Parties' respective businesses,
and each Party expressly agrees that monetary damages would be inadequate to
compensate a Party for any breach by the other Party of its covenants and
agreements set forth herein. Accordingly, the Parties agree and acknowledge that
any such violation or threatened violation will cause irreparable injury to a
Party and that, in addition to any other remedies that may be available, in law
and equity or otherwise, any Party shall be entitled to obtain injunctive relief
against the threatened breach of the provisions of this Clause 7, or a
continuation of any such breach by the other Party, specific performance and
other equitable relief to redress such breach together with its damages and
reasonable counsel fees and expenses to enforce its rights hereunder, without
the necessity of proving actual or express damages.

8       WARRANTIES/INDEMNITIES

        8.1    Elan represents and warrants to Orasense that:

               (a)  Elan is a corporation duly organized under the laws of its 
jurisdiction of organization and has all the requisite corporate power and
authority to own


                                       20
<PAGE>   23

and lease its respective properties, to carry on its respective business as
presently conducted and as proposed to be conducted and to carry out the
transactions contemplated hereby;

               (b)  Elan has full corporate power and authority enter into this
Agreement and to perform its obligations hereunder, which have been duly
authorized by all requisite corporate action of Elan. This Agreement is the
valid and binding obligation of Elan, enforceable against it in accordance with
its terms, except as limited by applicable bankruptcy, insolvency,
reorganization, moratorium and other laws of general application affecting the
enforcement of creditors' rights generally, and by general equity principles and
limitations on the availability of equitable relief, including specific
performance;

               (c)  The execution, delivery and performance by Elan of this
Agreement will not: (i) violate any provision of applicable law, statute, rule
or regulation known by and applicable to Elan or any ruling, writ, injunction,
order, judgment or decree of any court, arbitrator, administrative agency or
other governmental body applicable to Elan or any of its properties or assets;
or (ii) conflict with or result in any breach of any of the terms, conditions or
provisions of, or constitute (with notice or lapse of time or both) a default
(or give rise to any right of termination, cancellation or acceleration) under
the charter or organizational documents of Elan to which Elan is a party, except
where such violation, conflict or breach would not, individually or in the
aggregate, have an adverse material effect on the business, assets, liabilities
(contingent or otherwise), operations, condition (financial or otherwise), or
prospects of Elan;

               (d)  To Elan's best knowledge, except as set forth on Schedule 3
hereto, (i) Elan has the right to grant the Elan License and any other rights
granted herein, (ii) Schedule 1 contains primary examples of the Elan
Intellectual Property existing as of the Effective Date, which listing is not
necessarily exhaustive, (iii) there are no agreements between Elan and any third
parties that conflict with the Elan License which would have a material adverse
effect on the ability of Orasense to conduct its business as presently proposed
to be conducted, (iv) Elan is the owner or licensee of all rights, title and
interest in the Elan Intellectual Property; (v) Elan has no knowledge of any
pending or threatened action, suit, proceeding or claim by others challenging
Elan's rights in or to such Elan Intellectual Property as related to the Field,
which would have a material adverse effect on the ability of Orasense to conduct
its business as presently proposed to be conducted, and (vi) the Elan
Intellectual Property constitutes all material intellectual property in Elan's
Control reasonably applicable to the Project as it relates to Oral controlled
release in the Field.

        8.2    Orasense represents and warrants to Elan the following:

               (a)  Orasense is duly and validly existing in good standing in 
the jurisdiction of its incorporation and each other jurisdiction in which the
conduct of its business requires such qualification (except where such failure
to so qualify shall not have a material adverse affect on the business and
assets of Orasense), and Orasense is in compliance with all applicable laws,
rules, regulations or orders relating to its business and assets;


                                       21
<PAGE>   24

               (b) Orasense has full corporate authority to execute and deliver
this Agreement and to consummate the transactions contemplated hereby; this
Agreement has been duly executed and delivered and constitutes the legal and
valid obligations of Orasense and is enforceable against Orasense in accordance
with its terms; and the execution, delivery and performance of this Agreement
and the transactions contemplated hereby will not violate or result in a default
under or creation of lien or encumbrance under Orasense's certificate of
incorporation, by-laws or other organic documents, any material agreement or
instrument binding upon or affecting Orasense, or its properties or assets or
any applicable laws, rules, regulations or orders affecting Orasense or its
properties or assets;

               (c) Orasense is not in default of its charter or by-laws, any
applicable laws or regulations or any material contract or agreement binding
upon or affecting it or its properties or assets and the execution, delivery and
performance of this Agreement and the transactions contemplated hereby will not
result in any such violation;

               (d) Orasense represents and warrants to Elan that the execution
of this Agreement by Orasense and the full performance and enjoyment of the
rights of Orasense under this Agreement will not breach the terms and conditions
of any license, contract, understanding or agreement, whether express, implied,
written or oral between Orasense and any third party.

        8.3    Orasense represents and warrants to and covenants with Elan that
it has the sole, exclusive and unencumbered right to grant the licenses and
rights herein granted to Elan and that it has not granted and will not grant any
option, license, right or interest in or to the Elan Intellectual Property, the
Orasense Technology, or other property to any third party which would conflict
with the rights granted by this Agreement and the Definitive Documents.

        8.4    Orasense represents and warrants to and covenants and agrees with
Elan that the Products shall be developed, manufactured, transported, stored,
handled, packaged, marketed, promoted, distributed, offered for sale and sold in
accordance with all regulations and requirements of the FDA and foreign
regulatory authorities including, without limitation, cGCP, cGLP, cGMP
regulations. The Products shall not be adulterated or misbranded as defined by
the Federal Food, Drug and Cosmetic Act (or applicable foreign law) and shall
not be a product which would violate any section of such Act if introduced in
interstate commerce.

        8.5    Orasense represents and warrants to Elan that it is fully 
cognizant of all applicable statutes, ordinances and regulations of the United
States of America and countries in the Territory with respect to the manufacture
of the Products including, but not limited to, the U.S. Federal Food, Drug and
Cosmetic Act and regulations thereunder and similar statutes in countries
outside of the United States. Orasense shall manufacture or procure the
manufacture of the Products in conformity with the Marketing Authorizations and
in a manner which fully complies with all United States of America and foreign
statutes,


                                       22
<PAGE>   25

ordinances, regulations and practices.

        8.6    In addition to any other indemnifications provided for herein, 
Elan shall indemnify and hold harmless Orasense and its Affiliates and their
respective employees, agents, partners, officers and directors from and against
any claims, losses, liabilities or damages (including reasonable attorney's fees
and expenses) incurred or sustained by Orasense arising out of or in connection
with any (a) breach of any representation, covenant, warranty or obligation by
Elan hereunder, or (b) any act or omission on the part of Elan or any of its
agents or employees in the performance of this Agreement.

        8.7    In addition to any other indemnifications provided for herein,
Orasense shall indemnify and hold harmless Elan and its Affiliates and their
respective employees, agents, partners, officers and directors from and against
any claims, losses, liabilities or damages (including reasonable attorney's fees
and expenses) incurred or sustained by Elan arising out of or in connection with
any (a) breach of any representation, covenant, warranty or obligation by
Orasense hereunder, or (b) any act or omission on the part of Orasense or any of
its agents or employees in the performance of this Agreement.

        8.8    The Party seeking an indemnity shall:

          8.8.1  fully and promptly notify the other Party of any claim or 
                 proceeding, or threatened claim or proceeding;

          8.8.2  permit the indemnifying Party to take full care and control of
                 such claim or proceeding;

          8.8.3  cooperate in the investigation and defense of such claim or 
                 proceeding;

          8.8.4  not compromise or otherwise settle any such claim or proceeding
                 without the prior written consent of the other Party, which
                 consent shall not be unreasonably withheld, conditioned or
                 delayed; and

          8.8.5  take all reasonable steps to mitigate any loss or liability in
                 respect of any such claim or proceeding.

        8.9    NOTWITHSTANDING ANYTHING TO THE CONTRARY IN THIS AGREEMENT, 
NEITHER ELAN NOR ORASENSE SHALL BE LIABLE TO THE OTHER PARTY, OTHER BY REASON OF
ANY REPRESENTATION OR WARRANTY, CONDITION OR OTHER TERM OR ANY DUTY OF COMMON
LAW, OR UNDER THE EXPRESS TERMS OF THIS AGREEMENT, OR FOR ANY CONSEQUENTIAL OR
INCIDENTAL LOSS OR DAMAGE (WHETHER FOR LOSS OF PROFIT OR OTHERWISE) AND WHETHER
OCCASIONED BY THE APPLICABLE PARTY'S NEGLIGENCE OR OF ITS EMPLOYEES OR AGENTS OR
OTHERWISE

        8.10   EXCEPT AS SET FORTH IN THIS CLAUSE 8, ELAN IS GRANTING THE


                                       23
<PAGE>   26

ELAN LICENSE HEREUNDER ON AN "AS IS" BASIS WITHOUT RECOURSE, REPRESENTATION OR
WARRANTY WHETHER EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE, OR INFRINGEMENT OF THIRD PARTY RIGHTS, AND ALL
SUCH WARRANTIES ARE EXPRESSLY DISCLAIMED.

9.      INTELLECTUAL PROPERTY OWNERSHIP RIGHTS

        9.1 Subject to the terms and conditions of this Agreement, including,
without limitation Section 11 below, Orasense shall own the legal and equitable
title to the Orasense Technology.

        9.2 Elan shall own the legal and equitable title to the Elan
Intellectual Property, including without limitation, Elan Improvements.

        9.3 Orasense shall permanently mark or otherwise use reasonable efforts
to cause any third party to permanently mark all Products and/or the packaging
therefor with such license or patent notices to comply with the laws of the
country of sale or otherwise to generally communicate the existence of any Elan
Patents for the countries of the Territory and in such manner as Elan may
reasonably request in writing prior to the sale or commercial use thereof.

        9.4 Elan, at its expense, shall make a good faith effort (i) to secure
the grant of any material patent applications within the Elan Patents that
relate to the Field; (ii) to file and prosecute patent applications on material
patentable inventions and discoveries within the Elan Improvements that relate
to the Field; (iii) to defend all such applications against third party
oppositions; and (iv) to maintain in force any material issued letters patent
within the Elan Patents that relate to the Field (including any letters patent
that may issue covering any such Elan Improvements that relate to the Field).
Elan shall have the right in its discretion to control such filing, prosecution,
defense and maintenance provided that Orasense and Isis at their request shall
be provided with copies of all documents relating to such filing, prosecution,
defense and maintenance in sufficient time to review such documents and comment
thereon prior to filing.

        9.5 In the event that Elan informs the Orasense and Isis that it does
not intend to file patent applications on patentable inventions and discoveries
within the Elan Intellectual Property that relate to the Field in one or more
countries in the Territory or fails to file such an application within a
reasonable period of time, Orasense shall have the option at its expense to file
and prosecute such patent application(s) in the joint names of Orasense and
Elan. Upon written request from Orasense, Elan shall execute all documents,
forms and declarations and to do all things as shall be reasonably necessary to
enable Orasense to exercise such option.

        9.6 Orasense, Isis and Elan shall promptly inform each other in writing
of any alleged infringement of any patents within the Elan Patents or any
alleged misappropriation


                                       24
<PAGE>   27

of trade secrets within the Elan Intellectual Property by a third party of which
it becomes aware and provide the others with any available evidence of such
infringement or misappropriation insofar as such infringements or
misappropriation relate solely to the Field.

        9.7 Orasense shall have the right to prosecute at its own expense and
for its own benefit any infringements of the Elan Patents or misappropriation of
the Elan Intellectual Property, insofar as such infringements or
misappropriation relate solely to the Field. In the event that Orasense takes
such action, Orasense shall do so at its own cost and expense. At Orasense's
request, Elan shall cooperate with such action. Any recovery remaining after the
deduction by Orasense of the reasonable expenses (including attorney's fees and
expenses) incurred in relation to such infringement proceeding [...***...].
Should Orasense decide not to pursue such infringers, within a reasonable period
but in any event within twenty (20) days after receiving written notice of such
alleged infringement or misappropriation Elan may in its discretion initiate
such proceedings in its own name, at its expense and for its own benefit, and at
Elan's request, Orasense shall cooperate with such action. Alternatively, the
Participants may agree to institute such proceedings in their joint names and
shall reach agreement as to the proportion in which they shall share the
proceeds of any such proceedings, and the expense of any costs not recovered, or
the costs or damages payable to the third party. If the infringement of the Elan
Patents affects both the Field as well as other products being developed or
commercialized by Elan or its commercial partners outside the Field, Orasense
and Elan shall endeavor to agree as to the manner in which the proceedings
should be instituted and as to the proportion in which they shall share the
proceeds of any such proceedings, and the expense of any costs not recovered, or
the costs or damages payable to the third party.

        9.8 Orasense shall indemnify, defend and hold harmless Elan, against all
actions, losses, claims, demands, damages, costs and liabilities (including
reasonable attorneys fees) relating directly or indirectly to all such claims or
proceedings referred to herein, provided that Elan, shall not acknowledge to the
third party or to any other person the validity of any claims of such a third
party, and shall not compromise or settle any claim or proceedings relating
thereto without the prior written consent to Orasense, not to be unreasonably
withheld or delayed. At its option, Elan or Isis, as the case may be, may elect
to take over the conduct of such proceedings from Orasense provided that
Orasense's indemnification obligations shall continue; the costs of defending
such claim shall be borne by Elan or Isis, as the case may be and such
Participant shall not compromise or settle any such claim or proceeding without
the prior written consent of Orasense, such consent not to be unreasonably
withheld or delayed.

10.     RIGHTS EXPLOITATION OUTSIDE THE FIELD

        10.1 Licenses to Elan Program Technology. Orasense hereby grants to Elan
a perpetual, exclusive, royalty free and sublicensable license to Elan Program
Technology outside of the Field.

        10.2 Licenses for Orasense Program Technology Outside the Field.
Orasense


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       25
<PAGE>   28

hereby grants to Elan a perpetual exclusive license for the use of Orasense
Program Technology in all fields other than (i) the Field or (ii) in connection
with Isis proprietary drug products. The terms of such license for the use of
Orasense Program Technology shall be decided by the unanimous decision of the
Management Committee on such terms and conditions as the Management Committee
shall approve after good faith negotiations with Elan.

11.     NON-COMPETITION

        11.1. During the Research Term (and any extension thereto), Elan shall
not develop or Commercialize, or assist in the development or Commercialization
of Oligonucleotide Drugs in the Field or develop or Commercialize, or assist in
the development or Commercialization of an Oral Platform for systemic and
topical delivery of Oligonucleotide Drugs, except (a) for or on behalf of
Orasense, or (b) with the prior written, unanimous consent of the Management
Committee. In no event, however, shall the foregoing non-competition
restrictions apply to the entities listed in Section 1.16(b) above. Nothing
contained herein shall be construed as (i) limiting the activities of an
existing third party licensee of Elan from developing Oligonucleotide Drugs
utilizing Elan Intellectual Property to the extent such rights have been
previously granted by Elan, provided Elan does not provide any active support to
any such activities in excess of its existing contractual obligations or (ii)
prohibiting Elan from licensing Elan Intellectual Property to an Independent
Third Party or limiting the activities of any such future Independent Third
Party licensee of Elan from developing Oligonucleotide Drugs utilizing Elan
Intellectual Property; provided that the primary purpose of any such license is
not the development of an Oral Platform for Oligonucleotide Drugs and Elan does
not provide any active support to any such activities.
 .

12.     TERM AND TERMINATION OF AGREEMENT

        12.1. The term of this Agreement and the term of the Licenses granted
hereunder with respect to a Product utilizing or based on the Licensed
Technologies shall commence as of the Effective Date and continue, on a
Product-by-Product basis and country by country basis, for the life of the
patent rights upon which such Product is based on or utilizes in such country
(the "Term"); provided, however, that all royalty and fee obligations contained
herein shall survive for the greater of (i) the Term or (ii) 15 years from the
first commercial sale of such Product.

        12.2. Nothing contained herein shall obligate or restrict any party from
utilizing public, non-proprietary information which is not subject to the
protection of applicable patent laws.

        12.3. If either party breaches any material provision of this Agreement
and if such breach is (i) not capable of being cured or (ii) is capable of being
cured but is not corrected within sixty (60) days after the non-breaching party
gives written notice of the breach to the



                                       26
<PAGE>   29

breaching party, the non-breaching party may terminate this Agreement
immediately by giving notice of the termination, effective on the date of the
notice, provided, however, that (x) if any such curable breach is not capable of
being cured within such sixty (60) day period, so long as the breaching party
commences to cure the breach promptly after receiving notice of the breach from
the non-breaching party and thereafter diligently prosecutes the cure to
completion as soon as is practicable, the non-breaching Party may not terminate
this Agreement so long as the breaching party is acting in good faith to rectify
such breach or (y) the default involves a good faith dispute regarding the
amount of any required payment, provided any undisputed amount is paid, such
default shall be stayed and the remainder may be withheld for a reasonable
period during which a good faith resolution of the amount owed is being pursued.

        12.4. In the event that a Competitive Change of Control Event shall
occur, at the sole option of Elan and upon written notice to Isis and Orasense,
the Elan License shall be immediately terminated. Upon written notice from Isis
to Elan of a proposed Competitive Change of Control Event or the occurrence of a
Competitive Change of Control Event, Elan shall have thirty (30) days from such
notice to Isis to provide written notice to Isis as to whether it intends to
terminate the Elan License. In the event Elan does not provide written notice to
Isis during such thirty (30) day period of its intention to terminate the Elan
License, such termination right shall be deemed waived with respect to such
occurrence.

        12.5. In the event that the Isis License Agreement shall be terminated,
at the sole option of Elan and upon written notice to Isis and Orasense, the
Elan License shall be immediately terminated.

        12.6. Upon the occurrence of an Event of Bankruptcy with respect to
Orasense or Elan, the other Party may, upon written notice to Isis and the Party
with respect to which such Event of Bankruptcy has occurred, immediately
terminate the Elan License. As used in this Clause 12.6, the term "Event of
Bankruptcy" relating to either Orasense or Elan shall mean:

           12.6.1. the appointment of a liquidator, receiver, administrator,
           examiner, trustee or similar officer of either Party of it or over
           all or a substantial part of its assets under the law of any
           applicable jurisdiction, including without limit, Bermuda, the United
           States of America or Ireland; or

           12.6.2 an application or petition for bankruptcy, corporate
           re-organization, composition, administration, examination,
           arrangement or any other procedure similar to any of the foregoing
           under the law of any applicable jurisdiction, including without
           limit, Bermuda, the United States of America or Ireland (other than
           as part of a bona fide restructuring or reorganization), is filed,
           and is not discharged within forty-five (45) days, or if either Party
           applies for or consents to the appointment of a receiver,
           administrator, examiner or similar officer of it or of all or a
           material part of its assets, rights or revenues or the assets and/or
           the business of either Party are for any reason seized, confiscated
           or condemned.



                                       27
<PAGE>   30

        12.7. Upon exercise of those rights of termination as specified in
Clause 12.1 to Clause 12.6 inclusive or elsewhere within this Agreement, this
Agreement shall, subject to the other provisions of this Agreement,
automatically terminate forthwith and be of no further legal force or effect.

        12.8.  Upon expiration or termination of the Agreement:

               12.8.1 any sums that were due from Orasense to Elan with respect
to license granted hereunder, including without limitation on Net Sales, in the
Territory or in such particular country or countries in the Territory (as the
case may be) prior to the expiration or termination of this Agreement as set
forth herein shall be paid in full within sixty (60) days after the expiration
or termination of this Agreement for the Territory or for such particular
country or countries in the Territory (as the case may be);

               12.8.2 any provisions clearly meant to survive termination or
expiration of this Agreement, including without limitation Clause 7, shall
remain in full force and effect;

               12.8.3 all representations, warranties and indemnities shall
insofar as are appropriate remain in full force and effect;

               12.8.4 the rights of inspection and audit set out in Clause 6
shall continue in force for a period of one year;

               12.8.5 termination of this Agreement for any reason shall not
release any Party hereto from any liability which, at the time of such
termination, has already accrued to the other Party or which is attributable to
a period prior to such termination nor preclude either Party from pursuing all
rights and remedies it may have hereunder or at law or in equity with respect to
any breach of this Agreement;

               12.8.6 the Elan Intellectual Property and all rights, licenses
and sublicenses granted by Elan in and pursuant to this Agreement shall cease
for the Territory or for such particular country or countries in the Territory
(as the case may be) and shall immediately revert to Elan and all Elan Program
Technology shall be deemed immediately transferred and assigned to Elan.
Following such expiration or termination, Orasense may not thereafter use in the
Territory or in such particular country or countries in the Territory (as the
case may be) (a) any valid and unexpired Elan Patents, (b) any Elan Intellectual
Property that remains confidential or otherwise proprietary to Elan, and/or (c)
Trademarks. All rights to Orasense Technology (other than Elan Program
Technology and Isis Program Technology) shall be transferred to and jointly
owned by Elan and Isis and may only be utilized by such parties royalty-free,
consistent with the other restriction contained in Section 10 of this Agreement
and the comparable section of the Isis License Agreement regarding the
limitation of such rights outside the Field. Rights of permitted Independent
Third Party sublicensees in and to the Elan Intellectual Property shall survive
the termination of the license and sublicense agreements granting said
intellectual property rights to Orasense; and Orasense, Elan and Isis shall in
good faith agree upon the form most advantageous to Elan and Isis in which the


                                       28
<PAGE>   31

rights of the sublicensor under any such sublicenses are to be held (which form
may include continuation of Orasense solely as the holder of such licenses or
assignment of such rights to a third party or parties, including an assignment
to both Elan and Isis). Any sublicense agreement between Orasense and such
permitted sublicensee shall permit an assignment of rights by Orasense to Elan
and shall contain additional reasonable confidentiality protections which an
assignee shall reasonably require. Upon any such assignment, Elan and Isis shall
enter into good faith negotiations with respect to additional reasonable
confidentiality protections which either party shall reasonably require.

13.     IMPOSSIBILITY OF PERFORMANCE - FORCE MAJEURE

        13.1. Neither Party to this Agreement shall be liable for delay in the
performance of any of its obligations hereunder if such delay results from
causes beyond its reasonable control, including, without limitation, acts of
God, fires, strikes, acts of war, or intervention of a government authority, non
availability of raw materials, but any such delay or failure shall be remedied
by such Party as soon as practicable.

14.     SETTLEMENT OF DISPUTES; GOVERNING LAW

        14.1. Any dispute between the Parties arising out of or relating to this
Agreement will be subject to resolution in accordance with Clause 24.9 of the
Development Agreement, which is incorporated by reference and shall for such
purposes survive termination of the Development Agreement.

        14.2. This Agreement is construed under and ruled by the laws of the
State of New York, without regard to the conflict of law principles.

15.     ASSIGNMENT

        15.1. This Agreement may not be assigned by either Party without the
prior written consent of the other, which consent shall not be unreasonably
withheld, conditioned or delayed, save that (i) either Party may assign this
Agreement to its Affiliate without such consent, provided that such assignment
does not have any adverse tax consequences on the other Party, and (ii) Elan may
assign its rights and obligations hereunder in connection with a sale of all or
substantially all of the business of Elan to which the Transaction Documents
relate, whether by merger, sale of stock, sale of assets or otherwise (provided
that, in the event of such transaction, no intellectual property rights of any
third party that is the acquiring corporation in such transaction shall be
included in the Elan Intellectual Property licensed hereunder). Elan and
Orasense will discuss any assignment by either Party to an Affiliate prior to
its implementation in order to avoid or reduce any additional tax liability to
the other Party resulting solely from different tax law provisions applying
after such assignment to an Affiliate. For the purpose hereof, an additional tax
liability shall be deemed to have occurred if either Party would be subject to a
higher net tax on payments made hereunder after taking into account any
applicable tax treaty and available tax credits than such Party was subject to
before the proposed assignment. Notwithstanding any assignment


                                       29
<PAGE>   32

hereof to an Affiliate, each Party will remain fully liable hereunder.

16.     NOTICES

        16.1. Any notice to be given under this Agreement shall be sent in
writing in English by registered airmail or telefaxed to the following
addresses:


           If to Orasense at:   Orasense Ltd.
                                c/o Isis Pharmaceuticals, Inc.
                                2292 Faraday Avenue
                                Carlsbad, California 92008
                                Attention:     Ms. Lynne Parshall
                                Telephone:  (760) 603-2460
                                Telefax:    (760) 931-9639

           If to Isis to:       Isis Pharmaceuticals, Inc.
                                2292 Faraday Avenue
                                Carlsbad, California 92008
                                Attention:     Ms Lynne Parshall
                                Telephone:  (760) 603-2460
                                Telefax:    (760) 931-9639

           with a copy to:      Cooley Godward LLP
                                4365 Executive Drive
                                Suite 1100
                                San Diego, CA 91212
                                Attention:  L. Kay Chandler
                                Telephone:  (619) 550-6000
                                Telefax:    (619) 453-3555

           If to Elan at:       Elan Corporation plc
                                Lincoln House, Lincoln Place, Dublin 2, Ireland
                                Attention: Vice President, General Counsel,
                                Elan Pharmaceutical Technologies,
                                a division of Elan Corporation, plc
                                Telephone:  + 353 1 709 4000
                                Telefax:    + 353  1 709 4124

           with a copy to:      Cohen & Tauber LLP
                                1350 Avenue of the Americas
                                26th Floor
                                New York, New York 10019
                                Attention:  Laurence S. Tauber
                                Telephone:  (212) 519-5195


                                       30
<PAGE>   33

                                    Telefax:      (212) 262-1766

         or to such other address(es) and telefax numbers as may from time to
         time be notified by either Party to the other hereunder.

        16.2. Any notice sent by mail shall be deemed to have been delivered
within seven (7) working days after dispatch and any notice sent by telex or
telefax shall be deemed to have been delivered within twenty four (24) hours of
the time of the dispatch. Notice of change of address shall be effective upon
receipt.

17.     MISCELLANEOUS CLAUSES

        17.1. No waiver of any right under this Agreement shall be deemed
effective unless contained in a written document signed by the Party charged
with such waiver, and no waiver of any breach or failure to perform shall be
deemed to be a waiver of any other breach or failure to perform or of any other
right arising under this Agreement.

        17.2. If any provision in this Agreement is agreed by the Parties to be,
or is deemed to be, or becomes invalid, illegal, void or unenforceable under any
law that is applicable hereto, (i) such provision will be deemed amended to
conform to applicable laws so as to be valid and enforceable or, if it cannot be
so amended without materially altering the intention of the Parties, it will be
deleted, with effect from the date of such agreement or such earlier date as the
Parties may agree, and (ii) the validity, legality and enforceability of the
remaining provisions of this Agreement shall not be impaired or affected in any
way.

        17.3. The Parties shall use their respective reasonable endeavors to
ensure that the Parties and any necessary third party shall execute and perform
all such further deeds, documents, assurances, acts and things as any of the
Parties hereto may reasonably require by notice in writing to the other Party or
such third party to carry the provisions of this Agreement.

        17.4. This Agreement shall be binding upon and inure to the benefit of
the Parties hereto, their successors and permitted assigns and sub-licenses.
Isis shall be a third party beneficiary to this Agreement and shall have the
right to cause Orasense to enforce Orasense's rights against Elan.

        17.5. No provision of this Agreement shall be construed so as to negate,
modify or affect in any way the provisions of any other agreement between the
Parties unless specifically referred to, and solely to the extent provided, in
any such other agreement. In the event of a conflict between the provisions of
this Agreement and the provisions of the Development Agreement, the terms of the
Development Agreement shall prevail unless this Agreement specifically provides
otherwise.

        17.6. No amendment, modification or addition hereto shall be effective
or binding on either Party unless set forth in writing and executed by a duly
authorized representative of


                                       31
<PAGE>   34

each Party. Amendments hereto shall be subject to the prior approval of Isis,
which approval shall not be unreasonably withheld or delayed.

        17.7. This Agreement may be executed in any number of counterparts, each
of which when so executed shall be deemed to be an original and all of which
when taken together shall constitute this Agreement.

        17.8. Each of the Parties undertakes to do all things reasonably within
its power which are necessary or desirable to give effect to the spirit and
intent of this Agreement.

        17.9. Each of the Parties hereby acknowledges that in entering into this
Agreement it has not relied on any representation or warranty save as expressly
set out herein or in any document referred to herein.

        17.10. Nothing contained in this Agreement is intended or is to be
construed to constitute Elan, Isis and Orasense as partners, or Elan as an
employee of Orasense and Isis, or Orasense and Isis as an employee of Elan.
Neither Party hereto shall have any express or implied right or authority to
assume or create any obligations on behalf of or in the name of


                                       32
<PAGE>   35

the other Party or to bind the other Party to any contract, agreement or
undertaking with any third party.

IN WITNESS WHEREOF, the Parties hereto have executed this Agreement as of the
date first set forth above.

ELAN PHARMACEUTICAL TECHNOLOGIES,
A DIVISION OF ELAN CORPORATION, PLC

By: /s/ KEVIN INSLEY
    -----------------------
    Kevin Insley
    Authorized Signatory


ORASENSE LTD.


By: /s/ B. LYNNE PARSHALL
   -----------------------
   B. Lynne Parshall
   President

AGREED TO:

ISIS PHARMACEUTICAL, INC.

By: /s/ B. LYNNE PARSHALL
   -----------------------
   B. Lynne Parshall
   Executive Vice President







                                       33
<PAGE>   36



                     [ELAN LICENSE AGREEMENT EXECUTION PAGE]































                                       34
<PAGE>   37

                                    EXHIBIT A

                      DESCRIPTION OF DEVELOPMENT CANDIDATE

[...***...]






























                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       35

<PAGE>   1
                                                                    EXHIBIT 10.8

                                            ***TEXT OMITTED AND FILED SEPARATELY
                                                CONFIDENTIAL TREATMENT REQUESTED
                                          UNDER 17 C.F.R. SECTIONS 200.80(b)(4),
                                                            200.83 AND 240.24B-2

                                LICENSE AGREEMENT




                                 BY AND BETWEEN




                                  ORASENSE LTD

                            A BERMUDA LIMITED COMPANY



                                       AND



                           ISIS PHARMACEUTICALS, INC.

                             A DELAWARE CORPORATION





                                 APRIL 20, 1999


<PAGE>   2



                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
SECTION                                                                                     PAGE



<S>     <C>                                                                                    <C>
1.      DEFINITIONS..........................................................................1

2.      GRANT OF RIGHTS......................................................................9

3.      IMPROVEMENTS AND AFTER ACQUIRED TECHNOLOGY..........................................13

4.      DEVELOPMENT OF PRODUCTS.............................................................14

5       REGULATORY APPROVALS................................................................15

6       FINANCIAL PROVISIONS................................................................15

7       CONFIDENTIAL INFORMATION............................................................19

8       WARRANTIES/INDEMNITIES..............................................................21

9.      INTELLECTUAL PROPERTY OWNERSHIP RIGHTS..............................................25

10.     RIGHTS EXPLOITATION OUTSIDE THE FIELD...............................................26

11.     NON-COMPETITION.....................................................................27

12.     TERM AND TERMINATION OF AGREEMENT...................................................27

13.     IMPOSSIBILITY OF PERFORMANCE - FORCE MAJEURE........................................30

14.     SETTLEMENT OF DISPUTES; GOVERNING LAW...............................................30

15.     ASSIGNMENT..........................................................................30

16.     NOTICES.............................................................................31

17.     MISCELLANEOUS CLAUSES...............................................................32
</TABLE>



                                       i
<PAGE>   3

LICENSE AGREEMENT dated as of March 31, 1999 between Orasense Ltd,. a Bermuda
limited company, and Isis Pharmaceuticals, Inc., a Delaware corporation.

                                    RECITALS:

A.      Contemporaneously herewith, Elan and Isis (capitalized terms used herein
        are defined below) propose to enter into the Development Agreement for
        the purpose of recording the terms and conditions of a joint venture and
        of regulating their relationship with each other and certain aspects of
        the affairs of and their dealings with Orasense.

B.      Isis is beneficially entitled to the use of certain know-how and certain
        patents that have been granted or are pending in relation to the
        development and production of various drug delivery technologies and
        drug products.

C.      Orasense desires to enter into this Agreement with Isis so as to permit
        Orasense to utilize the Isis Intellectual Property in the research,
        development, manufacture, distribution and sale of the Products in the
        Field and in the Territory.

D.      Elan, EIS and Isis entered into a letter agreement dated March 31, 1999
        (the "Letter Agreement") pursuant to which they agreed to enter into
        definitive documents, including this Agreement, and the Elan License
        Agreement relating to Orasense's use of the Elan Intellectual Property.

        NOW THEREFORE IT IS HEREBY AGREED AS FOLLOWS:

1.      DEFINITIONS; INTERPRETATION.

        A. Definitions. In this Agreement, the following definitions shall
apply:

        1.1. "Affiliate" shall mean, with respect to Elan or Isis, any
corporation or entity other than Orasense (and entities controlled by it)
controlling, controlled or under the common control of Elan or Isis, as the case
may be, and, with respect to Orasense, any corporation or entity under control
of Orasense. A corporation or non-corporate entity shall be regarded as in
control of another corporation if it owns or directly or indirectly controls at
least fifty percent (50%) of the voting stock of the other corporation or (a) in
the absence of the ownership of at least fifty percent (50%) of the voting stock
of a corporation or (b) in the case of a non-corporate entity, the power to
direct or cause the direction of the management and policies of such corporation
or non-corporate entity, as applicable.

        1.2. "Agreement" shall mean this agreement (which expression shall be
deemed to include the Recitals and the Schedules hereto);

        1.3. "cGCP", "cGLP" and "cGMP" shall mean current Good Clinical
Practices, current Good Laboratory Practices and current Good Manufacturing
Practices respectively;

        1.4. "Change of Control" shall mean, with respect to a Party, the
acquisition of


                                       1.
<PAGE>   4

fifty percent (50%) or more of its voting securities, the ability, by contract
or otherwise, to control the board of directors or management of any such
entity, or a sale of all or substantially all of the business of such Party to
which the Definitive Documents relate, whether by merger, sale of stock, sale of
assets or otherwise;

        1.5. "Commercialization" shall mean the manufacture, promotion,
distribution, marketing and sale of the Products;

        1.6. "Competitive Change of Control Event" shall mean that a Primary
Technological Competitor of Elan acquires directly or indirectly voting stock or
equivalent securities in Isis or Orasense representing [...***...] percent or
more of the stock which carries entitlement to vote, or a Primary Technological
Competitor of Elan acquires by all or substantially all of the business of Isis
or Orasense to which the Definitive Documents relate, whether by merger, sale of
stock, sale of assets or otherwise;

        1.7. "Control" shall mean the ability to grant a license or sublicense
as contemplated herein without violating the terms of any agreement with any
third party;

        1.8. "Cost of Living Increase" shall mean, with respect to any year of
the Term, any increase in the Consumer Price Index published by the Bureau of
Labor Statistics of the United States Department of Labor, All Urban Consumers,
United States City Average, All Items (1982/84=100);

        1.9. "Definitive Documents" shall have the same meaning as given to the
term "Transaction Documents" in the Development Agreement;

        1.10. "Development Agreement" shall mean the Joint Development and
Operating Agreement of even date entered into among Isis, Elan, EIS and
Orasense;

        1.11. "Development Candidate" shall mean [...***...] antisense inhibitor
of TNF-(alpha), as more specifically detailed in Exhibit A hereto;

        1.12. "Development Product" shall mean any product containing as an
active ingredient the Development Candidate (or a Substituted Development
Candidate) in an Oral formulation for humans;

        1.13. "Effective Date" shall mean the date of execution and delivery of
the Definitive Documents;

        1.14. "EIS" shall mean Elan International Services, Ltd., a Bermuda
limited company;

        1.15. "Elan" shall mean Elan Pharmaceutical Technologies, a division of
Elan Corporation, plc, a public limited company incorporated under the laws of
Ireland, its, successors and permitted assigns;


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       2.
<PAGE>   5

        1.16. "Elan Improvements" shall mean any improvements to the Elan
Patents and Elan Know-How developed by Elan (other than pursuant to the Research
and Development Program). Subject to contractual restrictions, Elan Improvements
shall be deemed part of and shall be included in the term "Elan Intellectual
Property" and shall be deemed, immediately upon development by Elan, to be
included in the license of the Elan Intellectual Property hereunder. If the
inclusion of an Elan Improvement in the license of Elan Intellectual Property is
restricted or limited by a third party agreement, Elan shall use reasonable
commercial efforts to exclude or where applicable minimize any such restriction
or limitation;

        1.17. "Elan Intellectual Property" shall mean the Elan Know-How, the
Elan Patent Rights and/or the Elan Improvements. Examples of the Elan
Intellectual Property existing as of the Effective Date include, but are not
limited to, technology related to the modification of the solubility, intrinsic
dissolution, stability and/or permeability of a drug or modification of the
surface(s) of particles, pharmaceutical formulation excipient technology,
formulation, scale-up and manufacturing know-how. Schedule 1 to the Elan License
Agreement shall contain, by way of illustration but not limitation, examples of
Elan Intellectual Property. For the avoidance of doubt, Elan Intellectual
Property shall consist of Oral drug delivery technology Controlled by Elan doing
business as Elan Pharmaceutical Technologies and shall exclude (a) the Excluded
Elan Technology, as such term is defined in the Elan License Agreement, (b)
inventions, patents and know-how Controlled by all other affiliates or
subsidiaries of Elan, including, but not limited to the Elan Pharmaceuticals
division which incorporates Athena Neurosciences, Inc., Carnrick Laboratories,
Targon Corporation and Neurex Corporation and (c) inventions, patents and
know-how that are subject to contractual obligations of Elan to third parties as
of the Effective Date to the extent the licensing of such inventions, patents
and know-how is restricted or limited;

        1.18. "Elan Know-How" shall mean any and all rights Controlled by Elan
as of the Effective Date to any discovery, invention (whether or not
patentable), know-how, substances, data, techniques, processes, systems,
formulations and designs relating to Oral drug delivery;

        1.19. "Elan License" shall have the meaning set forth in Section 2.1 of
the Elan License Agreement;

        1.20. "Elan License Agreement" shall mean that certain license
agreement, of even date herewith, entered into between Elan and Orasense;

        1.21. "Elan Patents" shall mean any and all patents and patent
applications Controlled by Elan, existing and/or pending as of the Effective
Date or hereafter filed or obtained relating to Oral drug delivery technology
Controlled by Elan on the Effective Date. Elan Patent Rights shall also include
all extensions, continuations, continuations-in-part,



                                       3.
<PAGE>   6
divisionals, patents-of-additions, re-examinations, re-issues, supplementary
protection certificates and foreign counterparts of such patents and patent
applications and any patents issuing thereon and extensions of any patents
licensed hereunder;

        1.22. "Elan Program Technology" shall mean all Program Technology solely
conceived or made by Elan and/or its agents;

        1.23. "Excluded Isis Technology" shall mean any Isis [...***...]
technology including, without limitation, [...***...];

        1.24. "FDA" shall mean the United States Food and Drug Administration or
any successors or agency the approval of which is necessary to market a product
in the United States of America;

        1.25. "Field" shall mean the research, development and Commercialization
of in an Oral Platform for delivery of Oligonucleotide Drugs;

        1.26. "Full Time Equivalent Rate" shall mean, for the services proposed
to be rendered by Isis, $[...***...] for developmental chemistry (including
pharmaceutics) and $[...***...] for all other services (including pharmacology,
toxicology, clinical work, etc.);

        1.27. "Independent Third Party" shall mean any person other than
Orasense, Isis, Elan or any of their respective Affiliates;

        1.28. "In market" shall mean sales of Products whether by Orasense or
its Affiliates, or where applicable by a sublicensee, to an Independent Third
Party being a wholesaler, distributor, managed care organization, hospital,
pharmacy and/or the like;

        1.29. "Isis" shall mean Isis Pharmaceuticals, Inc., a Delaware
corporation;

        1.30. "Isis Delivery Know-How" shall mean any and all rights Controlled
by Isis as of the Effective Date to any discovery, invention (whether or not
patentable), know-how, substances, data, techniques, processes, systems,
formulations and designs relating to Oral Oligonucleotide drug delivery;

        1.31. "Isis Delivery Patents" shall mean any and all patents and patent
applications Controlled by Isis, existing and/or pending as of the Effective
Date or hereafter filed or obtained relating to Oral drug delivery technology
Controlled by Isis on the Effective Date. Isis Delivery Patents shall also
include all extensions, continuations, continuations-in-part, continuing
prosecution applications divisionals, patents-of-additions, re-examinations,
re-issues, supplementary protection certificates and foreign counterparts of
such patents and patent applications and any patents issuing thereon and
extensions of any patents licensed hereunder;


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       4.
<PAGE>   7

        1.32. "Isis Delivery Technology" shall mean Isis Delivery Patents, Isis
Delivery Know-How and Isis Improvements with respect thereto. Schedule 1A
contains by way of illustration but not limitation, examples of existing Isis
Delivery Technology;

        1.33. "Isis Development Candidate Know-How" shall mean any and all
rights Controlled by Isis to any discovery, invention (whether or not
patentable), know-how, substances, data, techniques, processes, systems,
formulations and designs which are necessary or useful for the manufacture or
Commercialization of the Development Product;

        1.34. "Isis Development Candidate Patents" shall mean any and all
patents and patent applications Controlled by Isis, existing and/or currently
pending as of the Effective Date or hereafter filed or obtained relating to the
Development Candidate, or, if applicable, the Substituted Development Candidate,
Controlled by Isis on the Effective Date which are necessary or useful for the
manufacture or Commercialization of the Development Product. Isis Development
Candidate Patents shall also include all extensions, continuations,
continuations-in-part, continuing prosecution applications divisionals,
patents-of-additions, re-examinations, re-issues, supplementary protection
certificates and foreign counterparts of such patents and patent applications
and any patents issuing thereon and extensions of any patents licensed
hereunder;

        1.35. "Isis Development Candidate Technology" shall mean Isis
Development Candidate Patents, Isis Development Candidate Know-How and Isis
Improvements with respect thereto. Schedule 1B contains by way of illustration
but not limitation, examples of existing Isis Development Candidate Technology;

        1.36. "Isis Improvements" shall mean any improvements to the Isis
Delivery Technology and Isis Development Candidate Technology developed by Isis
(other than pursuant to the Research and Development Program). Isis Improvements
shall be deemed part of and shall be included in the term "Isis Intellectual
Property" and shall be deemed, immediately upon development by Isis, to be
included in the license of the Isis Delivery Technology and Isis Development
Candidate Technology hereunder;

        1.37. "Isis Intellectual Property" shall mean the Isis Delivery
Technology and the Isis Development Candidate Technology. For the avoidance of
doubt, Isis Intellectual Property shall exclude the Excluded Isis Technology.

        1.38. "Isis License" shall have the meaning set forth in Section 2.2
hereof;

        1.39. "Isis Oligonucleotide" shall mean any Oligonucleotide Drug
Controlled by Isis other than the Development Candidate;

        1.40. "Isis Products" shall mean Products based upon Isis
Oligonucleotides that are made, designed, or otherwise created by or on behalf
of Isis or any of its Affiliates after the



                                       5.
<PAGE>   8

date hereof pursuant to the Project using the Orasense Technology and/or the
Licensed Technologies;

        1.41. "Isis Program Technology" shall mean all Program Technology solely
conceived by Isis and/or its agents.

        1.42. "Licensed Technologies" shall mean the Elan Intellectual Property
and the Isis Intellectual Property;

        1.43.  "Licenses" shall mean the Elan License and the Isis License;

        1.44. "Lien" shall mean any and all liens, security interests,
restrictions, claims, encumbrances or rights of third parties of every kind and
nature;

        1.45. "Management Committee" shall have the meaning given to such term
in the Development Agreement;

        1.46. "Marketing Authorization" shall mean the procurement of
registrations and permits required by applicable government authorities in a
country in the Territory for the marketing, sale, and distribution of a Product
in such country;

        1.47. "Net Sales" shall mean the amount billed, invoiced and/or received
on sales of a Product sold by Orasense or its Affiliates or sublicensees to an
Independent Third Party, less, to the extent included in such invoice price the
total of: (1) ordinary and customary trade quantity or cash discounts and
nonaffiliated brokers' or agents' commissions actually allowed, including
government managed care and other contract rebates, pharmacy incentive programs,
including chargebacks of pharmacy or hospital performance incentive programs or
similar programs; (2) credits, rebates and returns (including, but not limited
to, wholesaler and retailer returns); (3) freight, postage and duties paid for
and separately identified on the invoice or other documentation maintained in
the ordinary course of business, and (4) import, export and sales taxes, excise
taxes, other consumption taxes, customs duties, tariffs and compulsory payments
to governmental authorities actually paid and separately identified on the
invoice or other documentation maintained in the ordinary course of business and
based on sales or turnover or delivery of the Products. Net Sales shall also
include the amount or fair market value of all other consideration received by
Orasense or its Affiliates or sublicensees in respect of Products, whether such
consideration is payment in kind, exchange or another form. If a Product is
provided to an Independent Third Party by Orasense or its Affiliates or
sublicensees without charge or provision of invoice and used by such Independent
Third Party, then Orasense or its Affiliates or sublicensees shall be treated as
having sold such Product to such Independent Third Party for an amount equal to
the fair market value of such Product. Sales between or among Orasense and its
respective Affiliates or authorized licensees shall be excluded from the
computation of Net Sales. A "sale" of a Product is deemed to occur upon the
earlier of invoicing, shipment or transfer of title in the Product to an
Independent Third Party. For avoidance of doubt, Net Sales shall include



                                       6.
<PAGE>   9

royalties received by Orasense or its Affiliates from any Independent Third
Party in respect of Products;

        1.48. "Oligonucleotide Drug" shall mean any single stranded, [...***...]
oligonucleotide including those [...***...] used as a human therapeutic and/or
prophylactic compound containIng between [...***...] nucleotides and/or
nucleosides including oligonucleotide analogs which may include [...***...]. For
purposes of this agreement, Oligonucleotide Drug shall specifically exclude
oligonucleotides used in [...***...], oligonucleotides used as [...***...] an
oligonucleotide, oligonucleotides used as [...***...] or oligonucleotides used
as adjuvants. Oligonucleotide Drug shall also specifically exclude polymers in
which the [...***...] but shall not exclude [...***...]. Should Isis develop
[...***...] oligonucleotides or should Elan independently discover drug delivery
technology it believes to be potentially applicable to [...***...]
oligonucleotides, then the Participants shall discuss in good faith whether such
oligonucleotides can be formulated for Oral delivery using the Oral Platform,
and whether such formulation appears feasible without requiring a significant
further investment in developing or enhancing the Oral Platform; if such
formulation appears feasible, the Participants shall discuss in good faith the
inclusion of such oligonucleotides as Oligonucleotide Drugs;

        1.49. "Oral" shall mean administration by way of the mouth for the
purpose of topical or systemic delivery by way of the alimentary canal;

        1.50. "Oral Delivery Devices" shall mean devices for delivering an
active agent orally such as those employing [...***...] technologies;

        1.51. "Oral Platform" shall mean formulation and excipient systems and
technologies including [...***...] and including the use of [...***...], which
can be employed to develop dosage forms of Oligonucleotide Drugs, deliver said
dosage forms to the alimentary canal and facilitate and promote the systemic and
topical delivery of Oligonucleotide Drugs;

        1.52.  "Orasense" shall mean Orasense, Ltd., a Bermuda limited company;

        1.53. "Orasense Program Technology" shall mean all Program Technology
other than Elan Program Technology and Isis Program Technology;

        1.54. "Orasense Technology" shall mean all Program Technology and all
technology licensed or acquired by Orasense or developed by Orasense whether or
not


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       7.
<PAGE>   10

pursuant to the Research and Development Program, excluding, however, Isis
Intellectual Property and Elan Intellectual Property;

        1.55. "Participant" shall mean Elan or Isis, as the case may be.
"Participants" shall mean both Elan and Isis;

        1.56.  "Parties" shall mean Isis and Orasense;

        1.57. "Person" shall mean an individual, partnership, corporation,
limited liability company, business trust, joint stock company, trust,
unincorporated association, joint venture, or other entity of whatever nature;

        1.58. "Plan" shall mean the business plan and program of development
agreed to by Elan and Isis within sixty (60) days of the date hereof, with
respect to the research, development, prosecution and commercialization of the
Products, which Plan shall be reviewed and mutually agreed to in writing by Elan
and Isis on an annual basis;

        1.59. "Primary Technological Competitor of Elan" shall have the meaning
given to such term in the Elan License Agreement;

        1.60. "Project" shall mean all activity as undertaken by Elan, Isis and
Orasense to develop the Products in accordance with the Plan;

        1.61. "Product" shall mean any Oligonucleotide Drug under development or
developed by or on behalf of Orasense in an Oral formulation for administration
to humans;

        1.62. "Program Technology" shall mean all technology developed by or on
behalf of Orasense, whether by Elan, Isis, a third party or jointly by any
combination thereof, pursuant to the Research and Development Program;

        1.63. "Regulatory Authority" shall mean any regulatory authority outside
the United States of America, the approval of which is necessary to market a
Product;

        1.64. "Research and Development Program" shall have the same meaning as
ascribed to such term in the Development Agreement;

        1.65. "Research Term" shall mean the period commencing on the Effective
Date and continuing for a period of [...***...] thereafter, unless extended by
the mutual writTen agreement of Elan and Isis; provided, however, that if a
Participant shall be prevented by (i) events beyond the Participants' control,
or (ii) by such Participant's delay or negligent act or omission, from
performing its obligations under the Definitive Documents within said
[...***...], then the other Participant at its option, may extend the duration
of the Research Term by a term equal in length to the period during which the
first Participant was unable to perform its obligations hereunder;


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                       8.
<PAGE>   11

        1.66. "Technological Competitor of Elan" shall have the meaning given to
such term in the Elan License Agreement;

        1.67. "Technological Competitor of Isis" shall mean any entity listed on
Schedule 2 hereto, subject to amendment from time to time upon mutual written
agreement of Orasense, Isis and Elan;

        1.66.  "Term" shall have the meaning given to it in Clause 12 below;

        1.67.  "Territory" shall mean all the countries of the world;

        1.68. "Third Party Oligonucleotide Drug" shall mean any Oligonucleotide
Drug Controlled by an Independent Third Party, other than an Isis
Oligonucleotide Drug;

        1.69. "Third Party Product" shall mean Products based upon Third Party
Oligonucleotide Drug that are made, designed, or otherwise created by or on
behalf of an Independent Third Party after the date hereof pursuant to the
Project using the Orasense Technology and/or the Licensed Technologies. For
avoidance of doubt, any Product based upon an Oligonucleotide Drug jointly
developed by an Independent Third Party and Isis other than pursuant of the
Program shall be deemed to be an Isis Product;

        1.70. "Trademark" shall mean the trademark(s) belonging to Isis as may
be selected by Orasense or its permitted sub-licensees, with Isis's consent, for
use in connection with the Products.

        1.71. "United States Dollar" and "US$" shall mean the lawful currency
for the time being of the United States of America;

        B. Interpretation. In this Agreement the following shall apply:

        1.1 The singular includes the plural and vice versa, the masculine
includes the feminine and vice versa.

        1.2. Any reference to a Clause or Schedule shall, unless otherwise
specifically provided, be to a Clause or Schedule of this Agreement.

        1.3. The headings of this Agreement are for ease of reference only and
shall not affect its construction or interpretation.

2.      GRANT OF RIGHTS

        2.1. Subject to the terms and conditions contained herein and, in
consideration of the payments specified in Clause 6.1(i), Isis hereby grants to
Orasense for the Term a non-


                                       9.
<PAGE>   12

exclusive license, including the limited right to grant sublicenses pursuant to
Clause 2.6 hereof, to the Isis Delivery Technology within the Field for the
Territory, solely to research, develop, manufacture, have manufactured, and
Commercialize the Products in the Territory, subject to any contractual
obligations of Isis to Independent Third Parties as of the Effective Date and,
unless prohibited by the paragraph below titled Non Competition, contractual
obligations to Independent Third Parties that Isis may enter into after the
Effective Date.

        2.2. Subject to the terms and conditions contained herein and, in
consideration of the payments specified in Clause 6.1(i), Isis hereby grants to
Orasense for the Term an exclusive license in the Territory of Isis's rights in
the Isis Development Candidate Technology to manufacture and Commercialize the
Development Candidate, or if applicable, the Substituted Development Candidate,
in an Oral formulation for administration to humans, subject to any contractual
obligations of Isis to Independent Third Parties as of the Effective Date. The
licenses granted by Isis pursuant to Sections 2.1 and 2.2 are hereafter referred
to as the "Isis License".

        2.3. In the event, as of the Effective Date, the Isis License granted to
Orasense hereunder is restricted or limited by any contractual obligations of
Isis to Independent Third Parties, then Isis shall use reasonable commercial
efforts to exclude or, where applicable, to minimize any such restriction or
limitation. Except as expressly provided herein, all proprietary rights and
rights of ownership with respect to the Isis Intellectual Property shall at all
times remain solely with Isis. Isis shall disclose to Orasense inventions made
by or on behalf of Isis in connection with the performance of the Project, any
patentable inventions and discoveries within the Isis Intellectual Property that
relate to the Field and any patentable Isis Improvements developed by or on
behalf of Isis.

        2.4. To the extent royalty or other compensation obligations to
Independent Third Parties that are payable with respect to Isis Intellectual
Property would be triggered by a proposed use of Isis Intellectual Property in
connection with the Project, Isis will inform Orasense and Elan of such royalty
or compensation obligation. If Orasense decides to utilize such Isis
Intellectual Property in connection with the Project, Orasense will be
responsible for the payment of such royalty or other compensation obligations
relating thereto.

        2.5. Notwithstanding anything contained in this Agreement to the
contrary, Isis shall have the right, and subject to the paragraph below titled
Non-Competition, to fully exploit and grant licenses and sublicenses with
respect to the Isis Delivery Technology. Isis's rights to exploit and grant
licenses referred to in the immediately preceding sentence shall include the
right to research, develop, manufacture, license or Commercialize products.

        2.6. Orasense shall not be permitted to (a) encumber any of its rights
under the Licenses or the Orasense Technology without the prior written consent
of Isis; (b) assign or sublicense any of its rights under the licenses for the
Licensed Technologies and the Orasense Technology without the prior written
consent of Isis, which consent may be withheld in Isis's sole discretion. Any
agreement between Orasense and any permitted third party for the


                                      10.
<PAGE>   13

development or exploitation of the Isis Intellectual Property shall require such
third party to maintain the confidentiality of all information concerning the
Isis Intellectual Property and shall provide that any Isis Improvements shall
belong to Isis and shall permit an assignment of rights by Orasense to Isis in
accordance with the terms of this Agreement. Orasense shall remain responsible
for all acts and omissions of any sub-licensee, as if they were acts and
omissions by Orasense. Rights of permitted third party sublicensees in and to
the Isis Intellectual Property shall survive the termination of the license and
sublicense agreements granting said intellectual property rights to Orasense;
and Orasense and Isis shall in good faith agree upon the form most advantageous
to Isis in which the rights of the sublicensor under any such sublicenses are to
be held (which form may include continuation of Orasense solely as the holder of
such licenses or assignment of such rights to a third party or parties,
including an assignment to Isis).

        2.7. Orasense will use its reasonable commercial endeavours to exploit
the Elan Intellectual Property, the Isis Intellectual Property and Orasense
Technology in accordance with this Agreement, the Elan License Agreement and the
Plan. Orasense shall employ diligent efforts to research, develop, register, and
Commercialize the Products in the Territory. Orasense shall employ or have
employed on its behalf a level of advertising, sales, marketing, and promotion
efforts in each country in the Territory where Marketing Authorization for
Product has been obtained which is: (i) commensurate with that used by other
pharmaceutical manufacturers for products of similar market potential in that
country in the Territory, and (ii) sufficient with respect to the potential for
that country to fully exploit the market potential for the Product as depicted
in the Plan and as determined by the Management Committee in accordance with the
Development Agreement.

        2.8. Orasense will be solely responsible for ensuring that it or its
sublicensees manufacture and Commercialize the Products within each country of
the Territory strictly in accordance with all the legal and regulatory
requirements of each country of the Territory.

        2.9. Upon the request of Orasense and with the consent of Isis, Isis
shall grant to Orasense during the Term a non-exclusive royalty free license in
the Territory, solely for use in connection with the sale of the Products, to
use one or more Trademark, on the following terms:

           2.9.1  Orasense shall as soon as it becomes aware of any infringement
                  give to Isis in writing full particulars of any use or
                  proposed use by any other person, firm or company of a trade
                  name or trademark or promotional or advertising activity which
                  may constitute infringement.

           2.9.2  If Orasense becomes aware that any other person, firm or
                  company alleges that such Trademark is invalid or that the use
                  of such Trademark infringes any rights of another party or
                  that the Trademark is otherwise attacked or attackable,
                  Orasense shall immediately give to Isis full particulars in
                  writing thereof and shall make no comment or admission to any
                  third party


                                      11.
<PAGE>   14

                  in respect thereof.

           2.9.3  Isis shall have the right to conduct all proceedings relating
                  to such Trademark and shall in its sole discretion decide what
                  action, if any, to take in respect of any infringement or
                  alleged infringement of such Trademark or any other claim or
                  counter-claim brought or threatened in respect of the use or
                  registration of such Trademark. Any such proceedings shall be
                  conducted at Isis's expense and for its own benefit.

           2.9.4  Nothing contained in this Agreement shall grant to Orasense
                  any right, title, or interest in or to such Trademark, whether
                  or not specifically recognized or perfected under applicable
                  laws, except for the non-exclusive license granted herein. At
                  no time during or after the term of this Agreement shall
                  Orasense challenge or assist others to challenge any such
                  Trademark or the registration thereof or attempt to register
                  any trademarks, marks, or trade names confusingly similar to
                  any such trademark. All displays of any such Trademark that
                  Orasense intends to adopt shall first be submitted to Isis for
                  approval (which shall not be unreasonably withheld) of design,
                  color, and other details, or shall be exact copies of those
                  used by Isis. In addition, Orasense shall fully comply with
                  all reasonable guidelines, if any, communicated by Isis
                  concerning the use of any such Trademark as well as all rules
                  and regulations of such use throughout the Territory.

           2.9.5  The rights granted to Orasense under this Article 2.9 shall
                  automatically terminate respect to a Product in a country in
                  the Territory upon termination of Orasense's right to market
                  such Product in any such country.

        2.10. When packaged, and to the extent permitted by law, a product label
shall include an acknowledgement that the Product is made under license from
Isis. Such acknowledgement shall take into consideration regulatory requirements
and Orasense's reasonable commercial requirements. Orasense shall wherever
possible give due acknowledgement and recognition to Isis in all printed
promotional and other material regarding the Product such as stating that the
Product is under license from Isis and that the applicable Isis Intellectual
Property has been applied to the Products. Orasense shall consult with and
obtain the written approval of Isis as to the format and content of the
promotional and other material insofar as it relates to a description of, or
other reference to, the application of the Isis Intellectual Property, such
approval not to be unreasonably withheld or delayed. The further consent of Isis
shall not be required where the format and content of such materials is
substantively similar as the materials previously furnished to and approved in
writing by Isis.

        2.11. Isis shall have the first option to manufacture the active
ingredient of the


                                      12.
<PAGE>   15

Development Product for Orasense and meet its requirements, and Orasense shall
agree to utilize Isis as its sole supplier, subject to the customary terms and
conditions contained in a supply agreement to be executed by the parties at a
price equal to [...***...]. If, despite good faith negotiations, Isis and
Orasense do not reach agreement on the terms of such manufacturing agreement
within [...***...] from the Parties' commencement of discussion of such terms,
then Orasense shall be free to offer a third party (other than a Technological
Competitor of Isis unless consented to by Isis which consent may be withheld for
any reason, and otherwise subject to the terms and conditions of this Agreement)
terms to manufacture the active ingredient of the Development Product in the
Territory, which terms when taken as a whole, are more favorable to Orasense
than the principal terms of the last written proposal offered to Orasense by
Isis, or by Orasense to Isis, as the case may be. Subject to the foregoing
rights of Isis with respect to the Development Product, Orasense shall not be
permitted to contract the manufacture or Commercialization of any Product
without the prior written consent of Elan and Isis, which consent will not be
unreasonably withheld or delayed; provided that such reasonableness standard, in
the case of Elan, shall not be applicable in the case of a proposed sublicense
to any Technological Competitor of Elan and in the case of Isis, shall not be
applicable in the case of a proposed sublicense to any Technological Competitor
of Isis.


3.      IMPROVEMENTS AND AFTER ACQUIRED TECHNOLOGY

        3.1 Isis Improvements shall be deemed, immediately upon development, to
be included in the license of the Isis Intellectual Property granted to Orasense
hereunder.

        3.2 The Isis License specifically excludes any right to use Isis
Improvements outside of the Field.

        3.3 If the inclusion of an Isis Improvement in the license of Isis
Intellectual Property granted to Orasense hereunder is restricted or limited by
a third party agreement, then Isis shall use reasonable commercial efforts to
exclude, or where applicable, to minimize any such restriction or limitation.

        3.4 All rights, title, and interest to any Isis Improvements developed
by Orasense, Isis or any third party shall be the property of Isis. Orasense,
Isis and any such third party shall execute and deliver documents, and take such
other actions as Isis may reasonably request, to effect or evidence such
ownership.

        3.5 If Isis acquires know-how or patent rights relating to the Field, or
if Isis acquires or merges with an Independent Third Party that has know-how or
patent rights relating to the Field, then Isis shall offer to license such
know-how and patent rights to Orasense (subject to existing contractual
obligations), on such terms as would be offered to an Independent Third Party
negotiating in good faith on an arms-length basis, and if the Management
Committee determines that Orasense should not acquire such license, then Isis


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      13.
<PAGE>   16

shall be free to fully exploit such know-how and patent rights, and to grant to
third parties licenses and sublicenses with respect thereto.


4.      DEVELOPMENT OF PRODUCTS

        4.1 During the Research Term, Orasense will diligently pursue the
research and development of the Elan Intellectual Property, Isis Intellectual
Property and Orasense Technology in accordance with the Research and Development
Program. The objectives of this initial phase of the Research and Development
Program will be (a) to develop the Oral Platform, and (b) to develop the
Development Product.

        4.2 The results of Orasense's research pursuant to the Research and
Development Program shall be shared with Isis and, in the event Isis utilizes
such data in connection with a product based upon the Development Candidate in a
non-Oral formulation and includes such data in any regulatory submission and the
use of such data substantially enhances such application, and a product which is
the subject of such application is Commercialized, Isis agrees to negotiate in
good faith reasonable compensation to Orasense for the use of such data.

        4.3 Isis agrees to provide at Orasense's cost such amounts of the Isis
Oligonucleotide Drugs designated by Isis as [...***...] and [...***...] as
Orasense shall require for testing and research purposes only; provided however,
that no clinical studies on humans may be performed utilizing [...***...].

        4.4 Orasense will diligently pursue the research, development and
Commercialization of the Development Product and other Products in accordance
with the Plan, this Agreement, the Elan License Agreement and the Development
Agreement.

        4.5 In the event the Management Committee, by unanimous vote of its
members, shall determine that preclinical toxicology or pharmacology studies
indicate that clinical trials of the Development Candidate should not be
undertaken, or the Management Committee determines that development of the
Development Candidate is not economically viable, Isis in good faith shall
offer, and the Management Committee, by unanimous vote of its members shall
approve, an Isis Oligonucleotide in pre-clinical development that it deems
economically viable as a Substituted Development Candidate, subject to the
agreement of the Participants, negotiating in good faith, to changes concerning
the budget, Plan and funding of Orasense.

        4.6 Except as otherwise provided herein, upon designation of an Isis
Oligonucleotide as a Substituted Development Candidate, (i) all rights to the
Development Candidate shall revert to Isis and (ii) all provisions contained
herein other than in the preceding clause (i) relating to the Development
Candidate shall be deemed to apply to the Substituted Development Candidate as
if it were the Development Candidate.


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      14.
<PAGE>   17

5       REGULATORY APPROVALS

        5.1 Orasense shall, or shall cause its sublicensees, at its or their
sole cost file and shall use its reasonable best efforts to prosecute to
approval or cause its sublicensees to prosecute to approval, the Marketing
Authorizations for the Products in the Territory in accordance with the Plan.
During any Marketing Authorization registration procedure, Orasense shall keep
Isis promptly and fully advised of Orasense's registration activities, progress
and procedures. Each Party shall inform the other Party and Isis of any dealings
such Party has with the FDA and any other Regulatory Authority. The Parties and
Elan shall collaborate in relation to obtaining any approval of the FDA or
Regulatory Authority for final approved labeling.

        5.2 Subject to agreement to the contrary, any and all Marketing
Authorizations filed hereunder for Products shall, to the extent owned by
Orasense, remain the property of Orasense, provided that Orasense shall allow
Isis access thereto to enable Isis to fulfill its obligations and exercise its
rights under this Agreement and the Development Agreement. Orasense shall
maintain or cause its sublicensees to maintain such Marketing Authorizations at
its or their own cost.

        5.3 Orasense shall indemnify and hold harmless Isis, its agents and
employees from and against all claims, damages, losses, liabilities and expenses
to which Isis, its agents, and employees may become subject related to or
arising out of Orasense's bad faith, negligence or intentional misconduct in
connection with the filing or maintenance of the Marketing Authorizations.

6       FINANCIAL PROVISIONS

        6.1 In consideration of the license to the Isis Patents, Orasense shall
pay to Isis, and, in consideration for license to Isis of Orasense Technology in
connection with the Commercialization of Isis Products, Isis shall pay to
Orasense, the following amounts:

               6.1.1 Development Product Fees and Royalties. Payments to Isis
        with respect to services rendered in connection with the Development
        Product shall be paid as provided below and net proceeds derived by
        Orasense from the Development Product shall be allocated as additional
        royalties in proportion to [...***...], as more particularly or as
        otherwise set forth below.

               (a)       Development Work - Research and development work 
        performed during the Research Term pursuant to the Research and
        Development Program regarding the Oral Platform and the Development
        Candidate contracted by Orasense to Isis shall be payable by Orasense to
        Isis based on [...***...] at Isis's Full Time Equivalent Rate, with
        annual Cost of Living Increases. In the event Isis is required to
        perform additional research and development work beyond that


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      15.
<PAGE>   18

        contemplated during the Research Term (without any extensions thereto),
        Orasense shall pay to Isis [...***...].

               (b)  Milestone Payments - If any Independent Third Party shall
        make milestone payments (e.g., for NDA filing, approvals, etc.) to
        Orasense, Orasense shall pay to Elan and Isis an additional royalty in
        the amount of [...***...].

               (c)  Royalties payable to Isis Upon Sales of the Development
        Product - Isis shall receive royalties of [...***...] of the In-market
        Net Sales of Development Products by OraseNse or its sublicensees.
        Notwithstanding the foregoing, in no event shall royalties payable to
        [...***...] with respect to sales of the Development Product
        [...***...].

               6.1.2  Isis Product Fees and Royalties. Net proceeds derived by
        Orasense from Isis Products shall be allocated between the Participants
        as additional royalties in proportion to [...***...], as more
        particularly or as otherwise set forth below.

               (a)  Milestone Payments - If any Independent Third party shall
        make milestone payments (e.g., for NDA filing, approvals, etc.) to Isis
        with respect to an Isis Product, then [...***...] of such milestone
        payment shall be paid to Orasense by Isis as an additional royalty and
        Orasense shall pay a royalty equal in such amount to Elan; provided
        however, that development related milestone payments with respect to any
        Isis Product shall not be payable by Isis to Orasense or by Orasense to
        Elan except to the extent such payments exceed [...***...] with respect
        to such Isis Product (or, in the event the milestone is intended to be
        applied towards future work to be performed by Isis, in excess of
        [...***...].

               (c)  Royalty Payments. Any marketing and/or development agreement
        between Orasense and Isis with respect to Isis Products shall provide
        for a royalty payment by Isis to Orasense of [...***...] of In-market
        Net Sales of the Isis Products. At such time as royalty payments by Isis
        to Orasense shall equal [...***...] for the particular Isis Product
        subject to any such agreement, the royalty payable by Isis to Orasense
        with respect to In-market Net Sales of the Isis Product shall be
        [...***...] and the royalty payable by Orasense to Elan with respect to
        such Isis Product shall be [...***...] of In-market Net Sales of such
        Isis Product.

               6.1.3 Third Party Products. Payments to Isis with respect to
        services


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      16.
<PAGE>   19

        rendered in connection with Third Party Products shall be paid as
        provided below and net proceeds derived by Orasense from Third Party
        Products shall be allocated as additional royalties with [...***...] of
        such amount being paid to Elan and [...***...] to Isis, as more
        particularly or as otherwise set forth below set forth below; provided,
        however, that in the event [...***...] significantly contributes to the
        research And development work related to a Third Party Product, the
        Participants shall negotiate in good faith an appropriate adjustment to
        the allocation of such additional royalties to reflect their relative
        contributions to the development of such Third Party Product.

               (a)  Development Work - Research and development work performed 
        by Isis for Orasense related to Third Party Products shall be payable
        Isis at [...***...]. Orasense shall Pay to Isis an additional fee equal
        to [...***...] of all amounts paid by an Independent Third Parties to
        Orasense for development work to the extent the amounts paid to Orasense
        for such work exceeds any charges by Elan and Isis; with the remaining
        [...***...] of such excess amount being payable to Elan.

               (b)  Royalty Payments - In the event Orasense contracts
        development work to Elan for any Third Party Product, Orasense shall pay
        Isis, a royalty equal to [...***...] of the royalties it receives with
        respect to such Product (with the remaining [...***...] of such
        royalties payable to Elan) until such time as Elan has been paid a sum
        equal to [...***...] paid to it. Thereafter, [...***...] of the
        royalties received by Orasense With respect to such Third Party Product
        shall be paid to Isis (with the balance payable to Elan).

               (c)  Milestone Payments - If any Independent Third Party shall
        make milestone payments (e.g., for NDA filing, approvals, etc.) to
        Orasense, then [...***...] of such milestone payment shall be paid by
        Orasense to Elan as an additional royalty and [...***...] shall be paid
        by Orasense to Isis as an additional royalty to Isis.

               (d)  Manufacturing and Supply of Products - In the event Orasense
        contracts with Elan to manufacture Third Party Products, Orasense shall
        pay to Isis an additional fee equal to [...***...] of all amounts paid
        by an Independent Third Parties to Orasense for the manufacture of such
        Third Party Products to the extent such amounts exceed the amount
        previously charged by Elan; with the remaining [...***...] of such
        excess amount being payable to Elan.

        6.2 Payment of royalties pursuant to Clauses 6.1.2-6.1.4, if any, shall
be made quarterly in arrears within forty-five (45) days after the expiry of the
calendar quarter. The method of payment shall be by wire transfer to an account
specified by Isis and shall be


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      17.
<PAGE>   20

nonrefundable to Orasense. Each payment made to Isis shall be accompanied by a
true accounting of all Products sold by Orasense, its Affiliates and its
permitted sublicensees, if any, during such quarter. Such accounting shall show,
on a country-by-country and Product-by-Product basis, Net Sales or royalties
received by Orasense (and the calculation thereof) and each calculation of
royalties with respect thereto, including the calculation of all adjustments and
currency conversions.

        6.3 Orasense shall maintain and keep clear, detailed, complete, accurate
and separate records for a period of three (3) years following the completion of
such records so: (i) as to enable any royalties which shall have accrued
hereunder to be determined; and (ii) that any deductions made in arriving at the
Net Sales can be determined.

        6.4 All payments due hereunder shall be made in United States Dollars.
Payments due on Net Sales of any Product or royalties received by Orasense with
respect to any Product for each calendar quarter made in a currency other than
United States Dollars shall first be calculated in the foreign currency and then
converted to United States Dollars on the basis of the average exchange rate in
effect for such quarter for the purchase of United States Dollars with such
foreign currency quoted in the Wall Street Journal (or comparable publication if
not quoted in the Wall Street Journal) with respect to the currency of the
country of origin of such payment, determined by averaging the rates so quoted
on each business day of such quarter.

        6.5 If Orasense claims in good faith that one or more of its devices,
products, parts or components thereof, compounds and/or drug products does not
utilize, incorporate, apply or is not based on the Elan Intellectual Property,
the Isis Intellectual Property and/or Orasense Technology, then Orasense shall
immediately notify Isis in writing and establish same to Isis's reasonable
satisfaction.

        6.6 If, at any time, legal restrictions in the Territory prevent the
prompt payment when due of royalties or any portion thereof, the Parties shall
meet to discuss suitable and reasonable alternative methods of reimbursing Isis
the amount of such royalties. In the event that Orasense is prevented from
making any payment under this Agreement by virtue of the statutes, laws, codes
or government regulations of the country from which the payment is to be made,
then such payments may be paid by depositing them in the currency in which they
accrue to Isis's account in a bank acceptable to Isis in the country the
currency of which is involved or as otherwise agreed by the Parties.

        6.7 Isis and Orasense agree to co-operate in all respects necessary to
take advantage of any double taxation agreements or similar agreements as may,
from time to time, be available.

        6.8 Any taxes payable by Isis on any payment made to Isis pursuant to
this Agreement shall be for the account of Isis. If so required by applicable
law, any payment made pursuant to this Agreement shall be made by Orasense after
deduction of the appropriate withholding tax, in which event the Parties shall
co-operate to obtain the



                                      18.
<PAGE>   21

appropriate tax clearance as soon as is practicable. On receipt of such
clearance, Orasense shall forthwith procure that the amount so withheld is paid
to Isis.

        6.9 Orasense shall, not more than once in each calendar year, permit
Isis or its duly authorized representatives upon reasonable notice and at any
reasonable time during normal business hours to have access to inspect and audit
the accounts and records of Orasense and any other book, record, voucher,
receipt or invoice relating to the calculation of the royalty payments on Net
Sales submitted to Isis. Any such inspection of Orasense's records shall be at
the expense of Isis, except that if any such inspection reveals a deficiency in
the amount of the royalty actually paid to Isis hereunder in any calendar
quarter of five percent (5%) or more of the amount of any royalty actually due
to Isis hereunder, then the expense of such inspection shall be borne solely by
Orasense. Any amount of deficiency shall be paid promptly to Isis by Orasense.
If such inspection reveals a surplus in the amount of royalties actually paid to
Isis by Orasense, Isis shall reimburse Orasense the surplus within fifteen (15)
days after determination.

        6.10 In the event of any unresolved dispute regarding any alleged
deficiency or overpayment of royalty payments hereunder, the matter will be
subject to resolution in accordance with Clause 24.9 of the Development
Agreement, which is incorporated by reference and shall for such purposes
survive termination of the Development Agreement.

7       CONFIDENTIAL INFORMATION

        7.1 The Parties acknowledge that it may be necessary, from time to time,
to disclose to each other confidential and proprietary information, including
without limitation, inventions, works of authorship, trade secrets,
specifications, designs, data, know-how and other information relating to the
Field, the Products, Elan Intellectual Property, Isis Intellectual Property or
the Orasense Technology, as the case may be, processes, services and business of
the disclosing Party. The foregoing shall be referred to collectively as
"Confidential Information". Any Confidential Information revealed by a Party to
another Party shall be used by the receiving Party exclusively for the purposes
of fulfilling the receiving Party's obligations under this Agreement and the
Development Agreement and for no other purpose.

        7.2 Each Party agrees to disclose Confidential Information of another
Party only to those employees, representatives and agents requiring knowledge
thereof in connection with their duties directly related to the fulfilling of
the Party's obligations under this Agreement. Each Party further agrees to
inform all such employees, representatives and agents of the terms and
provisions of this Agreement and their duties hereunder and to obtain their
consent hereto as a condition of receiving Confidential Information. Each Party
agrees that it will exercise the same degree of care, but in no event less than
a reasonable degree, and protection to preserve the proprietary and confidential
nature of the Confidential Information disclosed by a Party, as the receiving
Party would exercise to preserve its own proprietary and confidential
information. Each Party agrees that it will, upon request of a Party, return all


                                      19.
<PAGE>   22

documents and any copies thereof containing Confidential Information belonging
to or disclosed by, such Party.

        7.3    Notwithstanding the above, each Party may use or disclose
Confidential Information disclosed to it by another party to the extent such use
or disclosure is reasonably necessary in filing or prosecuting patent
applications, prosecuting or defending litigation, complying with patent
applications, complying with applicable governmental regulations or otherwise
submitting information to tax or other governmental authorities, conducting
clinical trials, or making a permitted sub-license or otherwise exercising its
rights hereunder, provided that if a Party is required to make any such
disclosure of the other Party's Confidential Information, other than pursuant to
a confidentiality agreement, such Party shall inform the recipient of the terms
and provisions of this Agreement and their duties hereunder and to obtain their
consent hereto as a condition of receiving Confidential Information.

        7.4    Any breach of this Clause 7 by any of the Persons informed by one
        of the Parties is considered a breach by the Party itself.

        7.5    Confidential Information shall not be deemed to include:

               (i)       information that is generally available to the public;

               (ii)      information which is made public by the disclosing 
Party;

               (iii)     information which is independently developed by a Party
as evidenced by such Party's written records, without the aid, application or
use of the disclosing Party's Confidential Information;

               (iv)      information that is published or otherwise becomes part
of the public domain without any disclosure by a Party, or on the part of a
Party's directors, officers, agents, representatives or employees;

               (v)       information that becomes available to a Party on a
non-confidential basis, whether directly or indirectly, from a source other than
a Party, which source did not acquire this information on a confidential basis;

               (vi)      information  which the receiving Party is required to 
disclose pursuant to:

                      (A)     a valid order of a court or other governmental 
body or any political subdivision thereof or otherwise required by law; or

                      (B)     any other requirement of law;

provided that if the receiving Party becomes legally required to disclose any
Confidential


                                      20.
<PAGE>   23

Information, the receiving Party shall give the disclosing Party prompt notice
of such fact so that the disclosing Party may obtain a protective order or other
appropriate remedy concerning any such disclosure. The receiving Party shall
fully cooperate with the disclosing Party in connection with the disclosing
Party's efforts to obtain any such order or other remedy. If any such order or
other remedy does not fully preclude disclosure, the receiving Party shall make
such disclosure only to the extent that such disclosure is legally required;

               (v) information which was already in the possession of the
receiving Party at the time of receiving such information, as evidenced by its
written records, provided such information was not previously provided to the
receiving Party from a source which was under an obligation to keep such
information confidential; or

               (vi) information that is the subject of a written permission to
disclose, without restriction or limitation, by the disclosing Party.

        7.6    The provisions relating to confidentiality in this Clause 7 shall
remain in effect during the term of this Agreement, and for a period of seven
(7) years following the expiration or earlier termination of this Agreement but
shall not apply to any information which a Party is required to file or
otherwise disclose in accordance with requirements which are legally binding on
it.

        7.7    The Parties agree that the obligations of this Clause 7 are
necessary and reasonable in order to protect the Parties' respective businesses,
and each Party expressly agrees that monetary damages would be inadequate to
compensate a Party for any breach by the other Party of its covenants and
agreements set forth herein. Accordingly, the Parties agree and acknowledge that
any such violation or threatened violation will cause irreparable injury to a
Party and that, in addition to any other remedies that may be available, in law
and equity or otherwise, any Party shall be entitled to obtain injunctive relief
against the threatened breach of the provisions of this Clause 7, or a
continuation of any such breach by the other Party, specific performance and
other equitable relief to redress such breach together with its damages and
reasonable counsel fees and expenses to enforce its rights hereunder, without
the necessity of proving actual or express damages.

8       WARRANTIES/INDEMNITIES

        8.1    Isis represents and warrants to Orasense that:

               (a)  Isis is a corporation duly organized under the laws of its
jurisdiction of organization and has all the requisite corporate power and
authority to own and lease its respective properties, to carry on its respective
business as presently conducted and as proposed to be conducted and to carry out
the transactions contemplated hereby;

               (b)  Isis has full corporate power and authority enter into this
Agreement and to perform its obligations hereunder, which have been duly
authorized by


                                      21.
<PAGE>   24

all requisite corporate action of Isis. This Agreement is the valid and binding
obligation of Isis, enforceable against it in accordance with its terms, except
as limited by applicable bankruptcy, insolvency, reorganization, moratorium and
other laws of general application affecting the enforcement of creditors' rights
generally, and by general equity principles and limitations on the availability
of equitable relief, including specific performance;

               (c)  The execution, delivery and performance by Isis of this
Agreement will not: (i) violate any provision of applicable law, statute, rule
or regulation known by and applicable to Isis or any ruling, writ, injunction,
order, judgment or decree of any court, arbitrator, administrative agency or
other governmental body applicable to Isis or any of its properties or assets;
or (ii) conflict with or result in any breach of any of the terms, conditions or
provisions of, or constitute (with notice or lapse of time or both) a default
(or give rise to any right of termination, cancellation or acceleration) under
the charter or organizational documents of Isis to which Isis is a party, except
where such violation, conflict or breach would not, individually or in the
aggregate, have an adverse material effect on the business, assets, liabilities
(contingent or otherwise), operations, condition (financial or otherwise), or
prospects of Isis;

               (d)  To Isis best knowledge, except as set forth on Schedule 3
hereto, (i) Isis has the right to grant the Isis License and any other rights
granted herein, (ii) Schedule 1 contains primary examples of the Isis
Intellectual Property existing as of the Effective Date, which listing is not
necessarily exhaustive, (iii) there are no agreements between Isis and any third
parties that conflict with the Isis License which would have a material adverse
effect on the ability of Orasense to conduct its business as presently proposed
to be conducted, (iv) Isis is the owner or licensee of all rights, title and
interest in the Isis Intellectual Property; and (v) Isis has no knowledge of any
pending or threatened action, suit, proceeding or claim by others challenging
Isis`s rights in or to such Isis Intellectual Property as related to the Field,
which would have a material adverse effect on the ability of Orasense to conduct
its business as presently proposed to be conducted.

        8.2    Orasense represents and warrants to Isis the following:

               (a)  Orasense is duly and validly existing in good standing in 
the jurisdiction of its incorporation and each other jurisdiction in which the
conduct of its business requires such qualification (except where such failure
to so qualify shall not have a material adverse affect on the business and
assets of Orasense), and Orasense is in compliance with all applicable laws,
rules, regulations or orders relating to its business and assets;

               (b)  Orasense has full corporate authority to execute and deliver
this Agreement and to consummate the transactions contemplated hereby; this
Agreement has been duly executed and delivered and constitutes the legal and
valid obligations of Orasense and is enforceable against Orasense in accordance
with its terms; and the execution, delivery and performance of this Agreement
and the transactions contemplated hereby will not violate


                                      22.
<PAGE>   25

or result in a default under or creation of lien or encumbrance under Orasense's
certificate of incorporation, by-laws or other organic documents, any material
agreement or instrument binding upon or affecting Orasense, or its properties or
assets or any applicable laws, rules, regulations or orders affecting Orasense
or its properties or assets;

               (c)  Orasense is not in default of its charter or by-laws, any
applicable laws or regulations or any material contract or agreement binding
upon or affecting it or its properties or assets and the execution, delivery and
performance of this Agreement and the transactions contemplated hereby will not
result in any such violation;

               (d)  Orasense represents and warrants to Elan that the execution
of this Agreement by Orasense and the full performance and enjoyment of the
rights of Orasense under this Agreement will not breach the terms and conditions
of any license, contract, understanding or agreement, whether express, implied,
written or oral between Orasense and any third party.

        8.3    Orasense represents and warrants to and covenants with Isis that 
it has the sole, exclusive and unencumbered right to grant the licenses and
rights herein granted to Isis and that it has not granted and will not grant any
option, license, right or interest in or to the Isis Intellectual Property, the
Orasense Technology, or other property to any third party which would conflict
with the rights granted by this Agreement and the Definitive Documents.

        8.4    Orasense represents and warrants to and covenants and agrees with
Isis that the Products shall be developed, manufactured, transported, stored,
handled, packaged, marketed, promoted, distributed, offered for sale and sold in
accordance with all regulations and requirements of the FDA and foreign
regulatory authorities including, without limitation, cGCP, cGLP, cGMP
regulations. The Products shall not be adulterated or misbranded as defined by
the Federal Food, Drug and Cosmetic Act (or applicable foreign law) and shall
not be a product which would violate any section of such Act if introduced in
interstate commerce.

        8.5    Orasense represents and warrants to Isis that it is fully 
cognizant of all applicable statutes, ordinances and regulations of the United
States of America and countries in the Territory with respect to the manufacture
of the Products including, but not limited to, the U.S. Federal Food, Drug and
Cosmetic Act and regulations thereunder and similar statutes in countries
outside of the United States. Orasense shall manufacture or procure the
manufacture of the Products in conformity with the Marketing Authorizations and
in a manner which fully complies with all United States of America and foreign
statutes, ordinances, regulations and practices.

        8.6    In addition to any other indemnifications provided for herein, 
Isis shall indemnify and hold harmless Orasense and its Affiliates and their
respective employees, agents, partners, officers and directors from and against
any claims, losses, liabilities or damages (including reasonable attorney's fees
and expenses) incurred or sustained by


                                      23.
<PAGE>   26

Orasense arising out of or in connection with any (a) breach of any
representation, covenant, warranty or obligation by Isis hereunder, or (b) any
act or omission on the part of Isis or any of its agents or employees in the
performance of this Agreement.

        8.7    In addition to any other indemnifications provided for herein,
Orasense shall indemnify and hold harmless Isis and its Affiliates and their
respective employees, agents, partners, officers and directors from and against
any claims, losses, liabilities or damages (including reasonable attorney's fees
and expenses) incurred or sustained by Isis arising out of or in connection with
any (a) breach of any representation, covenant, warranty or obligation by
Orasense hereunder, or (b) any act or omission on the part of Orasense or any of
its agents or employees in the performance of this Agreement.

        8.8    The Party seeking an indemnity shall:

          8.8.1  fully and promptly notify the other Party of any claim or
                 proceeding, or threatened claim or proceeding;

          8.8.2  permit the indemnifying Party to take full care and control of
                 such claim or proceeding;

          8.8.3  cooperate in the investigation and defense of such claim or
                 proceeding;

          8.8.4  not compromise or otherwise settle any such claim or proceeding
                 without the prior written consent of the other Party, which
                 consent shall not be unreasonably withheld, conditioned or
                 delayed; and

          8.8.5  take all reasonable steps to mitigate any loss or liability in
                 respect of any such claim or proceeding.

        8.9    NOTWITHSTANDING ANYTHING TO THE CONTRARY IN THIS AGREEMENT, 
NEITHER ISIS NOR ORASENSE SHALL BE LIABLE TO THE OTHER PARTY, OTHER BY REASON OF
ANY REPRESENTATION OR WARRANTY, CONDITION OR OTHER TERM OR ANY DUTY OF COMMON
LAW, OR UNDER THE EXPRESS TERMS OF THIS AGREEMENT, OR FOR ANY CONSEQUENTIAL OR
INCIDENTAL LOSS OR DAMAGE (WHETHER FOR LOSS OF PROFIT OR OTHERWISE) AND WHETHER
OCCASIONED BY THE APPLICABLE PARTY'S NEGLIGENCE OR OF ITS EMPLOYEES OR AGENTS OR
OTHERWISE

        8.10   EXCEPT AS SET FORTH IN THIS CLAUSE 8, ISIS IS GRANTING THE ISIS
LICENSE HEREUNDER ON AN "AS IS" BASIS WITHOUT RECOURSE, REPRESENTATION OR
WARRANTY WHETHER EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE, OR INFRINGEMENT OF THIRD PARTY RIGHTS, AND ALL
SUCH WARRANTIES ARE EXPRESSLY DISCLAIMED.



                                      24.
<PAGE>   27

9.      INTELLECTUAL PROPERTY OWNERSHIP RIGHTS

        9.1    Subject to the terms and conditions of this Agreement, including,
without limitation Section 11 below, Orasense shall own the legal and equitable
title to the Orasense Technology.

        9.2    Isis shall own the legal and equitable title to the Isis
Intellectual Property, including without limitation, Isis Improvements.

        9.3    Orasense shall permanently mark or otherwise use reasonable 
efforts to cause any third party to permanently mark all Products and/or the
packaging therefor with such license or patent notices to comply with the laws
of the country of sale or otherwise to generally communicate the existence of
any Isis Delivery Patents or Isis Development Candidate Patents for the
countries of the Territory and in such manner as Isis may reasonably request in
writing prior to the sale or commercial use thereof.

        9.4    Isis, at its expense, shall make a good faith effort (i) to 
secure the grant of any material patent applications within the Isis Delivery
Patents that relate to the Field and the Isis Development Candidate Patents;
(ii) to file and prosecute patent applications on material patentable inventions
and discoveries within the Isis Improvements that relate to the Field or the
Isis Development Candidate Patents; (iii) to defend all such applications
against third party oppositions; and (iv) to maintain in force any material
issued letters patent within the Isis Delivery Patents that relate to the Field
and the Isis Development Candidate Patents (including any letters patent that
may issue covering any such Isis Improvements that relate to the Field or the
Development Candidate). Isis shall have the right in its discretion to control
such filing, prosecution, defense and maintenance provided that Orasense and
Elan at their request shall be provided with copies of all documents relating to
such filing, prosecution, defense and maintenance in sufficient time to review
such documents and comment thereon prior to filing.

        9.5    In the event that Isis informs the Orasense and Elan that it does
not intend to file patent applications on patentable inventions and discoveries
within the Isis Intellectual Property that relate to the Field in one or more
countries in the Territory or fails to file such an application within a
reasonable period of time, Orasense shall have the option at its expense to file
and prosecute such patent application(s) in the joint names of Orasense and
Isis. Upon written request from Orasense, Isis shall execute all documents,
forms and declarations and to do all things as shall be reasonably necessary to
enable Orasense to exercise such option.

        9.6    Orasense, Isis and Elan shall promptly inform each other in 
writing of any alleged infringement of any patents within the Isis Patents or
any alleged misappropriation of trade secrets within the Isis Intellectual
Property by a third party of which it becomes aware and provide the others with
any available evidence of such infringement or misappropriation


                                      25.
<PAGE>   28

insofar as such infringements or misappropriation relate solely to the Field.

        9.7    Orasense shall have the right to prosecute at its own expense and
for its own benefit any infringements of the Isis Patents or misappropriation of
the Isis Intellectual Property, insofar as such infringements or
misappropriation relate solely to the Field. In the event that Orasense takes
such action, Orasense shall do so at its own cost and expense. At Orasense's
request, Isis shall cooperate with such action. Any recovery remaining after the
deduction by Orasense of the reasonable expenses (including attorney's fees and
expenses) incurred in relation to such infringement proceeding [...***...].
Should Orasense decide not to pursue such infringers, within a reasonable period
but in any event within twenty (20) days after receiving written notice of such
alleged infringement or misappropriation Isis may in its discretion initiate
such proceedings in its own name, at its expense and for its own benefit, and at
Isis's request, Orasense shall cooperate with such action. Alternatively, the
Participants may agree to institute such proceedings in their joint names and
shall reach agreement as to the proportion in which they shall share the
proceeds of any such proceedings, and the expense of any costs not recovered, or
the costs or damages payable to the third party. If the infringement of the Isis
Patents affects both the Field as well as other products being developed or
commercialized by Isis or its commercial partners outside the Field, Orasense
and Isis shall endeavor to agree as to the manner in which the proceedings
should be instituted and as to the proportion in which they shall share the
proceeds of any such proceedings, and the expense of any costs not recovered, or
the costs or damages payable to the third party.

        9.8    Orasense shall indemnify, defend and hold harmless Isis, against 
all actions, losses, claims, demands, damages, costs and liabilities (including
reasonable attorneys fees) relating directly or indirectly to all such claims or
proceedings referred to herein, provided that Isis shall not acknowledge to the
third party or to any other person the validity of any claims of such a third
party, and shall not compromise or settle any claim or proceedings relating
thereto without the prior written consent to Orasense, not to be unreasonably
withheld or delayed. At its option, Elan or Isis, as the case may be, may elect
to take over the conduct of such proceedings from Orasense provided that
Orasense's indemnification obligations shall continue; the costs of defending
such claim shall be borne by Elan or Isis, as the case may be and such
Participant shall not compromise or settle any such claim or proceeding without
the prior written consent of Orasense, such consent not to be unreasonably
withheld or delayed.

10.     RIGHTS EXPLOITATION OUTSIDE THE FIELD

        10.1   Licenses to Isis Program Technology. Orasense hereby grants to 
Isis a perpetual, exclusive, royalty free and sublicensable license to Isis
Program Technology outside of the Field.

        10.2   Licenses for Orasense Program Technology Outside the Field. 
Orasense hereby grants to Isis a perpetual exclusive license for the use of
Orasense Program


                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      26.
<PAGE>   29

Technology outside the Field in the Territory solely for use in connection with
Isis proprietary drug products (including drug products discovered or developed
in collaborative partnerships). The terms of such license for the use of
Orasense Program Technology shall be decided by the unanimous decision of the
Management Committee on such terms and conditions as the Management Committee
shall approve after good faith negotiations with Isis.

11.     NON-COMPETITION

        11.1. During the Research Term (and any extension thereto), Isis shall
not develop or Commercialize, or assist in the development or Commercialization
of Oligonucleotide Drugs in the Field or develop or Commercialize, or assist in
the development or Commercialization of an Oral Platform for systemic and
topical delivery of Oligonucleotide Drugs, except (a) for or on behalf of
Orasense, or (b) with the prior written, unanimous consent of the Management
Committee. During the Term and provided that Orasense is maintaining an active
program for the development and Commercialization of the Development Candidate
in the Field, Isis shall not develop or Commercialize or assist in the
development for Commercialization of an Oral TNF-(alpha) inhibitor, or, if a
Substituted Development Candidate is selected, an Oral inhibitor of the
Substituted Development Candidate. Nothing contained herein shall be construed
as (i) limiting the activities of an existing third party licensee of Isis from
developing Oligonucleotide Drugs utilizing Isis Delivery Technology to the
extent such rights have been previously granted by Isis, provided Isis does not
provide any active support to any such activities in excess of its existing
contractual obligations or (ii) prohibiting Isis from licensing Isis Delivery
Technology to an Independent Third Party or limiting the activities of any such
future Independent Third Party licensee of Isis from developing Oligonucleotide
Drugs utilizing Isis Delivery Technology; provided that the primary purpose of
any such license is not the development of an Oral Platform for Oligonucleotide
Drugs and Isis does not provide any active support to any such activities.
 .

12.     TERM AND TERMINATION OF AGREEMENT

        12.1. The term of this Agreement and the term of the Licenses granted
hereunder with respect to a Product utilizing or based on the Licensed
Technologies shall commence as of the Effective Date and continue, on a
Product-by-Product basis and country by country basis, for the life of the
patent rights upon which such Product is based on or utilizes in such country
(the "Term"); provided, however, that all royalty and fee obligations contained
herein shall survive for the greater of (i) the Term or (ii) 15 years from the
first commercial sale of such Product.


                                      27.
<PAGE>   30

        12.2. Nothing contained herein shall obligate or restrict any party from
utilizing public, non-proprietary information which is not subject to the
protection of applicable patent laws.

        12.3. If either party breaches any material provision of this Agreement
and if such breach is (i) not capable of being cured or (ii) is capable of being
cured but is not corrected within sixty (60) days after the non-breaching party
gives written notice of the breach to the breaching party, the non-breaching
party may terminate this Agreement immediately by giving notice of the
termination, effective on the date of the notice, provided, however, that (x) if
any such curable breach is not capable of being cured within such sixty (60) day
period, so long as the breaching party commences to cure the breach promptly
after receiving notice of the breach from the non-breaching party and thereafter
diligently prosecutes the cure to completion as soon as is practicable, the
non-breaching Party may not terminate this Agreement so long as the breaching
party is acting in good faith to rectify such breach or (y) the default involves
a good faith dispute regarding the amount of any required payment, provided any
undisputed amount is paid, such default shall be stayed and the remainder may be
withheld for a reasonable period during which a good faith resolution of the
amount owed is being pursued.

        12.4. In the event that the Elan License Agreement shall be terminated,
at the sole option of Isis and upon written notice to Elan and Orasense, the
Isis License shall be immediately terminated.

        12.5. Upon the occurrence of an Event of Bankruptcy with respect to
Orasense or Elan, the other Party may, upon written notice to Isis and the Party
with respect to which such Event of Bankruptcy has occurred, immediately
terminate the Elan License. As used in this Clause 12.5, the term "Event of
Bankruptcy" relating to either Orasense or Elan shall mean:

           12.5.1.the appointment of a liquidator, receiver, administrator,
           examiner, trustee or similar officer of either Party of it or over
           all or a substantial part of its assets under the law of any
           applicable jurisdiction, including without limit, Bermuda, the United
           States of America or Ireland; or

           12.5.2 an application or petition for bankruptcy, corporate
           re-organization, composition, administration, examination,
           arrangement or any other procedure similar to any of the foregoing
           under the law of any applicable jurisdiction, including without
           limit, Bermuda, the United States of America or Ireland (other than
           as part of a bona fide restructuring or reorganization), is filed,
           and is not discharged within forty-five (45) days, or if either Party
           applies for or consents to the appointment of a receiver,
           administrator, examiner or similar officer of it or of all or a
           material part of its assets, rights or revenues or the assets and/or
           the business of either Party are for any reason seized, confiscated
           or condemned.


                                      28.
<PAGE>   31

        12.6. Upon exercise of those rights of termination as specified in
Clause 12.1 to Clause 12.5 inclusive or elsewhere within this Agreement, this
Agreement shall, subject to the other provisions of this Agreement,
automatically terminate forthwith and be of no further legal force or effect.

        12.7.  Upon expiration or termination of the Agreement:

               12.7.1 any sums that were due from Orasense to Isis with respect
to license granted hereunder, including without limitation on Net Sales, in the
Territory or in such particular country or countries in the Territory (as the
case may be) prior to the expiration or termination of this Agreement as set
forth herein shall be paid in full within sixty (60) days after the expiration
or termination of this Agreement for the Territory or for such particular
country or countries in the Territory (as the case may be);

               12.7.2 any provisions clearly meant to survive termination or
expiration of this Agreement, including without limitation Clause 7, shall
remain in full force and effect;

               12.7.3 all representations, warranties and indemnities shall
insofar as are appropriate remain in full force and effect;

               12.7.4 the rights of inspection and audit set out in Clause 6
shall continue in force for a period of one year;

               12.7.5 termination of this Agreement for any reason shall not
release any Party hereto from any liability which, at the time of such
termination, has already accrued to the other Party or which is attributable to
a period prior to such termination nor preclude either Party from pursuing all
rights and remedies it may have hereunder or at law or in equity with respect to
any breach of this Agreement;

               12.7.6 the Isis Intellectual Property and all rights, licenses
and sublicenses granted by Isis in and pursuant to this Agreement shall cease
for the Territory or for such particular country or countries in the Territory
(as the case may be) and shall immediately revert to Isis and all Isis Program
Technology shall be deemed immediately transferred and assigned to Elan.
Following such expiration or termination, Orasense may not thereafter use in the
Territory or in such particular country or countries in the Territory (as the
case may be) (a) any valid and unexpired Isis Patents, (b) any Isis Intellectual
Property that remains confidential or otherwise proprietary to Isis, and/or (c)
Trademarks. All rights to Orasense Technology (other than Elan Program
Technology and Isis Program Technology) shall be transferred to and jointly
owned by Elan and Isis and may only be utilized by such parties royalty-free,
consistent with the other restriction contained in Section 10 of this Agreement
and the comparable section of the Elan License Agreement regarding the
limitation of such rights outside the Field. Rights of permitted Independent
Third Party sublicensees in and to the Isis Intellectual Property shall survive
the termination of the license and sublicense agreements granting said
intellectual property rights to Orasense; and Orasense, Elan and Isis


                                      29.
<PAGE>   32

shall in good faith agree upon the form most advantageous to Elan and Isis in
which the rights of the sublicensor under any such sublicenses are to be held
(which form may include continuation of Orasense solely as the holder of such
licenses or assignment of such rights to a third party or parties, including an
assignment to both Elan and Isis). Any sublicense agreement between Orasense and
such permitted sublicensee shall permit an assignment of rights by Orasense to
Isis and shall contain additional reasonable confidentiality protections which
an assignee shall reasonably require. Upon any such assignment, Elan and Isis
shall enter into good faith negotiations with respect to additional reasonable
confidentiality protections which either party shall reasonably require.

13.     IMPOSSIBILITY OF PERFORMANCE - FORCE MAJEURE

        13.1. Neither Party to this Agreement shall be liable for delay in the
performance of any of its obligations hereunder if such delay results from
causes beyond its reasonable control, including, without limitation, acts of
God, fires, strikes, acts of war, or intervention of a government authority, non
availability of raw materials, but any such delay or failure shall be remedied
by such Party as soon as practicable.

14.     SETTLEMENT OF DISPUTES; GOVERNING LAW

        14.1. Any dispute between the Parties arising out of or relating to this
Agreement will be subject to resolution in accordance with Clause 24.9 of the
Development Agreement, which is incorporated by reference and shall for such
purposes survive termination of the Development Agreement.

        14.2. This Agreement is construed under and ruled by the laws of the
State of New York, without regard to the conflict of law principles.

15.     ASSIGNMENT

        15.1. This Agreement may not be assigned by either Party without the
prior written consent of the other, which consent shall not be unreasonably
withheld, conditioned or delayed, save that (i) either Party may assign this
Agreement to its Affiliate without such consent, provided that such assignment
does not have any adverse tax consequences on the other Party, and (ii) subject
to the rights of Elan under the Development Agreement upon the occurrence of a
Change of Control and the rights of Elan under the Elan License Agreement upon
the occurrence of a Competitive Change of Control Event, Isis may assign its
rights and obligations hereunder in connection with a sale of all or
substantially all of the business of Isis to which the Transaction Documents
relate, whether by merger, sale of stock, sale of assets or otherwise (provided
that, in the event of such transaction, no intellectual property rights of any
third party that is the acquiring corporation in such transaction shall be
included in the Isis Intellectual Property licensed hereunder). Isis and
Orasense will discuss any assignment by either Party to an Affiliate prior to
its implementation in order to avoid or reduce any additional tax liability to
the other Party resulting solely from different tax law


                                      30.
<PAGE>   33

provisions applying after such assignment to an Affiliate. For the purpose
hereof, an additional tax liability shall be deemed to have occurred if either
Party would be subject to a higher net tax on payments made hereunder after
taking into account any applicable tax treaty and available tax credits than
such Party was subject to before the proposed assignment. Notwithstanding any
assignment hereof to an Affiliate, each Party will remain fully liable
hereunder.

16.     NOTICES

        16.1. Any notice to be given under this Agreement shall be sent in
writing in English by registered airmail or telefaxed to the following
addresses:


           If to Orasense at:   Orasense Ltd.
                                c/o Isis Pharmaceuticals, Inc.
                                2292 Faraday Avenue
                                Carlsbad, California 92008
                                Attention:     Ms. Lynne Parshall
                                Telephone:  (760) 603-2460
                                Telefax:      (760) 931-9639

           If to Isis to:       Isis Pharmaceuticals, Inc.
                                2292 Faraday Avenue
                                Carlsbad, California 92008
                                Attention:     Ms Lynne Parshall
                                Telephone:  (760) 603-2460
                                Telefax:      (760) 931-9639

           with a copy to:      Cooley Godward LLP
                                4365 Executive Drive
                                Suite 1100
                                San Diego, CA 91212
                                Attention:  L. Kay Chandler
                                Telephone:  (619) 550-6000
                                Telefax:      (619) 453-3555

           If to Elan at:       Elan Corporation plc
                                Lincoln House, Lincoln Place, Dublin 2, Ireland
                                Attention: Vice President, General Counsel,
                                Elan Pharmaceutical Technologies,
                                a division of Elan Corporation, plc
                                Telephone:  + 353 1 709 4000
                                Telefax:      + 353  1 709 4124


                                      31.
<PAGE>   34

           with a copy to:      Cohen & Tauber LLP
                                1350 Avenue of the Americas
                                26th Floor
                                New York, New York 10019
                                Attention:  Laurence S. Tauber
                                Telephone:  (212) 519-5195
                                Telefax:    (212) 262-1766

         or to such other address(es) and telefax numbers as may from time to
         time be notified by either Party to the other hereunder.

        16.2. Any notice sent by mail shall be deemed to have been delivered
within seven (7) working days after dispatch and any notice sent by telex or
telefax shall be deemed to have been delivered within twenty four (24) hours of
the time of the dispatch. Notice of change of address shall be effective upon
receipt.

17.     MISCELLANEOUS CLAUSES

        17.1. No waiver of any right under this Agreement shall be deemed
effective unless contained in a written document signed by the Party charged
with such waiver, and no waiver of any breach or failure to perform shall be
deemed to be a waiver of any other breach or failure to perform or of any other
right arising under this Agreement.

        17.2. If any provision in this Agreement is agreed by the Parties to be,
or is deemed to be, or becomes invalid, illegal, void or unenforceable under any
law that is applicable hereto, (i) such provision will be deemed amended to
conform to applicable laws so as to be valid and enforceable or, if it cannot be
so amended without materially altering the intention of the Parties, it will be
deleted, with effect from the date of such agreement or such earlier date as the
Parties may agree, and (ii) the validity, legality and enforceability of the
remaining provisions of this Agreement shall not be impaired or affected in any
way.

        17.3. The Parties shall use their respective reasonable endeavors to
ensure that the Parties and any necessary third party shall execute and perform
all such further deeds, documents, assurances, acts and things as any of the
Parties hereto may reasonably require by notice in writing to the other Party or
such third party to carry the provisions of this Agreement.

        17.4. This Agreement shall be binding upon and inure to the benefit of
the Parties hereto, their successors and permitted assigns and sub-licenses.
Elan shall be a third party beneficiary to this Agreement and shall have the
right to cause Orasense to enforce Orasense's rights against Isis.

        17.5. No provision of this Agreement shall be construed so as to negate,
modify or affect in any way the provisions of any other agreement between the
Parties unless


                                      32.
<PAGE>   35

specifically referred to, and solely to the extent provided, in any such other
agreement. In the event of a conflict between the provisions of this Agreement
and the provisions of the Development Agreement, the terms of the Development
Agreement shall prevail unless this Agreement specifically provides otherwise.

        17.6. No amendment, modification or addition hereto shall be effective
or binding on either Party unless set forth in writing and executed by a duly
authorized representative of each Party. Amendments hereto shall be subject to
the prior approval of Isis, which approval shall not be unreasonably withheld or
delayed.

        17.7. This Agreement may be executed in any number of counterparts, each
of which when so executed shall be deemed to be an original and all of which
when taken together shall constitute this Agreement.

        17.8. Each of the Parties undertakes to do all things reasonably within
its power which are necessary or desirable to give effect to the spirit and
intent of this Agreement.

        17.9. Each of the Parties hereby acknowledges that in entering into this
Agreement it has not relied on any representation or warranty save as expressly
set out herein or in any document referred to herein.

        17.10. Nothing contained in this Agreement is intended or is to be
construed to constitute Elan, Isis and Orasense as partners, or Isis as an
employee of Orasense and Elan, or Orasense and Elan as an employee of Isis.
Neither Party hereto shall have any express or implied right or authority to
assume or create any obligations on behalf of or in the name of


                                      33.
<PAGE>   36

the other Party or to bind the other Party to any contract, agreement or
undertaking with any third party.

IN WITNESS WHEREOF, the Parties hereto have executed this Agreement as of the
date first set forth above.

ISIS PHARMACEUTICAL, INC.


By: /s/ B. LYNNE PARSHALL
    -----------------------
    B. Lynne Parshall
    Executive Vice President


ORASENSE LTD.


By: /s/ B. LYNNE PARSHALL
    -----------------------
    B. Lynne Parshall
    President

AGREED TO:

ELAN PHARMACEUTICAL TECHNOLOGIES,
A DIVISION OF ELAN CORPORATION, PLC

By: /s/ KEVIN INSLEY
    -----------------------
    Kevin Insley
    Authorized Signatory















                     [ISIS LICENSE AGREEMENT EXECUTION PAGE]


                                      34.
<PAGE>   37

                                    EXHIBIT A

                      DESCRIPTION OF DEVELOPMENT CANDIDATE

[...***...]














                                               *CONFIDENTIAL TREATMENT REQUESTED

                                      35.



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