AMGEN INC
SC 14D1, 1994-11-23
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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<PAGE>   1
 
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- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                                 SCHEDULE 14D-1
 
              TENDER OFFER STATEMENT PURSUANT TO SECTION 14(D)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934
 
                                 SYNERGEN, INC.
                           (NAME OF SUBJECT COMPANY)
 
                       AMGEN ACQUISITION SUBSIDIARY, INC.
                                   AMGEN INC.
                                    (BIDDER)
 
                          COMMON STOCK, $.01 PAR VALUE
                         (TITLE OF CLASS OF SECURITIES)
 
                                   871594107
                     (CUSIP NUMBER OF CLASS OF SECURITIES)
 
                            ------------------------
 
                         MARGARET VALEUR-JENSEN, PH.D.
                                 SENIOR COUNSEL
                                   AMGEN INC.
                                  AMGEN CENTER
                             1840 DEHAVILLAND DRIVE
                          THOUSAND OAKS, CA 91320-1789
                           TELEPHONE: (805) 447-1000
                     (NAME, ADDRESS AND TELEPHONE NUMBER OF
                     PERSONS AUTHORIZED TO RECEIVE NOTICES
                    AND COMMUNICATIONS ON BEHALF OF BIDDER)
 
                            ------------------------
 
                                    COPY TO:
 
                            GEORGE A. VANDEMAN, ESQ.
                                LATHAM & WATKINS
                       633 WEST FIFTH STREET, SUITE 4000
                         LOS ANGELES, CALIFORNIA 90071
                           TELEPHONE: (213) 485-1234
 
                               NOVEMBER 23, 1994
             (DATE OF EVENT WHICH REQUIRES FILING OF THE STATEMENT)
 
                        CALCULATION OF REGISTRATION FEE
 
<TABLE>
<S>                                            <C>
- --------------------------------------------------------------------------------------------
- --------------------------------------------------------------------------------------------
TRANSACTION VALUATION*                         AMOUNT OF FILING FEE**
- --------------------------------------------------------------------------------------------
$262,728,027.50                                $52,545.61
- --------------------------------------------------------------------------------------------
- --------------------------------------------------------------------------------------------
</TABLE>
 
 *   Calculated by multiplying $9.25, the per share tender offer price, by
     28,403,030, the sum of the number of shares of Common Stock outstanding and
     the 2,466,782 shares of Common Stock subject to options outstanding.
**   1/50 of 1% of Transaction Valuation.
/ /  Check box if any part of the fee is offset as provided by Rule 0-11(a)(2)
     and identify the filing with which the offsetting fee was previously paid.
     Identify the previous filing by registration statement number, or the Form
     or Schedule and the date of its filing.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>   2
 
                                  TENDER OFFER
 
     This Tender Offer Statement on Schedule 14D-1 (the "Statement") relates to
the offer by Amgen Acquisition Subsidiary, Inc., a Delaware corporation
("Purchaser") and a wholly owned subsidiary of Amgen Inc., a Delaware
corporation ("Parent"), to purchase all outstanding shares of Common Stock, par
value $.01 per share (the "Shares"), of Synergen, Inc., a Delaware corporation
(the "Company"), including the associated preferred stock purchase rights
(unless the context requires otherwise, all references to "Shares" shall include
a reference to such rights) at a price of $9.25 per Share, net to the seller in
cash, upon the terms and subject to the conditions set forth in Purchaser's
Offer to Purchase dated November 23, 1994 (the "Offer to Purchase") and in the
related Letter of Transmittal (which together constitute the "Offer"), copies of
which are submitted herewith as Exhibits 99.(a)(1) and 99.(a)(2), respectively.
 
<TABLE>
  <S>                 <C>
  ITEM 1. SECURITY AND SUBJECT COMPANY.
       (a)            The name of the subject company is Synergen, Inc., a Delaware
                      corporation (the "Company"), which has its principal executive offices
                      at 1885 33rd Street, Boulder, Colorado, 80301.
       (b)            The class of equity securities being sought is all the outstanding
                      shares of Common Stock, par value $.01 per share, of the Company,
                      including associated rights to purchase units of Series A Junior
                      Participating Preferred Stock, par value $.01 per share, of the Company
                      issued pursuant to the Rights Agreement dated as of October 24, 1991
                      between the Company and Chemical Trust Company of California, as Rights
                      Agent. The information set forth in the Introduction and Section 1
                      ("Terms of the Offer; Expiration Date") of the Offer to Purchase is
                      incorporated herein by reference.
       (c)            The information concerning the principal market in which the Shares are
                      traded and certain high and low sales prices for the Shares in such
                      principal market set forth in Section 6 ("Price Range of Shares") of
                      the Offer to Purchase is incorporated herein by reference.
 
  ITEM 2. IDENTITY AND BACKGROUND.
       (a)-(d)
       and (g)        This Statement is filed by Purchaser and Parent. The information
                      concerning the name, state or other place of organization, principal
                      business and address of the principal office of each of Purchaser and
                      Parent, and the information concerning the name, business address,
                      present principal occupation or employment and the name, principal
                      business and address of any corporation or other organization in which
                      such employment or occupation is conducted, material occupations,
                      positions, offices or employments during the last five years and
                      citizenship of each of the executive officers and directors of
                      Purchaser and Parent are set forth in the Introduction, Section 8
                      ("Certain Information Concerning Purchaser and Parent") and Schedule I
                      of the Offer to Purchase and are incorporated herein by reference.
       (e)-(f)        During the last five years, neither of Purchaser nor Parent, and, to
                      the best of the knowledge of Purchaser and Parent, none of the persons
                      listed in Schedule I of the Offer to Purchase has been (i) convicted in
                      a criminal proceeding (excluding traffic violations or similar
                      misdemeanors) or (ii) a party to a civil proceeding of a judicial or
                      administrative body of competent jurisdiction and as a result of such
                      proceeding was or is subject to a judgment, decree or final order
                      enjoining future violations of, or prohibiting activities subject to,
                      federal or state securities law or finding any violation of such laws.
 
  ITEM 3. PAST CONTACTS, TRANSACTIONS OR NEGOTIATIONS WITH THE SUBJECT COMPANY.
       (a)            The information set forth in Section 8 ("Certain Information Concerning
                      Purchaser and Parent") is incorporated herein by reference.
</TABLE>
 
                                        2
<PAGE>   3
 
<TABLE>
  <S>                 <C>
       (b)            The information set forth in the Introduction, Section 8 ("Certain
                      Information Concerning Purchaser and Parent"), Section 10 ("Background
                      of the Offer; Contacts with the Company; the Merger Agreement") and
                      Section 11 ("Purpose of the Offer; Plans for the Company After the
                      Offer and the Merger") of the Offer to Purchase is incorporated herein
                      by reference.
 
  ITEM 4. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.
       (a)-(c)        The information set forth in Section 9 ("Financing of the Offer and the
                      Merger") of the Offer to Purchase is incorporated herein by reference.
 
  ITEM 5. PURPOSE OF THE TENDER OFFER AND PLANS OR PROPOSALS OF THE BIDDER.
       (a)-(e)        The information set forth in the Introduction, Section 10 ("Background
                      of the Offer; Contacts with the Company; the Merger Agreement") and
                      Section 11 ("Purpose of the Offer; Plans for the Company After the
                      Offer and the Merger") of the Offer to Purchase is incorporated herein
                      by reference.
       (f)-(g)        The information set forth in Section 13 ("Effect of the Offer on the
                      Market for Shares, Exchange Listing and Exchange Act Registration") of
                      the Offer to Purchase is incorporated herein by reference.
 
  ITEM 6. INTEREST IN SECURITIES OF THE SUBJECT COMPANY.
       (a)-(b)        Not applicable.
 
  ITEM 7. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO THE
          SUBJECT COMPANY'S SECURITIES.
                      The information set forth in the Introduction, Section 8 ("Certain
                      Information Concerning Purchaser and Parent"), Section 10 ("Background
                      of the Offer; Contacts with the Company; the Merger Agreement"),
                      Section 11 ("Purpose of the Offer; Plans for the Company After the
                      Offer and the Merger") and Section 16 ("Rights Agreement and Employment
                      Contracts") of the Offer to Purchase is incorporated herein by
                      reference.
 
  ITEM 8. PERSONS RETAINED, EMPLOYED OR TO BE COMPENSATED.
                      The information set forth in the Introduction and Section 17 ("Fees and
                      Expenses") of the Offer to Purchase is incorporated herein by
                      reference.
 
  ITEM 9. FINANCIAL STATEMENTS OF CERTAIN BIDDERS.
                      The information set forth in Section 8 ("Certain Information Concerning
                      Purchaser and Parent") of the Offer to Purchase is incorporated herein
                      by reference.
 
  ITEM 10. ADDITIONAL INFORMATION.
       (a)            The information set forth in Section 16 ("Rights Agreement") of the
                      Offer to Purchase is incorporated herein by reference.
       (b)-(c)        The information set forth in Section 15 ("Certain Legal Matters and
                      Regulatory Approvals") of the Offer to Purchase is incorporated herein
                      by reference.
       (d)            Not applicable.
       (e)            The information set forth in Section 15 ("Certain Legal and Regulatory
                      Approvals") of the Offer to Purchase is incorporated herein by
                      reference.
       (f)            The information set forth in the Offer to Purchase is incorporated
                      herein by reference.
</TABLE>
 
                                        3
<PAGE>   4
 
<TABLE>
  <S>                 <C>
  ITEM 11. MATERIAL TO BE FILED AS EXHIBITS.
        2.(c)(1)      Agreement and Plan of Merger, dated as of November 17, 1994 among
                      Parent, Purchaser and the Company.
       99.(a)(1)      Offer to Purchase dated November 23, 1994.
       99.(a)(2)      Form of Letter of Transmittal.
       99.(a)(3)      Form of Notice of Guaranteed Delivery.
       99.(a)(4)      Form of Letter from CS First Boston Corporation to Brokers, Dealers,
                      Commercial Banks, Trust Companies and Nominees.
       99.(a)(5)      Form of Letter from Brokers, Dealers, Commercial Banks, Trust Companies
                      and Nominees to Clients.
       99.(a)(6)      Form of Guidelines for Certification of Taxpayer Identification Number
                      on Substitute Form W-9.
       99.(a)(7)      Summary Advertisement as published in The Wall Street Journal on
                      November 23, 1994.
       99.(a)(8)      Joint Press Release issued by Parent and the Company on November 18,
                      1994.
       99.(a)(9)      Press Release issued by Parent on November 23, 1994.
</TABLE>
 
                                        4
<PAGE>   5
 
                                   SIGNATURE
 
     After due inquiry and to the best of the undersigned's knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, correct and complete.
 
                                          AMGEN ACQUISITION SUBSIDIARY, INC.
 
                                          By   /s/  Thomas E. Workman, Jr.
                                             -------------------------------
                                                 Chief Executive Officer
 
Dated: November 23, 1994
 
                                        5
<PAGE>   6
 
                                   SIGNATURE
 
     After due inquiry and to the best of the undersigned's knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, correct and complete.
 
                                          AMGEN INC.
 
                                          By       /s/  Gordon M. Binder
                                             ---------------------------------
                                                Chief Executive Officer and
                                                   Chairman of the Board
 
Dated: November 23, 1994
 
                                        6
<PAGE>   7
 
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
                                                                                     SEQUENTIALLY
 EXHIBIT                                                                               NUMBERED
  NUMBER                                   DESCRIPTION                                   PAGE
- ----------   ----------------------------------------------------------------------- ------------
<C>          <S>                                                                     <C>
  2.(c)(1)   Agreement and Plan of Merger dated as of November 17, 1994, among
             Parent, Purchaser and the Company......................................
 99.(a)(1)   Offer to Purchase dated November 23, 1994..............................
 99.(a)(2)   Form of Letter of Transmittal..........................................
 99.(a)(3)   Form of Notice of Guaranteed Delivery..................................
 99.(a)(4)   Form of Letter from CS First Boston Corporation to Brokers, Dealers,
             Commercial Banks, Trust Companies and Nominees.........................
 99.(a)(5)   Form of Letter from Brokers, Dealers, Commercial Banks, Trust Companies
             and Nominees to Clients................................................
 99.(a)(6)   Form of Guidelines for Certification of Taxpayer Identification Number
             on Substitute Form W-9.................................................
 99.(a)(7)   Summary Advertisement as published in The Wall Street Journal on
             November 23, 1994......................................................
 99.(a)(8)   Joint Press Release issued by Parent and the Company on November 18,
             1994...................................................................
 99.(a)(9)   Press Release issued by Parent on November 23, 1994....................
</TABLE>
 
                                        7

<PAGE>   1
 
                                                                  CONFORMED COPY
 
                          AGREEMENT AND PLAN OF MERGER

                                     AMONG
 
                                   AMGEN INC.

                       AMGEN ACQUISITION SUBSIDIARY, INC.

                                      AND
 
                                 SYNERGEN, INC.
<PAGE>   2
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                         PAGE
                                                                                         ----
<S>                                                                                      <C>
RECITALS...............................................................................     1
AGREEMENT..............................................................................     1
 
  1. THE OFFER.........................................................................     1
    1.1     The Offer..................................................................     1
    1.2     Company Action.............................................................     2
    1.3     Directors..................................................................     3
  2. THE MERGER........................................................................     3
    2.1     The Merger.................................................................     3
    2.2     Effect of the Merger.......................................................     3
    2.3     Consummation of the Merger.................................................     3
    2.4     Certificate of Incorporation; Bylaws; Directors and Officers...............     4
    2.5     Conversion of Securities...................................................     4
    2.6     Company Stock Options and Related Matters..................................     4
    2.7     Treatment of Warrants......................................................     4
    2.8     Exchange of Certificates...................................................     5
 
  3. REPRESENTATIONS AND WARRANTIES OF PARENT AND PURCHASER............................     5
    3.1     Organization and Qualification.............................................     5
    3.2     Authority Relative to this Agreement.......................................     6
    3.3     Compliance.................................................................     6
    3.4     Available Funds............................................................     6
    3.5     Company Stock..............................................................     6
 
  4. REPRESENTATIONS AND WARRANTIES OF COMPANY.........................................     7
    4.1     Organization and Qualification.............................................     7
    4.2     Subsidiaries...............................................................     7
    4.3     Capitalization.............................................................     7
    4.4     Authority Relative to this Agreement.......................................     8
    4.5     Compliance.................................................................     8
    4.6     Commission Filings.........................................................     8
    4.7     Absence of Undisclosed Liabilities.........................................     9
    4.8     Litigation.................................................................     9
    4.9     Board Recommendation; Qualifying Offer.....................................     9
    4.10    Compliance with Law........................................................     9
    4.11    Changes....................................................................     9
    4.12    Taxes......................................................................    10
    4.13    Title to Properties; Condition of Properties...............................    10
    4.14    Contracts..................................................................    11
    4.15    Employee Benefit Plans.....................................................    11
    4.16    Compliance With Legislation Regulating Environmental Quality...............    14
    4.17    Labor Matters..............................................................    15
    4.18    Absence of Questionable Payments...........................................    15
    4.19    Intellectual Property......................................................    15
    4.20    Cash and Cash Equivalents and Short-term Investments.......................    15
</TABLE>   
 
                                        i
<PAGE>   3
 
<TABLE>
<CAPTION>
                                                                                         PAGE
                                                                                         ----
<S>                                                                                      <C>
  5. CONDUCT OF BUSINESS PENDING THE MERGER............................................    16
    5.1     Ordinary Course of Business................................................    16
    5.2     Preservation of Organization...............................................    16
    5.3     Capitalization Changes.....................................................    16
    5.4     Sale of Assets.............................................................    16
    5.5     Dividends and Repurchases..................................................    16
    5.6     Acquisitions...............................................................    16
    5.7     Indebtedness...............................................................    16
    5.8     Severance and Termination Pay..............................................    16
    5.9     Employee Benefits..........................................................    17
    5.10    Tax Election...............................................................    17
    5.11    Subsequent Financials......................................................    17
           
  6. ADDITIONAL AGREEMENTS.............................................................    17
    6.1     Proxy Statement............................................................    17
    6.2     Meeting of Stockholders of Company; Voting and Disposition of the Shares...    17
    6.3     Stock Options..............................................................    18
    6.4     Fees and Expenses..........................................................    18
    6.5     Additional Agreements......................................................    18
    6.6     No Solicitation of Transactions............................................    18
    6.7     Notification of Certain Matters............................................    19
    6.8     Access to Information......................................................    19
    6.9     Officers' and Directors' Insurance; Indemnification........................    19
    6.10    Severance..................................................................    20
    6.11    Liquidated Damages.........................................................    20
           
  7. CONDITIONS........................................................................    20
    7.1     Conditions to Obligation of Each Party to Effect the Merger................    20
 
  8. TERMINATION, AMENDMENT AND WAIVER.................................................    20
    8.1     Termination................................................................    20
    8.2     Effect of Termination......................................................    21
    8.3     Amendment..................................................................    21
    8.4     Waiver.....................................................................    21
 
  9. GENERAL PROVISIONS................................................................    22
    9.1     Brokers....................................................................    22
    9.2     Public Statements..........................................................    22
    9.3     Notices....................................................................    22
    9.4     Interpretation.............................................................    22
    9.5     Representations and Warranties; Etc........................................    23
    9.6     Miscellaneous..............................................................    23
 
Annex I................................................................................   I-1
</TABLE>
 
                                       ii
<PAGE>   4
 
                          AGREEMENT AND PLAN OF MERGER
 
     THIS AGREEMENT AND PLAN OF MERGER (this "Agreement"), dated as of November
17, 1994, is among Amgen Inc., a Delaware corporation ("Parent"), Amgen
Acquisition Subsidiary, Inc., a Delaware corporation and a wholly owned
subsidiary of Parent ("Purchaser") and Synergen, Inc., a Delaware corporation
("Company").
 
                                    RECITALS
 
     A.  The respective Boards of Directors of Parent, Purchaser and Company
have approved the acquisition of Company pursuant to the terms of this
Agreement.
 
     B.  In furtherance of such acquisition it is proposed that Purchaser will
make a tender offer (the "Offer") to purchase all of the issued and outstanding
shares of Common Stock, par value $0.01 per share, of Company (the "Common
Stock"), together with all of the associated rights to purchase units of Series
A Junior Participating Preferred Stock, par value $0.01 per share, of Company
(the "Rights"), for $9.25 per share net to the seller in cash. The Common Stock
and the Rights are hereinafter collectively referred to as the "Shares."
 
     C.  The Board of Directors of Company (the "Board of Directors") has duly
approved the Offer and resolved to recommend its acceptance by Company's
stockholders.
 
     D.  The respective Boards of Directors of Parent, Purchaser and Company
have each duly approved the merger of Purchaser and Company (the "Merger")
following consummation of the Offer, in accordance with the General Corporation
Law of the State of Delaware (the "Delaware Law").
 
                                   AGREEMENT
 
     NOW, THEREFORE, in consideration of the premises and the mutual covenants
herein contained and for other good and valuable consideration the receipt and
adequacy of which are hereby acknowledged, Parent, Purchaser and Company hereby
agree as follows:
 
 1. THE OFFER
 
     1.1  The Offer.
 
     (a) Provided that this Agreement shall not have been terminated pursuant to
Section 8.1 and that none of the events set forth in Annex I hereto shall have
occurred, Purchaser shall, and Parent shall cause Purchaser to, as soon as
practicable after the date hereof, and in any event within five business days of
the day on which the proposed Offer is announced, commence (within the meaning
of Rule 14d-2(a) of the Securities Exchange Act of 1934, as amended (the
"Exchange Act")) the Offer for all of the outstanding Shares at a price of $9.25
per Share net to the seller in cash.
 
     (b) The obligations of Purchaser to consummate the Offer and to accept for
payment and pay for any of the Shares tendered shall be subject only to the
conditions set forth on Annex I, including the condition that a minimum of not
less than a majority of the Shares outstanding on a fully diluted basis
(including for purposes of such calculation all Shares issuable upon exercise of
outstanding Options (as defined in Section 2.6), but excluding for purposes of
such calculation all Shares issuable upon exercise of outstanding Warrants (as
defined in Section 2.7), Rights and any other rights or securities to purchase
or acquire the Shares) being validly tendered and not withdrawn prior to the
expiration of the Offer (the "Minimum Condition"). The Offer shall remain open
for a minimum of 20 business days after commencement of the Offer as provided in
Rule 14e-1 promulgated by the Commission (the "Expiration Date"), unless
Purchaser extends the Offer as permitted by this Agreement, in which case the
"Expiration Date" means the latest time and date to which the Offer is extended.
 
     (c) Purchaser reserves the right to waive any conditions to the Offer,
other than the Minimum Condition, to increase the price per Share payable in the
Offer or to make any other changes in the terms and
<PAGE>   5
 
conditions of the Offer; provided, however, that no such change may be made
which decreases the price per Share, changes the form of consideration payable
in the Offer, reduces the maximum number of Shares to be purchased in the Offer,
imposes conditions to the Offer in addition to those set forth in Annex I or
amends any other material term of the Offer in a manner materially adverse to
Company's stockholders without Company's prior written consent; provided,
further, however, that notwithstanding the foregoing Purchaser may waive the
Minimum Condition if Purchaser after consultation with Company, upon
consummation of the Offer, accepts for payment and pays for a majority of the
Shares outstanding at the time of such consummation. The Offer may not, without
Company's prior written consent, be extended, except as necessary to provide
time to satisfy the conditions set forth in Annex I; provided, however, that
Purchaser may extend (and re-extend) the Offer for up to a total of 10 business
days, if as of the initial Expiration Date, there shall not have been validly
tendered and not withdrawn at least 90% of the outstanding Shares so that the
Merger can be effected without a meeting of Company's stockholders in accordance
with the Delaware Law. Purchaser agrees that if all conditions set forth in
Annex I are satisfied on the initial Expiration Date, other than the Minimum
Condition or the condition set forth in paragraph (b) of Annex I, Purchaser
shall extend (and re-extend) the Offer for up to a maximum of 20 business days
to provide time to satisfy either such conditions, so long as all such other
conditions remain satisfied.
 
     (d) The Offer shall be made by means of an offer to purchase (the "Offer to
Purchase") containing the terms set forth in this Agreement and the conditions
set forth in Annex I. As soon as practicable on the date of commencement of the
Offer, Parent and Purchaser shall file with the Securities and Exchange
Commission (the "Commission") with respect to the Offer a Schedule 14D-1 (the
"Schedule 14D-1") which will comply as to form in all material respects with the
provisions of applicable federal securities law, and will contain the Offer to
Purchase and forms of the related letter of transmittal and summary
advertisement (which documents, together with any supplements or amendments
thereto, are referred to herein collectively as the "Offer Documents"). The
Schedule 14D-1 and the Offer Documents, on the date the Schedule 14D-1 is filed
with the Commission, and on the date the Offer Documents are first published,
sent or given to Company's stockholders, as the case may be, shall not contain
any untrue statement of a material fact or omit to state any 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 Parent and Purchaser agree promptly to correct the Schedule
14D-1 or the Offer Documents if and to the extent that either shall have become
false or misleading in any material respect and to take all steps necessary to
cause such Schedule 14D-1 as so corrected to be filed with the Commission and
such Offer Documents as so corrected to be disseminated to holders of Shares, in
each case as and to the extent required by applicable federal securities laws.
Company and its counsel shall be given reasonable opportunity to review the
Offer Documents prior to the filing with the Commission. Company agrees to file
contemporaneously with the commencement of the Offer with the Commission a
Solicitation/Recommendation Statement on Schedule 14D-9 (the "Schedule 14D-9")
which will comply as to form in all material respects with the provisions of
applicable federal securities laws. The Schedule 14D9, on the date filed with
the Commission and on the date first published, sent or given to Company's
stockholders, as the case may be, shall not contain any untrue statement of a
material fact or omit to state any 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 Company agrees
promptly to correct the Schedule 14D-9 if and to the extent that it shall have
become false or misleading in any material respect and to take all steps
necessary to cause such Schedule 14D-9 as so corrected to be filed with the
Commission and mailed to Company's stockholders to the extent required by
applicable federal securities laws. Subject to the fiduciary duties of the Board
of Directors, as advised by counsel, the Offer Documents and the Schedule 14D-9
shall contain the recommendation of the Board of Directors that Company's
stockholders accept the Offer.
 
     1.2  Company Action.  Company represents that the Board of Directors has
duly approved by a unanimous vote the Offer and the Merger and resolved to
recommend acceptance of the Offer and approval of the Merger by Company's
stockholders. Company will promptly furnish Parent or Purchaser with mailing
labels containing the names and addresses of the record holders of Shares and,
to the extent available (including upon request), lists of securities positions
of Shares held in stock depositories, each as of a recent date, and shall
furnish Purchaser with such additional information, including updated lists of
stockholders,
 
                                        2
<PAGE>   6
 
mailing labels and lists of securities positions, and assistance as Purchaser
may reasonably request in connection with communicating the Offer. Subject to
the requirements of law, and except for such steps as are necessary to
disseminate the Offer Documents, Parent and Purchaser shall hold in confidence
the information contained in any of such labels and lists and the additional
information referred to in the preceding sentence, shall use such information
only in connection with the Offer, and, if this Agreement is terminated, shall
deliver to Company all such written information and any copies or extracts
thereof then in their possession.
 
     1.3  Directors.  Promptly upon the acceptance for payment and payment by
Purchaser or any of its subsidiaries of such number of Shares which satisfies
the Minimum Condition and from time to time thereafter, Parent shall be entitled
to designate a majority of the members of the Board of Directors, subject to
compliance with Section 14(f) of the Exchange Act. Subject to applicable law,
Company shall take all action necessary to effect any such election, including
mailing to its stockholders the information required by Section 14(f) of the
Exchange Act and Rule 14f-1 promulgated thereunder. Notwithstanding anything in
this Agreement to the contrary, the affirmative vote of a majority of Company's
directors (or the approval of the director, if there is only one remaining) then
in office who are directors on the date hereof or are directors (other than
directors designated by Purchaser) designated by such persons to fill any
vacancy, shall be required to (i) amend or modify Company's Certificate of
Incorporation or Bylaws, (ii) take any action by Company pursuant to Sections
8.1, 8.3 or 8.4 of this Agreement or (iii) approve any other action by Company
which adversely affects the interests of the stockholders of Company (other than
Parent, Purchaser and their affiliates) with respect to the transactions
contemplated hereby.
 
2.  THE MERGER
 
     2.1  The Merger.  At the Effective Date, in accordance with this Agreement
and the Delaware Law, Purchaser shall be merged with and into Company, the
separate existence of Purchaser (except as may be continued by operation of law)
shall cease, and Company shall continue as the surviving corporation under the
corporate name it possesses immediately prior to the Effective Date. Company
hereinafter sometimes is referred to as the "Surviving Corporation." At the
election of Parent, the Merger may be structured so that Company shall be merged
with and into Purchaser with the result that Purchaser shall be the "Surviving
Corporation." If Parent elects to structure the Merger so that Purchaser, rather
than Company, is the Surviving Corporation, the inaccuracy of any representation
or warranty of Company which is premised on the assumption that Company shall be
the Surviving Corporation, which representation or warranty becomes inaccurate
solely as a result of Purchaser, rather than Company, being the Surviving
Corporation, shall not be deemed to be a breach of such representation or
warranty and shall not release Purchaser from its duties and obligations under
the Offer and this Agreement.
 
     2.2  Effect of the Merger.  When the Merger has been effected, the
Surviving Corporation shall thereupon and thereafter possess all the rights,
privileges, immunities and franchises, of a public as well as of a private
nature, of Purchaser and Company (the "Constituent Corporations"); all property,
real, personal and mixed, and all debts due on whatever account and all choses
in action, and all and every other interest, of or belonging to or due each of
the Constituent Corporations shall be vested in the Surviving Corporation
without further act or deed; and the title to any real estate, or any interest
therein, vested in Purchaser, Company or the Surviving Corporation shall not
revert or be in any way impaired by reason of the Merger. The Surviving
Corporation shall thereupon and thereafter be responsible and liable for all the
liabilities and obligations of each of the Constituent Corporations so merged;
any claim existing or action or proceeding pending by or against any of the
Constituent Corporations may be prosecuted as if the Merger had not taken place,
or the Surviving Corporation may be substituted in its place. The Surviving
Corporation thereupon and thereafter shall have all the rights, privileges,
immunities and powers and shall be subject to all the duties and liabilities of
a corporation organized under the Delaware Law, and neither the rights of
creditors nor any liens upon the respective properties of the Constituent
Corporations and the Surviving Corporation shall be impaired by the Merger; all
with the effect set forth in the Delaware Law.
 
     2.3  Consummation of the Merger.  As soon as is practicable after the
satisfaction or waiver of the conditions hereinafter set forth, the parties
hereto will cause the Merger to be consummated by filing with the
 
                                        3
<PAGE>   7
 
Secretary of State of Delaware a certificate of merger in such form as required
by, and executed in accordance with, the relevant provisions of the Delaware Law
(the time of such filing being the "Effective Date").
 
     2.4  Certificate of Incorporation; Bylaws; Directors and Officers.  The
Certificate of Incorporation and Bylaws of Purchaser shall be the Certificate of
Incorporation and Bylaws of the Surviving Corporation, as in effect immediately
prior to the Effective Date, until thereafter amended as provided therein and
under the Delaware Law. The directors of Purchaser immediately prior to the
Effective Date will be the initial directors of the Surviving Corporation, and
the officers of Company immediately prior to the Effective Date will be the
initial officers of the Surviving Corporation, in each case until their
successors are elected and qualified.
 
     2.5  Conversion of Securities.  At the Effective Date, by virtue of the
Merger and without any action on the part of Purchaser, Company, the Surviving
Corporation or the holder of any of the following securities:
 
          (a) Each Share issued and outstanding immediately prior to the
     Effective Date (other than Shares to be cancelled pursuant to Section
     2.5(b) hereof and Shares held by any holder who becomes entitled to the
     payment of the fair value for his Shares under the Delaware Law if the
     Delaware Law provides for such payment in connection with the Merger
     ("Dissenting Shares")) shall be cancelled and extinguished and be converted
     into and become a right to receive $9.25 in cash, or such higher amount per
     share as is paid pursuant to the Offer (the "Merger Consideration").
 
          (b) Each Share which is issued and outstanding immediately prior to
     the Effective Date and owned by Purchaser, Parent or Company or any direct
     or indirect subsidiary of Purchaser, Parent or Company, shall be cancelled
     and retired, and no payment shall be made with respect thereto.
 
          (c) Each share of Common Stock, par value $0.01 per share, of
     Purchaser issued and outstanding immediately prior to the Effective Date
     shall be converted into and become one validly issued, fully paid and
     nonassessable share of Common Stock, par value $0.01 per share, of the
     Surviving Corporation.
 
          (d) All notes and other debt instruments of Company which are
     outstanding at the Effective Date shall continue to be outstanding
     subsequent to the Effective Date as debt instruments of the Surviving
     Corporation, if permitted by their respective terms and provisions.
 
     The holders of Dissenting Shares, if any, shall be entitled to payment for
such Shares only to the extent permitted by and in accordance with the
provisions of Section 262 of the Delaware Law; provided, however, that if, in
accordance with such Section of the Delaware Law, any holder of Dissenting
Shares shall forfeit such right to payment of the fair value of such Shares,
such Shares shall thereupon be deemed to have been converted into and to have
become exchangeable for, as of the Effective Date, the right to receive the
Merger Consideration provided in Section 2.5(a) of this Agreement.
 
     2.6  Company Stock Options and Related Matters.  As promptly as practicable
after the Effective Date, each holder of a then outstanding employee or director
stock option (an "Option") to purchase Shares heretofore granted under any
Employee Plan (as defined in Section 4.15), other than any Options that are held
by any director of Company or any officer (as that term is defined in Rule
16a-1(f) promulgated by the Commission) of Company and that were granted (or
deemed granted) at any time on or after the date that is six months prior to the
Effective Date (the "Recent Insider Options"), will be entitled (whether or not
such Option is then exercisable) to receive in consideration of cancellation of
such Option (and any outstanding stock appreciation right related thereto) a
cash payment from Company in an amount equal to the difference between the
Merger Consideration and the per Share exercise price of such Option, multiplied
by the number of Shares covered by such Option. The Recent Insider Options shall
remain outstanding in accordance with their terms and shall not be affected in
any way by the consummation of the Merger.
 
     2.7  Treatment of Warrants.  Each (i) warrant outstanding pursuant to the
Warrant Agreement dated as of February 1, 1990 by and between Company and Bank
of America, NT & SA, as Warrant Agent (the "Warrant Agreement") (the "Syntex
Joint Venture Warrants"), (ii) Class A Warrant outstanding issued in connection
with the Sales Agency Agreement dated January 4, 1991 by and between, among
others, PaineWebber Development Corporation and Company (the "Sales Agency
Agreement") (the "Class A Warrants"), (iii) Class B Warrant outstanding issued
in connection with the Sales Agency Agreement (the "Class B Warrants"), (iv)
Investment Executive Warrant outstanding issued in connection with the Sales
 
                                        4
<PAGE>   8
 
Agency Agreement (the "Investment Executive Warrants") and (v) warrant
outstanding issued in connection with Company's purchase of the assets of
Synergen Development Partners Limited (the "Development Partners Warrants")
(collectively, the Syntex Joint Venture Warrants, Class A Warrants, Class B
Warrants, Investment Executive Warrants and Development Partners Warrants are
referred to herein as the "Warrants") will be unaffected by the Merger, except
as otherwise provided in the Warrant Agreement or Warrants.
 
     2.8  Exchange of Certificates.
 
     (a) From and after the Effective Date, a bank or trust company to be
designated by Parent (the "Exchange Agent") shall act as exchange agent in
effecting the exchange of certificates (the "Certificates") for the Merger
Consideration, which Certificates, prior to the Effective Date, represented
Shares entitled to payment pursuant to Section 2.5. On or before the Effective
Date, Parent or Purchaser shall deposit with the Exchange Agent the Merger
Consideration in trust for the benefit of the holders of Certificates. Upon the
surrender of each such Certificate and the issuance and delivery by the Exchange
Agent of the Merger Consideration in exchange therefor, such Certificates shall
forthwith be cancelled. Until so surrendered and exchanged, each such
Certificate (other than Certificates representing Shares held by Purchaser,
Parent or Company or any direct or indirect subsidiary of Purchaser, Parent or
Company or Dissenting Shares) shall represent solely the right to receive the
Merger Consideration multiplied by the number of Shares represented by such
Certificate. Upon the surrender and exchange of such an outstanding Certificate,
the holder shall receive the Merger Consideration, without any interest thereon.
If any cash is to be paid to a name other than the name in which the Certificate
representing Shares surrendered in exchange therefor is registered, it shall be
a condition to such payment or exchange that the person requesting such payment
or exchange shall pay to the Exchange Agent any transfer or other taxes required
by reason of the payment of such cash to a name other than that of the
registered holder of the Certificate surrendered, or such person shall establish
to the satisfaction of the Exchange Agent that such tax has been paid or is not
applicable. Notwithstanding the foregoing, neither the Exchange Agent nor any
party hereto shall be liable to a holder of Shares for any Merger Consideration
or interest or other payments made with respect to the Merger Consideration
delivered to a public official pursuant to applicable abandoned property,
escheat and similar laws.
 
     (b) Promptly following the date which is six months after the Effective
Date, the Exchange Agent shall return to the Surviving Corporation all Merger
Consideration in its possession relating to the transactions described in this
Agreement, and the Exchange Agent's duties shall terminate. Thereafter, each
holder of a Certificate representing a Share may surrender such Certificate to
the Surviving Corporation and (subject to applicable abandoned property, escheat
and similar laws) receive in exchange therefor the Merger Consideration, without
any interest thereon.
 
     (c) Promptly after the Effective Date, the Exchange Agent shall mail to
each record holder of Certificates which immediately prior to the Effective Date
represented Shares, a form of letter of transmittal and instructions for use in
surrendering such Certificates and receiving the Merger Consideration therefor.
 
     (d) After the Effective Date, there shall be no transfers on the stock
transfer books of the Surviving Corporation of any Shares. If, after the
Effective Date, Certificates for Shares are presented to the Surviving
Corporation or the Exchange Agent, they shall be cancelled and exchanged for the
Merger Consideration, as provided in this Article 2, subject to applicable law
in the case of Dissenting Shares.
 
 3.  REPRESENTATIONS AND WARRANTIES OF PARENT AND PURCHASER
 
     Each of Parent and Purchaser represents and warrants to Company as follows:
 
     3.1  Organization and Qualification.  Each of Parent and Purchaser is a
corporation duly organized, validly existing and in good standing under the laws
of Delaware and has the requisite corporate power to carry on its respective
business as now conducted. Each of Parent and Purchaser is duly qualified as a
foreign corporation to do business, and is in good standing, in each
jurisdiction where the character of its properties owned or leased or the nature
of its activities makes such qualification necessary, except for failures to be
so qualified or in good standing which would not have a material adverse effect
on the condition (financial or other), results of operations, business or
properties (a "Material Adverse Effect") of Parent and its subsidiaries
 
                                        5
<PAGE>   9
 
taken as a whole. Copies of the Certificates of Incorporation and Bylaws of
Parent and Purchaser delivered to Company are accurate and complete as of the
date hereof.
 
     3.2  Authority Relative to this Agreement.  Each of Parent and Purchaser
has the requisite corporate power and authority to enter into this Agreement, to
perform its obligations hereunder and to consummate the transactions
contemplated hereunder. The execution and delivery of this Agreement by Parent
and Purchaser and the consummation by Parent and Purchaser of the transactions
contemplated hereby have been duly authorized by the respective Boards of
Directors of Parent and Purchaser and no other corporate proceeding on the part
of Parent and Purchaser is necessary to authorize the execution, delivery and
performance of this Agreement and the transactions contemplated hereby, except
for the corporate proceedings, if any, necessary to amend the Certificate of
Incorporation of Purchaser to provide the capital structure required for the
Merger (which proceedings shall be taken prior to the Effective Date). This
Agreement has been duly executed and delivered by Parent and Purchaser and
constitutes a valid and binding obligation of each such company, enforceable
against each such company in accordance with its terms, except to the extent
that its enforceability may be limited by applicable bankruptcy, insolvency,
reorganization or other laws affecting the enforcement of creditors' rights
generally or by general equitable principles.
 
     3.3  Compliance.
 
     (a) Neither the execution and delivery of this Agreement by Parent and
Purchaser, nor the consummation by Parent and Purchaser of the transactions
contemplated hereby, nor compliance by Parent and Purchaser with any of the
provisions hereof will (i) violate, conflict with, or result in a breach of any
provision of, or constitute a default (or an event which, with notice or lapse
of time or both, would constitute a default) under, or result in the termination
of, or accelerate the performance required by, or result in a right of
termination or acceleration under, or result in the creation of any lien,
security interest, charge or encumbrance upon any of the properties or assets of
Parent and Purchaser or any other direct or indirect subsidiary of Parent under,
any of the terms, conditions or provisions of (x) the Certificates of
Incorporation or Bylaws of Parent or Purchaser or any other direct or indirect
subsidiary of Parent or (y) any material note, bond, mortgage, indenture, deed
of trust, license, lease, agreement or other material instrument or obligation
to which Parent and Purchaser or any other direct or indirect subsidiary of
Parent is a party, or to which any of them, or any of their respective
properties or assets, may be subject, or (ii) subject to compliance with the
statutes and regulations referred to in the next paragraph, violate any
judgment, ruling, order, writ, injunction, decree, statute, rule or regulation
applicable to Parent or Purchaser or any other direct or indirect subsidiary of
Parent or any of their respective properties or assets; except, in the case of
each of clauses (i) and (ii) above, for such violations, conflicts, breaches,
defaults, terminations, accelerations or creations of liens, security interests,
charges or encumbrances which would not have a Material Adverse Effect on Parent
and its subsidiaries taken as a whole.
 
     (b) Other than in connection with or in compliance with the provisions of
the Delaware Law, the Exchange Act, the "takeover" or "blue sky" laws of various
states, the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended,
and the rules and regulations thereunder (the "Hart-Scott-Rodino Act"), and any
required material foreign regulatory approvals, no notice to, filing with, or
authorization, consent or approval of, any domestic or foreign public body or
authority is necessary for the consummation by Parent and Purchaser of the
transactions contemplated by this Agreement, except where failure to give such
notice, make such filings, or obtain such authorizations, consents or approvals
would not have a Material Adverse Effect on Parent and its subsidiaries taken as
a whole or prevent Parent and Purchaser from performing their obligations
hereunder.
 
     3.4  Available Funds.  Parent has or has available to it out of internal
corporate funds, and will make available to Purchaser, all funds necessary to
satisfy all of Parent's and Purchaser's obligations under this Agreement and in
connection with the transactions contemplated hereby, including, without
limitation, the obligation to purchase all outstanding Shares pursuant to the
Offer and the Merger and to pay, subject to Section 6.4, all related fees and
expenses in connection with the Offer and the Merger.
 
     3.5  Company Stock.  Parent does not beneficially own any Shares.
 
                                        6
<PAGE>   10
 
 4.  REPRESENTATIONS AND WARRANTIES OF COMPANY
 
     Company represents and warrants to Parent and Purchaser, except as set
forth on a Disclosure Schedule previously delivered to Parent (the "Disclosure
Schedule") or as set forth in, or incorporated by reference into, the SEC
Reports (as defined in Section 4.6), the following:
 
     4.1  Organization and Qualification.  Company is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has the requisite corporate power to carry on its business as it is
now being conducted. Company is duly qualified as a foreign corporation to do
business, and is in good standing, in each jurisdiction where the character of
its properties owned or leased or the nature of its activities makes such
qualification necessary. Copies of the Certificate of Incorporation and Bylaws
of Company heretofore delivered to Parent are accurate and complete as of the
date hereof. All material corporate actions taken by Company and each of its
subsidiaries (the "Subsidiaries") since incorporation have been duly authorized
or ratified by all appropriate action.
 
     4.2  Subsidiaries.  The only Subsidiaries are those named in the Disclosure
Schedule or in Exhibit 21.1 to Company's Annual Report on Form 10-K for the
Fiscal Year Ended December 31, 1993, as filed with the Commission and heretofore
delivered to Parent. Except as set forth in such exhibit and except for
directors' qualifying shares in the case of non-United States Subsidiaries, (i)
Company is, directly or indirectly, the record and beneficial owner of all of
the outstanding shares of capital stock of each of the Subsidiaries, (ii) there
are no irrevocable proxies with respect to such shares, (iii) no equity
securities of any of the Subsidiaries are or may become required to be issued by
reason of any options, warrants, scrip, rights to subscribe to, calls or
commitments of any character whatsoever relating to, or securities or rights
convertible into or exchangeable for, shares of any capital stock of any
Subsidiary, and (iv) there are no contracts, commitments, understandings or
arrangements by which any Subsidiary is bound to issue additional shares of its
capital stock or securities convertible into or exchangeable for such shares.
All of such shares so owned by Company are owned by it free and clear of any
claim, lien, encumbrance or agreement with respect thereto. Each Subsidiary is a
corporation duly organized, validly existing and in good standing under the laws
of its jurisdiction of incorporation and has the requisite corporate power to
carry on its business as it is now being conducted. Each Subsidiary is duly
qualified as a foreign corporation to do business, and is in good standing, in
each jurisdiction where the character of its properties owned or leased or the
nature of its activities makes such qualification necessary. Copies of the
charter documents, Bylaws, and regulations, if any, of each Subsidiary, which
have been heretofore delivered or made available to Parent, are accurate and
complete.
 
     4.3  Capitalization.  The authorized capital stock of Company consists of
120,000,000 Shares and 10,000,000 shares of Preferred Stock, par value $0.01 per
share (the "Preferred Stock"). As of the date of this Agreement (i) 25,936,248
Shares are validly issued and outstanding, fully paid and nonassessable, (ii) no
shares of Preferred Stock are issued and outstanding, (iii) 2,466,782 Shares are
issuable upon exercise of outstanding Options heretofore granted under the
Employee Plans, true and complete copies of which have heretofore been furnished
to Parent, and (iv) 5,419,491 Shares are issuable upon exercise of outstanding
Warrants. Upon the announcement of the Offer, each Warrant shall only represent
the right to receive the per Share Merger Consideration upon payment by the
holder thereof of the per Share exercise price provided for in each such
Warrant. The per Share exercise price of each Warrant is as follows: (1) Syntex
Joint Venture Warrants -- $12.67, (2) Class A Warrants -- $15.69, (3) Class B
Warrants -- $15.69, (4) Investment Executive Warrants -- $16.31 and (5)
Development Partners Warrants -- $67.77. Except as contemplated by clauses (i)
through (iv) above, there are no other shares of capital stock, or other equity
securities of Company outstanding, and no other outstanding options, warrants,
rights to subscribe to (including any preemptive rights), calls or commitments
of any character whatsoever to which Company or any of its Subsidiaries is a
party or may be bound, requiring the issuance or sale of, shares of any capital
stock or other equity securities of Company or securities or rights convertible
into or exchangeable for such shares or other equity securities, and there are
no contracts, commitments, understandings or arrangements by which Company is or
may become bound to issue additional shares of its capital stock or other equity
securities or options, warrants or rights to purchase or acquire any additional
shares of its capital stock or other equity securities or securities convertible
into or exchangeable for such shares or other equity securities.
 
                                        7
<PAGE>   11
 
     4.4  Authority Relative to this Agreement.  Company has the requisite
corporate power and authority to enter into this Agreement, to perform its
obligations hereunder and to consummate the transactions contemplated hereunder.
The execution and delivery of this Agreement by Company and the consummation by
Company of the transactions contemplated hereby have been duly authorized by the
Board of Directors and no other corporate proceeding on the part of Company is
necessary to authorize the execution, delivery and performance of this Agreement
and the transactions contemplated hereby, except for the approval of Company's
stockholders as set forth in Section 6.2 of this Agreement. This Agreement has
been duly executed and delivered by Company and constitutes a valid and binding
obligation of Company, enforceable against Company in accordance with its terms,
except to the extent that its enforceability may be limited by applicable
bankruptcy, insolvency, reorganization or other laws affecting the enforcement
of creditors rights generally or by general equitable principles.
 
     4.5  Compliance.
 
     (a) Neither the execution and delivery of this Agreement by Company, nor
the consummation of the transactions contemplated hereby (including the purchase
of the Shares by Purchaser pursuant to the Offer), nor compliance by Company
with any of the provisions hereof will (i) violate, conflict with, or result in
a breach of any provision of, or constitute a default (or an event which, with
notice or lapse of time or both, would constitute a default) under, or result in
the termination of, or accelerate the performance required by, or result in the
loss of any material benefit under, or result in a right of termination or
acceleration under, or result in the creation of any lien, security interest,
charge or encumbrance upon any of the properties or assets of Company or any of
its Subsidiaries under, any of the terms, conditions or provisions of (x) their
respective charter documents or Bylaws or (y) any material note, bond, mortgage,
indenture, deed of trust, license, lease, agreement or other material instrument
or obligation to which Company or any such Subsidiary is a party, or to which
any of them or any of their respective properties or assets may be subject, or
(ii) subject to compliance with the statutes and regulations referred to in the
next paragraph, violate any judgment, ruling, order, writ, injunction, decree,
statute, rule or regulation applicable to Company and its Subsidiaries or any of
their respective properties or assets; except, in the case of each of clauses
(i) and (ii) above, for such violations, conflicts, breaches, defaults,
terminations, accelerations, losses and creations as to which requisite waivers
have been obtained. As used in Articles 4 and 5, Section 6.6 and Annex I, the
term assets shall include, but not be limited to, all Proprietary Matter,
products, product rights and technologies of Company.
 
     (b) Other than in connection with or in compliance with the provisions of
the Delaware Law, the Exchange Act, the "takeover" or "blue sky" laws of various
states, the Hart-Scott-Rodino Act, and any required material foreign regulatory
approvals, no notice to, filing with, or authorization, consent or approval of,
any domestic or foreign public body or authority is necessary for the
consummation by Company of the transactions contemplated by this Agreement.
 
     4.6  Commission Filings.  Company has filed with the Commission all
reports, registration statements and definitive proxy statements required to be
filed with the Commission since January 1, 1992 (collectively, with any
documents filed as exhibits thereto, the "SEC Reports"). Company has heretofore
made available to Parent its (i) Annual Reports on Form 10-K for the years ended
December 31, 1991, 1992 and 1993, as filed with the Commission, (ii) Quarterly
Reports on Form 10-Q for the quarters ended March 31, 1994, June 30, 1994 and
September 30, 1994, (iii) proxy statements relating to all of Company's meetings
of stockholders (whether annual or special) since January 1, 1992, and (iv) all
other reports or registration statements filed by Company with the Commission
since January 1, 1992. As of their respective dates, such reports and statements
(including all exhibits and schedules thereto and documents incorporated by
reference therein) 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 made, in light of the circumstances under which
they were made, not misleading. The audited consolidated financial statements
and unaudited consolidated interim financial statements of Company and its
Subsidiaries included or incorporated by reference in such reports, and in
Company's Annual Reports for the years ended December 31, 1991, 1992 and 1993
heretofore delivered to Parent, have been prepared in accordance with generally
accepted accounting principles applied on a consistent basis during the periods
involved (except as may be indicated in the notes, or schedules thereto and
except in the case of the unaudited interim statements, as may be permitted
under Form 10-Q of the
 
                                        8
<PAGE>   12
 
Exchange Act), and fairly present the consolidated financial position of Company
and its consolidated Subsidiaries as of the dates thereof and the consolidated
results of their operations and changes in financial position for the periods
then ended (subject, in the case of any unaudited interim financial statements,
to normal year-end adjustments).
 
     4.7  Absence of Undisclosed Liabilities.  Neither Company nor any of its
Subsidiaries has any material liabilities of any nature, whether absolute,
contingent or otherwise, and whether due or to become due (including, without
limitation, all tax liabilities) which should be reflected or reserved against,
in accordance with generally accepted accounting principles, and which are not
adequately reflected or reserved against in Company's balance sheet as of
December 31, 1993, including the footnotes thereto (the "Balance Sheet"), except
such as have arisen in the ordinary course of business since December 31, 1993.
 
     4.8  Litigation.  There are no actions, suits or proceedings pending or
threatened against Company or any of its Subsidiaries, ERISA Affiliates or
Employee Plans (as such terms are defined in Section 4.15), nor is Company or
any of its Subsidiaries, ERISA Affiliates or Employee Plans subject to any
order, judgment, writ, injunction or decree.
 
     4.9  Board Recommendation; Qualifying Offer.  The Board of Directors has
duly approved and adopted this Agreement, the Offer and the Merger and other
transactions contemplated herein on the terms and conditions set forth herein,
and recommended that the stockholders of Company tender their Shares and approve
and adopt this Agreement and the Merger. The Offer is a "Qualifying Offer" as
such term is defined in the Rights Agreement dated as of October 24, 1991 by and
between Company and Manufacturers Hanover Trust Company of California, as Rights
Agent (the "Rights Agreement").
 
     4.10  Compliance with Law.  Company has not violated or failed to comply
with any material statute, law, ordinance, regulation, rule or order of any
foreign, federal, state or local government or any other governmental department
or agency, or any material judgment, decree or order of any court, applicable to
its business or operations. Company has not received any notice asserting a
failure to comply with any such statute, law, ordinance, regulation, rule,
judgment, decree or order. Company has all material permits, licenses and
franchises from governmental agencies required to conduct its present business
as it is now conducted.
 
     4.11  Changes.  Except as contemplated by this Agreement, or reflected in
any financial statement or notes thereto referred to in Section 4.6, since
December 31, 1993, none of the following have occurred:
 
          (a) any change (or any development involving a prospective change) or
     threatened change which has had, or may reasonably be expected to have, a
     Material Adverse Effect on Company and its Subsidiaries taken as a whole;
 
          (b) any material change in accounting methods, principles or practices
     by Company affecting its assets, liabilities or business;
 
          (c) any revaluation by Company of any of its assets, including without
     limitation, writing down the value of inventory or writing off notes or
     accounts receivable other than in the ordinary course of business;
 
          (d) any material damage, destruction or loss;
 
          (e) any cancellation of any material debts or waiver or release of any
     material right or claim of Company relating to its business activities or
     properties;
 
          (f) any declaration, setting aside or payment of dividends or
     distributions in respect of the Shares or any redemption, purchase or other
     acquisition of any of its securities;
 
          (g) any issuance by Company of, or commitment of Company to issue, any
     shares of stock, options, warrants or other equity securities or
     obligations or securities convertible into or exchangeable for shares of
     stock, options, warrants or other equity securities, other than upon
     exercise of Options, or pursuant to the terms of an Employee Plan in the
     ordinary course of business and consistent with past practices;
 
                                        9
<PAGE>   13
 
          (h) negotiation or execution of any material arrangement, agreement or
     understanding to which Company or any of its Subsidiaries is a party which
     cannot be terminated by it on notice of 30 days or less without cost or
     penalty;
 
          (i) any loan or similar transaction with any person who is an officer,
     director or stockholder of Company or any of its Subsidiaries, or who is an
     affiliate or associate of such a person, except in the ordinary course of
     business and consistent with past practices;
 
          (j) any capital expenditures other than in the ordinary course of
     business and consistent with past practice by Company or any of its
     Subsidiaries;
 
          (k) any adoption of a plan of liquidation or resolutions providing for
     the liquidation, dissolution, merger, consolidation or other reorganization
     of Company;
 
          (l) any increase in salary, bonus, fringe benefit, or incentive or
     other compensation payable or to become payable to any officer, director,
     employee or other person receiving compensation of any nature from Company
     or any of its Subsidiaries; or any increase in the number of shares
     obtainable under, or the acceleration or creation of any rights of any
     person to benefits under, any Employee Plan (including, without limitation,
     the acceleration of the vesting or exercisability of any stock options, the
     acceleration of the vesting of any restricted stock, the acceleration of
     the accrual or vesting of any benefits under any Pension Plan or the
     acceleration or creation of any rights under any severance, parachute or
     change in control agreement); or
 
          (m) any agreement by Company to do any of the things described in the
     preceding clauses (a) through (l) other than as expressly provided for
     herein.
 
     4.12  Taxes.  Each of Company and its Subsidiaries has duly filed all
material tax returns it is required to file. Each of Company and its
Subsidiaries has paid (or made adequate provision for payment of) all taxes
shown as due on those returns as well as all taxes, interest, penalties,
assessments and deficiencies due or claimed due from foreign, federal, state or
local taxing authorities (including without limitation taxes on properties,
income, franchises, licenses, sales and payrolls). The filed returns are correct
in all material respects and neither Company nor any of its Subsidiaries is
required to pay, for the periods represented by such tax returns, any material
taxes other than those shown in those returns or reflected on the balance sheet
of Company contained in the most recent SEC Report. Company's and each of its
Subsidiaries' federal income tax returns have not been audited by the Internal
Revenue Service since December 31, 1985. The provision for taxes on the Balance
Sheet is adequate to cover all accrued and unpaid taxes as of the date of the
Balance Sheet. Since December 31, 1991, neither Company nor any of its
Subsidiaries has requested or been granted any extension of limitation periods
applicable to audits or claims by any taxing authority. No material claim,
audit, action, suit, proceeding or investigation is pending or threatened with
respect to any taxes of Company or any of its Subsidiaries. There is no fact or
circumstance that, if known by any federal, state or local taxing authority,
could result in the assertion of a material deficiency with respect to any taxes
of Company or any of its Subsidiaries.
 
     4.13  Title to Properties; Condition of Properties.  The Disclosure
Schedule lists and reasonably describes all material real property owned or
leased by Company and its Subsidiaries. Company and each of its Subsidiaries has
good and valid title (in fee simple absolute in the case of real property) to
all properties and assets used in its business, except for leased properties and
assets; none of those owned properties is subject to any mortgage, deed of
trust, pledge, lien, claim, charge, equity, covenant, condition, restriction,
easement, right-of-way or encumbrance, except (i) liens, claims, charges and
encumbrances disclosed, or reserved against, in the Balance Sheet, (ii) liens
for current taxes not yet due and payable, and (iii) minor imperfections of
title not material (individually or in the aggregate) and not materially
detracting from the value, or the use (either actual or intended) Company and
its Subsidiaries make, of the property in question. All of the buildings,
fixtures, machinery and equipment owned or used by Company and its Subsidiaries
are in reasonably good operating condition and repair, normal wear and tear
excepted, and comply in all material respects with applicable zoning, building
and fire codes.
 
                                       10
<PAGE>   14
 
     4.14  Contracts.  The Disclosure Schedule lists all material contracts and
agreements to which Company or any of its Subsidiaries is a party which were not
filed as exhibits to the SEC Reports; all such contracts and agreements are duly
and validly executed by Company, are in full force and effect as of the date of
this Agreement and will be in full force and effect at the Effective Date. No
event has occurred which, after notice or the passage of time or both, would
constitute a material default under any such contract or agreement. All such
contracts and agreements will continue, after the Effective Date, to be binding
in accordance with their respective terms until their respective expiration
dates.
 
     4.15  Employee Benefit Plans.
 
     (a) Definitions.  The following terms, when used in this Section, shall
have the following meanings. Any of these terms may, unless the context
otherwise requires, be used in the singular or the plural depending on the
reference.
 
          (i) Benefit Arrangement.  "Benefit Arrangement" shall mean any
     material employment, consulting, severance or other similar contract,
     arrangement or policy and each material plan, arrangement (written or
     oral), program, agreement or commitment providing for insurance coverage
     (including without limitation any self-insured arrangements), workers'
     compensation, disability benefits, supplemental unemployment benefits,
     vacation benefits, retirement benefits, life, health, disability or
     accident benefits (including without limitation any "voluntary employees'
     beneficiary association" as defined in Section 501(c)(9) of the Code
     providing for the same or other benefits) or for deferred compensation,
     profit-sharing bonuses, stock options, stock appreciation rights, stock
     purchases or other forms of incentive compensation or post-retirement
     insurance, compensation or benefits which
 
               (A) (1) is not a Welfare Plan, Pension Plan or Multiemployer   
          Plan, (2) is entered into, maintained, contributed to or required to
          be contributed to, as the case may be, by Company or an ERISA 
          Affiliate or under which Company or any ERISA Affiliate may incur any 
          liability, and (3) covers any employee or former employee of Company
          or any ERISA Affiliate (with respect to their relationship with such
          entities), or
 
               (B) any plan covering employees or former employees of any 
          Foreign Subsidiary (with respect to their relationship with such 
          entities) which if maintained or administered in or otherwise 
          subject to the laws of the United States would be described in 
          paragraph (A).
 
          (ii) Code.  "Code" shall mean the Internal Revenue Code of 1986, as   
     amended.
 
          (iii) Employee Plans.  "Employee Plans" shall mean all Benefit        
     Arrangements, Multiemployer Plans, Pension Plans and Welfare Plans.
 
          (iv) ERISA.  "ERISA" shall mean the Employee Retirement Income        
     Security Act of 1974, as amended.
 
          (v) ERISA Affiliate.  "ERISA Affiliate" shall mean any entity which
     is (or at any relevant time was) a member of a "controlled group of
     corporations" with, under "common control" with, or a member of an 
     "affiliated service group" with, Company as defined in Section 414(b),
     (c), (m) or (o) of the Code.
 
          (vi) Foreign Subsidiary.  "Foreign Subsidiary" shall mean any 
     Subsidiary organized under the laws of or doing business in any country 
     other than the United States.
 
          (vii) Multiemployer Plan.  "Multiemployer Plan" shall mean
 
               (A) any "multiemployer plan," as defined in Section 4001(a)(3) or
          Section 3(37) of ERISA, (1) which Company or any ERISA Affiliate      
          maintains, administers, contributes to or is required to contribute
          to, or, after September 25, 1980, maintained, administered,
          contributed to or was required to contribute to, or under which
          Company or any ERISA Affiliate may incur any liability and (2) which
          covers any employee or former employee of Company or any ERISA
          Affiliate (with respect to their relationship with such entities), or
 
                                       11
<PAGE>   15
 
               (B) any plan covering employees or former employees of any  
          Foreign Subsidiary (with respect to their relationship with such 
          entities) which if maintained or administered in or otherwise 
          subject to the laws of the United States would be described in 
          paragraph (A).
 
          (viii) PBGC.  "PBGC" shall mean the Pension Benefit Guaranty  
    Corporation.
 
          (ix) Pension Plan.  "Pension Plan" shall mean
 
               (A) any "employee pension benefit plan" as defined in Section  
          3(2) of ERISA (other than a Multiemployer Plan) (1) which Company or 
          any ERISA Affiliate maintains, administers, contributes to or is 
          required to contribute to, or, within the five years prior to the 
          Effective Date, maintained, administered, contributed to or was 
          required to contribute to, or under which Company or any ERISA 
          Affiliate may incur any liability and (2) which covers any employee 
          or former employee of Company or any ERISA Affiliate (with respect 
          to their relationship with such entities), or
 
               (B) any plan covering employees or former employees of any 
          Foreign Subsidiary (with respect to their relationship with such 
          entities) which if maintained or administered in or otherwise 
          subject to the laws of the United States would be described in 
          paragraph (A).
 
          (x) Welfare Plan.  "Welfare Plan" shall mean
 
               (A) any "employee welfare benefit plan" as defined in Section 
          3(1) of ERISA, (1) which Company or any ERISA Affiliate maintains,
          administers, contributes to or is required to contribute to, or under
          which Company or any ERISA Affiliate may incur any liability and (2)
          which covers any employee or former employee of Company or any ERISA
          Affiliate (with respect to their relationship with such entities), or
 
               (B) any plan covering employees or former employees of any 
          Foreign Subsidiary (with respect to their relationship with such 
          entities) which if maintained or administered in or otherwise 
          subject to the laws of the United States would be described in 
          paragraph (A).
 
     (b) Disclosure; Delivery of Copies of Relevant Documents and Other 
Information. The Disclosure Schedule contains a complete list of Employee Plans
which cover or have covered employees of Company (with respect to their
relationship with such entities). True and complete copies of each of the
following documents have been delivered by Company to Parent: (i) each Welfare
Plan, Pension Plan and Multiemployer Plan (and, if applicable, related trust
agreements) which covers or has covered employees of Company (with respect to
their relationship with such entities) and all amendments thereto, all written
interpretations thereof and written descriptions thereof which have been
distributed to Company's employees and all annuity contracts or other funding
instruments, (ii) each Employee Plan which covers or has covered employees of
Company (with respect to their relationship with such entities) including
written interpretations thereof and written descriptions thereof which have
been distributed to Company's employees (including descriptions of the number
and level of employees covered thereby) and a complete description of any
Employee Plan which is not in writing, (iii) the most recent determination or
opinion letter issued by the Internal Revenue Service or analogous ruling under
foreign law with respect to each Pension Plan and each Welfare Plan (other than
a "multiemployer plan", as defined in Section 3(37) of ERISA) which covers or
has covered employees of Company (with respect to its relationship with such
entities), (iv) for the three most recent plan years, Annual Reports on Form
5500 Series required to be filed with any governmental agency for each Pension
Plan which covers or has covered employees of Company (with respect to its
relationship with such entities), (v) all actuarial reports prepared for the
last three plan years for each Pension Plan which covers or has covered
employees of Company (with respect to its relationship with such entities),
(vi) a description of complete age, salary, service and related data as of the
last day of the last plan year for employees and former employees of Company,
and (vii) a description setting forth the amount of any liability of the
company as of the Effective Date for payments more than thirty (30) calendar
days past due with respect to each Welfare Plan which covers or has covered
employees or former employees of Company.
 
                                       12
<PAGE>   16
 
     (c) Representations.  Company represents and warrants as follows:
 
          (i) Pension Plans
 
               (A) Neither Company nor any of its ERISA Affiliates has, at any 
          time, maintained, administered or contributed to, or was required to
          contribute to, a Pension Plan that is or was subject to Title IV of   
          ERISA or the minimum funding requirements of Section 302 of ERISA or
          Section 412 of the Code.
 
               (B) Each Pension Plan and each related trust agreement, annuity
          contract or other funding instrument which covers or has covered
          employees or former employees of Company that is intended to be       
          qualified and tax exempt under the provisions of Code sections 401(a)
          and 501(a) has received a favorable determination letter from the
          Internal Revenue Service and nothing has occurred that would
          adversely affect such plan's tax qualification or exemption.
 
               (C) Each Pension Plan, each related trust agreement, annuity 
          contract or other funding instrument which covers or has covered
          employees or  former employees of Company (with respect to their      
          relationship with such entities) presently complies and has been
          maintained in material compliance with its terms and, both as to form
          and in operation, with the requirements prescribed by any and all
          statutes, orders, rules and regulations which are applicable to such
          plans, including without limitation ERISA and the Code.
 
          (ii) Multiemployer Plans
 
               (A) Neither Company nor any ERISA Affiliate has, at any time,
          maintained, administered or contributed to, or was required to        
          contribute to, a Multiemployer Plan.
 
          (iii) Welfare Plans
 
               (A) Each Welfare Plan which covers or has covered employees or 
          former employees of Company (with respect to their relationship with  
          such  entities) has been maintained in material compliance with its
          terms and, both as to form and operation, with the requirements
          prescribed by any and all statutes, orders, rules and regulations
          which are applicable to such Welfare Plan, including without
          limitation ERISA and the Code.
 
               (B) None of Company, any ERISA Affiliate or any Welfare Plan 
          has any present or future obligation to make any payment to, or with
          respect to any present or former employee of Company or any ERISA
          Affiliate pursuant to, any retiree medical benefit plan, or other
          retiree Welfare Plan, and no condition exists which would prevent
          Company from amending or terminating any such benefit plan or Welfare
          Plan.
 
               (C) Each Welfare Plan which covers or has covered employees or 
          former employees of Company and which is a "group health plan," as
          defined in Section 607(1) of ERISA, has been operated in compliance 
          with provisions of Part 6 of Title I, Subtitle B of ERISA and 
          Sections 162(k) and 4980B of the Code at all times.
 
               (D) Neither Company nor any ERISA Affiliate has incurred any
          liability with respect to any Welfare Plan that is a "multiemployer   
          plan", as defined in Section 3(37) of ERISA, under the terms of such
          Welfare Plan, any collective bargaining agreement or otherwise
          resulting from any cessation of contributions, cessation of
          obligation to make contributions or other form of withdrawal from
          such Welfare Plan.
 
          (iv) Benefit Arrangements.  Each Benefit Arrangement which covers or
     has covered employees or former employees of Company (with respect to their
     relationship with such entities) has been maintained in material compliance
     with its terms and with the requirements prescribed by any and all
     statutes, orders, rules and regulations which are applicable to such
     Benefit Arrangement, including without limitation the Code. Except as
     provided by law, the employment of all persons presently employed or
     retained by Company is terminable at will.
 
                                       13
<PAGE>   17
 
          (v) Unrelated Business Taxable Income.  No Employee Plan (or trust or
     other funding vehicle pursuant thereto) is subject to any tax under Code
     Section 511.
 
          (vi) Deductibility of Payments.  There is no contract, agreement, plan
     or arrangement covering any employee or former employee of Company (with
     respect to its relationship with such entities) that, individually or
     collectively, provides for the payment by Company of any amount (i) that is
     not deductible under Section 404 of the Code, (ii) that is an "excess
     parachute payment" pursuant to Section 280G of the Code or (iii) that is
     not deductible pursuant to Section 162(m) of the Code.
 
          (vii) Foreign Plans.  Each Employee Plan that covers any employee or
     former employee of any Foreign Subsidiary (with respect to their
     relationship with such entities) or is otherwise not subject to ERISA or
     the Code has been maintained in substantial compliance with its terms and
     with the requirements prescribed by any and all applicable statutes,
     orders, rules and regulations (including without limitation any special
     provisions relating to the tax status of contributions to, earnings of or
     distributions from such Plans where each such Plan was intended to have
     such tax status) and has been maintained in good standing with applicable
     regulatory authorities.
 
          (viii) Fiduciary Duties and Prohibited Transactions.  Neither Company
     nor any plan fiduciary of any Welfare Plan or Pension Plan which covers or
     has covered employees or former employees of Company or any ERISA
     Affiliate, has engaged in any transaction in violation of Sections 404 or
     406 of ERISA or any "prohibited transaction," as defined in Section
     4975(c)(1) of the Code, for which no exemption exists under Section 408 of
     ERISA or Section 4975(c)(2) or (d) of the Code, or for which a class of
     individual exemption has not been granted by the Department of Labor, or
     has otherwise violated the provisions of Part 4 of Title I, Subtitle B of
     ERISA. Company has not knowingly participated in a violation of Part 4 of
     Title I, Subtitle B of ERISA by any plan fiduciary of any Welfare Plan or
     Pension Plan and has not been assessed any civil penalty under Section
     502(l) of ERISA.
 
          (ix) No Amendments.  Neither Company nor any ERISA Affiliate has any
     announced plan or legally binding commitment to create any additional
     Employee Plans which are intended to cover employees or former employees of
     Company (with respect to their relationship with such entities) or to amend
     or modify any existing Employee Plan which covers or has covered employees
     or former employees of Company (with respect to their relationship with
     such entities).
 
          (x) No Other Material Liability.  No event has occurred in connection
     with which Company or any ERISA Affiliate or any Employee Plan, directly or
     indirectly, could be subject to any material liability (A) under any
     statute, regulation or governmental order relating to any Employee Plans or
     (B) pursuant to any obligation of Company to indemnify any person against
     liability incurred under any such statute, regulation or order as they
     relate to the Employee Plans.
 
          (xi) Insurance Contracts.  Neither Company nor any Employee Plan
     (other than a "multiemployer plan", as defined in Section 3(37) of ERISA)
     holds as an asset of any Employee Plan any interest in any annuity
     contract, guaranteed investment contract or any other investment or
     insurance contract issued by an insurance company that is the subject of
     bankruptcy, conservatorship or rehabilitation proceedings.
 
          (xii) No Acceleration or Creation of Rights.  Neither the execution
     and delivery of this Agreement or other related agreements by Company nor
     the consummation of the transactions contemplated hereby or the related
     transactions will result in the acceleration or creation of any rights of
     any person to benefits under any Employee Plan (including, without
     limitation, the acceleration of the vesting or exercisability of any stock
     options, the acceleration of the vesting of any restricted stock, the
     acceleration of the accrual or vesting of any benefits under any Pension
     Plan or the acceleration or creation of any rights under any severance,
     parachute or change in control agreement).
 
     4.16 Compliance With Legislation Regulating Environmental Quality.  All
plants, offices, manufacturing facilities, stores, warehouses, improvements,
administration buildings, and real property and related facilities of Company,
whether currently or previously owned, operated or leased by Company
(collectively, the "Facilities") are, and at all times owned, operated or leased
by Company, have been maintained and operated in material compliance with all
applicable federal, state and local environmental protection,
 
                                       14
<PAGE>   18
 
occupational, health and safety or similar laws, ordinances, restrictions,
orders, regulations and licenses (collectively "Environmental Laws") including
but not limited to the Federal Water Pollution Control Act (33 U.S.C sec. 1251
et seq. ), Resource Conservation & Recovery Act (42 U.S.C. sec. 6901 et seq.),
Safe Drinking Water Act (21 U.S.C. sec. 349, 42 U.S.C. sec.sec. 201, 300f),
Toxic Substances Control Act (15 U.S.C. sec. 2601 et seq.), Clean Air Act (42
U.S.C. sec. 7401 et seq.), and Comprehensive Environmental Response,
Compensation and Liability Act (42 U.S.C. sec. 9601 et seq.). No materials,
substances, or products have been at any time placed, held, located, disposed of
or released on, under, at, within, or about the Facilities which may reasonably
be expected to result in a regulatory agency or other governmental entity
requiring clean up, removal or other remedial action by Company under
Environmental Laws. No litigation, administrative enforcement actions,
proceedings or notices of potential liability have been received, served, filed
or threatened against Company relating to any material damage, contribution,
cost recovery, compensation, loss or injury resulting from any hazardous or
toxic substance, waste or material (collectively, "Hazardous Materials") or
arising out of the use, generation, storage, treatment, release, discharge,
transportation, handling or disposal of Hazardous Materials or resulting from a
violation or alleged violation of Environmental Laws.
 
     4.17  Labor Matters.  Company is not a party to any labor agreement with
respect to its employees with any labor organization, group or association.
Company has not experienced any attempt by organized labor or its
representatives to make Company conform to demands of organized labor relating
to its employees or to enter into a binding agreement with organized labor that
would cover the employees of Company. Company is in compliance in all material
respects with all applicable laws respecting employment practices, terms and
conditions of employment and wages and hours and is not engaged in any unfair
labor practice. There is no unfair labor practice charge or complaint against
Company pending before the National Labor Relations Board or any other
governmental agency arising out of Company's activities, and Company has no
knowledge of any facts or information which would give rise thereto; there is no
labor strike or labor disturbance pending or threatened against Company nor is
any grievance currently being asserted; and Company has not experienced a work
stoppage or other labor difficulty.
 
     4.18  Absence of Questionable Payments.  Neither Company nor any of its
Subsidiaries nor any of their respective officers, directors, agents or
employees purporting to act on behalf of Company or any of its Subsidiaries has
made or agreed to make any payment or other use of Company's or any of its
Subsidiaries' assets (i) to or on behalf of an official of any government, or
for any purpose related to political activity, except as permitted by applicable
law or (ii) for any of the purposes described in Section 162(c) of the United
States Internal Revenue Code.
 
     4.19  Intellectual Property.  The Disclosure Schedule contains detailed
information (including where applicable the federal registration number and the
date of registration or application for registration and the name in which
registration was applied for) concerning: (i) patents, copyrights, trademarks,
trade names and service marks, and all currently pending applications for any
thereof (collectively, "Proprietary Matter"), held by Company and it
Subsidiaries; (ii) any licenses or options to obtain rights or licenses granted
by Company or any of its Subsidiaries to others covering any Proprietary Matter;
and (iii) any licenses or options to obtain rights or licenses granted to
Company or any of its Subsidiaries covering any Proprietary Matter owned by
others. Neither Company nor any of its Subsidiaries has been sued, charged or
threatened with any suit or action relating to infringement by Company or any of
its Subsidiaries of any third party Proprietary Matter and no proceedings have
been instituted or are pending (or are threatened) that challenge the validity
of the ownership or use of any Proprietary Matter by Company or any of its
Subsidiaries. Each of Company and its Subsidiaries owns (or possesses adequate
and enforceable licenses or other rights to use) all Proprietary Matter now used
or required to be used in their respective businesses as now conducted and as
proposed to be conducted and neither Company nor any of its Subsidiaries has
received any notice of conflict with the asserted rights of others with respect
to any Proprietary Matter.
 
     4.20  Cash and Cash Equivalents and Short-term Investments.  As of the date
hereof, Company owns cash and cash equivalents and short-term investments in an
amount not less than $115,000,000.
 
                                       15
<PAGE>   19
 
 5. CONDUCT OF BUSINESS PENDING THE MERGER
 
     Company covenants and agrees that, prior to the Effective Date, unless
Parent shall otherwise agree in writing or unless the failure to comply with any
of the following covenants results from actions by the Board of Directors which
are approved by a majority of the directors appointed by Purchaser pursuant to
Section 1.3 or except as otherwise expressly contemplated by this Agreement or
as disclosed in the Disclosure Schedule:
 
     5.1  Ordinary Course of Business.  The business of Company and its
Subsidiaries shall be conducted only in, and Company and its Subsidiaries shall
not take any action except in, the ordinary course of business and consistent
with past practices.
 
     5.2  Preservation of Organization.  Company shall use its reasonable
efforts to maintain and preserve its business organization, assets, employees,
United States Food and Drug Administration and equivalent regulatory agency
licenses and approvals, and United States Patent and Trademark Office and
equivalent agency filings and advantageous business relationships. Neither
Company nor any of its Subsidiaries shall directly or indirectly amend or
propose to amend its charter, regulations or Bylaws or similar organizational
documents.
 
     5.3  Capitalization Changes.  Neither Company nor any of its Subsidiaries
shall directly or indirectly (i) issue, sell, pledge, transfer, dispose of or
encumber, or authorize, propose or agree to the issuance, sale, pledge,
transfer, disposition or encumbrance of, any shares of, or any options, warrants
or rights of any kind (including, without limitation, the Rights) to acquire any
shares of, or any securities convertible into or exchangeable for any shares of,
capital stock of any class of Company or any of its Subsidiaries, other than
Shares issuable upon exercise of Options or Warrants outstanding on the date
hereof as referred to in clauses (iii) or (iv) of Section 4.3 and consistent
with past practices, in accordance with the terms of the applicable agreements
and Employee Plans or (ii) authorize, recommend or propose any change in its
capitalization.
 
     5.4  Sale of Assets.  Neither Company nor any of its Subsidiaries shall
directly or indirectly (i) except in the ordinary course of business and
consistent with past practices, sell, pledge, transfer, assign, license, dispose
of, encumber or lease any assets of Company or of any of its Subsidiaries
(including, without limitation, any indebtedness owed to them or any claims held
by them) or (ii) whether or not in the ordinary course of business, sell,
pledge, transfer, assign, license, dispose of, encumber or lease any material
assets of Company and its Subsidiaries (including, without limitation, any
Facilities of Company, or any assets or the stock of any Subsidiaries
constituting a substantial portion of any line of business of Company).
 
     5.5  Dividends and Repurchases.  Neither Company nor any of its
Subsidiaries shall directly or indirectly (i) split, combine or reclassify any
shares of its capital stock or declare, set aside or pay any dividend or
distribution, payable in cash, stock, property or otherwise with respect to any
of its capital stock other than, dividends and distributions by a Subsidiary of
Company to Company or to a Subsidiary all of the capital stock of which (other
than directors' qualifying shares) is owned directly or indirectly by Company or
(ii) redeem, purchase or otherwise acquire or offer to redeem, purchase or
otherwise acquire any of its capital stock other than pursuant to Section 2.6.
 
     5.6  Acquisitions.  Neither Company nor any of its Subsidiaries or
affiliates shall, directly or indirectly, except in the ordinary course of
business and consistent with past practices, acquire (by merger, consolidation
or acquisition of stock or assets) any corporation, partnership or other
business organization or division thereof or make any investment either by
purchase of stock or securities, contributions to capital (other than to
Subsidiaries), property transfer or purchase of any amount of property or
assets, in any other individual or entity;
 
     5.7  Indebtedness.  Neither Company nor any of its Subsidiaries or
affiliates shall, directly or indirectly incur any indebtedness for borrowed
money or issue any debt securities or assume, guarantee, endorse or otherwise as
an accommodation become responsible for, the obligations of any other individual
or entity, or make any material loans or advances.
 
     5.8  Severance and Termination Pay.  Neither Company nor any of its
Subsidiaries shall take any action with respect to the grant of any severance or
termination pay (otherwise than pursuant to policies or
 
                                       16
<PAGE>   20
 
agreements of Company or any of its Subsidiaries in effect on or prior to the
date hereof) or with respect to any increase of benefits payable under its
severance or termination pay policies or agreements in effect on or prior to the
date hereof.
 
     5.9  Employee Benefits.  Neither Company nor any of its Subsidiaries shall
(except for annual salary increases not to exceed 5% adopted in the ordinary
course of business) adopt or amend any bonus, profit sharing, compensation,
stock option, pension, retirement, deferred compensation, employment or other
employee benefit plan, agreement, trust, fund or other arrangement for the
benefit or welfare of any employee or increase in any manner the compensation or
fringe benefits of any employee or pay any benefit not required by any existing
plan, arrangement or agreement.
 
     5.10  Tax Election.  Without the prior approval of Parent, neither Company
nor any of its Subsidiaries shall make any tax election or settle or compromise
any material federal, state, local or foreign income tax liability.
 
     5.11  Subsequent Financials.  Company shall deliver to Parent all of
Company's monthly and quarterly, if any, financial statements for periods and
dates subsequent to September 30, 1994, as soon as practicable after the same
are available to Company.
 
 6. ADDITIONAL AGREEMENTS
 
     6.1  Proxy Statement.  If a meeting (or written consent in place of) of
Company's stockholders is required by the Delaware Law to approve this Agreement
and the Merger, then promptly after consummation of the Offer, Company shall
prepare and shall file with the Commission as promptly as practicable a
preliminary proxy statement, together with a form of proxy, with respect to the
meeting (or written consent in place of) of Company's stockholders at which the
stockholders of Company will be asked to vote upon and approve this Agreement
and the Merger as provided in Section 6.2. As promptly as practicable after such
filing, subject to compliance with the rules and regulations of the Commission,
Company shall prepare and file a definitive Proxy Statement and form of proxy
with respect to such meeting (or written consent in place of) (the "Proxy
Statement") and shall use all reasonable efforts to have the Proxy Statement
cleared by the Commission as promptly as practicable, and promptly thereafter
shall mail the Proxy Statement to stockholders of Company. The term "Proxy
Statement" shall mean such proxy or information statement at the time it
initially is mailed to Company's stockholders and all amendments or supplements
thereto, if any, similarly filed and mailed. The information provided and to be
provided by Parent, Purchaser and Company, respectively, for use in the Proxy
Statement shall, on the date the Proxy Statement is filed with the Commission,
first mailed to Company's stockholders and on the date of the Special Meeting
(as defined in Section 6.2) be true and correct in all material respects and
shall not omit to state any material fact necessary in order to make such
information not misleading, and Parent, Purchaser and Company each agree to
correct as promptly as practicable any information provided by it for use in the
Proxy Statement which shall have become false or misleading in any material
respect. The Proxy Statement shall comply as to form in all material respects
with all applicable requirements of federal securities laws.
 
     6.2  Meeting of Stockholders of Company; Voting and Disposition of the
Shares.  If a meeting of Company's Stockholders is required by the Delaware Law
to approve this Agreement and the Merger, then as promptly as practicable after
consummation of the Offer, Company shall take all action necessary, in
accordance with the Delaware Law and its Certificate of Incorporation and
Bylaws, to convene a meeting (or obtain the written consents) of its
stockholders (the "Special Meeting") to consider and vote upon this Agreement
and the Merger. The affirmative vote of stockholders required for approval of
this Agreement and Merger shall be no greater than a majority. Subject to the
fiduciary duties of the Board of Directors under the Delaware Law, as advised by
counsel, the Proxy Statement shall contain the recommendation of the Board of
Directors that the stockholders of Company vote to adopt and approve this
Agreement and the Merger and Company shall use its reasonable efforts to solicit
from stockholders of Company proxies in favor of such adoption and approval (and
Purchaser shall vote all Shares purchased by it in favor of such adoption and
approval) and to take all other action necessary or, in the reasonable judgment
of Parent, helpful to secure the vote or consent of stockholders required by the
Delaware Law to effect the Merger.
 
                                       17
<PAGE>   21
 
     6.3  Stock Options.  Company and its Subsidiaries shall take such action as
may be permitted under the Employee Plans to effect the cancellations described
in Section 2.6 and shall comply with all requirements regarding income tax
withholding in connection therewith. In addition to the foregoing and subject to
the terms of the Employee Plans and applicable law, Company will take all steps
necessary to cause the Employee Plans to be terminated on or prior to the
Effective Date, and to satisfy Parent that no holder of Options or participant
in any Employee Plans will have any right to acquire any interest in Company or
Parent as a result of the exercise of Options or other rights pursuant to such
Employee Plans on or after the Effective Date.
 
     6.4  Fees and Expenses.  If Purchaser shall have elected to terminate this
Agreement pursuant to Section 8.1(c)(ii) or Section 8.1(c)(iv), or if Company
shall have elected to terminate this Agreement pursuant to Section 8.1(b)(ii),
then Company shall promptly, but in no event later than two days after such
termination, pay Purchaser a fee of $8,000,000 (which includes a non-accountable
allowance for expenses and fees), which amount shall be payable in same day
funds, provided, that no fee shall be paid pursuant to this Section 6.4 if
either Parent or Purchaser shall be in material breach of its obligations
hereunder.
 
     6.5  Additional Agreements.  Subject to the terms and conditions herein
provided, each of the parties hereto agrees to use all reasonable efforts to
take, or cause to be taken, all actions and to do, or cause to be done, all
things necessary, proper or advisable to consummate and make effective as
promptly as practicable the transactions contemplated by the Offer, this
Agreement, and to cooperate with each other in connection with the foregoing,
including using reasonable efforts (A) to obtain all necessary waivers, consents
and approvals from other parties to material loan agreements, leases, licenses
and other contracts, (B) to obtain all necessary consents, approvals and
authorizations as are required to be obtained under any federal, state or
foreign law or regulations, (C) to defend all lawsuits or other legal
proceedings challenging this Agreement, or the consummation of the transactions
contemplated hereby, and thereby, (D) to obtain final court approval of the
Stipulation of Settlement (as defined in Annex I), (E) to lift or rescind any
injunction or restraining order or other order adversely affecting the ability
of the parties to consummate the transactions contemplated hereby, (F) to effect
all necessary registrations and filings, including, but not limited to, filings
under the Hart-Scott-Rodino Act, and submissions of information requested by
governmental authorities; and (G) to fulfill all conditions to this Agreement.
 
     6.6  No Solicitation of Transactions.
 
     (a) Company and its Subsidiaries will not, directly or indirectly, and will
use its reasonable efforts to cause its officers, directors and agents not to,
solicit, initiate or deliberately encourage submission of, or participate in
discussions concerning, or supply any information in response to, proposals or
offers from any person relating to any acquisition or purchase of all or (other
than in the ordinary course of business) a material amount of the assets of, or
any equity interest in, Company or any merger, consolidation or business
combination with Company (an "Acquisition Proposal"). Company shall promptly
notify Parent if any such proposal or offer, or any inquiry or contact with any
person with respect thereto, is made.
 
     (b) Notwithstanding the foregoing, to the extent required by the fiduciary
obligations of the Board of Directors, as advised by counsel, Company may, in
response to a request or inquiry that could reasonably be expected to result in
an Acquisition Proposal, which request or inquiry was unsolicited after the date
of this Agreement, participate in discussions or negotiations with, or furnish
information with respect to Company pursuant to a confidentiality agreement
substantially similar to the Confidentiality Agreement (as defined in Section
6.8), to any person. In addition, following the receipt of an Acquisition
Proposal, which the Board of Directors determines in good faith, based upon the
advice of its outside financial advisors, to be more favorable to Company's
stockholders than the Offer and the Merger (a "Superior Proposal"), Company may
terminate this Agreement under Section 8.1(b)(ii) and accept such Superior
Proposal, and the Board of Directors may approve or recommend (and, in
connection therewith, withdraw or modify the approval or recommendation of the
Offer, this Agreement or the Merger) such Superior Proposal. Nothing contained
in this Section 6.6(b) shall prohibit Company or its Board of Directors from (i)
taking, and disclosing to Company's stockholders, a position with respect to an
Acquisition Proposal pursuant to Rules 14d-9 and 14e-2(a) under the Exchange Act
or (ii) making any disclosure to Company's stockholders that, in the judgment of
the Board of Directors or Company, is required under applicable law.
 
                                       18
<PAGE>   22
 
     6.7  Notification of Certain Matters.  Company shall give prompt notice to
Parent, and Parent shall give prompt notice to Company, of (i) the occurrence,
or failure to occur, of any event which occurrence or failure would be likely to
cause any representation or warranty contained in this Agreement, the Disclosure
Schedule or any written certificate or schedule delivered pursuant hereto to be
untrue or inaccurate in any material respect at any time from the date hereof to
the time Purchaser first pays for any Shares tendered pursuant to the Offer and
(ii) any material failure of Company, or Parent, Purchaser or any of their
affiliates, as the case may be, or of any officer, director, employee or agent
thereof, to comply with or satisfy any covenant, condition or agreement to be
complied with or satisfied by it under this Agreement; provided, however, that
no such notification shall affect the representations or warranties of the
parties or the conditions to the obligations to the parties hereunder.
 
     6.8  Access to Information.
 
     (a) Subject to the terms and conditions of that certain Confidentiality
Agreement dated August 22, 1994 by and between Parent and Company (the
"Confidentiality Agreement"), Company shall, and shall cause its subsidiaries,
officers, directors, employees and agents to, provide to the officers, employees
and agents (including, without limitation, lawyers and investment bankers) of
Parent, Purchaser and their affiliates reasonable access, at all reasonable
times upon reasonable notice and in such manner as will not unreasonably
interfere with the conduct of Company's business, to, from the date hereof to
the Effective Date, Company's officers, employees, agents, properties, books,
records and contracts, and shall furnish to Parent, Purchaser and their
affiliates all financial, operating and other data and information as Parent,
Purchaser or their affiliates, through their respective officers, employees or
agents, may reasonably request.
 
     (b) No investigation pursuant to this Section 6.8 shall affect any
representations or warranties of the parties herein or the conditions to the
obligations of the parties hereto.
 
     6.9  Officers' and Directors' Insurance; Indemnification.  It is understood
and agreed that Company shall, to the fullest extent permitted under applicable
laws, indemnify and hold harmless, and, after the Effective Date, Parent and the
Surviving Corporation shall, to the fullest extent permitted under applicable
laws, indemnify and hold harmless, each present and former director and officer
of Company (the "Indemnified Parties") against any losses, claims, damages,
liabilities, costs, expenses, judgments and amounts paid in settlement in
connection with any claim, action, suit, proceeding or investigation arising out
of or pertaining to any action or omission by such director or officer prior to
the Effective Date in his/her capacity as such (including, without limitation,
any claims, actions, suits, proceedings or investigations which arise out of or
relate to the transactions contemplated by this Agreement; provided, however,
that neither Company, Parent nor Surviving Corporation shall have any obligation
under this Section to indemnify any Indemnified Party hereunder against any
losses, claims, damages, liabilities, costs, expenses, judgments or amounts to
the extent the same is found to have resulted from such Indemnified Person's own
gross negligence or willful misconduct. In the event any such claim, action,
suit, proceeding or investigation is brought against any Indemnified Party
(whether arising before or after the Effective Date), (a) the Indemnified
Parties may retain counsel satisfactory to them and Company (or them and the
Surviving Corporation and Parent after the Effective Date), (b) Company (or
after the Effective Date, the Surviving Corporation and Parent) shall pay all
fees and expenses of such counsel for the Indemnified Parties promptly as
statements therefor are received, and (c) Company (or after the Effective Date,
the Surviving Corporation and Parent) will use their respective reasonable
efforts to assist in the vigorous defense of any such matter, provided, that
neither Company, the Surviving Corporation nor Parent shall be liable for any
such settlement effected without their written consent, which consent, however,
shall not be unreasonably withheld. Any Indemnified Party wishing to claim
indemnification under this Section 6.9, upon learning of any such claim, action,
suit, proceeding or investigation, shall notify Company, the Surviving
Corporation or Parent thereof and shall deliver to Company or the Surviving
Corporation an undertaking to repay any amounts advanced pursuant hereto when
and if a court of competent jurisdiction shall ultimately determine, after
exhaustion of all avenues of appeal, that such Indemnified Party was not
entitled to indemnification under this Section. The Indemnified Parties as a
group may retain only one law firm in each jurisdiction to represent them with
respect to any such matter unless there is, under applicable standards of
professional conduct as determined by such counsel, a conflict on any
significant issue between the positions of any two or more Indemnified Parties.
This Section 6.9 shall survive
 
                                       19
<PAGE>   23
 
the consummation of the Merger. The Certificate of Incorporation and Bylaws of
Company will not be amended in a manner which adversely affects the rights of
the Indemnified Parties under this Section 6.9. Nothing contained herein shall
in any way limit the rights of any director or officer under any indemnification
agreement or charter or Bylaw provision of Company existing on the date hereof.
 
     6.10  Severance.  If at any time during the one year period following the
Effective Date, Company effects any reduction in employment of any employee who
as of the Effective Date had been an employee of Company, Company shall, except
as otherwise required pursuant to applicable severance agreements, substantially
comply with the Synergen, Inc. August 1, 1994 Severance Benefits Program For
Eligible Employees Below Director Level; Synergen, Inc. August 1, 1994 Severance
Benefits Program For Eligible Director Level Employees; and Synergen, Inc.
August 1, 1994 Severance Benefits Program For Eligible Vice Presidents.
 
     6.11  Liquidated Damages.  If Purchaser shall have elected to terminate
this Agreement pursuant to Section 8.1(c)(v), then Company shall be obligated to
pay Purchaser $8,000,000 as liquidated damages. The parties acknowledge and
agree that it is difficult or impossible to determine with precision the amount
of damages that would or might be incurred by Purchaser if an event described in
Section 8.1(c)(v) were to occur. It is understood and agreed by the parties that
if Purchaser shall be damaged by an event described in Section 8.1(c)(v), (i) it
would be impracticable or extremely difficult to fix the actual damages
resulting therefrom, (ii) any sums which would be payable by Company under this
Agreement are in the nature of liquidated damages, and not a penalty, and are
fair and reasonable, and (iii) such payment represents a reasonable estimate of
fair compensation for the losses that may reasonably be anticipated from the
occurrence of any such events, and, except for the termination rights of
Purchaser set forth in Section 8.1(c)(v) and Annex I, shall be the sole and
exclusive measure of damages with respect to any such occurrence. Once such
liquidated damages have been paid in accordance with the provisions of this
Agreement, Company shall be relieved of any further liability in respect of
damages relating to the fact or circumstance giving rise to such liquidated
damages.
 
 7. CONDITIONS
 
     7.1  Conditions to Obligation of Each Party to Effect the Merger.  The
respective obligations of each party to effect the Merger shall be subject to
the fulfillment at or prior to the Effective Date of the following conditions:
 
          (a) If required by the Delaware Law, this Agreement and the Merger
     shall have been approved and adopted by the requisite vote or consent of
     the stockholders of Company;
 
          (b) Subject to Section 1.1(c), Shares shall have been purchased
     pursuant to the Offer; and
 
          (c) No preliminary or permanent injunction or other order, decree or
     ruling issued by a court of competent jurisdiction or by a governmental,
     regulatory or administrative agency or commission nor any statute, rule,
     regulation or executive order promulgated or enacted by any governmental
     authority shall be in effect, which would make the acquisition or holding
     by Parent, its subsidiaries or affiliates of the shares of Common Stock of
     the Surviving Corporation illegal or otherwise prevent the consummation of
     the Merger; provided, however, that the parties shall have used all
     reasonable efforts to prevent such event.
 
 8. TERMINATION, AMENDMENT AND WAIVER
 
     8.1  Termination.  This Agreement may be terminated at any time prior to
the Effective Date, whether prior to or after approval by the stockholders of
Company:
 
          (a) By mutual written consent of the Boards of Directors of Purchaser
     and Company; or
 
          (b) By Company:
 
             (i) If (A) Purchaser or any of its subsidiaries or affiliates shall
          have (1) failed to commence the Offer within the time period specified
          in Section 1.1; (2) terminated the Offer in accordance with its terms;
          or (3) failed to purchase Shares pursuant to the Offer within 120 days
          after the
 
                                       20
<PAGE>   24
 
          commencement of the Offer; or (B) the Offer shall expire without any
          Shares having been purchased and without Purchaser having an 
          obligation to extend the Offer under Section 1.1, except that in 
          each case, Company may not terminate this Agreement pursuant to this 
          clause if it shall have failed to perform in any material respect 
          any of its material obligations under this Agreement;
 
               (ii) In the event Company has complied in all material respects
          with Section 6.6 and has determined to accept a Superior Proposal;
 
               (iii) If the Effective Date shall not have occurred on or before
          one year after the date hereof due to a failure of any of the 
          conditions to the obligations of Company set forth in Section 7.1; or
 
               (iv) If Purchaser shall have breached or failed to perform in all
          material respects any of its material obligations or agreements under
          this Agreement, or any of Purchaser's material representations and
          warranties shall be, or have become, inaccurate or incomplete in any
          material respect.
 
          (c) By Purchaser:
 
               (i) If (A) Purchaser or any of its subsidiaries or affiliates  
          shall have (1) failed to commence the Offer within the time period
          specified in Section 1.1; (2) terminated the Offer in accordance
          with its terms; or (3) failed to purchase Shares pursuant to the
          Offer within 120 days after the commencement of the Offer; or (B) the
          Offer shall expire without any Shares having been purchased and
          without Purchaser having an obligation to extend the Offer under
          Section 1.1, except that in  each case, Purchaser may not terminate
          this Agreement pursuant to  this clause if it shall have failed to
          perform in any material  respect any of its material obligations
          under this Agreement;
 
               (ii) In the event that Company has complied in all material
          respects with Section 6.6 and has determined to accept a Superior
          Proposal;
 
               (iii) If the Effective Date shall not have occurred on or before
          one year after the date hereof due to a failure of any of the 
          conditions to the obligations of Purchaser set forth in Section 7.1;
 
               (iv) If Company shall have withdrawn or modified in a manner
          adverse to Purchaser its approval or recommendation of the Offer, this
          Agreement or the Merger, or the Board of Directors shall have resolved
          to do any of the foregoing, except that Purchaser may not terminate 
          this Agreement pursuant to this clause if it shall have failed to 
          perform in any material respect any of its obligations under this 
          Agreement; or
 
               (v) If Company shall have breached or failed to perform in all
          material respects any of its obligations or agreements under this
          Agreement, or any of the representations and warranties of Company set
          forth in this Agreement, the Disclosure Schedule or in any written
          certificate or schedule delivered pursuant thereto shall be, or have
          become, inaccurate or incomplete in any respect, in each case, with 
          such exceptions as would not in the aggregate have a Material 
          Adverse Effect on Company and its Subsidiaries taken as a whole.
 
     8.2  Effect of Termination.  In the event of the termination of this
Agreement as provided in Section 8.1, (A) this Agreement shall forthwith become
void, and there shall be no liability on the part of Parent, Purchaser or
Company, except as set forth in this Section 8.2 and in Section 6.4 and (B)
Purchaser shall terminate the Offer, if still pending, without purchasing any
additional Shares.
 
     8.3  Amendment.  Subject to applicable law, this Agreement may be amended,
modified or supplemented by written agreement of the parties hereto at any time
before the Effective Date.
 
     8.4  Waiver.  Subject to applicable law, at any time prior to the Effective
Date, whether before or after the Special Meeting, any party hereto may (i)
extend the time for the performance of any of the obligations or other acts of
any other party hereto or (ii) waive compliance with any of the agreements of
any other party or with any conditions to its own obligations. Any agreement on
the part of a party hereto to any such extension or waiver shall be valid only
if set forth in an instrument in writing signed on behalf of such party by a
duly authorized officer.
 
                                       21
<PAGE>   25
 
 9. GENERAL PROVISIONS
 
     9.1  Brokers.
 
     (a) Company represents and warrants that no broker, finder or investment
banker other than Morgan Stanley & Co. Incorporated and Alex. Brown & Sons
Incorporated are entitled to any brokerage, finder's or other fee or commission
in connection with the Offer or the Merger based upon arrangements made by or on
behalf of Company.
 
     (b) Parent represents and warrants that no broker, finder or investment
banker other than CS First Boston Corporation is entitled to any brokerage,
finder's or other fee or commission in connection with the Offer or the Merger
based upon arrangements made by or on behalf of Parent or its affiliates.
 
     9.2  Public Statements.  The parties agree to consult with each other prior
to issuing any public announcement or statement with respect to the Offer or the
Merger.
 
     9.3  Notices.  All notices and other communications hereunder shall be in
writing and shall be deemed to have been duly given if delivered personally or
sent by cable, telegram, telecopies or telex to the parties at the following
addresses or at such other addresses as shall be specified by the parties by
like notice:
 
     (a) If to Parent or Purchaser:
         Amgen Inc.
         Amgen Center
         1840 DeHavilland Drive
         Thousand Oaks, California 91320-1789
         Attention: Secretary
 
      with a copy to:
 
         Amgen Inc.
         Amgen Center
         1840 DeHavilland Drive
         Thousand Oaks, California 91320-1789
         Attention: Senior Vice President, Corporate Development
 
         Latham & Watkins
         633 West Fifth Street, Suite 4000
         Los Angeles, California 90071
         Attention: George A. Vandeman, Esq.
 
     (b) If to Company:
 
         Synergen, Inc.
         1885 33rd Street
         Boulder, Colorado 80301
         Attention: Secretary
 
      with a copy to:
 
         Wilson, Sonsini, Goodrich & Rosati
         650 Page Mill Road
         Palo Alto, California 94304-1050
         Attention: Larry W. Sonsini, Esq.
 
     9.4  Interpretation.  All defined terms herein include the plural as well
as the singular. All references in this Agreement to designated "Articles,"
"Sections" and other subdivisions are to the designated Articles, Sections and
other subdivisions of this Agreement. The words "herein," "hereof" and
"hereunder" and other words of similar import refer to this Agreement as a whole
and not to any particular Article, Section or other subdivision. This Agreement
shall not be construed for or against either party by reason of the authorship
or alleged authorship of any provisions hereof or by reason of the status of the
respective parties. When a
 
                                       22
<PAGE>   26
 
reference is made in this Agreement to subsidiaries of Parent or Purchaser or
Company, the word "subsidiaries" means any corporation more than 50 percent of
whose outstanding voting securities, or any partnership, joint venture or other
entity more than 50 percent of whose total equity interest, is directly or
indirectly owned by Parent or Purchaser or Company, as the case may be. For
purposes of this Agreement, Company shall not be deemed to be an affiliate or
subsidiary of Purchaser or Parent. The headings contained in this Agreement are
for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.
 
     9.5  Representations and Warranties; Etc.  The respective representations
and warranties of Company, Parent and Purchaser contained herein shall expire
with, and be terminated and extinguished upon, consummation of the Merger, and
thereafter neither Company, Parent nor Purchaser nor any officer, director or
principal thereof shall be under any liability whatsoever with respect to any
such representation or warranty. This Section 9.5 shall have no effect upon any
other obligation of the parties hereto, whether to be performed before or after
the consummation of the Merger.
 
     9.6  Miscellaneous.  This Agreement (including the Disclosure Schedule
referred to herein) (i) constitutes the entire agreement and supersedes all
other prior agreements and undertakings, both written and oral, among the
parties, or any of them, with respect to the subject matter hereof; (ii) except
for Sections 2.6, 6.8, 6.9 and 6.10, is not intended to confer upon any other
person any rights or remedies hereunder; (iii) shall not be assigned, except by
Parent and Purchaser to a directly or indirectly wholly owned subsidiary of
Parent which, in a written instrument shall agree to assume all of such party's
obligations hereunder and be bound by all of the terms and conditions of this
Agreement; provided, however, that no such assignment shall relieve the
assigning party of the obligations hereunder; and (iv) shall be governed in all
respects, including validity, interpretation and effect, by the internal laws of
the State of Delaware, without giving effect to the principles of conflict of
laws thereof. Only Purchaser (or Parent, or a directly or indirectly wholly
owned subsidiary of Parent, to which Purchaser assigns such rights and
obligations) may commence the Offer or purchase Shares thereunder. This
Agreement may be executed in one or more counterparts which together shall
constitute a single agreement.
 
     IN WITNESS WHEREOF, Parent and Purchaser and Company have caused this
Agreement to be executed as of the date first written above by their respective
officers thereunder duly authorized.
 
                                          AMGEN INC.
 
                                          /s/  GORDON M. BINDER
                                          -------------------------------------
                                          Name: Gordon M. Binder
                                          Title: Chief Executive Officer and
                                                 Chairman of the Board
 

                                          AMGEN ACQUISITION SUBSIDIARY, INC.
 
                                          /s/  THOMAS E. WORKMAN, JR.
                                          -------------------------------------
                                          Name: Thomas E. Workman, Jr.
                                          Title: Chief Executive Officer
 

                                          SYNERGEN, INC.
 
                                          /s/  GREGORY B. ABBOTT
                                          -------------------------------------
                                          Name: Gregory B. Abbott
                                          Title: President and Chief Executive
                                                 Officer
 
                                       23
<PAGE>   27
 
                                    ANNEX I
 
     Certain Conditions of the Offer.  Notwithstanding any other provisions of
the Offer, but subject to the terms of this Agreement, and in addition to the
Minimum Condition, Purchaser shall not be required to accept for payment or pay
for, or may delay the acceptance for payment of or payment for, tendered Shares,
or may, in the sole discretion of Purchaser, terminate the Offer as to any
Shares not then accepted for payment or paid for, if any of the following events
shall occur, which, in the reasonable judgment of Purchaser with respect to each
and every matter referred to below and regardless of the circumstances giving
rise to any of the following events, makes it inadvisable to proceed with the
Offer, the acceptance for payment or payment for the Shares or the Merger:
 
          (a) The affirmative vote of the holders of more than a majority of the
     outstanding Shares is required to consummate the Merger or Purchaser is not
     entitled to vote its Shares for the Merger, or the affirmative vote of the
     holders of any securities of Company other than the Shares is required to
     consummate the Merger;
 
          (b) Any waiting period (and any extension thereof) applicable to the
     consummation of the transactions contemplated by this Agreement under the
     Hart-Scott-Rodino Act shall not have expired or been terminated;
 
          (c) Company shall not have obtained such licenses, permits, consents,
     approvals, authorizations, qualifications and orders of governmental
     authorities and parties to contracts with Company and its Subsidiaries as
     are necessary for consummation of the Merger (excluding licenses, permits,
     consents, approvals, authorizations, qualifications or orders, the failure
     of which to obtain would not in the aggregate have a Material Adverse
     Effect on Company and its Subsidiaries taken as a whole);
 
          (d) Company shall have withdrawn or modified in a manner adverse to
     Purchaser its approval or recommendation of the Offer, this Agreement or
     the Merger, or the Board of Directors shall have resolved to do any of the
     foregoing, except in the case that Purchaser or Parent shall have failed to
     perform in any material respect any of their respective material
     obligations under this Agreement;
 
          (e) There shall be instituted or pending any action or proceeding
     which has a reasonable probability of success before any domestic or
     foreign court, legislative body or governmental agency or other regulatory
     or administrative agency or commission (i) challenging the acquisition in
     whole or in part of the Shares, seeking to restrain or prohibit the making
     or consummation of the Offer or seeking to obtain any material damages or
     otherwise directly or indirectly relating to the transaction contemplated
     by the Offer, (ii) seeking to prohibit or restrict the ownership or
     operation by Parent or Purchaser (or any of their respective affiliates or
     subsidiaries) of any material portion of its or Company's business or
     assets, or to compel Parent or Purchaser (or any of their respective
     affiliates or subsidiaries) to dispose of or hold separate all or any
     material portion of Company's business or assets as a result of the Offer,
     (iii) making the purchase of, or payment for, some or all of the Shares
     illegal, (iv) resulting in a delay in the ability of Purchaser to accept
     for payment or pay for some or all of the Shares, (v) imposing material
     limitations on the ability of Purchaser effectively to acquire or to hold
     or to exercise full rights of ownership of the Shares, including, without
     limitation, the right to vote the Shares purchased by Purchaser on all
     matters properly presented to the stockholders of Company, (vi) imposing
     any limitations on the ability of Parent or Purchaser or any of their
     respective affiliates or subsidiaries effectively to control in any
     material respect the business and operations of Company; (vii) which
     otherwise is reasonably likely to have a Material Adverse Effect on Company
     and its Subsidiaries taken as a whole; or (viii) which may result in a
     material limitation on the benefits expected to be derived by Parent and
     Purchaser as a result of the Offer, including without limitation, any
     limitation on the ability to consummate the Merger;
 
          (f) Any statute, rule, regulation or order shall be enacted,
     promulgated, entered or deemed applicable to the Offer or the Merger, or
     any other action shall have been taken, proposed or threatened, by any
     domestic or foreign government or governmental authority or by any court,
     domestic or foreign, which, in the reasonable judgment of Purchaser, is
     reasonably likely, directly or indirectly, to result in any of the
     consequences referred to in clauses (i)-(viii) of subsection (e) above;
 
                                       I-1
<PAGE>   28
 
          (g) Any change (or any development involving a prospective change)
     shall have occurred which in the judgment of Purchaser had, or may
     reasonably be expected to have, a Material Adverse Effect on Company and
     its Subsidiaries taken as a whole;
 
          (h) Company shall have breached or failed to perform in all material
     respects any of its obligations or agreements under this Agreement, or any
     of the representations and warranties of Company set forth in this
     Agreement, the Disclosure Schedule or in any written certificate or
     schedule delivered pursuant thereto shall be, or have become, inaccurate or
     incomplete in any respect, in each case, with such exceptions as would not
     in the aggregate have a Material Adverse Effect on Company and its
     Subsidiaries taken as a whole;
 
          (i) This Agreement shall have been terminated by Company, Parent or
     Purchaser pursuant to its terms;
 
          (j) Any "Triggering Event" under the Rights Agreement shall have
     occurred and the Rights shall not be redeemable by Company; or
 
          (k) (1) a Stipulation of Settlement shall not have been entered into
     by Company and certain plaintiffs (the "Plaintiffs") (the "Stipulation of
     Settlement") constituting, subject to court approval, a legally binding
     agreement for the full and complete settlement of the class action
     litigation captioned In re Synergen, Inc. Securities Litigation, Case No.
     93-B-402, pending in the United States District Court for the District of
     Colorado (the "Court"), as such settlement is described in that certain
     Memorandum of Understanding dated the date hereof by and between Company
     and the Plaintiffs (the "MOU"), (2) the Stipulation of Settlement shall not
     be in full force and effect or shall not reasonably reflect the terms and
     conditions of the MOU or (3) the Court shall not have entered a Scheduling
     Order providing for, (a) approval of a form of notice to the class members
     of the Stipulation of Settlement and a deadline for giving notice to the
     class members, (b) deadlines for class members to object to the settlement
     and/or to opt out of the class and (c) a hearing date upon which the Court
     will consider whether to grant final approval of the Stipulation of
     Settlement.
 
     The foregoing conditions are for the sole benefit of Purchaser and may be
asserted regardless of the circumstances giving rise to any such conditions or
may be waived in whole or in part. The failure to exercise any of the foregoing
rights shall not be deemed a waiver of any such right, and each right shall be
deemed a continuing right which may be asserted at any time and from time to
time.
 
                                       I-2

<PAGE>   1
 
                           OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
                                      OF
                                SYNERGEN, INC.
                                      AT
                             $9.25 NET PER SHARE
                                      BY
                      AMGEN ACQUISITION SUBSIDIARY, INC.
                         A WHOLLY OWNED SUBSIDIARY OF
                                  AMGEN INC.
        THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,
             NEW YORK CITY TIME, ON WEDNESDAY, DECEMBER 21, 1994
                        UNLESS THE OFFER IS EXTENDED.
                           ------------------------
 
THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS, THERE BEING VALIDLY TENDERED
      AND NOT WITHDRAWN PRIOR TO THE EXPIRATION OF THE OFFER A NUMBER OF
          SHARES THAT CONSTITUTES AT LEAST A MAJORITY OF THE SHARES
          OUTSTANDING ON A FULLY DILUTED BASIS. SEE INTRODUCTION AND
                                 SECTION 14.
                           ------------------------
                                      
 THE BOARD OF DIRECTORS OF SYNERGEN, INC. UNANIMOUSLY HAS DETERMINED THAT THE
       OFFER AND THE MERGER ARE FAIR TO, AND IN THE BEST INTERESTS OF,
       SYNERGEN, INC. AND ITS STOCKHOLDERS, HAS APPROVED THE OFFER, THE
             MERGER AGREEMENT AND THE MERGER AND RECOMMENDS THAT
            STOCKHOLDERS ACCEPT THE OFFER AND TENDER THEIR SHARES
                            PURSUANT TO THE OFFER.
                           ------------------------
                                      
                                  IMPORTANT
 
     Any stockholder desiring to tender all or any portion of such stockholder's
shares of Common Stock, par value $.01 per share (the "Shares"), of Synergen,
Inc. should either (1) complete and sign the Letter of Transmittal (or a
facsimile thereof) in accordance with the instructions in the Letter of
Transmittal and mail or deliver it together with the certificate(s) evidencing
tendered Shares, and any other required documents, to the Depositary or tender
such Shares pursuant to the procedures for book-entry transfer set forth in
Section 3 or (2) request such stockholder's broker, dealer, commercial bank,
trust company or other nominee to effect the transaction for such stockholder.
Any stockholder whose Shares are registered in the name of a broker, dealer,
commercial bank, trust company or other nominee must contact such broker,
dealer, commercial bank, trust company or other nominee if he desires to tender
such Shares.
 
     A stockholder who desires to tender Shares and whose certificates
evidencing such Shares are not immediately available, or who cannot comply with
the procedures for book-entry transfer described in this Offer to Purchase on a
timely basis, may tender such Shares by following the procedures for guaranteed
delivery set forth in Section 3.
 
     Questions and requests for assistance or for additional copies of this
Offer to Purchase, the Letter of Transmittal or other tender materials, may be
directed to the Information Agent or to the Dealer Manager at their respective
addresses and telephone numbers set forth on the back cover of this Offer to
Purchase. Holders of Shares may also contact brokers, dealers, commercial banks
and trust companies for assistance concerning the Offer.
 
                           ------------------------
                                      
                     The Dealer Manager for the Offer is:
 
                               CS First Boston
November 23, 1994
<PAGE>   2
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                          PAGE
                                                                                          ----
<S>   <C>                                                                                 <C>
INTRODUCTION.............................................................................    3
 1.   Terms of the Offer; Expiration Date................................................    4
 2.   Acceptance for Payment and Payment for Shares......................................    6
 3.   Procedures for Accepting the Offer and Tendering Shares............................    7
 4.   Withdrawal Rights..................................................................    9
 5.   Certain Federal Income Tax Consequences............................................   10
 6.   Price Range of Shares..............................................................   11
 7.   Certain Information Concerning the Company.........................................   11
 8.   Certain Information Concerning Purchaser and Parent................................   13
 9.   Financing of the Offer and the Merger..............................................   15
10.   Background of the Offer; Contacts with the Company and the Merger Agreement........   15
11.   Purpose of the Offer; Plans for the Company After the Offer and the Merger.........   22
12.   Dividends and Distributions........................................................   23
13.   Effect of the Offer on the Market for the Shares, Exchange Listing and Exchange Act
      Registration.......................................................................   24
14.   Certain Conditions of the Offer....................................................   25
15.   Certain Legal Matters and Regulatory Approvals.....................................   26
16.   Rights Agreement...................................................................   29
17.   Fees and Expenses..................................................................   30
18.   Miscellaneous......................................................................   30
Schedule I   Directors and Executive Officers of Parent and Purchaser....................  I-1
</TABLE>
 
                                        2
<PAGE>   3
 
To the Holders of Shares of Common Stock of Synergen, Inc.:
 
                                  INTRODUCTION
 
     Amgen Acquisition Subsidiary, Inc., a Delaware corporation ("Purchaser")
and a wholly owned subsidiary of Amgen Inc., a Delaware corporation ("Parent"),
hereby offers to purchase all outstanding shares of Common Stock, par value $.01
per share (the "Shares"), of Synergen, Inc., a Delaware corporation (the
"Company"), including the associated preferred stock purchase rights (unless the
context requires otherwise, all references to "Shares" shall include a reference
to such rights), at a price of $9.25 per Share, net to the seller in cash, upon
the terms and subject to the conditions set forth in this Offer to Purchase and
in the related Letter of Transmittal (which together constitute the "Offer").
 
     Tendering stockholders will not be obligated to pay brokerage fees or
commissions or, except as otherwise provided in Instruction 6 of the Letter of
Transmittal, stock transfer taxes with respect to the purchase of Shares by
Purchaser pursuant to the Offer. Purchaser will pay all charges and expenses of
CS First Boston Corporation ("CS First Boston"), which is acting as Dealer
Manager for the Offer (in such capacity, the "Dealer Manager"), American Stock
Transfer & Trust Company (the "Depositary") and D.F. King & Co., Inc. (the
"Information Agent") incurred in connection with the Offer. See Section 16.
 
     THE BOARD OF DIRECTORS OF THE COMPANY (THE "BOARD") UNANIMOUSLY HAS
DETERMINED THAT THE OFFER AND THE MERGER (AS DEFINED BELOW) ARE FAIR TO, AND IN
THE BEST INTERESTS OF, THE COMPANY AND ITS STOCKHOLDERS, HAS APPROVED THE OFFER,
THE MERGER AGREEMENT AND THE MERGER AND RECOMMENDS THAT STOCKHOLDERS ACCEPT THE
OFFER AND TENDER THEIR SHARES PURSUANT TO THE OFFER.
 
     Morgan Stanley & Co. Incorporated ("Morgan Stanley") and Alex. Brown & Sons
Incorporated ("Alex. Brown") have delivered to the Board written opinions that
the consideration to be received by the stockholders of the Company pursuant to
each of the Offer and the Merger is fair to such stockholders from a financial
point of view. Copies of the opinions of Morgan Stanley and Alex. Brown are
contained in the Company's Solicitation/Recommendation Statement on Schedule
14D-9 (the "Schedule 14D-9"), which is being mailed to stockholders herewith.
 
     THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS, THERE BEING VALIDLY
TENDERED AND NOT WITHDRAWN PRIOR TO THE EXPIRATION OF THE OFFER A NUMBER OF
SHARES THAT CONSTITUTES AT LEAST A MAJORITY OF THE SHARES THEN OUTSTANDING ON A
FULLY DILUTED BASIS (THE "MINIMUM CONDITION"). SEE SECTION 14, WHICH SETS FORTH
IN FULL THE CONDITIONS TO THE OFFER. As used in this Offer to Purchase, the
phrase "on a fully diluted basis" when used with reference to the Minimum
Condition includes all shares issuable upon exercise of outstanding employee and
director stock options, but excludes all Shares issuable upon exercise of
outstanding warrants, rights or other securities to purchase or acquire Shares.
The Offer is also conditioned upon, among other things, the Company entering
into a legally binding agreement (subject to court approval) for the full and
complete settlement of certain stockholder litigation, as such settlement is
described in a Memorandum of Understanding dated November 17, 1994 by and
between the Company and certain stockholders. See Sections 14 and 15.
 
     The Offer is being made pursuant to an Agreement and Plan of Merger dated
as of November 17, 1994 (the "Merger Agreement") among Parent, Purchaser and the
Company. The Merger Agreement provides that, among other things, as soon as
practicable after the purchase of Shares pursuant to the Offer and the
satisfaction of the other conditions set forth in the Merger Agreement and in
accordance with the relevant provisions of the General Corporation Law of the
State of Delaware ("Delaware Law"), Purchaser will be merged with and into the
Company (the "Merger"). Following consummation of the Merger, the Company will
continue as the surviving corporation (the "Surviving Corporation") and will be
a wholly owned subsidiary of Parent. At the effective time of the Merger (the
"Effective Time"), each Share issued and outstanding immediately prior to the
Effective Time (other than Shares held in the treasury of the Company
 
                                        3
<PAGE>   4
 
or owned by Purchaser, Parent or any direct or indirect subsidiary of Purchaser,
Parent or the Company, and other than Shares held by stockholders who shall have
demanded and perfected appraisal rights, if any, under Delaware Law) will be
cancelled and converted automatically into the right to receive $9.25 in cash,
or any higher price per Share that may be paid in the Offer, without interest
(the "Merger Consideration"). The Merger Agreement is more fully described in
Section 10.
 
     The Merger Agreement provides that, promptly upon the purchase by Purchaser
of such number of Shares that satisfies the Minimum Condition, Parent shall be
entitled to designate a majority of the members of the Board. In the Merger
Agreement, the Company has agreed to take all actions necessary to cause
Parent's designees to be elected as directors of the Company.
 
     The consummation of the Merger is subject to the satisfaction or waiver of
certain conditions, including the approval and adoption of the Merger Agreement
by the requisite vote of the stockholders of the Company, if such a vote is
required under Delaware Law. See Section 11. Under the Company's Certificate of
Incorporation and Delaware Law, the affirmative vote of the holders of a
majority of the outstanding Shares is required to approve and adopt the Merger
Agreement and the Merger. Consequently, if Purchaser acquires (pursuant to the
Offer or otherwise) at least a majority of the outstanding Shares, Purchaser
will have sufficient voting power to approve and adopt the Merger Agreement and
the Merger without the vote of any other stockholder.
 
     Under Delaware Law, if Purchaser acquires, pursuant to the Offer or
otherwise, at least 90% of the then outstanding Shares, Purchaser will be able
to approve and adopt the Merger Agreement and the transactions contemplated
thereby, including the Merger, without a vote of the Company's stockholders. If,
however, Purchaser does not acquire at least 90% of the then outstanding Shares
pursuant to the Offer or otherwise and a vote of the Company's stockholders is
required under Delaware Law, a significantly longer period of time will be
required to effect the Merger. See Section 11.
 
     The Company has advised Purchaser that as of November 17, 1994, 25,936,248
Shares were issued and outstanding and 2,466,782 Shares are reserved for
issuance pursuant to employee and director stock option plans. As a result, as
of such date, the Minimum Condition would be satisfied if Purchaser acquired
14,201,516 Shares.
 
     THIS OFFER TO PURCHASE AND THE RELATED LETTER OF TRANSMITTAL CONTAIN
IMPORTANT INFORMATION WHICH SHOULD BE READ BEFORE ANY DECISION IS MADE WITH
RESPECT TO THE OFFER.
 
     1. TERMS OF THE OFFER; EXPIRATION DATE. Upon the terms and subject to the
conditions of the Offer (including, if the Offer is extended or amended, the
terms and conditions of such extension or amendment), Purchaser will accept for
payment and pay for all Shares validly tendered prior to the Expiration Date (as
hereinafter defined) and not withdrawn as permitted by Section 4. The term
"Expiration Date" means 12:00 midnight, New York City time, on Wednesday,
December 21, 1994, unless, subject to the terms and conditions of the Merger
Agreement (as discussed below), Purchaser, in its discretion, shall have
extended the period during which the Offer is open, in which event the term
"Expiration Date" shall mean the latest time and date at which the Offer, as so
extended by Purchaser, shall expire.
 
     Subject to the terms and conditions of the Merger Agreement (as discussed
below), Purchaser expressly reserves the right, at any time and from time to
time, to extend for any reason the period of time during which the Offer is
open, including the occurrence of any of the conditions specified in Section 14,
by giving oral or written notice of such extension to the Depositary. During any
such extension, all Shares previously tendered and not withdrawn will remain
subject to the Offer and to the rights of a tendering stockholder to withdraw
such stockholder's Shares. See Section 4.
 
     The Merger Agreement provides that the Offer may not, without the Company's
prior written consent, be extended, except as necessary to provide time to
satisfy the conditions set forth in Section 14; provided, however, that
Purchaser may extend (and re-extend) the Offer for up to a total of 10 business
days, if as of the initial Expiration Date there shall not have been validly
tendered and not withdrawn at least 90% of the outstanding Shares, so that the
Merger can be effected without a meeting of the Company's stockholders in
 
                                        4
<PAGE>   5
 
accordance with Delaware Law. The Merger Agreement further provides that if all
conditions set forth in Section 14 are satisfied on the initial Expiration Date,
other than the Minimum Condition or the condition described in paragraph (b) of
Section 14 (relating to the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended (the "HSR Act")), Purchaser shall extend (and re-extend) the
Offer for up to a maximum of 20 business days to provide time to satisfy either
such conditions, so long as all such other conditions remain satisfied.
 
     Subject to the applicable regulations of the Securities and Exchange
Commission (the "Commission"), Purchaser also expressly reserves the right (but
subject to the terms and conditions of the Merger Agreement (as discussed
below)), at any time and from time to time, (i) to waive any condition to the
Offer (other than the Minimum Condition, which can only be waived if Purchaser,
after consultation with the Company and upon consummation of the Offer, accepts
for payment and pays for a majority of the Shares outstanding at the time of
such consummation), (ii) to increase the price per Share payable in the Offer,
(iii) to make any other changes in the terms and conditions of the Offer or (iv)
not to accept for payment or pay for, or delay the acceptance for payment of a
payment for, tendered Shares, or to terminate the Offer as to any Shares not
then accepted for payment or paid for, upon the occurrence of any of the
conditions specified in Section 14, by giving oral or written notice of such
waiver, increase, change, non-acceptance, delay or termination to the Depositary
and by making a public announcement thereof.
 
     The Merger Agreement provides that, without the written consent of the
Company, Purchaser will not (i) decrease the price per Share payable pursuant to
the Offer, (ii) change the form of consideration payable in the Offer, (iii)
reduce the maximum number of Shares to be purchased in the Offer, (iv) impose
conditions to the Offer in addition to those set forth in Section 14 or (v)
amend any other material term of the Offer in a manner materially adverse to the
Company's stockholders. Purchaser acknowledges that (i) Rule 14e-1(c) under the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), requires
Purchaser to pay the consideration offered or return the Shares tendered
promptly after the termination or withdrawal of the Offer and (ii) Purchaser may
not delay acceptance for payment of, or payment for any Shares upon the
occurrence of any of the conditions specified in Section 14 without extending
the period of time during which the Offer is open.
 
     Any such waiver, increase, change, non-acceptance, delay or termination
will be followed as promptly as practicable by public announcement thereof, such
announcement in the case of an extension to be made no later than 9:00 a.m., New
York City time, on the next business day after the previously scheduled
Expiration Date. Subject to applicable law (including Rules 14d-4(c) and
14d-6(d) under the Exchange Act, which require that material changes be promptly
disseminated to stockholders in a manner reasonably designed to inform them of
such changes) and without limiting the manner in which Purchaser may choose to
make any public announcement, Purchaser shall have no obligation to publish,
advertise or otherwise communicate any such public announcement other than by
issuing a press release to the Dow Jones News Service.
 
     If Purchaser makes a material change in the terms of the Offer or the
information concerning the Offer, or if it waives a material condition of the
Offer, Purchaser will extend the Offer to the extent required by Rules 14d-4(c)
and 14d-6(d) under the Exchange Act.
 
     Subject to the terms of the Merger Agreement (as discussed above), if,
prior to the Expiration Date, Purchaser should decide to decrease the number of
Shares being sought or to increase or decrease the consideration being offered
in the Offer, such decrease in the number of Shares being sought or such
increase or decrease in the consideration being offered will be applicable to
all stockholders whose Shares are accepted for payment pursuant to the Offer
and, if at the time notice of any such decrease in the number of Shares being
sought or such increase or decrease in the consideration being offered is first
published, sent or given to holders of such Shares, the Offer is scheduled to
expire at any time earlier than the period ending on the tenth business day from
and including the date that such notice is first so published, sent or given,
the Offer will be extended at least until the expiration of such ten business
day period. For purposes of the Offer a "business day" means any day other than
a Saturday, Sunday or federal holiday and consists of the time period from 12:01
a.m. through 12:00 midnight, New York City time.
 
                                        5
<PAGE>   6
 
     The Company has provided Purchaser with the Company's stockholder list and
security position listings for the purpose of disseminating the Offer to holders
of Shares. This Offer to Purchase and the related Letter of Transmittal will be
mailed to record holders of Shares whose names appear on the Company's
stockholder list and will be furnished, for subsequent transmittal to beneficial
owners of Shares, to brokers, dealers, commercial banks, trust companies and
similar persons whose names, or the names of whose nominees, appear on the
stockholder list or, if applicable, who are listed as participants in a clearing
agency's security position listing.
 
     2. ACCEPTANCE FOR PAYMENT AND PAYMENT FOR SHARES. Upon the terms and
subject to the conditions of the Offer (including, if the Offer is extended or
amended, the terms and conditions of any such extension or amendment), Purchaser
will accept for payment, and will pay for, all Shares validly tendered prior to
the Expiration Date and not properly withdrawn promptly after the later to occur
of (i) the Expiration Date and (ii) the satisfaction or waiver of the conditions
to the Offer set forth in Section 14. Subject to applicable rules of the
Commission, Purchaser expressly reserves the right to delay acceptance for
payment of, or payment for, Shares pending receipt of any HSR Act approval
described in Section 15.
 
     In all cases, payment for Shares tendered and accepted for payment pursuant
to the Offer will be made only after timely receipt by the Depositary of (i) the
certificates evidencing such Shares (the "Share Certificates") or timely
confirmation (a "Book-Entry Confirmation") of a book-entry transfer of such
Shares into the Depositary's account at The Depository Trust Company, the
Midwest Securities Trust Company or the Philadelphia Depository Trust Company
(each, a "Book-Entry Transfer Facility" and, collectively, the "Book-Entry
Transfer Facilities") pursuant to the procedures set forth in Section 3, (ii)
the Letter of Transmittal (or a facsimile thereof), properly completed and duly
executed, with any required signature guarantees or an Agent's Message, as
defined below, in connection with a book-entry transfer and (iii) any other
documents required under the Letter of Transmittal. The term "Agent's Message"
means a message, transmitted by a Book-Entry Transfer Facility to, and received
by, the Depositary and forming a part of a Book-Entry Confirmation, which states
that such Book-Entry Transfer Facility has received an express acknowledgement
from the participant in such Book-Entry Transfer Facility tendering the Shares
which are the subject of such Book-Entry Confirmation, that such participant has
received and agrees to be bound by the terms of the Letter of Transmittal and
that Purchaser may enforce such agreement against such participant.
 
     On November 18, 1994, Parent filed with the Federal Trade Commission (the
"FTC") and the Antitrust Division of the Department of Justice (the "Antitrust
Division") a Premerger Notification and Report Form under the HSR Act with
respect to the Offer. Accordingly, it is anticipated that the waiting period
under the HSR Act applicable to the Offer will expire at 11:59 p.m., New York
City time, on December 3, 1994. Prior to the expiration or termination of such
waiting period, the FTC or the Antitrust Division may extend such waiting period
by requesting additional information from Parent with respect to the Offer. If
such a request is made with respect to the purchase of Shares in the Offer, the
waiting period will expire at 11:59 p.m., New York City time, on the tenth
calendar day after substantial compliance by Parent with such a request.
Thereafter, the waiting period may only be extended by court order. The waiting
period under the HSR Act may be terminated prior to its expiration by the FTC
and the Antitrust Division. Parent has requested early termination of the
waiting period, although there can be no assurance that this request will be
granted. See Section 15 for additional information regarding the HSR Act.
 
     For purposes of the Offer, Purchaser will be deemed to have accepted for
payment (and thereby purchased) Shares validly tendered and not properly
withdrawn, if and when Purchaser gives oral or written notice to the Depositary
of Purchaser's acceptance for payment of such Shares pursuant to the Offer. Upon
the terms and subject to the conditions of the Offer, payment for Shares
accepted for payment pursuant to the Offer will be made by deposit of the
purchase price therefor with the Depositary, which will act as agent for
tendering stockholders for the purpose of receiving payments from Purchaser and
transmitting such payments to tendering stockholders whose Shares have been
accepted for payment. UNDER NO CIRCUMSTANCES WILL INTEREST ON THE PURCHASE PRICE
FOR THE SHARES BE PAID, REGARDLESS OF ANY DELAY IN MAKING SUCH PAYMENT.
 
                                        6
<PAGE>   7
 
     If any tendered Shares are not accepted for payment pursuant to the terms
and conditions of the Offer for any reason, or if Share Certificates are
submitted evidencing more Shares than are tendered, Share Certificates
evidencing unpurchased Shares will be returned, without expense to the tendering
stockholder (or, in the case of Shares tendered by book-entry transfer into the
Depositary's account at a Book-Entry Transfer Facility pursuant to the procedure
set forth in Section 3, such Shares will be credited to an account maintained at
such Book-Entry Transfer Facility), as promptly as practicable following the
expiration or termination of the Offer.
 
     Purchaser reserves the right to transfer or assign, in whole or from time
to time in part, to one or more of its affiliates, the right to purchase all or
any portion of the Shares tendered pursuant to the Offer, but any such transfer
or assignment will not relieve Purchaser of its obligations under the Offer and
will in no way prejudice the rights of tendering stockholders to receive payment
for Shares validly tendered and accepted for payment pursuant to the Offer.
 
     3. PROCEDURES FOR ACCEPTING THE OFFER AND TENDERING SHARES. In order for a
holder of Shares validly to tender Shares pursuant to the Offer, the Letter of
Transmittal (or a facsimile thereof), properly completed and duly executed,
together with any required signature guarantees or an Agent's Message in
connection with a book-entry delivery of Shares and any other documents required
by the Letter of Transmittal, must be received by the Depositary at its address
set forth on the back cover of this Offer to Purchase and either (i) the Share
Certificates evidencing tendered Shares must be received by the Depositary at
such address or such Shares must be tendered pursuant to the procedure for
book-entry transfer described below and a Book-Entry Confirmation must be
received by the Depositary, in each case prior to the Expiration Date or (ii)
the tendering stockholder must comply with the guaranteed delivery procedures
described below.
 
     THE METHOD OF DELIVERY OF SHARE CERTIFICATES AND ALL OTHER REQUIRED
DOCUMENTS, INCLUDING DELIVERY THROUGH ANY BOOK-ENTRY TRANSFER FACILITY, IS AT
THE OPTION AND SOLE RISK OF THE TENDERING STOCKHOLDER, AND THE DELIVERY WILL BE
DEEMED MADE ONLY WHEN ACTUALLY RECEIVED BY THE DEPOSITARY. IF DELIVERY IS BY
MAIL, REGISTERED MAIL WITH RETURN RECEIPT REQUESTED, PROPERLY INSURED, IS
RECOMMENDED. IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO ENSURE TIMELY
DELIVERY.
 
     Book-Entry Transfer. The Depositary will establish accounts with respect to
the Shares at the Book-Entry Transfer Facilities for purposes of the Offer
within two business days after the date of this Offer to Purchase. Any financial
institution that is a participant in the system of any Book-Entry Transfer
Facility may make a book-entry delivery of Shares by causing such Book-Entry
Transfer Facility to transfer such Shares into the Depositary's account at such
Book-Entry Transfer Facility in accordance with such Book-Entry Transfer
Facility's procedures for such transfer. However, although delivery of Shares
may be effected through book-entry transfer at a Book-Entry Transfer Facility,
the Letter of Transmittal (or a facsimile thereof), properly completed and duly
executed, together with any required signature guarantees or an Agent's Message
in connection with a book-entry transfer and any other required documents, must,
in any case, be received by the Depositary at its address set forth on the back
cover of this Offer to Purchase prior to the Expiration Date, or the tendering
stockholder must comply with the guaranteed delivery procedure described below.
DELIVERY OF DOCUMENTS TO A BOOK-ENTRY TRANSFER FACILITY DOES NOT CONSTITUTE
DELIVERY TO THE DEPOSITARY.
 
     Signature Guarantees. Signatures on all Letters of Transmittal must be
guaranteed by a bank, broker, dealer, credit union, savings association or other
entity that is a member in good standing of a recognized Medallion Program
approved by The Securities Transfer Association, Inc. (each of the foregoing
being referred to as an "Eligible Institution"), except in cases where Shares
are tendered (i) by a registered holder of Shares who has not completed either
the box entitled "Special Payment Instructions" or the box entitled "Special
Delivery Instructions" on the Letter of Transmittal or (ii) for the account of
an Eligible Institution. If a Share Certificate is registered in the name of a
person other than the signer of the Letter of Transmittal, or if payment is to
be made, or a Share Certificate not accepted for payment or not tendered is to
be returned, to a person other than the registered holder(s), then the Share
Certificate must be endorsed or accompanied by
 
                                        7
<PAGE>   8
 
appropriate stock powers, in either case signed exactly as the name(s) of the
registered holder(s) appear on the Share Certificate, with the signature(s) on
such Share Certificate or stock powers guaranteed by an Eligible Institution.
See Instructions 1 and 5 of the Letter of Transmittal.
 
     Guaranteed Delivery. If a stockholder desires to tender Shares pursuant to
the Offer and such stockholder's Share Certificates evidencing such Shares are
not immediately available or such stockholder cannot deliver the Share
Certificates and all other required documents to the Depositary prior to the
Expiration Date, or such stockholder cannot complete the procedure for delivery
by book-entry transfer on a timely basis, such Shares may nevertheless be
tendered, provided that all the following conditions are satisfied:
 
          (i) such tender is made by or through an Eligible Institution;
 
          (ii) a properly completed and duly executed Notice of Guaranteed
     Delivery, substantially in the form made available by Purchaser, is
     received prior to the Expiration Date by the Depositary as provided below;
     and
 
          (iii) the Share Certificates (or a Book-Entry Confirmation) evidencing
     all tendered Shares, in proper form for transfer, in each case together
     with the Letter of Transmittal (or a facsimile thereof), properly completed
     and duly executed, with any required signature guarantees (or, in the case
     of book-entry transfer, an Agent's Message), and any other documents
     required by the Letter of Transmittal are received by the Depositary within
     five Nasdaq National Market trading days after the date of execution of
     such Notice of Guaranteed Delivery.
 
     The Notice of Guaranteed Delivery may be delivered by hand or mail or
transmitted by telegram, telex or facsimile transmission to the Depositary and
must include a guarantee by an Eligible Institution in the form set forth in the
form of Notice of Guaranteed Delivery made available by Purchaser.
 
     In all cases, payment for Shares tendered and accepted for payment pursuant
to the Offer will be made only after timely receipt by the Depositary of the
Share Certificates evidencing such Shares, or a Book-Entry Confirmation of the
delivery of such Shares, and the Letter of Transmittal (or a facsimile thereof),
properly completed and duly executed, with any required signature guarantees,
and any other documents required by the Letter of Transmittal. Accordingly,
payment might not be made to all tendering stockholders at the same time and
will depend upon when Share Certificates or Book-Entry Confirmations with
respect to such Shares are received into the Depositary's account at a
Book-Entry Transfer Facility.
 
     Other Requirements. By executing the Letter of Transmittal as set forth
above, a tendering stockholder irrevocably appoints designees of Purchaser as
such stockholder's proxies, each with full power of substitution, in the manner
set forth in the Letter of Transmittal, to the full extent of such stockholder's
rights with respect to the Shares tendered by such stockholder and accepted for
payment by Purchaser (and with respect to any and all other Shares or other
securities issued or issuable in respect of such Shares on or after November 17,
1994). All such proxies shall be considered coupled with an interest in the
tendered Shares. Such appointment will be effective when, and only to the extent
that, Purchaser accepts such Shares for payment. Upon such Acceptance for
payment, all prior proxies given by such stockholder with respect to such Shares
(and such other Shares and securities) will be revoked without further action,
and no subsequent proxies may be given nor any subsequent written consent
executed by such stockholder (and, if given or executed, will not be deemed to
be effective) with respect thereto. The designees of Purchaser will, with
respect to the Shares for which the appointment is effective, be empowered to
exercise all voting and other rights of such stockholder as they in their sole
discretion may deem proper at any annual or special meeting of the Company's
stockholders or any adjournment or postponement thereof, by written consent in
lieu of any such meeting or otherwise. Purchaser reserves the right to require
that, in order for Shares to be deemed validly tendered, Purchaser must be able
to exercise full voting rights with respect to such Shares immediately upon
Purchaser's payment for such Shares.
 
     The acceptance for payment by Purchaser of Shares pursuant to any of the
procedures described above will constitute a binding agreement between the
tendering stockholder and Purchaser upon the terms and subject to the conditions
of the Offer.
 
                                        8
<PAGE>   9
 
     UNDER THE FEDERAL INCOME TAX LAWS, UNLESS AN EXCEPTION APPLIES UNDER THE
APPLICABLE LAWS AND REGULATIONS, THE DEPOSITARY WILL BE REQUIRED TO WITHHOLD 31%
OF THE AMOUNT OF ANY PAYMENTS MADE TO STOCKHOLDERS PURSUANT TO THE OFFER. TO
PREVENT BACKUP FEDERAL INCOME TAX WITHHOLDING WITH RESPECT TO PAYMENT TO CERTAIN
STOCKHOLDERS OF THE PURCHASE PRICE OF SHARES PURCHASED PURSUANT TO THE OFFER,
EACH SUCH STOCKHOLDER MUST PROVIDE THE DEPOSITARY WITH SUCH STOCKHOLDER'S
CORRECT TAXPAYER IDENTIFICATION NUMBER AND CERTIFY THAT SUCH STOCKHOLDER IS NOT
SUBJECT TO BACKUP FEDERAL INCOME TAX WITHHOLDING BY COMPLETING THE SUBSTITUTE
FORM W-9 IN THE LETTER OF TRANSMITTAL. SEE INSTRUCTION 10 OF THE LETTER OF
TRANSMITTAL.
 
     Determination of Validity. All questions as to the validity, form,
eligibility (including time of receipt) and acceptance for payment of any tender
of Shares will be determined by Purchaser in its sole discretion, which
determination shall be final and binding on all parties. Purchaser reserves the
absolute right to reject any and all tenders determined by it not to be in
proper form or the acceptance for payment of which may, in the opinion of its
counsel, be unlawful. Purchaser also reserves the absolute right (but subject to
the terms and conditions of the Merger Agreement) to waive any condition of the
Offer, or any defect or irregularity in the tender of any Shares of any
particular stockholder, whether or not similar defects or irregularities are
waived in the case of other stockholders. No tender of shares will be deemed to
have been validly made until all defects and irregularities have been cured or
waived. None of Purchaser, Parent, the Dealer Manager, the Depositary, the
Information Agent or any other person will be under any duty to give
notification of any defects or irregularities in tenders or incur any liability
for failure to give any such notification. Purchaser's interpretation of the
terms and conditions of the Offer (including the Letter of Transmittal and the
instructions thereto) will be final and binding.
 
     4. WITHDRAWAL RIGHTS. Tenders of Shares made pursuant to the Offer are
irrevocable except that such Shares may be withdrawn at any time prior to the
Expiration Date and, unless theretofore accepted for payment by Purchaser
pursuant to the Offer, may also be withdrawn at any time after January 21, 1995.
If Purchaser extends the Offer, is delayed in its acceptance for payment of
Shares or is unable to accept Shares for payment pursuant to the Offer for any
reason, then, without prejudice to Purchaser's rights under the Offer, the
Depositary may, nevertheless, on behalf of Purchaser, retain tendered Shares,
and such Shares may not be withdrawn except to the extent that tendering
stockholders are entitled to withdrawal rights as described in this Section 4.
Any such delay will be by an extension of the Offer to the extent required by
law.
 
     For a withdrawal to be effective, a written, telegraphic or facsimile
transmission notice of withdrawal must be timely received by the Depositary at
its address set forth on the back cover page of this Offer to Purchase. Any such
notice of withdrawal must specify the name of the person who tendered the Shares
to be withdrawn, the number of Shares to be withdrawn and the name of the
registered holder of such Shares, if different from that of the person who
tendered such Shares. If Share Certificates evidencing Shares to be withdrawn
have been delivered or otherwise identified to the Depositary, then, prior to
the physical release of such Share Certificates, the serial numbers shown on
such Share Certificates must be submitted to the Depositary and the signature(s)
on the notice of withdrawal must be guaranteed by an Eligible Institution,
unless such Shares have been tendered for the account of an Eligible
Institution. If Shares have been tendered pursuant to the procedure for
book-entry transfer as set forth in Section 3, any notice of withdrawal must
specify the name and number of the account at the Book-Entry Transfer Facility
to be credited with the withdrawn Shares.
 
     All questions as to the form and validity (including time of receipt) of
any notice of withdrawal will be determined by Purchaser, in its sole
discretion, whose determination will be final and binding. None of Purchaser,
Parent, the Dealer Manager, the Depositary, the Information Agent or any other
person will be under any duty to give notification of any defects or
irregularities in any notice of withdrawal or incur any liability for failure to
give any such notification.
 
                                        9
<PAGE>   10
 
     Any Shares properly withdrawn will thereafter be deemed not to have been
validly tendered for purposes of the Offer. However, withdrawn Shares may be
re-tendered at any time prior to the Expiration Date by following one of the
procedures described in Section 3.
 
     5. CERTAIN FEDERAL INCOME TAX CONSEQUENCES. The following summary, based
upon current law, is a general discussion of certain federal income tax
consequences of the Offer and the Merger to the stockholders of the Company.
This summary is based upon the Internal Revenue Code of 1986, as amended (the
"Code"), applicable Treasury regulations thereunder and administrative rulings
and judicial authority as of the date hereof. All of the foregoing are subject
to change, and any such change could affect the continuing validity of this
summary. This summary does not discuss all aspects of federal income taxation
that may be relevant to particular stockholders of the Company in light of such
stockholders' specific circumstances or to certain types of stockholders subject
to special treatment under the federal income tax laws (for example, foreign
persons, dealers in securities, banks, insurance companies, tax-exempt
organizations and stockholders who acquired Shares pursuant to the exercise of
options or otherwise as compensation or through a tax-qualified retirement
plan), and it does not discuss any aspect of state, local, foreign or other tax
laws.
 
     The receipt of cash for Shares pursuant to the Offer or the Merger will be
a taxable transaction for federal income tax purposes under the Code. In
general, a stockholder will recognize gain or loss equal to the difference
between the stockholder's tax basis in the Shares sold and the amount of any
cash received in exchange therefor. Such gain or loss will be a capital gain or
loss if the Shares sold were held as a capital asset and will be long-term
capital gain or loss if the Shares were held for more than one year.
 
     Backup Withholding. To prevent "backup withholding" of federal income tax
on payments of cash to a stockholder of the Company who exchanges Shares for
cash in the Offer or the Merger, a stockholder of the Company must, unless an
exception applies under the applicable law and regulations, provide the
Substitute Form W-9 and certify under penalties of perjury that such number is
correct and that such stockholder is not subject to backup withholding. A
Substitute Form W-9 is included in the Letter of Transmittal. If the correct
taxpayer identification number and certifications are not provided, a $50
penalty may be imposed on a stockholder of the Company by the Internal Revenue
Service, and cash received by such stockholder in exchange for Shares in the
Offer may be subject to backup withholding of 31%.
 
     Alternative Minimum Tax. Stockholders should consult their own tax advisors
as to the applicability and effect of the alternative minimum tax to gain
recognized upon sale of the Shares in the Offer or the Merger.
 
     THE FEDERAL INCOME TAX CONSEQUENCES SET FORTH ABOVE ARE BASED UPON PRESENT
LAW, ARE FOR GENERAL INFORMATION ONLY AND DO NOT PURPORT TO BE A COMPLETE
ANALYSIS OR LISTING OF ALL POTENTIAL TAX EFFECTS AS APPLICABLE TO A PARTICULAR
STOCKHOLDER OF THE COMPANY. EACH STOCKHOLDER IS URGED TO CONSULT SUCH
STOCKHOLDER'S OWN TAX ADVISOR TO DETERMINE THE PARTICULAR TAX CONSEQUENCES TO
SUCH STOCKHOLDER OF THE OFFER AND THE MERGER (INCLUDING THE APPLICABILITY AND
EFFECT OF FEDERAL, STATE, LOCAL, FOREIGN AND OTHER TAX LAWS). THE FOREGOING
DISCUSSION MAY NOT BE APPLICABLE WITH RESPECT TO SHARES RECEIVED PURSUANT TO THE
EXERCISE OF EMPLOYEE OR DIRECTOR STOCK OPTIONS OR OTHERWISE AS COMPENSATION OR
WITH RESPECT TO STOCKHOLDERS WHO ARE NOT CITIZENS OR RESIDENTS OF THE UNITED
STATES.
 
                                       10
<PAGE>   11
 
     6. PRICE RANGE OF SHARES. The Shares are traded on the Nasdaq National
Market under the symbol SYGN. The following table sets forth for the periods
indicated the high and low sale prices for the Shares as reported on the Nasdaq
National Market.
 
<TABLE>
<CAPTION>
                                CALENDAR YEAR                      HIGH       LOW
            -----------------------------------------------------  ----       ---
            <S>                                                    <C>        <C>
            1992
              First Quarter......................................  $ 75       $43 1/4
              Second Quarter.....................................    50 1/2    31 3/4
              Third Quarter......................................    55 3/4    41 1/4
              Fourth Quarter.....................................    66 1/4    36 3/4
            1993
              First Quarter......................................    65         9 7/8
              Second Quarter.....................................    13 1/2     8
              Third Quarter......................................    13         9 1/4
              Fourth Quarter.....................................    16 1/4    10
            1994
              First Quarter......................................    14 3/8     9 5/8
              Second Quarter.....................................    10 7/8     7 1/2
              Third Quarter......................................     9         3 7/8
              Fourth Quarter (through November 22)...............     9 13/32   4 3/8
</TABLE>
 
     On November 17, 1994, the last full trading day prior to the announcement
of the execution of the Merger Agreement and of Purchaser's intention to
commence the Offer, the high sale price per Share as reported on the Nasdaq
National Market was $5 5/8. On November 22, 1994, the last full trading day
prior to the commencement of the Offer, the high sale price per Share as
reported on the Nasdaq National Market was $9 3/32. STOCKHOLDERS ARE URGED TO
OBTAIN A CURRENT MARKET QUOTATION FOR THE SHARES.
 
     The Company paid no cash dividends on the Shares in the above-referenced
quarters. Moreover, the Company stated in its Form 10-K for the year ending
December 31, 1993 that it did not anticipate making dividend payments in the
near future.
 
     7. CERTAIN INFORMATION CONCERNING THE COMPANY. Except as otherwise set
forth herein, the information concerning the Company contained in this Offer to
Purchase, including financial information, has been furnished by the Company or
has been taken from or based upon publicly available documents and records on
file with the Commission and other public sources. Neither Purchaser nor Parent
assumes any responsibility for the accuracy or completeness of the information
concerning the Company furnished by the Company or contained in such documents
and records or for any failure by the Company to disclose events which may have
occurred or may affect the significance or accuracy of any such information but
which are unknown to Purchaser or Parent.
 
     General. The Company is a Delaware corporation with its principal executive
offices located at 1885 33rd Street, Boulder, Colorado. The Company is a
biopharmaceutical company engaged in the discovery, development and manufacture
of protein-based pharmaceuticals. The Company's research and development efforts
are focused primarily on inflammatory diseases and neurological disorders. The
Company's principal product candidates address diseases affecting patient
populations that cannot be treated satisfactorily with existing therapies.
 
     Financial Information. Set forth below is certain selected consolidated
financial information relating to the Company and its subsidiaries which has
been excerpted or derived from the audited financial statements contained in the
Company's Annual Reports on Form 10-K for the fiscal years ended December 31,
1993 and December 31, 1992 and the unaudited financial statements contained in
the Company's Quarterly Report on Form 10-Q for the quarter ended September 30,
1994. More comprehensive financial information is included in the Company's
Annual Reports on Form 10-K, and its Quarterly Report on Form 10-Q and other
documents filed by the Company with the Commission. The financial information
that follows is qualified in its entirety by reference to such reports and other
documents, including the financial statements and related notes contained
therein. Such reports and other documents may be examined at, and copies may be
obtained from, the offices of the Commission in the manner set forth below.
 
                                       11
<PAGE>   12
 
                                 SYNERGEN, INC.
 
                  SUMMARY SELECTED CONSOLIDATED FINANCIAL DATA
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                             NINE MONTHS ENDED
                                               SEPTEMBER 30,           YEAR ENDED DECEMBER 31,
                                            -------------------     ------------------------------
                                              1994       1993         1993       1992       1991
                                            --------   --------     --------   --------   --------
                                                (UNAUDITED)
<S>                                         <C>        <C>          <C>        <C>        <C>
Operating Data:
Revenue:
  Research and development................  $ 10,781   $ 10,112     $ 13,180   $ 31,634   $14,243
  Interest and other......................     4,003      7,629       10,306     19,775     9,579
                                            --------   --------     --------   --------   --------
                                              14,784     17,741       23,486     51,409    23,822
Expenses:
  Research and development................    53,192     66,602       88,249     60,264    24,101
  General and administrative..............    13,062     13,752       16,986     13,935     6,368
  Purchase of in-process research and
     development..........................        --         --           --     18,100        --
  Restructuring charge....................    39,079      2,000        2,000         --        --
  Interest................................       132        357          447        352       473
                                            --------   --------     --------   --------   --------
                                             105,466     82,711      107,682     92,651    30,942
                                            --------   --------     --------   --------   --------
  Loss before cumulative effect of change
     in accounting principle..............   (90,681)   (64,970)     (84,196)   (41,242)   (7,120 )
  Cumulative effect of change in
     accounting principle.................        --     (2,418)      (2,418)        --        --
                                            --------   --------     --------   --------   --------
  Net loss................................  $(90,681)  $(67,388)    $(86,614)  $(41,242)  $(7,120 )
                                            ========   ========     ========   ========   ========
Net loss per share:
  Loss before cumulative effect of change
     in accounting principle..............  $  (3.52)  $  (2.58)    $  (3.33)  $  (1.66)  $  (.36 )
  Cumulative effect of change in
     accounting principle.................        --       (.09)        (.09)        --        --
                                            --------   --------     --------   --------   --------
  Net loss per share......................  $  (3.52)  $  (2.67)    $  (3.42)  $  (1.66)  $  (.36 )
                                            ========   ========     ========   ========   ========
  Weighted Average Common Shares
     Outstanding..........................    25,747     25,164       25,309     24,805    19,529
                                            ========   ========     ========   ========   ========
</TABLE>
 
<TABLE>
<CAPTION>
                                                                             DECEMBER 31,
                                               SEPTEMBER 30,        ------------------------------
                                                   1994              1993       1992       1991
                                            -------------------     --------   --------   --------
                                                (UNAUDITED)         
<S>                                             <C>                 <C>        <C>        <C>
Balance Sheet Data:(1)
  Cash and investments(2).................        $119,704          $160,846   $243,029   $324,281
  Total assets............................         188,062           276,058    359,346    374,468
  Long-term debt..........................           6,000             6,000      6,000      6,000
  Stockholders' equity....................          70,523           258,829    341,722    361,130
</TABLE>
 
- ---------------
 
(1) No cash dividends were declared or paid during any of the periods presented.
 
(2) Includes restricted investment securities of $8,453 at September 30, 1994
    and $4,630, $4,499, and $3,015 at December 31, 1993, 1992 and 1991,
    respectively.
 
     The Company is subject to the informational filing requirements of the
Exchange Act and, in accordance therewith, is required to file periodic reports,
proxy statements and other information with the Commission relating to its
business, financial condition and other matters. Information as of particular
dates concerning the Company's directors and officers, their remuneration, stock
options granted to them, the principal holders of
 
                                       12
<PAGE>   13
 
the Company's securities and any material interest of such persons in
transactions with the Company is required to be disclosed in proxy statements
distributed to the Company's stockholders and filed with the Commission. Such
reports, proxy statements and other information should be available for
inspection at the public reference facilities maintained by the Commission at
Judiciary Plaza, 450 Fifth Street, N.W., Room 1024, Washington, D.C. 20549, and
also should be available for inspection at the Commission's regional offices
located at 7 World Trade Center, 13th Floor, New York, New York 10048 and the
Northwestern Atrium Center, 500 West Madison Street, Suite 1400, Chicago,
Illinois 60661. Copies of such materials may also be obtained by mail, upon
payment of the Commission's customary fees, by writing to its principal office
at Judiciary Plaza, 450 Fifth Street, N.W., Washington, D.C. 20549.
 
     8. CERTAIN INFORMATION CONCERNING PURCHASER AND PARENT. Purchaser is a
newly incorporated Delaware corporation organized in connection with the Offer
and the Merger and has not carried on any activities other than in connection
with the Offer and the Merger. The principal offices of Purchaser are located at
Amgen Center, 1840 DeHavilland Drive, Thousand Oaks, California 91320-1789.
Purchaser is a wholly owned subsidiary of Parent.
 
     Until immediately prior to the time that Purchaser will purchase Shares
pursuant to the Offer, it is not anticipated that Purchaser will have any
significant assets or liabilities or engage in activities other than those
incident to its formation and capitalization and the transactions contemplated
by the Offer and the Merger. Because Purchaser is newly formed and has minimal
assets and capitalization, no meaningful financial information regarding
Purchaser is available.
 
     Parent is a Delaware corporation. Its principal offices are located at
Amgen Center, 1840 DeHavilland Drive, Thousand Oaks, California 91320-1789.
Parent is a global biotechnology company that develops, manufactures and markets
human therapeutics based upon advanced cellular and molecular biology. Utilizing
proprietary recombinant DNA technology, Parent has developed several human
biopharmaceutical products and currently manufactures and markets NEUPOGEN(R)
(Filgrastim), a product that selectively stimulates the production of
neutrophils, a class of infection-fighting white blood cells, and EPOGEN(R)
(Epoetin alfa), which stimulates and regulates production of red blood cells.
Parent focuses its research and development efforts in the areas of
hematopoiesis, neurobiology, inflammation/auto-immune diseases and soft tissue
repair and regeneration. Parent operates research facilities in the United
States and Canada, has clinical development staff in the United States, Europe,
Canada, Australia, Japan and Hong Kong, manufactures NEUPOGEN(R) and EPOGEN(R)
in its facilities in the United States and has a fill and finish facility in
Puerto Rico which is currently awaiting approval by regulatory bodies.
 
     The name, citizenship, business address, principal occupation or
employment, and five-year employment history for each of the directors and
executive officers of Purchaser and Parent and certain other information are set
forth in Schedule I hereto.
 
     Set forth below are certain selected consolidated financial data relating
to Parent and its subsidiaries for Parent's last three fiscal years, which have
been excerpted or derived from the audited financial statements contained in
Parent's Annual Report on Form 10-K for the fiscal year ended December 31, 1993
and December 31, 1992 and from the unaudited financial statements contained in
Parent's Quarterly Report on Form 10-Q for the fiscal quarter ended September
30, 1994, in each case filed by Parent with the Commission. More comprehensive
financial information is included in such reports and other documents filed by
Parent with the Commission, and the following financial data is qualified in its
entirety by reference to such reports and other documents, including the
financial information and related notes contained therein. Such reports and
other documents may be inspected and copies may be obtained from the offices of
the Commission in the same manner as set forth with respect to information about
the Company in Section 7.
 
                                       13
<PAGE>   14
 
                                   AMGEN INC.
 
                  SUMMARY SELECTED CONSOLIDATED FINANCIAL DATA
                      (IN MILLIONS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                                 NINE MONTHS ENDED
                                                   SEPTEMBER 30,          YEAR ENDED DECEMBER 31,
                                                -------------------     ----------------------------
                                                  1994       1993         1993       1992      1991
                                                --------   --------     --------   --------   ------
                                                    (UNAUDITED)
<S>                                             <C>        <C>          <C>        <C>        <C>
Consolidated Statement of Operations Data:
Revenues:
  Product sales...............................  $1,136.0   $  959.0     $1,306.3   $1,050.7   $645.3
  Other revenues..............................      69.0       49.2         67.5       42.3     36.7
Total revenues................................   1,205.0    1,008.2      1,373.8    1,093.0    682.0
Cost of sales.................................     176.8      162.7        220.0      184.7    112.7
Research and development expenses.............     235.5      183.8        255.3      182.3    120.9
Marketing and selling expenses................     174.7      151.4        214.1      184.5    122.2
General and administrative expenses...........      90.4       83.8        114.3      107.6     80.4
Loss/(earnings) of affiliates, net............      25.7       10.2         12.6      (16.9)   (19.5)
Legal (award)/assessment......................        --      (13.9)       (13.9)     (77.1)   129.1
Total other income............................      (7.3)     (14.7)       (21.0)     (35.2)   (21.8)
Provision for income taxes....................     194.3      161.4        217.8      205.5     60.1
Net income(1).................................     314.9      292.2        383.3      357.6     97.9
Primary earnings per share(1).................      2.25       2.03         2.67       2.43      .67
Cash dividends declared per share.............        --         --           --         --       --
</TABLE>
 
<TABLE>
<CAPTION>
                                                 AT SEPTEMBER 30,             AT DECEMBER 31,
                                                       1994             ----------------------------
                                                -------------------       1993       1992      1991
                                                    (UNAUDITED)         --------   --------   ------
<S>                                             <C>        <C>          <C>        <C>        <C>
Consolidated Balance Sheet Data:
  Working capital.............................        $ 734.9           $  642.2   $  562.4   $294.9
  Total assets................................        1,892.5            1,765.5    1,374.3    865.5
  Long-term debt..............................         185.9               181.2      129.9     39.7
  Stockholders' equity........................        1,321.6            1,172.0      933.7    531.1
</TABLE>
 
- ---------------
 
(1) Includes an increase to net income of $8.7 million, or $.06 per share to
    reflect the cumulative effect of a change in accounting principles to adopt
    Statement of Financial Accounting Standard No. 109 in the 1993 period.
 
     Except as described in this Offer to Purchase, (i) none of Purchaser,
Parent nor, to the best knowledge of Purchaser and Parent, any of the persons
listed in Schedule I to this Offer to Purchase or any associate or
majority-owned subsidiary of Purchaser, Parent or any of the persons so listed
beneficially owns or has any right to acquire, directly or indirectly, any
Shares and (ii) none of Purchaser, Parent nor, to the best knowledge of
Purchaser and Parent, any of the persons or entities referred to above nor any
director, executive officer or subsidiary of any of the foregoing has effected
any transaction in the Shares during the past 60 days.
 
     Except as provided in the Merger Agreement and as otherwise described in
this Offer to Purchase, none of Purchaser, Parent nor, to the best knowledge of
Purchaser and Parent, any of the persons listed in Schedule I to this Offer to
Purchase, has any contract, arrangement, understanding or relationship with any
other person with respect to any securities of the Company, including, but not
limited to, any contract, arrangement, understanding or relationship concerning
the transfer or voting of such securities, joint ventures, loan or option
arrangements, puts or calls, guaranties of loans, guaranties against loss or the
giving or withholding of proxies. Except as set forth in this Offer to Purchase,
since January 1, 1991, neither Purchaser nor Parent nor, to the best knowledge
of Purchaser and Parent, any of the persons listed on Schedule I hereto,
 
                                       14
<PAGE>   15
 
has had any business relationship or transaction with the Company or any of its
executive officers, directors or affiliates that is required to be reported
under the rules and regulations of the Commission applicable to the Offer.
Except as set forth in this Offer to Purchase, since January 1, 1991, there have
been no contacts, negotiations or transactions between any of Purchaser, Parent,
or any of their respective subsidiaries or, to the best knowledge of Purchaser
and Parent, any of the persons listed in Schedule I to this Offer to Purchase,
on the one hand, and the Company or its affiliates, on the other hand,
concerning a merger, consolidation or acquisition, tender offer or other
acquisition of securities, an election of directors or a sale or other transfer
of a material amount of assets.
 
     9. FINANCING OF THE OFFER AND THE MERGER. The total amount of funds
required by Purchaser to consummate the Offer and the Merger and to pay related
fees and expenses is estimated to be approximately $255,000,000. Purchaser will
obtain all of such funds from Parent. Parent will provide such funds from its
working capital.
 
     10. BACKGROUND OF THE OFFER; CONTACTS WITH THE COMPANY AND THE MERGER
AGREEMENT.
 
     During a period of approximately five years preceding July 1994, Parent and
the Company engaged in informal, preliminary conversations from time to time on
a variety of matters, including the possible licensing of the Company's product
candidates by Parent. None of those discussions proceeded beyond the informal,
preliminary stage.
 
     From June through November 1993 there were a series of telephone calls and
meetings in Boulder, Colorado between representatives of Parent and the Company
relating to Parent's interest in licensing certain of the Company's product
candidates and Parent's making a related equity investment in the Company. On
November 17, 1993 Mr. Gordon Binder, the Chairman and Chief Executive Officer of
Parent, Mr. Lowell Sears, then Senior Vice President and acting Chief Financial
Officer of Parent, and Ms. Kathleen Stafford, then Treasurer of Parent, and Dr.
Larry Soll, Chairman and then Chief Executive Officer of the Company, Mr.
Gregory Abbott, then an Executive Vice President of the Company, and Mr. Kenneth
Collins, Executive Vice President, Finance and Administration of the Company,
met in Los Angeles to continue senior level discussions of Parent's licensing of
the Company's product candidates. At such meeting representatives of the Company
proposed that Parent provide financial support for an extraordinary corporate
transaction which management of the Company was considering at the time. Parent
advised such representatives that it was not interested in such a proposal, and
no further discussions with respect to licensing were pursued at that time.
 
     In July 1994 Mr. Binder had a telephone conversation with Mr. Abbott
(President and Chief Executive Officer of the Company). During this
conversation, the chief executives of the two companies engaged in a general
discussion regarding the Company, the prospects of the Company and the
possibility of a transaction involving Parent and the Company.
 
     On August 2, 1994 Mr. Robert Attiyeh, Senior Vice President and Chief
Financial Officer of Parent, and Dr. Daniel Vapnek, Senior Vice President,
Research of Parent met at the Company's headquarters in Boulder, Colorado with
Mr. Abbott, Mr. Collins and Dr. Robert Thompson, Executive Vice President,
Research and Clinical Affairs of the Company. During the meeting, the executives
of the two companies engaged in a general discussion regarding the Company, the
prospects of the Company and the possibility of a transaction involving Parent
and the Company.
 
     Subsequent to the August 2, 1994 meeting representatives of the Company and
Parent engaged in a number of telephone conversations, and on August 22, 1994
Parent and the Company entered into a confidentiality agreement, which provided
among other things that any information exchanged would be held in confidence by
the receiving party and contained customary "standstill" commitments by Parent.
After execution of the confidentiality agreement, the Company provided
scientific, business and patent information to Parent. In addition, the Company
also provided Parent with estimates as to potential future sales of the
Company's leading product candidates. While Parent reviewed such estimates,
Parent did not take such estimates into account in valuing the Company and
relied instead on its own estimates of potential performance of the Company's
product candidates.
 
                                       15
<PAGE>   16
 
     On August 31, 1994 Dr. Vapnek, Dr. Bruce Altrock, Vice President Biology
and Biochemistry of Parent, Dr. Michael Bevilacqua, Vice President, Inflammation
and Medicinal Chemistry of Parent and Dr. Thomas Ulich, Vice President, Biology
of Parent, Dr. Thompson and Mr. Collins discussed by telephone the development
status of the Company's product candidates, including the results of animal
tests and human clinical trials, and the possibility of a transaction involving
Parent and Company.
 
     On October 7, 1994 and October 19, 1994 additional meetings occurred at the
Company's headquarters in Boulder, Colorado among technical, scientific and
clinical personnel of Parent and the Company. At these meetings, the Company's
product candidates, animal testing, human clinical trials, process development,
manufacturing research methodologies and research resources were discussed.
 
     On October 24, 1994 Mr. Binder and Mr. Kevin Sharer, President and Chief
Operating Officer of Parent met at the Company's headquarters with Messrs.
Abbott, and Collins, Dr. Thompson, Dr. Mark Young, Executive Vice President,
Technical Operations of the Company, and other scientific and business personnel
of the Company. At these meetings the Company's business and product candidates
were discussed, as well as the possibility of a transaction involving Parent and
Company.
 
     On November 3, 1994 a meeting between the Company and Parent took place in
Camarillo, California. Present at the meeting were Mr. Abbott, Mr. Collins and
Mr. Paul Koivuniemi, Vice President and General Counsel of the Company on behalf
of the Company, as well as representatives of Wilson, Sonsini, Goodrich & Rosati
("Wilson Sonsini"), counsel to the Company, and Morgan, Stanley & Co.
Incorporated ("Morgan Stanley"), the Company's financial advisor, and Messrs.
Binder, Sharer and Attiyeh and others on behalf of Parent, as well as
representatives of Latham & Watkins and Cooley Godward Castro Huddleson & Tatum
("Cooley Godward"), Parent's counsel, and representatives of CS First Boston,
Parent's financial advisor. At the meeting, Parent expressed its interest in
acquiring the Company and discussions took place regarding timing, potential
transaction structures and due diligence informational requirements. Although
the companies expressed their respective views as to price and had preliminary
discussions regarding certain conditions that Parent would require the Company
to satisfy before Parent would complete a potential transaction, no agreement
regarding any particular price or price range was reached. Nonetheless, the
representatives of the two companies agreed that Parent would send its
representatives to the Company from November 8 through November 11 for the
purpose of conducting a due diligence review of the Company and that Parent
would prepare a preliminary draft of a merger agreement which it would provide
to the Company.
 
     During the week of November 8, 1994 Parent sent business, financial,
scientific, manufacturing and legal personnel to the Company to conduct a due
diligence review of the Company. On Thursday, November 11, Parent furnished the
Company with an initial draft of a merger agreement which contemplated a cash
tender offer for all outstanding shares of Common Stock of the Company and on
Tuesday, November 15, a meeting was held at the offices of Latham & Watkins
involving representatives of Parent, the Company and their respective legal and
financial advisors to discuss the draft merger agreement. At the meeting, the
companies agreed on most of the terms of the merger agreement; however, the
companies deferred any discussion relating to the proposed price Parent would
pay for the Company's outstanding shares. The parties agreed to meet again in
the afternoon of Thursday, November 17, to finalize the merger agreement and to
determine if the companies could agree on price.
 
     Present at the November 17, 1994 meeting from Parent were Messrs. Binder,
Sharer and Attiyeh, as well as representatives of Latham & Watkins, Cooley
Godward and CS First Boston. Present from the Company were Messrs. Abbott,
Collins and Koivuniemi, as well as representatives of Wilson Sonsini and Morgan
Stanley. During such meeting there were extensive negotiations on price and
other material terms of a transaction. Following meetings of their respective
Boards of Directors, the companies agreed on a purchase price of $9.25 per share
for the Company's Common Stock and executed a definitive merger agreement as of
November 17, 1994.
 
THE MERGER AGREEMENT
 
     The following is a summary of the Merger Agreement, a copy of which is
filed as an Exhibit to the Tender Offer Statement on Schedule 14D-1 (the
"Schedule 14D-1") filed by Purchaser and Parent with the
 
                                       16
<PAGE>   17
 
Commission in connection with the Offer. Such summary is qualified in its
entirety by reference to the Merger Agreement.
 
     The Offer. The Merger Agreement provides that the obligations of Purchaser
to consummate the Offer and to accept for payment and pay for any of the Shares
tendered will be subject to certain conditions, including the Minimum Condition,
which are described in Section 14. The Offer will remain open for a minimum of
20 business days after commencement of the Offer, unless Purchaser extends the
Offer as permitted by the Merger Agreement.
 
     Pursuant to the Merger Agreement, Purchaser reserves the right to waive any
conditions to the Offer, other than the Minimum Condition, to increase the price
per Share payable in the Offer or to make any other changes in the terms and
conditions of the Offer; provided, however, that no such change may be made
which decreases the price per Share, changes the form of consideration payable
in the Offer, reduces the maximum number of Shares to be purchased in the Offer,
imposes conditions to the Offer in addition to those described in Section 14
hereof or amends any other material term of the Offer in a manner materially
adverse to the Company's stockholders without the Company's prior written
consent; provided, further, however, that notwithstanding the foregoing
Purchaser may waive the Minimum Condition if Purchaser, after consultation with
the Company, upon consummation of the Offer, accepts for payment and pays for a
majority of the Shares outstanding at the time of such consummation.
 
     The Merger Agreement further provides that the Offer may not, without the
Company's prior written consent, be extended, except as necessary to provide
time to satisfy the conditions described in Section 14 hereof; provided,
however, that Purchaser may extend (and re-extend) the Offer for up to a total
of 10 business days, if as of the initial Expiration Date there will not have
been validly tendered and not withdrawn at least 90% of the outstanding Shares
so that the Merger can be effected without a meeting of the Company's
stockholders in accordance with Delaware Law. Purchaser has agreed that if all
conditions described in Section 14 hereof are satisfied on the initial
Expiration Date, other than the Minimum Condition or the condition described in
paragraph (b) of Section 14 hereof, Purchaser will extend (and re-extend) the
Offer for up to a maximum of 20 business days to provide time to satisfy either
such conditions, so long as all other conditions remain satisfied.
 
     Board of Directors. The Merger Agreement provides that promptly upon the
acceptance for payment and payment by Purchaser of such number of Shares which
satisfies the Minimum Condition, Parent will be entitled to designate a majority
of the members of the Board. The directors of Purchaser immediately prior to the
Effective Time will be the initial directors of the Surviving Corporation.
 
     The Merger. The Merger Agreement provides that at the Effective Time the
Company will be merged with Purchaser, and each then outstanding Share (other
than Shares held by Parent, Purchaser, the Company or any of their respective
subsidiaries (which Shares shall be canceled), or by holders who properly
exercise and perfect stockholder appraisal rights under Delaware Law) will be
converted into the right to receive in cash, without interest, the highest price
per Share paid pursuant to the Offer.
 
     Pursuant to the Merger Agreement, following the purchase of Shares pursuant
to the Offer, the approval (if required) of the Merger Agreement by the
stockholders of the Company and the satisfaction or waiver of the other
conditions to the Merger, Purchaser will be merged into the Company, the
separate existence of Purchaser will cease and the Company will continue, under
its name, as the Surviving Corporation. The Merger Agreement also provides that
Parent may elect to structure the Merger so that the Company will be merged into
Purchaser, and Purchaser will continue as the Surviving Corporation.
 
     The Merger Agreement provides that all notes and other debt instruments of
the Company that are outstanding at the Effective Time will continue to be
outstanding subsequent to the Effective Time as debt instruments of the
Surviving Corporation, if permitted by their respective terms and provisions.
 
     Pursuant to the Merger Agreement, as promptly as practicable after the
Effective Time, each holder of a then outstanding employee or director stock
option (an "Option") to purchase Shares granted under any employee or director
plan of the Company prior to November 17, 1994 (other than Options held by any
director or executive officer of the Company that were granted (or deemed
granted) at any time on or after the
 
                                       17
<PAGE>   18
 
date that is six months prior to the Effective Time (the "Recent Insider
Options")) will be entitled (whether or not such Option is then exercisable) to
receive in consideration of cancellation of such Option (and any outstanding
stock appreciation right related thereto) a cash payment from the Company in an
amount equal to the difference between the Merger Consideration and the per
Share exercise price of such Option, multiplied by the number of Shares covered
by such Option. The Recent Insider Options will remain outstanding in accordance
with their terms and will not be affected in any way by the consummation of the
Merger.
 
     The Merger Agreement further provides that each outstanding warrant of the
Company will be unaffected by the Merger, except as otherwise provided in the
relevant warrant agreements. In general, such agreements provide that, in
connection with the transactions contemplated by the Offer, each outstanding
warrant shall represent the right to receive only the per Share Merger
Consideration upon payment by the holder thereof of the per Share exercise price
provided for in each such outstanding warrant.
 
     Certain Conditions to the Obligations of Each Party to Effect the
Merger. The Merger Agreement provides that the respective obligations of each
party to effect the Merger will be subject to the fulfillment at or prior to the
Effective Time of the following conditions: (i) if required by Delaware Law, the
Merger Agreement and the Merger will have been approved and adopted by the
requisite vote or consent of the stockholders of the Company, (ii) Shares will
have been purchased pursuant to the Offer and (iii) no preliminary or permanent
injunction or other order, decree or ruling issued by a court of competent
jurisdiction or by a governmental, regulatory or administrative agency or
commission nor any statute, rule, regulation or executive order promulgated or
enacted by any governmental authority will be in effect, which would make the
acquisition or holding by Parent, its subsidiaries or affiliates of the shares
of Common Stock of the Surviving Corporation illegal or otherwise prevent the
consummation of the Merger; provided, however, that the parties will have used
all reasonable efforts to prevent such event.
 
     Representations and Warranties. The Merger Agreement contains various
customary representations and warranties of the parties thereto, including
representations and warranties by the Company as to financial statements, public
filings, undisclosed liabilities, litigation, taxes, real property, employee
benefit plans, environmental matters, labor matters and intellectual property.
The Company has also represented to Purchaser and Parent that the Offer is a
Qualifying Offer (as defined below). See Section 16.
 
     Covenants. The Merger Agreement provides that, unless otherwise consented
to by Parent or unless the failure to comply with any of the following covenants
results from actions by the Board that are approved by a majority of the
directors appointed by Purchaser, between November 17, 1994 and the Effective
Time, the Company and its subsidiaries will conduct business only in the
ordinary course and consistent with past practices. The Merger Agreement further
provides that the Company (i) will use its reasonable efforts to maintain and
preserve its business organization, assets, employees, the United States Food
and Drug Administration (the "FDA") and equivalent regulatory agency licenses
and approvals, and United States Patent and Trademark Office and equivalent
agency filings and advantageous business relationships, (ii) will not (A) issue,
sell, pledge, transfer, dispose of or encumber, or authorize, propose or agree
to the issuance, sale, pledge, transfer, disposition or encumbrance of, any
shares of, or any options, warrants or rights of any kind to acquire any shares
of, or any securities convertible into or exchangeable for any shares of,
capital stock of any class of the Company or any of its subsidiaries, other than
Shares issuable upon exercise of Options or warrants outstanding prior to
November 17, 1994 and, consistent with past practices, in accordance with the
terms of applicable agreements and employee plans or (B) authorize, recommend or
propose any change in its capitalization, (iii) will not (A) except in the
ordinary course of business and consistent with past practices, sell, pledge,
transfer, assign, license, dispose of, encumber or lease any assets of the
Company or of any of its subsidiaries or (B) whether or not in the ordinary
course of business, sell, pledge, transfer, assign, license, dispose of,
encumber or lease any material assets of the Company and its subsidiaries, (iv)
will not (A) split, combine or reclassify any shares of its capital stock or
declare, set aside or pay any dividend or distribution, payable in cash, stock,
property or otherwise with respect to any of its capital stock, other than
dividends and distributions by a subsidiary of the Company to the Company or to
a subsidiary all of the capital stock of which is owned directly or indirectly
by the Company or (B) redeem, purchase or otherwise acquire or offer to redeem,
purchase or otherwise acquire any of its capital stock, (v) will not, except in
the ordinary course of business and consistent with past practices, acquire (by
merger, consolidation or acquisition of stock or assets)
 
                                       18
<PAGE>   19
 
any corporation, partnership or other business organization or division thereof
or make any investment either by purchase of stock or securities, contributions
to capital (other than to subsidiaries), property transfer or purchase of any
amount of property or assets, in any other individual or entity, (vi) will not
incur any indebtedness for borrowed money or issue any debt securities or
assume, guarantee, endorse or otherwise as an accommodation become responsible
for, the obligations of any other individual or entity, or make any material
loans or advances, (vii) will not take any action with respect to the grant of
any severance or termination pay (other than pursuant to policies or agreements
of the Company or any of its subsidiaries in effect on or prior to the date
hereof) or with respect to any increase of benefits payable under its severance
or termination pay policies or agreements in effect prior to November 17, 1994,
(viii) will not (except for annual salary increases not to exceed 5% adopted in
the ordinary course of business) adopt or amend any bonus, profit sharing,
compensation, stock option, pension, retirement, deferred compensation,
employment or other employee benefit plan, agreement, trust, fund or other
arrangement for the benefit or welfare of any employee or increase in any manner
the compensation or fringe benefits of any employee or pay any benefit not
required by any existing plan, arrangement or agreement, (ix) will not make any
tax election or settle or compromise any material federal, state, local or
foreign income tax liability and (x) will deliver to Parent all of the Company's
monthly and quarterly, if any, financial statements for periods and dates
subsequent to September 30, 1994 as soon as practicable after the same are
available to the Company.
 
     Proxy Statement; Stockholders Meeting. The Merger Agreement provides that,
if a meeting of the Company's stockholders is required by Delaware Law to
approve the Merger Agreement and the Merger, then promptly after consummation of
the Offer, the Company will prepare and will file with the Commission as
promptly as practicable a preliminary proxy statement, together with a form of
proxy, with respect to the meeting of the Company's stockholders at which the
stockholders of the Company will be asked to vote upon and approve the Merger
Agreement and the Merger. As promptly as practicable after such filing, subject
to compliance with the rules and regulations of the Commission, the Company will
prepare and file a definitive Proxy Statement and form of proxy with respect to
such meeting (the "Proxy Statement") and will use all reasonable efforts to have
the Proxy Statement cleared by the Commission as promptly as practicable, and
promptly thereafter will mail the Proxy Statement to stockholders of the
Company. In lieu of a stockholders meeting, the Company could seek stockholder
approval of the Merger Agreement and the Merger by written consent.
 
     Pursuant to the Merger Agreement, if a meeting of the Company's
stockholders is required by Delaware Law to approve the Merger Agreement and the
Merger, then as promptly as practicable after consummation of the Offer, the
Company will take all action necessary, in accordance with Delaware Law and its
Certificate of Incorporation and Bylaws, to convene a meeting (or obtain the
written consents) of its stockholders (the "Special Meeting") to consider and
vote upon the Merger Agreement and the Merger. The Merger Agreement further
provides that the affirmative vote of stockholders required for approval of the
Merger Agreement and Merger will be no greater than a majority. It also provides
that, subject to the fiduciary duties of the Board under Delaware Law, the Proxy
Statement will contain the recommendation of the Board that the stockholders of
the Company vote to adopt and approve the Merger Agreement and the Merger and
the Company will use its reasonable efforts to solicit from stockholders of the
Company proxies in favor of such adoption and approval (and Purchaser will vote
all Shares purchased by it in favor of such adoption and approval) and to take
all other action necessary or, in the reasonable judgment of Parent, helpful to
secure the vote or consent of stockholders required by Delaware Law to effect
the Merger.
 
     Stock Options. The Merger Agreement provides that the Company will take
such action as may be permitted under its employee plans to effect the
cancellations described under "Merger" above and will comply with all
requirements regarding income tax withholding in connection therewith. In
addition, but subject to the terms of the employee plans and applicable law, the
Company will take all steps necessary to cause its employee plans to be
terminated on or prior to the Effective Time, and to satisfy Parent that no
holder of Options or participant in any employee plans will have any right to
acquire any interest in the Company or Parent as a result of the exercise of
Options or other rights pursuant to such employee plans on or after the
Effective Time.
 
                                       19
<PAGE>   20
 
     Solicitations of Transactions. The Merger Agreement provides that the
Company will not, and will use its reasonable efforts to cause its officers,
directors and agents not to, solicit, initiate or deliberately encourage
submission of, or participate in discussions concerning, or supply any
information in response to, proposals or offers from any person relating to any
acquisition or purchase of all or (other than in the ordinary course of
business) a material amount of the assets of, or any equity interest in, the
Company or any merger, consolidation or business combination with the Company
(an "Acquisition Proposal"). The Company has agreed to promptly notify Parent if
any such proposal or offer, or any inquiry or contact with any person with
respect thereto, is made.
 
     Pursuant to the Merger Agreement, however, to the extent required by the
fiduciary obligations of the Board, as advised by its counsel, the Company may,
in response to a request or inquiry that could reasonably be expected to result
in an Acquisition Proposal, which request or inquiry was unsolicited after
November 17, 1994, participate in discussions or negotiations with, or furnish
information with respect to the Company pursuant to a confidentiality agreement
substantially similar to the confidentiality agreement in effect with Parent, to
any person. In addition, following the receipt of an Acquisition Proposal, which
the Board determines in good faith, based upon the advice of its outside
financial advisors, to be more favorable to the Company's stockholders than the
Offer and the Merger (a "Superior Proposal"), the Company may, subject to
payment of the Termination Fee (as described below), terminate the Merger
Agreement and accept such Superior Proposal, and the Board may approve or
recommend (and, in connection therewith, withdraw or modify the approval or
recommendation of the Offer, the Merger Agreement or the Merger) such Superior
Proposal.
 
     Indemnification. The Merger Agreement provides that the Company will, to
the fullest extent permitted under applicable laws, indemnify and hold harmless,
and, after the Effective Time, Parent and the Surviving Corporation will, to the
fullest extent permitted under applicable laws, indemnify and hold harmless,
each present and former director and officer of the Company (the "Indemnified
Parties") against any losses, claims, damages, liabilities, costs, expenses,
judgments and amounts paid in settlement in connection with any claim, action,
suit, proceeding or investigation arising out of or pertaining to any action or
omission by such director or officer prior to the Effective Time in his/her
capacity as such (including, without limitation, any claims, actions, suits,
proceedings or investigations which arise out of or relate to the transactions
contemplated by the Merger Agreement); provided, however, that neither the
Company, Parent nor Surviving Corporation will have any obligation under the
Merger Agreement to indemnify any Indemnified Party against any losses, claims,
damages, liabilities, costs, expenses, judgments or amounts to the extent the
same is found to have resulted from such Indemnified Person's own gross
negligence or willful misconduct.
 
     In the event any such claim, action, suit, proceeding or investigation is
brought against any Indemnified Party (whether arising before or after the
Effective Time), (a) the Indemnified Parties may retain counsel satisfactory to
them and the Company (or them and the Surviving Corporation and Parent after the
Effective Time), (b) the Company (or after the Effective Time, the Surviving
Corporation and Parent) will pay all fees and expenses of such counsel for the
Indemnified Parties promptly as statements therefor are received, and (c) the
Company (or after the Effective Time, the Surviving Corporation and Parent) will
use their respective reasonable efforts to assist in the vigorous defense of any
such matter, provided, that neither the Company, the Surviving Corporation nor
Parent will be liable for any such settlement effected without their written
consent, which consent, however, will not be unreasonably withheld. Any
Indemnified Party wishing to claim indemnification under the Merger Agreement,
upon learning of any such claim, action, suit, proceeding or investigation, will
notify the Company, the Surviving Corporation or Parent thereof and will deliver
to the Company or the Surviving Corporation an undertaking to repay any amounts
advanced pursuant hereto when and if a court of competent jurisdiction will
ultimately determine, after exhaustion of all avenues of appeal, that such
Indemnified Party was not entitled to indemnification under this Section. The
Indemnified Parties as a group may retain only one law firm in each jurisdiction
to represent them with respect to any such matter unless there is, under
applicable standards of professional conduct as determined by such counsel, a
conflict on any significant issue between the positions of any two or more
Indemnified Parties. In addition to the indemnification provided under the
Merger Agreement, the Indemnified Parties shall retain all right to
 
                                       20
<PAGE>   21
 
indemnification under existing indemnification agreements and charter and Bylaw
provisions of the Company existing on November 17, 1994.
 
     Severance. The Merger Agreement further provides that, if at any time
during the one-year period following November 17, 1994, the Company effects any
reduction in employment of any employee who as of the Effective Time had been an
employee of the Company, the Company will, except as otherwise required pursuant
to applicable severance agreements, substantially comply with certain specified
termination policies and procedures of the Company in effect on November 17,
1994. The material severance agreements and termination policies and procedures
with respect to executive officers of the Company referred to in the foregoing
sentence have been filed with and/or described in the Company's public filings,
including the Schedule 14D-9 filed by the Company in connection with the Offer.
 
     Termination; Fees and Expenses. The Merger Agreement may be terminated at
any time prior to the Effective Time, whether prior to or after approval by the
stockholders of the Company, by mutual written consent of the Boards of
Directors of Purchaser and the Company.
 
     The Merger Agreement may also be terminated at any time prior to the
Effective Time, whether prior to or after approval by the stockholders of the
Company, by the Company (i) if (A) Purchaser or any of its subsidiaries or
affiliates (1) terminates the Offer in accordance with its terms, or (2) fails
to purchase Shares pursuant to the Offer within 120 days after the commencement
of the Offer or (B) the Offer expires without any Shares having been purchased
and without Purchaser having an obligation to extend the Offer pursuant to the
Merger Agreement, except that in each case, the Company may not terminate the
Merger Agreement as described in this clause (i) if it fails to perform in any
material respect any of its material obligations under the Merger Agreement,
(ii) in the event the Company has complied in all material respects with its
obligations with respect to any Acquisition Proposals as described under
"Solicitations of Transactions" above and has determined to accept a Superior
Proposal; provided, however, if the Company elects to terminate the Merger
Agreement as described in this clause (ii), then the Company will promptly, but
in no event later than two days after such termination, pay Purchaser a fee of
$8,000,000 (which includes a non-accountable allowance for expenses and fees),
which amount will be payable in same day funds (the "Termination Fee");
provided, further, however, that no fee will be payable if either Parent or
Purchaser is in material breach of their obligations under the Merger Agreement,
(iii) if the Effective Time has not occurred on or before November 17, 1995 due
to a failure of any of the conditions to the obligations of the Company to
effect the Merger or (iv) if Purchaser breaches or fails to perform in all
material respects any of its material obligations or agreements under the Merger
Agreement, or any of Purchaser's material representations and warranties is, or
becomes, inaccurate or incomplete in any material respect.
 
     The Merger Agreement may also be terminated at any time prior to the
Effective Time, whether prior to or after approval by the stockholders of the
Company, by Purchaser (i) if (A) Purchaser or any of its subsidiaries or
affiliates (1) terminates the Offer in accordance with its terms, or (2) fails
to purchase Shares pursuant to the Offer within 120 days after the commencement
of the Offer; or (B) the Offer expires without any Shares having been purchased
and without Purchaser having an obligation to extend the Offer pursuant to the
Merger Agreement, except that in each case, Purchaser may not terminate the
Merger Agreement as described in this clause (i) if it fails to perform in any
material respect any of its material obligations under the Merger Agreement,
(ii) in the event the Company has complied in all material respects with its
obligations with respect to any Acquisition Proposals as described under
"Solicitations of Transactions" above and has determined to accept a Superior
Proposal; provided, however, if Purchaser elects to terminate the Merger
Agreement as described in this clause (ii), then the Company will promptly, but
in no event later than two days after such termination, pay Purchaser the
Termination Fee; provided, further, however, that no fee will be payable if
either Parent or Purchaser is in material breach of their obligations under the
Merger Agreement, (iii) if the Effective Time has not occurred on or before
November 17, 1995 due to a failure of any of the conditions to the obligations
of Purchaser to effect the Merger, (iv) if the Company withdraws or modifies in
a manner adverse to Purchaser its approval or recommendation of the Offer, the
Merger Agreement or the Merger, or the Board resolves to do any of the
foregoing, except that Purchaser may not terminate the Merger Agreement as
described in this clause (iv) if it fails to perform in any material respect any
of its obligations under the Merger Agreement; provided, however, if Purchaser
elects to terminate the Merger Agreement as
 
                                       21
<PAGE>   22
 
described in this clause (iv), then the Company will promptly, but in no event
later than two days after such termination, pay Purchaser the Termination Fee;
provided, further, however, that no fee will be payable if either Parent or
Purchaser is in material breach of their obligations under the Merger Agreement
or (v) if the Company breaches or fails to perform in all material respects any
of its obligations or agreements under the Merger Agreement, or any of the
representations and warranties of the Company set forth in the Merger Agreement,
the disclosure schedule or in any written certificate or schedule delivered
pursuant thereto is, or becomes, inaccurate or incomplete in any respect, in
each case, with such exceptions as would not in the aggregate have a material
adverse effect on the Company and its subsidiaries taken as a whole; provided,
however, if Purchaser elects to terminate the Merger Agreement as described in
this clause (v), then the Company will be obligated to pay Purchaser $8,000,000
as liquidated damages.
 
     Amendment; Waiver. Subject to applicable law, the Merger Agreement may be
amended, modified or supplemented by written agreement of the parties hereto at
any time before the Effective Time.
 
     Subject to applicable law, at any time prior to the Effective Time, whether
before or after the Special Meeting, any party to the Merger Agreement may (i)
extend the time for the performance of any of the obligations or other acts of
any other party thereto or (ii) waive compliance with any of the agreements of
any other party or with any conditions to its own obligations. Any agreement on
the part of a party to the Merger Agreement to any such extension or waiver will
be valid only if set forth in an instrument in writing signed on behalf of such
party by a duly authorized officer.
 
     11. PURPOSE OF THE OFFER; PLANS FOR THE COMPANY AFTER THE OFFER AND THE
MERGER.
 
     Purpose of the Offer. The purpose of the Offer and the Merger is for Parent
to acquire control of, and the entire equity interest in, the Company. The
purpose of the Merger is for Parent to acquire all Shares not purchased pursuant
to the Offer. Upon consummation of the Merger, the Company will become a wholly
owned subsidiary of Parent. The Offer is being made pursuant to the Merger
Agreement.
 
     Under Delaware Law, the approval of the Board and the affirmative vote of
the holders of a majority of the outstanding Shares is required to approve and
adopt the Merger Agreement and the transactions contemplated thereby, including
the Merger. The Board has unanimously approved and adopted the Merger Agreement
and the transactions contemplated thereby, and, unless the Merger is consummated
pursuant to the short-form merger provisions under Delaware Law described below,
the only remaining required corporate action of the Company is the approval and
adoption of the Merger Agreement and the transactions contemplated thereby by
the affirmative vote of the holders of a majority of the Shares. Accordingly, if
the Minimum Condition is satisfied, Purchaser will have sufficient voting power
to cause the approval and adoption of the Merger Agreement and the transactions
contemplated thereby without the affirmative vote of any other stockholder.
 
     In the Merger Agreement, the Company has agreed to take all action
necessary to convene a meeting of its stockholders as soon as practicable after
the consummation of the Offer for the purpose of considering and taking action
on the Merger Agreement and the transactions contemplated thereby, if such
action is required by Delaware Law. Parent and Purchaser have agreed that all
Shares owned by them and their subsidiaries will be voted in favor of the Merger
Agreement and the transactions contemplated thereby.
 
     If Purchaser purchases such number of Shares pursuant to the Offer that
satisfies the Minimum Condition, the Merger Agreement provides that Parent will
be entitled to designate a majority of the members of the Board. See Section 10.
Purchaser expects that such representation would permit Purchaser to exert
substantial influence over the Company's conduct of its business and operations.
 
     Under Delaware Law, if Purchaser acquires, pursuant to the Offer or
otherwise, at least 90% of the outstanding Shares, Purchaser will be able to
approve the Merger without a vote of the Company's stockholders. If, however,
Purchaser does not acquire at least 90% of the outstanding Shares pursuant to
the Offer or otherwise and a vote of the Company's stockholders is required
under Delaware Law, a significantly longer period of time would be required to
effect the Merger.
 
                                       22
<PAGE>   23
 
     No appraisal rights are available in connection with the Offer. However, if
the Merger is consummated, stockholders will have certain rights under Delaware
Law to dissent and demand appraisal of, and to receive payment in cash of the
fair value of, their Shares. Such rights to dissent, if the statutory procedures
are complied with, could lead to a judicial determination of the fair value of
the Shares (excluding any element of value arising from the accomplishment or
expectation of the Merger), required to be paid in cash to such dissenting
holders for their Shares. In addition, such dissenting stockholders would be
entitled to receive payment of a fair rate of interest from the date of
consummation of the Merger on the amount determined to be the fair value of
their Shares. In determining the fair value of the Shares, the court is required
to take into account all relevant factors. Accordingly, such determination could
be based upon considerations other than, or in addition to, the market value of
the Shares, including, among other things, asset values and earning capacity. In
Weinberger v. UOP, Inc., the Delaware Supreme Court stated, among other things,
that "proof of value by any techniques or methods which are generally considered
acceptable in the financial community and otherwise admissible in court" should
be considered in an appraisal proceeding. Therefore, the value so determined in
any appraisal proceeding could be the same as, more or less than the Merger
Consideration.
 
     In addition, several decisions by Delaware courts have held that, in
certain circumstances, a controlling stockholder of a company involved in a
merger has a fiduciary duty to other stockholders which requires that the merger
be fair to such other stockholders. In determining whether a merger is fair to
minority stockholders, Delaware courts have considered, among other things, the
type and amount of consideration to be received by the stockholders and whether
there was fair dealing among the parties. The Delaware Supreme Court stated in
Weinberger and Rabkin v. Philip A. Hunt Chemical Corp. that the remedy
ordinarily available to minority stockholders in a cash-out merger is the right
to appraisal described above. However, a damages remedy or injunctive relief may
be available if a merger is found to be the product of procedural unfairness,
including fraud, misrepresentation or other misconduct.
 
     The Commission has adopted Rule 13e-3 under the Exchange Act which is
applicable to certain "going private" transactions and which may under certain
circumstances be applicable to the Merger or another business combination
following the purchase of Shares pursuant to the Offer in which Purchaser seeks
to acquire the remaining Shares not held by it. Purchaser believes, however,
that Rule 13e-3 will not be applicable to the Merger. Rule 13e-3 requires, among
other things, that certain financial information concerning the Company and
certain information relating to the fairness of the proposed transaction and the
consideration offered to minority stockholders in such transaction, be filed
with the Commission and disclosed to stockholders prior to consummation of the
transaction.
 
     Plans for the Company. It is expected that, initially following the Merger,
the business and operations of the Company will, except as set forth in this
Offer to Purchase, be continued by the Company substantially as they are
currently being conducted. Parent will continue to evaluate the business and
operations of the Company during the pendency of the Offer and after the
consummation of the Offer and the Merger, and will take such actions as Parent
deems appropriate under the circumstances then existing. Parent intends to seek
additional information about the Company and it business during such periods,
including, specifically, clinical and other information concerning the Company's
product candidates. Thereafter, Parent intends to review such information as
part of a comprehensive review of, and decisions concerning, the Company's
business, operations and management with a view to optimizing the Company's
potential in conjunction with Parent's business. It is expected that various
parts of the business and operations of the Company would form an important part
of Parent's future business. Parent intends to maintain the Company as a
separate subsidiary for approximately two years, and thereafter merge the
Company with and into Parent.
 
     Except as indicated in this Offer to Purchase, Parent does not have any
present plans or proposals which relate to or would result in an extraordinary
corporate transaction, such as a merger, reorganization or liquidation,
involving the Company or any subsidiary, a sale or transfer of a material amount
of assets of the Company or any subsidiary or any material change in the
Company's capitalization or dividend policy or any other material changes in the
Company's corporate structure or business, or the composition of the Board or
the Company's management.
 
     12. DIVIDENDS AND DISTRIBUTIONS. The Merger Agreement provides that neither
the Company nor any of its subsidiaries shall, directly or indirectly, between
the date of the Merger Agreement and the Effective
 
                                       23
<PAGE>   24
 
Time, without the prior written consent of Parent, (a) issue, sell, pledge,
transfer, dispose of or encumber, or authorize, propose or agree to the
issuance, sale, pledge, transfer, disposition or encumbrance of, any shares, or
any options, warrants or rights of any kind to acquire any shares of, or any
securities convertible into or exchangeable for any shares of, capital stock of
any class of the Company or any of its subsidiaries (except for the issuance of
a maximum of 2,466,782 Shares issuable pursuant to employee and director stock
options and a maximum of 5,419,491 Shares issuable pursuant to warrants, in each
case outstanding November 17, 1994), (b) authorize, recommend or propose any
change in its capitalization, (c) split, combine, or reclassify any Shares of
its capital stock or declare, set aside or pay any dividend or distribution,
payable in cash, stock, property or otherwise with respect to any of its capital
stock other than dividends from a subsidiary of the Company to the Company or
(d) redeem, purchase or otherwise acquire or offer to redeem, purchase or
otherwise acquire any of its capital stock, other than as contemplated by the
Merger Agreement. See Section 10.
 
     13. EFFECT OF THE OFFER ON THE MARKET FOR THE SHARES, EXCHANGE LISTING AND
EXCHANGE ACT REGISTRATION. The purchase of Shares by Purchaser pursuant to the
Offer will reduce the number of Shares that might otherwise trade publicly and
will reduce the number of holders of Shares, which could adversely affect the
liquidity and market value of the remaining Shares held by the public.
 
     Depending upon the number of Shares purchased pursuant to the Offer, the
aggregate market value of any Shares not purchased pursuant to the Offer, the
Shares may no longer meet the standards for continued inclusion in the Nasdaq
National Market, which require that an issuer have at least 200,000 publicly
held shares with a market value of $1 million. If these standards were not met,
quotations might continue to be published in the over-the-counter "additional
list" or in one of the "local lists," but if the number of holders of Shares
falls below 300, or if the number of publicly held Shares falls below 100,000,
or there are not at least two market makers for the Shares, the rules of the
National Association of Securities Dealers ("NASD") provide that the securities
would no longer be "authorized" for the Nasdaq Stock Market, and the Nasdaq
Stock Market would cease to provide any quotations. Shares held directly or
indirectly by an officer or director of the Company, or by any beneficial owner
of more than 10 percent of the Shares, ordinarily will not be considered as
being publicly held for this purpose. In the event the Shares were no longer
eligible for Nasdaq quotation, quotations might still be available from other
sources. The extent of the public market for the Shares and availability of such
quotations would, however, depend upon the number of holders of Shares remaining
at such time, the interest in maintaining a market in the Shares on the part of
securities firms, the possible termination of registration under the Exchange
Act, as described below, and other factors. The extent of the public market
therefor and the availability of such quotations would depend, however, upon
such factors as the number of stockholders and/or the aggregate market value of
such securities remaining at such time, the interest in maintaining a market in
the Shares on the part of securities firms, the possible termination of
registration under the Exchange Act as described below, and other factors.
Purchaser cannot predict whether the reduction in the number of Shares that
might otherwise trade publicly would have an adverse or beneficial effect on the
market price for or marketability of the Shares or whether it would cause future
market prices to be greater or less than the Merger Consideration.
 
     The Shares are currently "margin securities," as such term is defined under
the rules of the Board of Governors of the Federal Reserve System (the "Federal
Reserve Board"), which has the effect, among other things, of allowing brokers
to extend credit on the collateral of such securities. Depending upon factors
similar to those described above regarding listing and market quotations,
following the Offer it is possible that the Shares might no longer constitute
"margin securities" for purposes of the margin regulations of the Federal
Reserve Board, in which event such Shares could no longer be used as collateral
for loans made by brokers.
 
     The Shares are currently registered under the Exchange Act. Such
registration may be terminated upon application by the Company to the Commission
if the Shares are not listed on a national securities exchange and there are
fewer than 300 record holders. The termination of the registration of the Shares
under the Exchange Act would substantially reduce the information required to be
furnished by the Company to holders of Shares and to the Commission and would
make certain provisions of the Exchange Act, such as the short-swing profit
recovery provisions of Section 16(b), the requirement of furnishing a proxy
statement in connection with stockholders' meetings and the requirements of Rule
13e-3 under the Exchange Act with
 
                                       24
<PAGE>   25
 
respect to "going private" transactions, no longer applicable to the Shares. In
addition, "affiliates" of the Company and persons holding "restricted
securities" of the Company may be deprived of the ability to dispose of such
securities pursuant to Rule 144 promulgated under the Securities Act of 1933, as
amended. If registration of the Shares under the Exchange Act were terminated,
the Shares would no longer be "margin securities" or be eligible for Nasdaq
Stock Market reporting. Purchaser currently intends to seek to cause the Company
to terminate the registration of the Shares under the Exchange Act as soon after
consummation of the Offer as the requirements for termination of registration
are met.
 
     14. CERTAIN CONDITIONS OF THE OFFER. Notwithstanding any other provisions
of the Offer, but subject to the terms of the Merger Agreement, and in addition
to the Minimum Condition, Purchaser shall not be required to accept for payment
or pay for, or may delay the acceptance for payment of or payment for, tendered
Shares, or may, in the sole discretion of Purchaser, terminate the Offer as to
any Shares not then accepted for payment or paid for, if any of the following
events shall occur, which, in the reasonable judgment of Purchaser with respect
to each and every matter referred to below and regardless of the circumstances
giving rise to any of the following events, makes it inadvisable to proceed with
the Offer, the acceptance for payment or payment for the Shares or the Merger:
 
          (a) The affirmative vote of the holders of more than a majority of the
     outstanding Shares is required to consummate the Merger or Purchaser is not
     entitled to vote its Shares for the Merger, or the affirmative vote of the
     holders of any securities of the Company other than the Shares is required
     to consummate the Merger;
 
          (b) Any waiting period (and any extension thereof) applicable to the
     consummation of the transactions contemplated by the Merger Agreement under
     the HSR Act shall not have expired or been terminated;
 
          (c) The Company shall not have obtained such licenses, permits,
     consents, approvals, authorizations, qualifications and orders of
     governmental authorities and parties to contracts with the Company and its
     subsidiaries as are necessary for consummation of the Merger (excluding
     licenses, permits, consents, approvals, authorizations, qualifications or
     orders, the failure of which to obtain would not in the aggregate have a
     material adverse effect on the Company and its subsidiaries taken as a
     whole);
 
          (d) The Company shall have withdrawn or modified in a manner adverse
     to Purchaser its approval or recommendation of the Offer, the Merger
     Agreement or the Merger, or the Board shall have resolved to do any of the
     foregoing, except in the case that Purchaser or Parent shall have failed to
     perform in any material respect any of their respective material
     obligations under the Merger Agreement;
 
          (e) There shall be instituted or pending any action or proceeding
     which has a reasonable probability of success before any domestic or
     foreign court, legislative body or governmental agency or other regulatory
     or administrative agency or commission (i) challenging the acquisition in
     whole or in part of the Shares, seeking to restrain or prohibit the making
     or consummation of the Offer or seeking to obtain any material damages or
     otherwise directly or indirectly relating to the transaction contemplated
     by the Offer, (ii) seeking to prohibit or restrict the ownership or
     operation by Parent or Purchaser (or any of their respective affiliates or
     subsidiaries) of any material portion of its or the Company's business or
     assets, or to compel Parent or Purchaser (or any of their respective
     affiliates or subsidiaries) to dispose of or hold separate all or any
     material portion of the Company's business or assets as a result of the
     Offer, (iii) making the purchase of, or payment for, some or all of the
     Shares illegal, (iv) resulting in a delay in the ability of Purchaser to
     accept for payment or pay for some or all of the Shares, (v) imposing
     material limitations on the ability of Purchaser effectively to acquire or
     to hold or to exercise full rights of ownership of the Shares, including,
     without limitation, the right to vote the Shares purchased by Purchaser on
     all matters properly presented to the stockholders of the Company, (vi)
     imposing any limitations on the ability of Parent or Purchaser or any of
     their respective affiliates or subsidiaries effectively to control in any
     material respect the business and operations of the Company, (vii) which
     otherwise is reasonably likely to have a material adverse effect on the
     Company and its subsidiaries taken as a whole or (viii) which may result in
     a material limitation on the benefits expected to be derived by
 
                                       25
<PAGE>   26
 
     Parent and Purchaser as a result of the Offer, including without
     limitation, any limitation on the ability to consummate the Merger;
 
          (f) Any statute, rule, regulation or order shall be enacted,
     promulgated, entered or deemed applicable to the Offer or the Merger, or
     any other action shall have been taken, proposed or threatened, by any
     domestic or foreign government or governmental authority or by any court,
     domestic or foreign, which, in the reasonable judgment of Purchaser, is
     reasonably likely, directly or indirectly, to result in any of the
     consequences referred to in clauses (i) through (viii) of subsection (e)
     above;
 
          (g) Any change (or any development involving a prospective change)
     shall have occurred which in the judgment of Purchaser had, or may
     reasonably be expected to have, a material adverse effect on the Company
     and its subsidiaries taken as a whole;
 
          (h) The Company shall have breached or failed to perform in all
     material respects any of its obligations or agreements under the Merger
     Agreement, or any of the representations and warranties of the Company set
     forth in the Merger Agreement, the schedules thereto or in any written
     certificate or schedule delivered pursuant thereto shall be, or have
     become, inaccurate or incomplete in any respect, in each case, with such
     exceptions as would not in the aggregate have a material adverse effect on
     the Company and its subsidiaries taken as a whole;
 
          (i) The Merger Agreement shall have been terminated by the Company,
     Parent or Purchaser pursuant to its terms;
 
          (j) Any "Triggering Event" under the Rights Agreement dated as of
     October 24, 1991 by and between the Company and Chemical Trust Company of
     California, as Rights Agent (the "Rights Agreement") shall have occurred
     and the rights to purchase units of Series A Junior Participating Preferred
     Stock (the "Series A Preferred Stock"), par value $.01 per share of the
     Company (the "Rights"), shall not be redeemable by the Company, see Section
     16; or
 
          (k) (1) a Stipulation of Settlement shall not have been entered into
     by the Company and certain plaintiffs (the "Plaintiffs") (the "Stipulation
     of Settlement") constituting, subject to court approval, a legally binding
     agreement for the full and complete settlement of the class action
     litigation captioned In re Synergen, Inc. Securities Litigation, Case No.
     93-B-402, pending in the United States District Court for the District of
     Colorado (the "Court"), as such settlement is described in that certain
     Memorandum of Understanding dated as of November 17, 1994 by and between
     the Company and the Plaintiffs (the "MOU"), (2) the Stipulation of
     Settlement shall not be in full force and effect or shall not reasonably
     reflect the terms and conditions of the MOU or (3) the Court shall not have
     entered a Scheduling Order providing for, (i) approval of a form of notice
     to the class members of the Stipulation of Settlement and a deadline for
     giving notice to the class members, (ii) deadlines for class members to
     object to the settlement and/or to opt out of the class and (iii) a hearing
     date upon which the Court will consider whether to grant final approval of
     the Stipulation of Settlement. See Section 15.
 
     The foregoing conditions are for the sole benefit of Purchaser and may be
asserted regardless of the circumstances giving rise to any such conditions or
may be waived in whole or in part. The failure to exercise any of the foregoing
rights shall not be deemed a waiver of any such right, and each right shall be
deemed a continuing right which may be asserted at any time and from time to
time.
 
     15. CERTAIN LEGAL MATTERS AND REGULATORY APPROVALS.
 
     General. Based upon its examination of publicly available information with
respect to the Company and the review of certain information furnished by the
Company to Parent and discussions of representatives of Parent with
representatives of the Company during Parent's investigation of the Company (see
Section 10), neither Purchaser nor Parent is aware of any license or other
regulatory permit that appears to be material to the business of the Company and
its subsidiaries taken as a whole, which might be adversely affected by the
acquisition of Shares by Purchaser pursuant to the Offer or, except as set forth
below, of any approval or other action by any domestic (federal or state) or
foreign governmental, administrative or regulatory authority or agency which
would be required prior to the acquisition of Shares by Purchaser pursuant to
the Offer. Should any such approval or other action be required, it is
Purchaser's present intention to seek such approval or
 
                                       26
<PAGE>   27
 
action. Purchaser does not currently intend, however, to delay the purchase of
Shares tendered pursuant to the Offer pending the outcome of any such action or
the receipt of any such approval (subject to Purchaser's right to decline to
purchase Shares if any of the conditions in Section 14 shall have occurred).
There can be no assurance that any such approval or other action, if needed,
would be obtained without substantial conditions or that adverse consequences
might not result to the business of the Company, Purchaser or Parent or that
certain parts of the businesses of the Company, Purchaser or Parent might not
have to be disposed of or held separate or other substantial conditions complied
with in order to obtain such approval or other action or in the event that such
approval was not obtained or such other action was not taken. Purchaser's
obligation under the Offer to accept for payment and pay for Shares is subject
to certain conditions, including conditions relating to the legal matters
discussed in this Section 15. See Section 14.
 
     State Takeover Laws. The Company is incorporated under the Delaware Law. In
general, Section 203 of Delaware Law prevents an "interested stockholder"
(generally a person who owns or has the right to acquire 15% or more of a
corporation's outstanding voting stock, or an affiliate or associate thereof)
from engaging in a "business combination" (defined to include mergers and
certain other transactions) with a Delaware corporation for a period of three
years following the date such person became an interested stockholder unless,
among other things, prior to such date the board of directors of the corporation
approved either the business combination or the transaction in which the
interested stockholder became an interested stockholder. On November 17, 1994,
prior to the execution of the Merger Agreement; the Board unanimously has
determined that the Offer and the Merger are fair to, and in the best interests
of, the Company and its stockholders, has approved the Offer, the Merger
Agreement and the Merger and recommends that stockholders accept the Offer and
tender their Shares pursuant to the Offer. Accordingly, Section 203 is
inapplicable to the Offer and the Merger.
 
     A number of other states have adopted laws and regulations applicable to
attempts to acquire securities of corporations which are incorporated, or have
substantial assets, stockholders, principal executive offices or principal
places of business, or whose business operations otherwise have substantial
economic effects, in such states. In Edgar v. MITE Corp., the Supreme Court of
the United States invalidated on constitutional grounds the Illinois Business
Takeover Statute, which, as a matter of state securities law, made takeovers of
corporations meeting certain requirements more difficult. However, in 1987 in
CTS Corp. v. Dynamics Corp. of America, the Supreme Court held that the State of
Indiana may, as a matter of corporate law and, in particular, with respect to
those aspects of corporate law concerning corporate governance, constitutionally
disqualify a potential acquiror from voting on the affairs of a target
corporation without the prior approval of the remaining stockholders. The state
law before the Supreme Court was by its terms applicable only to corporations
that had a substantial number of stockholders in the state and were incorporated
there.
 
     The Company, directly or through subsidiaries, conducts business in a
number of states throughout the United States, some of which have enacted
takeover laws. Purchaser does not know whether any of these laws will, by their
terms, apply to the Offer or the Merger and has not complied with any such laws.
Should any person seek to apply any state takeover law, Purchaser will take such
action as then appears desirable, which may include challenging the validity or
applicability of any such statute in appropriate court proceedings. In the event
it is asserted that one or more state takeover laws is applicable to the Offer
or the Merger, and an appropriate court does not determine that it is
inapplicable or invalid as applied to the Offer, Purchaser might be required to
file certain information with, or receive approvals from, the relevant state
authorities. In addition, if enjoined, Purchaser might be unable to accept for
payment any Shares tendered pursuant to the Offer, or be delayed in continuing
or consummating the Offer, and the Merger. In such case, Purchaser may not be
obligated to accept for payment any Shares tendered. See Section 14.
 
     Antitrust. Under the HSR Act and the rules that have been promulgated
thereunder by the FTC, certain acquisition transactions may not be consummated
unless certain information has been furnished to the Antitrust Division and the
FTC and certain waiting period requirements have been satisfied. The acquisition
of Shares by Purchaser pursuant to the Offer is subject to such requirements.
See Section 2.
 
     Pursuant to the HSR Act, on November 18, 1994, Parent filed a Premerger
Notification and Report Form in connection with the purchase of Shares pursuant
to the Offer with the Antitrust Division and the
 
                                       27
<PAGE>   28
 
FTC. Under the provisions of the HSR Act applicable to the Offer, the purchase
of Shares pursuant to the Offer may not be consummated until the expiration of a
15-calendar day waiting period following the filing by Parent. Accordingly, the
waiting period under the HSR Act applicable to the purchase of Shares pursuant
to the Offer will expire at 11:59 p.m., New York City time, on December 3, 1994,
unless such waiting period is earlier terminated by the FTC and the Antitrust
Division or extended by a request from the FTC or the Antitrust Division for
additional information or documentary material prior to the expiration of the
waiting period. Pursuant to the HSR Act, Parent has requested early termination
of the waiting period applicable to the Offer. There can be no assurance,
however, that the 15-day HSR Act waiting period will be terminated early. If
either the FTC or the Antitrust Division were to request additional information
or documentary material from Parent with respect to the Offer, the waiting
period with respect to the Offer would expire at 11:59 p.m., New York City time,
on the tenth calendar day after the date of substantial compliance by Parent
with such request. Thereafter, the waiting period could be extended only by
court order. If the acquisition of Shares is delayed pursuant to a request by
the FTC or the Antitrust Division for additional information or documentary
material pursuant to the HSR Act, the Offer may be extended (and under certain
circumstances the Offer is required to be extended, see Section 10) and, in any
event, the purchase of and payment for Shares will be deferred until 10 days
after the request is substantially complied with, unless the extended period
expires on or before the date when the initial 15-day period would otherwise
have expired, or unless the waiting period is sooner terminated by the FTC and
the Antitrust Division. Only one extension of such waiting period pursuant to a
request for additional information is authorized by the HSR Act and the rules
promulgated thereunder, except by court order. Any such extension of the waiting
period will not give rise to any withdrawal rights not otherwise provided for by
applicable law. See Section 4. It is a condition to the Offer that the waiting
period applicable under the HSR Act to the Offer expire or be terminated. See
Section 2 and Section 14.
 
     The FTC and the Antitrust Division frequently scrutinize the legality under
the antitrust laws of transactions such as the proposed acquisition of Shares by
Purchaser pursuant to the Offer. At any time before or after the purchase of
Shares pursuant to the Offer by Purchaser, the FTC or the Antitrust Division
could take such action under the antitrust laws as it deems necessary or
desirable in the public interest, including seeking to enjoin the purchase of
Shares pursuant to the Offer or seeking the divestiture of Shares purchased by
Purchaser or the divestiture of substantial assets of Parent, the Company or
their respective subsidiaries. Private parties and state attorneys general may
also bring legal action under federal or state antitrust laws under certain
circumstances. Based upon an examination of information available to Parent
relating to the businesses in which Parent, the Company and their respective
subsidiaries are engaged, Parent and Purchaser believe that the Offer will not
violate the antitrust laws. Nevertheless, there can be no assurance that a
challenge to the Offer on antitrust grounds will not be made or, if such a
challenge is made, what the result would be. See Section 14 for certain
conditions to the Offer, including conditions with respect to litigation.
 
     Securities Litigation. Following a drop in the price of the Shares on
February 22, 1993, a number of class action complaints were filed against the
Company and certain of its officers and directors in the United States District
Court for the District of Colorado on behalf of various classes of the Company's
stockholders. The complaints were consolidated in In re Synergen, Inc.
Securities Litigation, Case No. 93-B-402, by a consolidated class action
complaint that was filed on April 15, 1993, and amended on May 2, 1994. In
addition to the Company, Larry Soll, Chairman of the Board and the Company's
former Chief Executive Officer, and Kenneth J. Collins, the Company's Executive
Vice President of Finance and Administration, were named as defendants in the
amended consolidated complaint, together with Jon S. Saxe, the Company's former
President and Chief Executive Officer and a former Director, and Michael A.
Catalano, the Company's former Vice President of Clinical Research. The original
consolidated complaint alleged violations of federal and state securities law.
The Court dismissed the state law claims on April 8, 1994. On May 30, 1994, the
defendants in the suit filed a motion to dismiss or in the alternative for
summary judgment, and a hearing was conducted on September 2, 1994. The motion
was denied on September 16, 1994. Trial has been set for May 22, 1995.
 
     On November 17, 1994, the parties executed a binding Memorandum of
Understanding containing the material terms of a settlement of the case. In
consideration of the payment of $28,000,000 by the Company
 
                                       28
<PAGE>   29
 
and its insurers, the plaintiffs agreed to dismiss the action with prejudice.
The settlement is subject to court approval and to the right of individual
stockholders to opt-out, object to, or otherwise request exclusion from, the
class. The preliminary approval hearing by the Court is scheduled for December
15, 1994.
 
     On November 16, 1994, three individual plaintiffs filed an action against
the Company and Mr. Saxe in the District Court of Colorado in and for the City
and County of Denver. The case is captioned Donald R. Temple, John Temple and
Mary Louise Temple v. Synergen, Inc. and Jon Saxe, Case No. 94-CV5717. The
complaint alleges violations of state securities law, fraud and
misrepresentation.
 
     On Friday, November 18, 1994, two stockholders filed a putative class
action suit in the Court of Chancery of the State of Delaware in and for New
Castle County against the Company and certain of its officers and directors. The
case is captioned Anna Stanley and Len Kahn v. Larry Soll, Gregory D. Abbott,
Robert C. Thompson, Arthur H. Hayes, David I. Hirsh, Barry Mactaggart, Glenn S.
Utt, Robert F. Hendrickson and Synergen, Inc., Case No. 13892 (Del. Ch. Nov. 18,
1994). The complaint alleges that the Offer and the Merger are unfair to the
Company's stockholders and that defendants' actions in connection therewith
constitute a breach of defendants' fiduciary duties of loyalty and due care.
Plaintiffs seek a preliminary injunction enjoining the Offer and the Merger or,
in the event the Offer and the Merger are consummated, an order rescinding the
Offer and the Merger, together with an accounting and compensatory damages in an
unstated amount.
 
     16. RIGHTS AGREEMENT
 
     Preferred Stock Purchase Rights. On October 21, 1991, the Board declared a
dividend of one Right for each outstanding Share. The dividend was paid on
November 5, 1991, to stockholders of record on that date. Holders of Shares
issued after that date and until the Rights become exercisable receive one Right
for each Share. The Rights trade automatically with the Shares and, until the
Rights are exercisable, are evidenced by the certificates for the Shares. The
terms of the Rights are set forth in the Rights Agreement, a copy of which was
filed as Exhibit 1 to the Company's Registration Statement on Form 8-A, as filed
with the Securities and Exchange Commission on November 5, 1991, as amended by
the Company's Form 8 Amendment, filed on November 7, 1991. Chemical Trust
Company of California has assumed all responsibilities as the Rights Agent under
the Rights Agreement. The following summary is not complete and is qualified in
its entirety by reference to the Rights Agreement.
 
     Each Right will entitle its registered holder to purchase from the Company
one one-hundredth of a share of the Series A Preferred Stock. The purchase price
for each one-hundredth share of Series A Preferred Stock is $335 (the "Purchase
Price"). The Rights will generally become exercisable upon the earlier of (a)
the tenth day after the first public disclosure that a person or group has
become an "Acquiring Person" (defined below) or (b) the tenth business day after
the commencement of a tender or exchange offer that, if consummated, would
result in one person or group becoming an Acquiring Person. In general,
"Acquiring Person" means any person or group that has beneficial ownership of 20
percent or more of the outstanding Shares, but does not include the Company or
certain related entities. Any Rights held by an Acquiring Person or certain
transferees of an Acquiring Person will become void at the time the person
becomes an Acquiring Person. The Rights expire on November 5, 2001, unless
earlier redeemed as described below.
 
     Under certain circumstances, the Rights will entitle their holders to
purchase securities other than Series A Preferred Stock. If any person becomes
an Acquiring Person (other than pursuant to an offer for all shares determined
by the disinterested directors to be fair to the stockholders and in the best
interests of the Company and its stockholders (a "Qualifying Offer")), each
Right will entitle its holder to purchase upon exercise, for the Purchase Price,
Shares with a market value of twice the Purchase Price. In general, if the
Company is acquired in a merger or other business combination in which the
Company is not the surviving corporation or if 50 percent or more of Company's
assets or earnings power is transferred to another entity after there is an
Acquiring Person (other than in certain acquisitions following a Qualifying
Offer), each Right will entitle its holder to purchase a number of shares of the
acquiring entity's common stock with a market value of twice the Purchase Price.
However, a merger or other business combination is exempted from this provision
if the amount and form of consideration being offered are the same as the amount
and form of consideration paid in the Qualifying Offer.
 
                                       29
<PAGE>   30
 
     At any time before the earlier of (a) ten days following the first public
announcement by Company or an Acquiring Person that the Acquiring Person has
become such or (b) November 5, 2001, the Board may redeem the Rights in whole,
but not in part, for $.001 per Right (the "Redemption Price"). Under certain
circumstances specified in the Rights Agreement, the Rights may be redeemed only
with the concurrence of a majority of the Continuing Directors (as defined in
the Rights Agreement). If the Board elects to redeem the Rights, the only right
of the holders of Rights will be to receive the Redemption Price.
 
     The Rights do not entitle their holders to any rights as stockholders of
the Company, such as voting or dividend rights. The Company may amend the Rights
Agreement without the approval of any holder of the Rights except as otherwise
specified in that agreement.
 
     As provided for in the Rights Agreement, the disinterested directors of the
Board have determined that the Offer is a Qualifying Offer. Accordingly, because
the amount and the form of the Merger Consideration are the same as the amount
and the form of consideration being offered in the Offer, the terms of the
Rights Agreement allowing for the exercise of the Rights in connection with a
tender offer followed by a second step Merger are inapplicable to the
transactions contemplated by the Offer and the Merger.
 
     17. FEES AND EXPENSES. Except as set forth below, Purchaser will not pay
any fees or commissions to any broker, dealer or other person for soliciting
tenders of Shares pursuant to the Offer.
 
     CS First Boston is acting as Dealer Manager in connection with the Offer
and has provided certain financial advisory services in connection with the
acquisition of the Company. Parent has agreed to pay CS First Boston for its
services an initial financial advisory fee of $150,000, an additional financial
advisory fee of $350,000 and a transaction fee of $1,000,000. Parent has also
agreed to reimburse CS First Boston for all reasonable out-of-pocket expenses
incurred by CS First Boston, including the reasonable fees and expenses of legal
counsel, and to indemnify CS First Boston against certain liabilities and
expenses in connection with its engagement, including certain liabilities under
the federal securities laws.
 
     Purchaser and Parent have retained D.F. King & Co., Inc., as the
Information Agent, and American Stock Transfer & Trust Company, as the
Depositary, in connection with the Offer. The Information Agent may contact
holders of Shares by mail, telephone, telex, telecopy, telegraph and personal
interview and may request banks, brokers, dealers and other nominee stockholders
to forward materials relating to the Offer to beneficial owners.
 
     As compensation for acting as Information Agent in connection with the
Offer, D.F. King & Co., Inc. will be paid reasonable and customary compensation
for its services and will also be reimbursed for certain out-of-pocket expenses
and may be indemnified against certain liabilities and expenses in connection
with the Offer, including certain liabilities under the federal securities laws.
Purchaser will pay the Depositary reasonable and customary compensation for its
services in connection with the Offer, plus reimbursement for out-of-pocket
expenses, and will indemnify the Depositary against certain liabilities and
expenses in connection therewith, including under federal securities laws.
Brokers, dealers, commercial banks and trust companies will be reimbursed by
Purchaser for customary handling and mailing expenses incurred by them in
forwarding material to their customers.
 
     18. MISCELLANEOUS. Purchaser is not aware of any jurisdiction where the
making of the Offer is prohibited by any administrative or judicial action
pursuant to any valid state statute. If Purchaser becomes aware of any valid
state statute prohibiting the making of the Offer or the acceptance of Shares
pursuant thereto, Purchaser will make a good faith effort to comply with any
such state statute. If, after such good faith effort, Purchaser cannot comply
with any such state statute, the Offer will not be made to (nor will tenders be
accepted from or on behalf of) the holders of Shares in such state. In any
jurisdiction where the securities, blue sky or other laws require the Offer to
be made by a licensed broker or dealer, the Offer shall be deemed to be made on
behalf of Purchaser by the Dealer Manager or by one or more registered brokers
or dealers licensed under the laws of such jurisdiction.
 
     NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR MAKE ANY
REPRESENTATION ON BEHALF OF PURCHASER OR THE COMPANY NOT CONTAINED IN THIS OFFER
TO PURCHASE OR IN THE LETTER OF TRANSMITTAL, AND IF GIVEN OR
 
                                       30
<PAGE>   31
 
MADE, SUCH INFORMATION OR REPRESENTATION MUST NOT BE RELIED UPON AS HAVING BEEN
AUTHORIZED.
 
     Pursuant to Rule 14d-3 of the General Rules and Regulations under the
Exchange Act, Parent and Purchaser have filed with the Commission the Schedule
14D-1, together with exhibits, furnishing certain additional information with
respect to the Offer. The Schedule 14D-1 and any amendments thereto, including
exhibits, may be inspected at, and copies may be obtained from, the same places
and in the same manner as set forth in Section 7 (except that they will not be
available at the regional offices of the Commission).
 
                                          Amgen Acquisition Subsidiary, Inc.
November 23, 1994
 
                                       31
<PAGE>   32
 
                                                                      SCHEDULE I
 
                      DIRECTORS AND EXECUTIVE OFFICERS OF
                              PARENT AND PURCHASER
 
     1.  Directors and Executive Officers of Parent. The following table sets
forth the name and present position(s) with Parent of the directors and
executive officers of Parent.
 
<TABLE>
<CAPTION>
          NAME                                  POSITION(S) WITH PARENT
- ------------------------    ---------------------------------------------------------------
<S>                         <C>
Gordon M. Binder            Chairman of the Board, Chief Executive Officer and Director
Kevin W. Sharer             President, Chief Operating Officer and Director
Raymond F. Baddour          Director
William K. Bowes, Jr.       Director
Franklin P. Johnson, Jr.    Director
Steven Lazarus              Director
Edward J. Ledder            Director
Gilbert S. Omenn            Director
Bernard H. Semler           Director
N. Kirby Alton              Senior Vice President, Development
Robert K. Andren            Senior Vice President, Operations
Robert S. Attiyeh           Senior Vice President, Finance and Corporate Development
Dennis M. Fenton            Senior Vice President, Sales and Marketing
Daryl D. Hill               Senior Vice President, Asia Pacific
Larry A. May                Vice President, Corporate Controller and Chief Accounting
                            Officer
Daniel Vapnek               Senior Vice President, Research
Thomas E. Workman, Jr.      Vice President, Secretary and General Counsel
Linda R. Wudl               Vice President, Quality Assurance
</TABLE>
 
     Set forth below with respect to each director and executive officer of
Parent is the present principal occupation or employment, and material
occupations, positions, offices or employments for the past five years of each
director and executive officer of Parent. Unless otherwise indicated, the
current business address of each person is c/o Amgen Inc., Amgen Center, 1840
DeHavilland Drive, Thousand Oaks, California 91320-1789. Each such person is a
citizen of the United States of America and unless otherwise indicated, each
person has held the position indicated above for the past five years.
 
     MR. GORDON M. BINDER has served as a director of Parent since October 1988.
He joined Parent in 1982 as Vice President-Finance and was named Senior Vice
President-Finance in February 1986. In October 1988, Mr. Binder was elected to
the position of Chief Executive Officer. In July 1990, Mr. Binder was elected to
the position of Chairman of the Board.
 
     MR. KEVIN W. SHARER has served as a director of Parent since November 1992.
He has served as President and Chief Operating Officer since October 1992. Prior
to joining Parent, Mr. Sharer served as President of the Business Markets
Division of MCI Communications Corporation, a telecommunications company, from
April 1989 to October 1992 and served in numerous executive capacities at
General Electric Company from February 1984 to March 1989.
 
     DR. RAYMOND F. BADDOUR has served as a director of Parent since October
1980. Prior to July 1, 1989, Dr. Baddour was Lammot du Pont Professor of
Chemical Engineering at the Massachusetts Institute of Technology. As of July 1,
1989, Dr. Baddour became Lammot du Pont Professor Emeritus. Mr. Baddour's
business address is c/o CRB, Inc., Attn: Annette C. Baddour, 2600 Douglas Road,
Suite 602, Coral Gables, Florida 33134.
 
     MR. WILLIAM K. BOWES, JR. has served as a director of Parent since April
1980. He has been a general partner of U.S. Venture Partners, a venture capital
investment entity, since July 1981. Mr. Bowes also serves
 
                                       I-1
<PAGE>   33
 
as a director of Glycomed Incorporated, Xoma Corporation, and a number of
privately held U.S. Venture Partners portfolio companies and serves as the
President of Presidio Management Group. Mr. Bowes's business address is U.S.
Venture Partners, 2180 Sand Hill Road, Suite 300, Menlo Park, California 94025.
 
     MR. FRANKLIN P. JOHNSON, JR. has served as a director of Parent since
October 1980. He is the general partner of Asset Management Partners, a venture
capital limited partnership. Mr. Johnson has been a private venture capital
investor for more than five years. He is also Chairman of the Board of Boole &
Babbage, Inc. and a director of BioSurface Technology, Inc., IDEC
Pharmaceuticals Corporation, Ross Stores, Inc., Tandem Computers Incorporated,
Teradyne Inc. and Trinzic Corporation. Mr. Johnson's business address is Asset
Management Partners, 2275 East Bayshore Road, Suite 150, Palo Alto, California
94303.
 
     MR. STEVEN LAZARUS has served as a director of Parent since May 1987. He
has been the President and Chief Executive Officer of the Argonne National
Laboratory/The University of Chicago Development Corporation ("ARCH") since it
was formed in October 1986. ARCH is involved in the process of transforming
scientific discoveries into viable high technology products and services. He is
also the Managing Partner of ARCH Venture Fund, L.P. Mr. Lazarus also has been
associate dean at the Graduate School of Business, the University of Chicago,
since October 1986. Mr. Lazarus also serves as a director of Cobra Industries,
Inc., Illinois Superconductor Corporation and Primark Corporation; and as Vice
Chairman of the Board of Directors of The Northwestern Healthcare Network,
Chicago, Illinois. Mr. Lazarus' business address is ARCH Venture Partners, 135
South LaSalle Street, Suite 3702, Chicago, Illinois 60603.
 
     MR. EDWARD J. LEDDER has served as a director of Parent since January 1991.
In April 1981, Mr. Ledder retired as Chairman and Chief Executive Officer of
Abbott Laboratories, a corporation in the principal business of developing and
providing human healthcare products, where he had been employed in various
executive positions since 1939. Mr. Ledder also serves as a director of Alliance
International Healthcare Fund.
 
     DR. GILBERT S. OMENN has served as a director of Parent since January 1987.
He has been Dean of the School of Public Health and Community Medicine at the
University of Washington for more than five years. Dr. Omenn also is a director
of Immune Response Corporation and Rohm & Haas Company. Mr. Omenn's business
address is School of Public Health, SC-30, University of Washington, Seattle,
Washington 98195.
 
     MR. BERNARD H. SEMLER has served as a director of Parent since August 1982.
He has been a management consultant since July 1982. From 1974 to July 1982, he
was Executive Vice President-Finance of Abbott Laboratories.
 
     DR. N. KIRBY ALTON became Senior Vice President, Development, in August
1993, having served as Senior Vice President, Therapeutic Product Development,
since August 1992. Dr. Alton previously served as Vice President, Therapeutic
Product Development, Responsible Head, from October 1988 to August 1992 and as
Director, Therapeutic Product Development, from February 1986 to October 1988.
 
     DR. ROBERT K. ANDREN became Senior Vice President, Operations, in August
1992, having served as Vice President, Manufacturing and Engineering, since July
1991. Dr. Andren had previously served as Vice President, Pharmaceutical
Manufacturing, from October 1988 to July 1991, and as Manager, Pharmaceutical
Manufacturing, from June 1985 to October 1988.
 
     MR. ROBERT S. ATTIYEH joined Parent in July 1994 as Senior Vice President,
Finance and Corporate Development. Prior to joining Parent, Mr. Attiyeh served
as a director of McKinsey & Company from 1967.
 
     DR. DENNIS M. FENTON became Senior Vice President, Sales and Marketing, in
August 1992, having served as Vice President, Process Development, Facilities
and Manufacturing Services since July 1991. Dr. Fenton had previously served as
Vice President, Pilot Plant Operations and Clinical Manufacturing, from October
1988 to July 1991, and as Director, Pilot Plant Operations from 1985 to October
1988.
 
     MR. DARYL D. HILL became Senior Vice President, Asia Pacific, in January
1994, having served as Vice President, Quality Assurance, from October 1988 to
January 1994 and as Director of Quality Assurance from January 1984 to October
1988.
 
                                       I-2
<PAGE>   34
 
     MR. LARRY A. MAY became Vice President, Corporate Controller and Chief
Accounting Officer in October 1991, having served as Corporate Controller and
Chief Accounting Officer from October 1988 to October 1991 and as Controller
from January 1983 to October 1988.
 
     DR. DANIEL VAPNEK became Senior Vice President, Research, in October 1988,
having served as Vice President, Research since January 1986.
 
     MR. THOMAS E. WORKMAN, JR. was appointed Vice President, Secretary and
General Counsel in December 1992, having served as Acting General Counsel since
September 1992. Prior to joining the Company, Mr. Workman was an advisory
partner of Pillsbury Madison & Sutro, a law firm, from January 1992 to September
1992 and was a regular partner of Pillsbury Madison & Sutro from 1986 through
December 1991.
 
     DR. LINDA R. WUDL became Vice President Quality Assurance in January 1994,
having served as Director of Quality Control from April 1991 to January 1994,
and as Manager of Quality Control from April 1987 to April 1991.
 
     2. Directors and Executive Officers of Purchaser. The following table sets
forth the name and present position(s) with Purchaser of the directors and
executive officers of Purchaser.
 
<TABLE>
<CAPTION>
                 NAME                                     POSITION(S) WITH PURCHASER
- --------------------------------------    -----------------------------------------------------------
<S>                                       <C>
Dr. N. Kirby Alton                        Director
Robert S. Attiyeh                         Director
Dr. Michael Bevilacqua                    Director
Dr. George Morstyn                        Director
Dr. Daniel Vapnek                         Director
Thomas E. Workman, Jr.                    Director, Chief Executive Officer, Secretary and Treasurer
</TABLE>
 
     Set forth below with respect to each director and executive officer of
Purchaser (other than Messrs. Attiyeh and Workman and Drs. Alton and Vapnek) is
the present principal occupation or employment of such persons and material
occupations, position, offices or employments for the past five years of each
such person. All present positions set forth below are with Parent. Each such
person's business address is c/o Amgen Inc., Amgen Center, 1840 DeHavilland
Drive, Thousand Oaks, CA 91320-1789, and each person is a citizen of the United
States.
 
     For information with respect to Messrs. Attiyeh and Workman and Drs. Alton
and Vapnek, please see the information set forth above with respect to their
positions with Parent.
 
     DR. MICHAEL BEVILACQUA became a Vice President, Inflammation and Medicinal
Chemistry in October 1993. Prior to joining Parent, Dr. Bevilacqua was an
Associate Investigator at the Howard Hughes Medical Institute in La Jolla,
California as well as an Associate Professor of Pathology at the University of
California at Davis from 1991 to 1993. Dr. Bevilacqua was an Assistant Professor
of Pathology at Harvard Medical School from 1987 to 1991.
 
     DR. GEORGE MORSTYN became Vice President, Chemical Development and Chief
Medical Officer in August 1993 having served as Vice President Medical and
Clinical Affairs from April 1992 to August 1993. Between July 1991 and April
1992, Dr. Morstyn held other development related positions at Amgen. Between
1983 and 1991, Dr. Morstyn held various medical and research positions at the
University of Melbourne, the Royal Melbourne Hospital, Austin Hospital and the
Ludwig Institute for Cancer Research.
 
                                       I-3
<PAGE>   35
 
     Facsimiles of the Letter of Transmittal will be accepted. The Letter of
Transmittal and certificates evidencing Shares and any other required documents
should be sent or delivered by each stockholder or his broker, dealer,
commercial bank, trust company or other nominee to the Depositary at the address
set forth below.
 
                        The Depositary for the Offer is:
 
                    AMERICAN STOCK TRANSFER & TRUST COMPANY
 
                                 40 Wall Street
                                   46th Floor
                            New York, New York 10005
                      Attention: Reorganization Department
                         Facsimile No.: (718) 234-5001
 
                   For Confirmation of Facsimile Transmission
                             or Other Information:
                                 (718) 921-8200
                        (800) 937-5449 (Call Toll Free)
 
     Questions or requests for assistance may be directed to the Information
Agent or the Dealer Manager at their respective addresses and telephone numbers
listed below. Additional copies of this Offer to Purchase, the Letter of
Transmittal and the Notice of Guaranteed Delivery may be obtained from the
Information Agent. A stockholder may also contact brokers, dealers, commercial
banks or trust companies for assistance concerning the Offer.
 
                    The Information Agent for the Offer is:
 
                            D. F. KING & CO., INC.
 
                               77 Water Street
                              New York, NY 10005
                        (212) 269-5550 (Call Collect)
                       (800) 628-8536 (Call Toll Free)
 
                      The Dealer Manager for the Offer is:
 
                                CS FIRST BOSTON
 
                               Park Avenue Plaza
                              55 East 52nd Street
                               New York, NY 10055
                         (212) 909-2000 (Call Collect)

<PAGE>   1
 
                             LETTER OF TRANSMITTAL
                        TO TENDER SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
 
                                       OF
 
                                 SYNERGEN, INC.
 
                       PURSUANT TO THE OFFER TO PURCHASE
                            DATED NOVEMBER 23, 1994
 
                                       OF
 
                       AMGEN ACQUISITION SUBSIDIARY, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
 
                                   AMGEN INC.
- --------------------------------------------------------------------------------
 
        THIS OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,
              NEW YORK CITY TIME, ON WEDNESDAY, DECEMBER 21, 1994,
                         UNLESS THE OFFER IS EXTENDED.
- --------------------------------------------------------------------------------
 
                        The Depositary for the Offer is:
 
                    AMERICAN STOCK TRANSFER & TRUST COMPANY
 
<TABLE>
<S>                                                <C>
        By Hand, Mail or Overnight Courier:                    By Facsimile Transmission:
      American Stock Transfer & Trust Company                        (718) 234-5001
                  40 Wall Street                       For Confirmation of Facsimile Transmission
                    46th Floor                                    or Other Information:
                New York, NY 10005                                   (718) 921-8200
       Attention: Reorganization Department                  (800) 937-5449 (Call Toll Free)
</TABLE>
 
     DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET
FORTH ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE TRANSMISSION OTHER
THAN AS SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
 
     THE INSTRUCTIONS ACCOMPANYING THIS LETTER OF TRANSMITTAL SHOULD BE READ
CAREFULLY BEFORE THIS LETTER OF TRANSMITTAL IS COMPLETED.
 
<TABLE>
<S>                                                       <C>             <C>             <C>
- ----------------------------------------------------------------------------------------------------------
                                      DESCRIPTION OF SHARES TENDERED
- ----------------------------------------------------------------------------------------------------------
     NAME(S) AND ADDRESS(ES) OF REGISTERED HOLDER(S)
      (PLEASE FILL IN, IF BLANK, EXACTLY AS NAME(S)          SHARE CERTIFICATE(S) AND SHARE(S) TENDERED
            APPEAR(S) ON SHARE CERTIFICATE(S))                 (ATTACH ADDITIONAL LIST, IF NECESSARY)
- ----------------------------------------------------------------------------------------------------------
                                                                            TOTAL NUMBER
                                                                             OF SHARES
                                                               SHARE        EVIDENCED BY     NUMBER OF
                                                            CERTIFICATE        SHARE           SHARES
                                                             NUMBER(S)*   CERTIFICATE(S)*    TENDERED**
                                                          ------------------------------------------------
 
                                                          ------------------------------------------------
 
                                                          ------------------------------------------------
 
                                                          ------------------------------------------------
 
                                                          ------------------------------------------------
 
                                                          ------------------------------------------------
                                                            TOTAL SHARES
- ----------------------------------------------------------------------------------------------------------
   * Need not be completed by stockholders delivering Shares by book-entry transfer.
  ** Unless otherwise indicated, it will be assumed that all Shares evidenced by each Share Certificate
     delivered to the Depositary are being tendered hereby. See Instruction 4.
- ----------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>   2
 
     This Letter of Transmittal is to be completed by stockholders either if
certificates evidencing Shares (as defined below) are to be forwarded herewith
or if delivery of Shares is to be made by book-entry transfer to the
Depositary's account at The Depository Trust Company ("DTC"), the Midwest
Securities Trust Company ("MSTC") or the Philadelphia Depository Trust Company
("PDTC") (each a "Book-Entry Transfer Facility" and collectively, the "Book-
Entry Transfer Facilities") pursuant to the book-entry transfer procedures
described in Section 3 of the Offer to Purchase (as defined below). DELIVERY OF
DOCUMENTS TO A BOOK-ENTRY TRANSFER FACILITY DOES NOT CONSTITUTE DELIVERY TO THE
DEPOSITARY. See Instruction 2.
 
     Stockholders whose certificates evidencing Shares ("Share Certificates")
are not immediately available or who cannot deliver their Share Certificates and
all other documents required hereby to the Depositary prior to the Expiration
Date (as defined in Section 1 of the Offer to Purchase) or who cannot complete
the procedure for delivery by book-entry transfer on a timely basis and who wish
to tender their Shares must do so pursuant to the guaranteed delivery procedure
described in Section 3 of the Offer to Purchase. See Instruction 2.
 
/ /  CHECK HERE IF SHARES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER TO THE
     DEPOSITARY'S ACCOUNT AT ONE OF THE BOOK-ENTRY TRANSFER FACILITIES AND
     COMPLETE THE FOLLOWING:

     Name of Tendering Institution -------------------------------------------
 
     Check Box of Applicable Book-Entry Transfer Facility:
 
         (check one)
         / /  DTC             / /  MSTC            / /  PDTC

         Account Number                 Transaction Code Number
                       ----------------                        ----------------
 
/ /  CHECK HERE IF SHARES ARE BEING TENDERED PURSUANT TO A NOTICE OF GUARANTEED
     DELIVERY PREVIOUSLY SENT TO THE DEPOSITARY AND COMPLETE THE FOLLOWING:

     Name(s) of Registered Holder(s)
                                    -------------------------------------------

     Window Ticket No. (if any)
                               ------------------------------------------------

     Date of Execution of Notice of Guaranteed Delivery
                                                       ------------------------

     Name of Institution which Guaranteed Delivery
                                                  -----------------------------
<PAGE>   3
 
                    NOTE: SIGNATURES MUST BE PROVIDED BELOW
              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY
 
Ladies and Gentlemen:
 
     The undersigned hereby tenders to Amgen Acquisition Subsidiary, Inc., a
Delaware corporation ("Purchaser") and a wholly owned subsidiary of Amgen Inc.,
a Delaware corporation, the above-described shares of Common Stock, par value
$.01 per share, of Synergen, Inc., a Delaware corporation (the "Company"),
including the associated preferred stock purchase rights (all shares of such
Common Stock from time to time outstanding being, collectively, the "Shares" and
unless the context requires otherwise all references to "Shares" shall include a
reference to such rights) pursuant to Purchaser's offer to purchase all Shares,
at $9.25 per Share, net to the seller in cash, upon the terms and subject to the
conditions set forth in the Offer to Purchase dated November 23, 1994 (the
"Offer to Purchase"), receipt of which is hereby acknowledged, and in this
Letter of Transmittal (which, together with the Offer to Purchase, constitutes
the "Offer"). The undersigned understands that Purchaser reserves the right to
transfer or assign, in whole or from time to time in part, to one or more of its
affiliates, the right to purchase all or any portion of the Shares tendered
pursuant to the Offer.
 
     Subject to, and effective upon, acceptance for payment of the Shares
tendered herewith, in accordance with the terms of the Offer, the undersigned
hereby sells, assigns and transfers to, or upon the order of, Purchase, all
right, title and interest in and to all the Shares that are being tendered
hereby (including, without limitation, the associated preferred stock purchase
rights) and irrevocably appoints the Depositary the true and lawful agent and
attorney-in-fact of the undersigned with respect to such Shares, with full power
of substitution (such power of attorney being deemed to be an irrevocable power
coupled with an interest), to (i) deliver Share Certificates evidencing such
Shares, or transfer ownership of such Shares on the account books maintained by
a Book-Entry Transfer Facility, together, in either case, with all accompanying
evidences of transfer and authenticity, to or upon the order of Purchaser, (ii)
present such Shares for transfer on the books of the Company and (iii) receive
all benefits and otherwise exercise all rights of beneficial ownership of such
Shares, all in accordance with the terms of the Offer.
 
     The undersigned hereby irrevocably appoints designees of Purchaser, and
each of them, as the attorneys and proxies of the undersigned, each with full
power of substitution, to vote in such manner as each such attorney and proxy or
his substitute shall, in his sole discretion, deem proper and otherwise act (by
written consent or otherwise) with respect to all Shares tendered hereby that
have been accepted for payment by Purchaser prior to the time of such vote or
other action and all Shares and other securities issued in distributions in
respect of such Shares, which the undersigned is entitled to vote at any meeting
of stockholders of the Company (whether annual or special and whether or not an
adjourned or postponed meeting) or consent in lieu of any such meeting or
otherwise. This proxy and power of attorney is coupled with an interest in the
Shares tendered hereby, is irrevocable and is granted in consideration of, and
is effective upon, the acceptance for payment of such Shares by Purchaser in
accordance with other terms of the Offer. Such acceptance for payment shall
revoke all other proxies and powers of attorney granted by the undersigned at
any time with respect to such Shares (and all Shares and other securities issued
in distributions in respect of such Shares), and no subsequent proxy or power of
attorney shall be given or written consent executed (and if given or executed,
shall not be effective) by the undersigned with respect thereto. The undersigned
understands that, in order for Shares to be deemed validly tendered, immediately
upon Purchaser's acceptance of such Shares for payment, Purchaser must be able
to exercise full voting and other rights with respect to such Shares, including,
without limitation, voting at any meeting of the Company's stockholders then
scheduled.
 
     The undersigned hereby represents and warrants that the undersigned has
full power and authority to tender, sell, assign and transfer the Shares
tendered hereby, that when such Shares are accepted for payment by Purchaser,
Purchaser will acquire good, marketable and unencumbered title thereto, free and
clear of all liens, restrictions, charges and encumbrances, and that none of
such Shares will be subject to any adverse claim. The undersigned, upon request,
shall execute and deliver all additional documents deemed by the Depositary or
Purchaser to be necessary or desirable to complete the sale, assignment and
transfer of the Shares tendered hereby.
 
     No authority herein conferred or agreed to be conferred shall be affected
by, and all such authority shall survive, the death or incapacity of the
undersigned. All obligations of the undersigned hereunder shall be binding upon
the heirs, personal representatives, successors and assigns of the undersigned.
Except as stated in the Offer to Purchase, this tender is irrevocable.
 
     The undersigned understands that tenders of Shares pursuant to any one of
the procedures described in Section 3 of the Offer to Purchase and in the
instructions hereto will constitute the undersigned's acceptance of the terms
and conditions of the Offer. Purchaser's acceptance of such Shares for payment
will constitute a binding agreement between the undersigned and Purchaser upon
the terms and subject to the conditions of the Offer.
 
     Unless otherwise indicated herein in the box entitled "Special Payment
Instructions," please issue the check for the purchase price of all Shares
purchased, and return all Share Certificates evidencing Shares not purchased or
not tendered in the name(s) of the registered holder(s) appearing above under
"Description of Shares Tendered." Similarly, unless
<PAGE>   4
 
otherwise indicated in the box entitled "Special Delivery Instructions," please
mail the check for the purchase price of all Shares purchased and all Share
Certificates evidencing Shares not tendered or not purchased (and accompanying
documents, as appropriate) to the address(es) of the registered holder(s)
appearing above under "Description of Shares Tendered." In the event that the
boxes entitled "Special Payment Instructions" and "Special Delivery
Instructions" are both completed, please issue the check for the purchase price
of all Shares purchased and return all Share Certificates evidencing Shares not
purchased or not tendered in the name(s) of, and mail such check and Share
Certificates to, the person(s) so indicated. Unless otherwise indicated herein
in the box entitled "Special Payment Instructions," please credit any Shares
tendered hereby and delivered by book-entry transfer, but which are not
purchased by crediting the account at the Book-Entry Transfer Facility
designated above. The undersigned recognizes that Purchaser has no obligation,
pursuant to the Special Payment Instructions, to transfer any Shares from the
name of the registered holder(s) thereof if Purchaser does not purchase any of
the Shares tendered hereby.
 
<TABLE>
  <S>                                                   <C>
  ---------------------------------------------         ----------------------------------------------
           SPECIAL PAYMENT INSTRUCTIONS                         SPECIAL DELIVERY INSTRUCTIONS
         (See Instructions 1, 5, 6 and 7)                      (See Instructions 1, 5, 6 and 7)
 
  To be completed ONLY if the check for the             To be completed ONLY if the check for the
  purchase price of Shares purchased or Share           purchase price of Shares purchased or Share
  Certificates evidencing Shares not tendered or        Certificates evidencing Shares not tendered or
  not purchased are to be issued in the name of         not purchased are to be mailed to someone
  someone other than the undersigned, or if             other than the undersigned, or to the
  Shares tendered hereby and delivered by               undersigned at an address other than that
  book-entry transfer which are not purchased           shown under "Description of Shares Tendered."
  are to be returned by credit to an account at                                                     
  one of the Book-Entry Transfer Facilities             Mail  / / check     / / Share Certificate(s) 
  other than that designated above.                     to:                                          
                                                                                                     
  Issue  / / check     / / Share Certificate(s)         Name ________________________________________
  to:                                                                     (PLEASE PRINT)             
                                                        Address _____________________________________
  Name _________________________________________                                           (ZIP CODE)
                    (PLEASE PRINT)                                                                    
  Address ______________________________________        (TAXPAYER IDENTIFICATION OR                  
                                                        SOCIAL SECURITY NUMBER)                      
  ______________________________________________        (SEE SUBSTITUTE FORM W-9 ON REVERSE SIDE)    
                                      (ZIP CODE)                                                     
                                                                                                 
  (TAXPAYER IDENTIFICATION OR                                                                    
  SOCIAL SECURITY NUMBER)                               
  (SEE SUBSTITUTE FORM W-9 ON REVERSE SIDE)             
                                                        
  / / Credit Shares delivered by book-entry             
      transfer and not purchased to the account         
      set forth below:                                  
                                                        
  Check appropriate box:                                
                                                        
  / / DTC     / / MSTC     / / PDTC                     
                                                        
  Account Number ________________________________       
                                                        
  ---------------------------------------------         ----------------------------------------------
</TABLE>
 
<PAGE>   5
 
                                   IMPORTANT
 
                            STOCKHOLDERS: SIGN HERE
           (PLEASE COMPLETE SUBSTITUTE FORM W-9 ON LAST PRINTED PAGE)
 
________________________________________________________________________________

________________________________________________________________________________
                           SIGNATURE(S) OF HOLDER(S)
 
                DATED:__________________________________________________, 199___
 
(Must be signed by registered holder(s) exactly as name(s) appear(s) on Share
Certificates or on a security position listing or by person(s) authorized to
become registered holder(s) by certificates and documents transmitted herewith.
If signature is by a trustee, executor, administrator, guardian,
attorney-in-fact, officer of a corporation or other person acting in a fiduciary
or representative capacity, please provide the following information and see
Instruction 5.)
 
Name(s):________________________________________________________________________

________________________________________________________________________________
                                 (PLEASE PRINT)
 
Capacity (full title):__________________________________________________________

Address:________________________________________________________________________
 
________________________________________________________________________________
                                                              (INCLUDE ZIP CODE)
 
Area code and Telephone No.:____________________________________________________
 
TAXPAYER IDENTIFICATION OR SOCIAL SECURITY NO.:_________________________________
                   (SEE SUBSTITUTE FORM W-9 ON REVERSE SIDE)
 
                           GUARANTEE OF SIGNATURE(S)
                           (SEE INSTRUCTIONS 1 AND 5)
 
Authorized Signature:___________________________________________________________
 
Name:___________________________________________________________________________
                             (PLEASE TYPE OR PRINT)
 
Title:__________________________________________________________________________
 
Name of Firm:___________________________________________________________________
 
Address:________________________________________________________________________
                                                              (INCLUDE ZIP CODE)
 
Area Code and Telephone No.:____________________________________________________

Dated:__________________________________________________________________, 199___
<PAGE>   6
 
                                  INSTRUCTIONS
 
             FORMING PART OF THE TERMS AND CONDITIONS OF THE OFFER
 
     1. GUARANTEE OF SIGNATURES. All signatures on this Letter of Transmittal
must be guaranteed by a firm which is a member of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.,
or by a commercial bank or trust company having an office or correspondent in
the United States (each of the foregoing being referred to as an "Eligible
Institution") unless (i) this Letter of Transmittal is signed by the registered
holder(s) of the Shares (which term, for purposes of this document, shall
include any participant in a Book-Entry Transfer Facility whose name appears on
a security position listing as the owner of such Shares) tendered hereby and
such holder(s) has (have) completed neither the box entitled "Special Payment
Instructions" nor the box entitled "Special Delivery Instructions" on the
reverse hereof or (ii) such Shares are tendered for the account of an Eligible
Institution. See Instruction 5.
 
     2. DELIVERY OF LETTER OF TRANSMITTAL AND SHARE CERTIFICATES. This Letter of
Transmittal is to be used either if Share Certificates are to be forwarded
herewith or if Shares are to be delivered by book-entry transfer pursuant to the
procedures set forth in Section 3 of the Offer to Purchase. Share Certificates
evidencing all physically tendered Shares, or a confirmation of a book-entry
transfer into the Depositary's account at a Book-Entry Transfer Facility of all
Shares delivered by book-entry transfer as well as a properly completed and duly
executed Letter of Transmittal (or facsimile thereof) and any other documents
required by this Letter of Transmittal, must be received by the Depositary at
one of its addresses set forth on the reverse hereof prior to the Expiration
Date (as defined in Section 1 of the Offer to Purchase). If Share Certificates
are forwarded to the Depositary in multiple deliveries, a properly completed and
duly executed Letter of Transmittal must accompany each such delivery.
Stockholders whose Share Certificates are not immediately available, who cannot
deliver their Share Certificates and all other required documents to the
Depositary prior to the Expiration Date or who cannot complete the procedures
for delivery by book-entry transfer on a timely basis may tender their Shares
pursuant to the guaranteed delivery procedure described in Section 3 of the
Offer to Purchase. Pursuant to such procedures: (i) such tender must be made by
or through an Eligible Institution; (ii) a properly completed and duly executed
Notice of Guaranteed Delivery, substantially in the form made available by
Purchaser, must be received by the Depositary prior to the Expiration Date; and
(iii) the Share Certificates evidencing all physically delivered Shares in
proper form for transfer by delivery, or a confirmation of a book-entry transfer
into the Depositary's account at a Book-Entry Transfer Facility of all Shares
delivered by book-entry transfer, in each case together with a Letter of
Transmittal (or a facsimile thereof), properly completed and duly executed, with
any required signature guarantees, and any other documents required by this
Letter of Transmittal, must be received by the Depositary within five Nasdaq
National Market trading days after the date of execution of such Notice of
Guaranteed Delivery, all as described in Section 3 of the Offer to Purchase.
 
     THE METHOD OF DELIVERY OF THIS LETTER OF TRANSMITTAL, SHARE CERTIFICATES
AND ALL OTHER REQUIRED DOCUMENTS, INCLUDING DELIVERY THROUGH ANY BOOK-ENTRY
TRANSFER FACILITY, IS AT THE OPTION AND RISK OF THE TENDERING STOCKHOLDER, AND
THE DELIVERY WILL BE DEEMED MADE ONLY WHEN ACTUALLY RECEIVED BY THE DEPOSITARY.
IF DELIVERY IS BY MAIL, REGISTERED MAIL WITH RETURN RECEIPT REQUESTED, PROPERLY
INSURED, IS RECOMMENDED. IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO
ENSURE TIMELY DELIVERY.
 
     No alternative, conditional or contingent tenders will be accepted, and no
fractional Shares will be purchased. By execution of this Letter of Transmittal
(or a facsimile hereof), all tendering stockholders waive any right to receive
any notice of the acceptance of their Shares for payment.
 
     3. INADEQUATE SPACE. If the space provided herein under "Description of
Shares Tendered" is inadequate, the Share Certificate numbers, the number of
Shares evidenced by such Share Certificates and the number of Shares tendered
should be listed on a separate schedule and attached hereto.
 
     4. PARTIAL TENDERS (NOT APPLICABLE TO STOCKHOLDERS WHO TENDER BY BOOK-ENTRY
TRANSFER). If fewer than all the Shares evidenced by any Share Certificate
delivered to the Depositary herewith are to be tendered hereby, fill in the
number of Shares which are to be tendered in the box entitled "Number of Shares
Tendered." In such cases, new Share Certificate(s) evidencing the remainder of
the Shares that were evidenced by the Share Certificates delivered to the
Depositary herewith will be sent to the person(s) signing this Letter of
Transmittal, unless otherwise provided in the box entitled "Special Delivery
Instructions" on the reverse hereof, as soon as practicable after the expiration
or termination of the Offer. All Shares evidenced by Share Certificates
delivered to the Depositary will be deemed to have been tendered unless
otherwise indicated.
 
     5. SIGNATURES ON LETTER OF TRANSMITTAL; STOCK POWERS AND ENDORSEMENTS. If
this Letter of Transmittal is signed by the registered holder(s) of the Shares
tendered hereby, the signature(s) must correspond with the name(s) as written on
the face of the Share Certificates evidencing such Shares without alteration,
enlargement or any other change whatsoever.
 
     If any Share tendered hereby is owned of record by two or more persons, all
such persons must sign this Letter of Transmittal.
 
     If any of the Shares tendered hereby are registered in the names of
different holders, it will be necessary to complete, sign and submit as many
separate Letters of Transmittal as there are different registrations of such
Shares.
<PAGE>   7
 
     If this Letter of Transmittal is signed by the registered holder(s) of the
Shares tendered hereby, no endorsements of Share Certificates or separate stock
powers are required, unless payment is to be made to, or Share Certificates
evidencing Shares not tendered or not purchased are to be issued in the name of,
a person other than the registered holder(s), in which case, the Share
Certificate(s) evidencing the Shares tendered hereby must be endorsed or
accompanied by appropriate stock powers, in either case signed exactly as the
name(s) of the registered holder(s) appear(s) on such Share Certificate(s).
Signatures on such Share Certificate(s) and stock powers must be guaranteed by
an Eligible Institution.
 
     If this Letter of Transmittal is signed by a person other than the
registered holder(s) of the Shares tendered hereby, the Share Certificate(s)
evidencing the Shares tendered hereby must be endorsed or accompanied by
appropriate stock powers, in either case signed exactly as the name(s) of the
registered holder(s) appear(s) on such Share Certificate(s). Signatures on such
Share Certificate(s) and stock powers must be guaranteed by an Eligible
Institution.
 
     If this Letter of Transmittal or any Share Certificate or stock power is
signed by a trustee, executor, administrator, guardian, attorney-in-fact,
officer of a corporation or other person acting in a fiduciary or representative
capacity, such person should so indicate when signing, and proper evidence
satisfactory to Purchaser of such person's authority so to act must be
submitted.
 
     6. STOCK TRANSFER TAXES. Except as otherwise provided in this Instruction
6, Purchaser will pay all stock transfer taxes with respect to the sale and
transfer of any Shares to it or its order pursuant to the Offer. If, however,
payment of the purchase price of any Shares purchased is to be made to, or Share
Certificate(s) evidencing Shares not tendered or not purchased are to be issued
in the name of, a person other than the registered holder(s), the amount of any
stock transfer taxes (whether imposed on the registered holder(s), such other
person or otherwise) payable on account of the transfer to such other person
will be deducted from the purchase price of such Shares purchased, unless
evidence satisfactory to Purchaser of the payment of such taxes, or exemption
therefrom, is submitted. EXCEPT AS PROVIDED IN THIS INSTRUCTION 6, IT WILL NOT
BE NECESSARY FOR TRANSFER TAX STAMPS TO BE AFFIXED TO THE SHARE CERTIFICATES
EVIDENCING THE SHARES TENDERED HEREBY.
 
     7. SPECIAL PAYMENT AND DELIVERY INSTRUCTIONS. If a check for the purchase
price of any Shares tendered hereby is to be issued, or Share Certificate(s)
evidencing Shares not tendered or not purchased are to be issued, in the name of
a person other than the person(s) signing this Letter of Transmittal or if such
check or any such Share Certificate is to be sent to someone other than the
person(s) signing this Letter of Transmittal or to the person(s) signing this
Letter of Transmittal but at an address other than that shown in the box
entitled "Description of Shares Tendered" on the reverse hereof, the appropriate
boxes on the reverse of this Letter of Transmittal must be completed.
Stockholders delivering Shares tendered hereby by book-entry transfer may
request that Shares not purchased be credited to such account maintained at a
Book-Entry Transfer Facility as such stockholder may designate in the box
entitled "Special Payment Instructions" on the reverse hereof. If no such
instructions are given, all such Shares not purchased will be returned by
crediting the account at the Book-Entry Transfer Facility designated on the
reverse hereof as the account from which such Shares were delivered.
 
     8. QUESTIONS AND REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES. Questions
and requests for assistance may be directed to the Information Agent or the
Dealer Manager at their respective addresses or telephone numbers set forth
below. Additional copies of the Offer to Purchase, this Letter of Transmittal
and the Notice of Guaranteed Delivery may be obtained from the Information Agent
or from brokers, dealers, commercial banks or trust companies.
 
     9. SUBSTITUTE FORM W-9. Each tendering stockholder is required to provide
the Depositary with a correct Taxpayer Identification Number ("TIN") on the
Substitute Form W-9, which is provided under "Important Tax Information" below,
and to certify whether such stockholder is subject to backup withholding of
federal income tax. If a tendering stockholder has been notified by the Internal
Revenue Service that such stockholder is subject to backup withholding, such
stockholder must cross out item (2) of the certification box of the Substitute
Form W-9, unless such stockholder has since been notified by the Internal
Revenue Service that such stockholder is no longer subject to backup
withholding. Failure to provide the information on the Substitute Form W-9 may
subject the tendering stockholder to 31% federal income tax withholding on the
payment of the purchase price of all Shares purchased from such stockholder. If
the tendering stockholder has not been issued a TIN and has applied for one or
intends to apply for one in the near future, such stockholder should write
"Applied For" in the space provided for the TIN in Part I of the Substitute Form
W-9, and sign and date the Substitute Form W-9. If "Applied For" is written in
Part I and the Depositary is not provided with a TIN within 60 days, the
Depositary will withhold 31% on all payments of the purchase price to such
stockholder until a TIN is provided to the Depositary.
 
     IMPORTANT: THIS LETTER OF TRANSMITTAL OR A FACSIMILE HEREOF, PROPERLY
COMPLETED AND DULY EXECUTED (TOGETHER WITH ANY REQUIRED SIGNATURE GUARANTEES AND
SHARE CERTIFICATES OR CONFIRMATION OF BOOK-ENTRY TRANSFER AND ALL OTHER REQUIRED
DOCUMENTS) OR A PROPERLY COMPLETED AND DULY EXECUTED NOTICE OF GUARANTEED
DELIVERY MUST BE RECEIVED BY THE DEPOSITARY PRIOR TO THE EXPIRATION DATE (AS
DEFINED IN THE OFFER TO PURCHASE).
<PAGE>   8
 
                           IMPORTANT TAX INFORMATION
 
     Under the federal income tax law, a stockholder whose tendered Shares are
accepted for payment is required by law to provide the Depositary (as payer)
with such stockholder's correct TIN on Substitute Form W-9 below. If such
stockholder is an individual, the TIN is such stockholder's social security
number. If the Depositary is not provided with the correct TIN, the stockholder
may be subject to a $50 penalty imposed by the Internal Revenue Service. In
addition, payments that are made to such stockholder with respect to Shares
purchased pursuant to the Offer may be subject to backup withholding.
 
     Certain stockholders (including, among others, all corporations and certain
foreign individuals) are not subject to these backup withholding and reporting
requirements. In order for a foreign individual to qualify as an exempt
recipient, such individual must submit a statement, signed under penalties of
perjury, attesting to such individual's exempt status. Forms of such statements
can be obtained from the Depositary. See the enclosed Guidelines for
Certification of Taxpayer Identification Number on Substitute Form W-9 for
additional instructions.
 
     If backup withholding applies, the Depositary is required to withhold 31%
of any payments made to the stockholder. Backup withholding is not an additional
tax. Rather, the tax liability of persons subject to backup withholding will be
reduced by the amount of tax withheld. If withholding results in an overpayment
of taxes, a refund may be obtained from the Internal Revenue Service.
 
PURPOSE OF SUBSTITUTE FORM W-9
 
     To prevent backup withholding on payments that are made to a stockholder
with respect to Shares purchased pursuant to the Offer, the stockholder is
required to notify the Depositary of such stockholder's correct TIN by
completing the form below certifying that the TIN provided on Substitute Form
W-9 is correct (or that such stockholder is awaiting a TIN), and that (i) such
stockholder has not been notified by the Internal Revenue Service that he is
subject to backup withholding as a result of a failure to report all interest or
dividends or (ii) the Internal Revenue Service has notified such stockholder
that such stockholder is no longer subject to backup withholding.
 
WHAT NUMBER TO GIVE THE DEPOSITARY
 
     The stockholder is required to give the Depositary the social security
number or employer identification number of the record holder of the Shares
tendered hereby. If the Shares are in more than one name or are not in the name
of the actual owner, consult the enclosed Guidelines for Certification of
Taxpayer Identification Number on Substitute Form W-9 for additional guidance on
which number to report. If the tendering stockholder has not been issued a TIN
and has applied for a number or intends to apply for a number in the near
future, the stockholder should write "Applied For" in the space provided for the
TIN in Part I, and sign and date the Substitute Form W-9. If "Applied For" is
written in Part I and the Depositary is not provided with a TIN within 60 days,
the Depositary will withhold 31% of all payments of the purchase price to such
stockholder until a TIN is provided to the Depositary.
<PAGE>   9
 
- --------------------------------------------------------------------------------
             PAYER'S NAME: AMERICAN STOCK TRANSFER & TRUST COMPANY
- --------------------------------------------------------------------------------
<TABLE>
<S>                              <C>                                                      <C>
SUBSTITUTE                       PART I -- Taxpayer Identification Number--For            Part III -- Social Security Number OR
FORM W-9                         all accounts, enter taxpayer identification number       Employer Identification Number
DEPARTMENT OF THE TREASURY       in the box at right.  (For most individuals, this is
INTERNAL REVENUE SERVICE         your social security number. If you do not have a        -------------------------------------
                                 number, see OBTAINING A NUMBER in the enclosed           (If awaiting TIN write "Applied For")
PAYER'S REQUEST FOR TAXPAYER     Guidelines.) Certify by signing and dating below.
IDENTIFICATION NUMBER (TIN)
                                 NOTE: If the account is in more than one name,
                                 see chart in the enclosed Guidelines to determine
                                 which number to give the payer.
                                 ---------------------------------------------------------------------------------------------
                                 PART II -- For Payees exempt from backup withholding, see the enclosed Guidelines and
                                 complete as instructed therein.

</TABLE> 
- --------------------------------------------------------------------------------
 CERTIFICATION -- Under penalties of perjury, I certify that:
 (1) The number shown on this form is my correct Taxpayer Identification Number
     (or I am waiting for a number to be issued to me); and
 
 (2) I am not subject to backup withholding either because I have not been
     notified by the Internal Revenue Service (IRS) that I am subject to backup
     withholding as a result of a failure to report all interest or dividends,
     or the IRS has notified me that I am no longer subject to backup
     withholding.
 
 CERTIFICATION INSTRUCTIONS -- You must cross out item (2) above if you have
 been notified by the IRS that you are subject to backup withholding because of
 underreporting interest or dividends on your tax return. However, if after
 being notified by the IRS that you were subject to backup withholding, you
 received another notification from the IRS that you were no longer subject to
 backup withholding, do not cross out item (2). (Also see instructions in the
 enclosed Guidelines.)
- --------------------------------------------------------------------------------
 SIGNATURE                                  DATE
- --------------------------------------------------------------------------------
 
               YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU
     ARE AWAITING (OR WILL SOON APPLY FOR) A TAXPAYER IDENTIFICATION NUMBER
- --------------------------------------------------------------------------------
 
             CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER
 
      I certify under penalties of perjury that a taxpayer identification
 number has not been issued to me, and either (a) I have mailed or delivered an
 application to receive a taxpayer identification number to the appropriate
 Internal Revenue Service Center or Social Security Administration Office or
 (b) I intend to mail or deliver an application in the near future. I
 understand that, notwithstanding the information I provided in Part III of the
 Substitute Form W-9 (and the fact that I have completed this Certificate of
 Awaiting Taxpayer Identification Number), all reportable payments made to me
 prior to the time I provide a properly certified taxpayer identification
 number to the Depository will be subject to a 31% backup withholding tax.
 
<TABLE>
  <S>                                      <C>
  ------------------------------------     -----------------------------------
                    Signature                            Date
</TABLE>
 
- --------------------------------------------------------------------------------
 
NOTE: FAILURE TO COMPLETE AND RETURN THE SUBSTITUTE FORM W-9 MAY RESULT IN
      BACKUP WITHHOLDING OF 31% OF ANY PAYMENTS MADE TO YOU PURSUANT TO THE
      OFFER TO PURCHASE. PLEASE REVIEW THE ENCLOSED GUIDELINES FOR CERTIFICATION
      OF TAXPAYER IDENTIFICATION NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL
      DETAILS.
 
                        The Information Agent for the Offer is:
                                D. F. KING & CO., INC.
                                    77 Water Street
                               New York, New York 10005
                             (212) 269-5550 (Call Collect)
                            (800) 628-8536 (Call Toll Free)
 
                         The Dealer Manager for the Offer is:
                                    CS FIRST BOSTON
                                   Park Avenue Plaza
                                  55 East 52nd Street
                               New York, New York 10055
                             (212) 909-2000 (Call Collect)

<PAGE>   1
 
                         NOTICE OF GUARANTEED DELIVERY
 
                                      FOR
 
                        TENDER OF SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
 
                                       OF
 
                                 SYNERGEN, INC.
                                       TO
 
                       AMGEN ACQUISITION SUBSIDIARY, INC.
                           A WHOLLY OWNED SUBSIDIARY
 
                                       OF
 
                                   AMGEN INC.
                   (NOT TO BE USED FOR SIGNATURE GUARANTEES)
 
     This Notice of Guaranteed Delivery, or one substantially in the form
hereof, must be used to accept the Offer (as defined below) if (i) certificates
("Share Certificates") evidencing shares of Common Stock, par value $.01 per
share (the "Shares"), of Synergen, Inc., a Delaware corporation (the "Company"),
including the associated preferred stock purchase rights (unless the context
requires otherwise, all references to "Shares" shall include a reference to such
rights) are not immediately available, (ii) Share Certificates and all other
required documents cannot be delivered to American Stock Transfer & Trust
Company, as Depositary (the "Depositary"), prior to the Expiration Date (as
defined in Section 1 of the Offer to Purchase (as defined below)) or (iii) the
procedures for delivery by book-entry transfer cannot be completed on a timely
basis. This Notice of Guaranteed Delivery may be delivered by hand, mail or
overnight courier or transmitted by facsimile transmission to the Depositary.
See Section 3 of the Offer to Purchase.
 
                        The Depositary for the Offer is:
 
                    AMERICAN STOCK TRANSFER & TRUST COMPANY
 
                      By Hand, Mail or Overnight Courier:
 
                    American Stock Transfer & Trust Company
                                 40 Wall Street
                                   46th Floor
                               New York, NY 10005
                      Attention: Reorganization Department
 
                           By Facsimile Transmission:
 
                                 (718) 234-5001
 
                   For Confirmation of Facsimile Transmission
                             or Other Information:
 
                                 (718) 921-8200
                           (800) 937-5449 (toll free)
 
     DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS
SET FORTH ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE TRANSMISSION OTHER
THAN AS SET FORTH ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.
<PAGE>   2
 
Ladies and Gentlemen:
 
     The undersigned hereby tenders to Amgen Acquisition Subsidiary, Inc., a
Delaware corporation and a wholly owned subsidiary of Amgen Inc., a Delaware
corporation, upon the terms and subject to the conditions set forth in the Offer
to Purchase, dated November 23, 1994 (the "Offer to Purchase"), and the related
Letter of Transmittal (which together constitute the "Offer"), receipt of which
is hereby acknowledged, the number of Shares specified below pursuant to the
guaranteed delivery procedures described in Section 3 of the Offer to Purchase.
 
Number of Shares: ..............................................................
Certificate Nos. (If Available): ...............................................
 ...............................................................................
Check ONE box if Shares will be delivered by book-entry transfer:
/ / The Depository Trust Company
/ / Midwest Securities Trust Company
/ / Philadelphia Depository Trust Company
Account Number: ................................................................
 ...............................................................................
 ...............................................................................
                           SIGNATURE(S) OF HOLDER(S)
Dated: ................................................................, 199....
Name(s) of Holders: ............................................................
 ...............................................................................
 ...............................................................................
                              PLEASE TYPE OR PRINT
 ...............................................................................
                                    ADDRESS
 ...............................................................................
                                                                        ZIP CODE
 ...............................................................................
                          AREA CODE AND TELEPHONE NO.
 
                                   GUARANTEE
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
     The undersigned, a firm which is a member of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.
or which is a commercial bank or trust company having an office or correspondent
in the United States, hereby (a) represents that the undersigned has a net long
position in Shares or equivalent securities within the meaning of Rule 14e-4
under the Securities Exchange Act of 1934, as amended, at least equal to the
Shares tendered (b) represents that such tender of Shares complies with Rule
14e-4 and (c) guarantees delivery to the Depositary, at its address set forth
above, Share Certificates evidencing the Shares tendered hereby, in proper form
for transfer, or confirmation of book-entry transfer of such Shares into the
Depositary's account at The Depository Trust Company, the Midwest Securities
Trust Company or the Philadelphia Depository Trust Company, in each case with
delivery of a Letter of Transmittal (or facsimile thereof) properly completed
and duly executed, and any other required documents, all within five Nasdaq
National Market trading days of the date hereof.
 
     The Eligible Institution that completes this form must communicate the
guarantee to the Depositary and must deliver the Letter of Transmittal and Share
Certificates to the Depositary within the time period shown herein. Failure to
do so could result in a financial loss to such Eligible Institution.

 ....................................      ....................................
            NAME OF FIRM                           AUTHORIZED SIGNATURE        
                                                                               
 ....................................      ....................................
              ADDRESS                                     TITLE               

 ....................................      Name: ..............................
                             ZIP CODE              PLEASE TYPE OR PRINT

 ....................................      Dated: ...................., 199....
      AREA CODE AND TELEPHONE NO.

           NOTE:  DO NOT SEND SHARE CERTIFICATES WITH THIS NOTICE.
           -----    SHARE CERTIFICATES SHOULD BE SENT WITH YOUR
                               LETTER OF TRANSMITTAL.
                                      
                                        2

<PAGE>   1
 
(LOGO)                                               CS FIRST BOSTON CORPORATION
                                                     PARK AVENUE PLAZA
                                                     NEW YORK, NEW YORK 10055
                                                     TEL: (212) 909-2000
                           OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
 
                                       OF
 
                                 SYNERGEN, INC.

                                       AT
 
                              $9.25 NET PER SHARE
 
                                       BY
 
                       AMGEN ACQUISITION SUBSIDIARY, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
 
                                   AMGEN INC.
 
________________________________________________________________________________

         THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,
              NEW YORK CITY TIME, ON WEDNESDAY, DECEMBER 21, 1994,
                         UNLESS THE OFFER IS EXTENDED.
________________________________________________________________________________

                                                               November 23, 1994
 
To Brokers, Dealers, Commercial Banks,
  Trust Companies and Other Nominees:
 
     We have been engaged by Amgen Acquisition Subsidiary, Inc. a Delaware
corporation ("Purchaser") and a wholly owned subsidiary of Amgen Inc., a
Delaware corporation ("Parent"), to act as Dealer Manager in connection with
Purchaser's offer to purchase all outstanding shares of Common Stock, par value
$.01 per share (the "Shares"), of Synergen, Inc., a Delaware corporation (the
"Company"), including the associated preferred stock purchase rights (unless the
context requires otherwise, all references to "Shares" shall include a reference
to such rights) at $9.25 per Share, net to the seller in cash without interest
thereon, upon the terms and subject to the conditions set forth in Purchaser's
Offer to Purchase dated November 23, 1994 (the "Offer to Purchase") and the
related Letter of Transmittal (which, together with the Offer to Purchase,
constitute the "Offer") enclosed herewith.
 
     THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS, THERE BEING VALIDLY
TENDERED AND NOT WITHDRAWN PRIOR TO THE EXPIRATION OF THE OFFER A NUMBER OF
SHARES THAT CONSTITUTES AT LEAST A MAJORITY OF THE SHARES OUTSTANDING ON A FULLY
DILUTED BASIS (INCLUDING SHARES ISSUABLE UPON EXERCISE OF OUTSTANDING EMPLOYEE
AND DIRECTOR STOCK OPTIONS, BUT EXCLUDING SHARES ISSUABLE UPON EXERCISE OF
OUTSTANDING WARRANTS, RIGHTS OR OTHER SECURITIES TO PURCHASE OR ACQUIRE SHARES).
<PAGE>   2
 
     For your information and for forwarding to your clients for whom you hold
shares registered in your name or in the name of your nominee, or who hold
shares registered in their own names, we are enclosing the following documents:
 
        1. Offer to Purchase, dated November 23, 1994;
 
        2. Letter of Transmittal to be used by holders of Shares in accepting
           the Offer and tendering Shares;
 
        3. Notice of Guaranteed Delivery to be used to accept the Offer if the
           Shares and all other required documents are not immediately available
           or cannot be delivered to American Stock Transfer & Trust Company
           (the "Depositary") by the Expiration Date (as defined in the Offer to
           Purchase) or if the procedure for book-entry transfer cannot be
           completed by the Expiration Date;
 
          4. A letter to stockholders of the Company from Gregory B. Abbott,
             President and Chief Executive Officer of the Company, together with
             a Solicitation/Recommendation Statement on Schedule 14D-9 filed
             with the Securities and Exchange Commission by the Company;
 
          5. A letter, which may be sent to your clients for whose accounts you
             hold Shares registered in your name or in the name of your nominee,
             with space provided for obtaining such clients' instructions with
             regard to the Offer;
 
          6. Guidelines for Certification of Taxpayer Identification Number on
             Substitute Form W-9; and
 
          7. A return envelope addressed to the Depositary.
 
     Upon the terms and subject to the conditions of the Offer (including, if
the Offer is extended or amended, the terms and conditions of any such extension
or amendment), Purchaser will be deemed to have accepted for payment (and
thereby purchased) all Shares that are validly tendered prior to the Expiration
Date and not properly withdrawn, if and when Purchaser gives oral or written
notice to the Depositary of Purchaser's acceptance of such Shares for payment
pursuant to the Offer. In all cases, payment for Shares purchased pursuant to
the Offer will be made only after timely receipt by the Depositary of
certificates for such Shares, or timely confirmation of a book-entry transfer of
such Shares into the Depositary's account at The Depository Trust Company, the
Midwest Securities Trust Company or the Philadelphia Depository Trust Company,
pursuant to the procedures described in Section 3, "Procedure for Accepting the
Offer and Tendering Shares," of the Offer to Purchase, a properly completed and
duly executed Letter of Transmittal (or facsimile thereof) and any other
documents required by the Letter of Transmittal.
 
     Purchaser will not pay any fees or commissions to any broker or dealer or
other person (other than the Dealer Manager as described in the Offer) in
connection with the solicitation of tenders of Shares pursuant to the Offer. The
Purchaser will, however, reimburse you for customary mailing and handling
expenses incurred by you in forwarding any of the enclosed materials to your
clients.
 
     Purchaser will pay or cause to be paid any transfer taxes payable with
respect to the transfer of Shares to it, except as otherwise provided in
Instruction 6 of the Letter of Transmittal.
 
     YOUR PROMPT ACTION IS REQUESTED. WE URGE YOU TO CONTACT YOUR CLIENTS AS
PROMPTLY AS POSSIBLE. THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00
MIDNIGHT, NEW YORK CITY TIME, ON WEDNESDAY, DECEMBER 21, 1994, UNLESS THE OFFER
IS EXTENDED.
 
     In order to take advantage of the Offer, a duly executed and properly
completed Letter of Transmittal (or facsimile thereof), with any required
signature guarantees and any other required documents, should be sent to the
Depositary, and certificates representing the tendered Shares should be
delivered or such Shares should be tendered by book-entry transfer, all in
accordance with the Instructions set forth in the Letter of Transmittal and the
Offer to Purchase.
 
                                        2
<PAGE>   3
 
     If holders of Shares wish to tender, but it is impracticable for them to
forward their certificates or other required documents prior to the expiration
of the Offer, a tender may be effected by following the guaranteed delivery
procedures specified under Section 3, "Procedure for Tendering Shares," in the
Offer to Purchase.
 
     Any inquiries you may have with respect to the Offer should be addressed to
CS First Boston Corporation or D. F. King & Co., Inc. (the "Information Agent")
at their respective addresses and telephone numbers set forth on the back cover
page of the Offer to Purchase.
 
     Additional copies of the enclosed materials may be obtained from the
undersigned, at CS First Boston Corporation, telephone (212) 909-2000 (collect)
or by calling the Information Agent, D.F. King & Co., Inc., at (212) 269-5550
(collect) or (800) 628-8536 (toll free), or from brokers, dealers, commercial
banks or trust companies.
 
                                          Very truly yours,
 
                                          CS First Boston Corporation
 
     NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU
OR ANY PERSON THE AGENT OF PARENT, PURCHASER, THE DEALER MANAGER, THE
INFORMATION AGENT OR THE DEPOSITARY, OR ANY AFFILIATE OF ANY OF THE FOREGOING,
OR AUTHORIZE YOU OR ANY OTHER PERSON TO USE ANY DOCUMENT OR TO MAKE ANY
STATEMENT ON BEHALF OF ANY OF THEM IN CONNECTION WITH THE OFFER OTHER THAN THE
DOCUMENTS ENCLOSED AND THE STATEMENTS CONTAINED THEREIN.
 
                                        3

<PAGE>   1
 
                           OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
 
                                       OF
 
                                 SYNERGEN, INC.
                                       AT
 
                              $9.25 NET PER SHARE
                                       BY
 
                       AMGEN ACQUISITION SUBSIDIARY, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
 
                                   AMGEN INC.
 
         THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,
              NEW YORK CITY TIME, ON WEDNESDAY, DECEMBER 21, 1994,
                         UNLESS THE OFFER IS EXTENDED.
 
                                                               November 23, 1994
 
To Our Clients:
 
     Enclosed for your consideration are an Offer to Purchase, dated November
23, 1994 (the "Offer to Purchase"), and a related Letter of Transmittal relating
to an offer by Amgen Acquisition Subsidiary, Inc., a Delaware corporation
("Purchaser") and a wholly owned subsidiary of Amgen, a Delaware corporation
("Parent"), to purchase all outstanding shares of Common Stock, par value $.01
per share (the "Shares"), of Synergen, Inc., a Delaware corporation (the
"Company") including the associated preferred stock purchase rights (unless the
context requires otherwise, all references to "Shares" shall include a reference
to such rights), at a price of $9.25 per Share, net to the seller in cash
without interest, upon the terms and subject to the conditions set forth in the
Offer to Purchase and in the related Letter of Transmittal (which together
constitute the "Offer"). We are the holder of record of Shares held by us for
your account. A TENDER OF SUCH SHARES CAN BE MADE ONLY BY US AS THE HOLDER OF
RECORD AND PURSUANT TO YOUR INSTRUCTIONS. THE LETTER OF TRANSMITTAL IS FURNISHED
TO YOU FOR YOUR INFORMATION ONLY AND CANNOT BE USED BY YOU TO TENDER SHARES HELD
BY US FOR YOUR ACCOUNT.
 
     We request instructions as to whether you wish to have us tender on your
behalf any or all of the Shares held by us for your account, upon the terms and
subject to the terms and conditions set forth in the Offer.
 
     Your attention is invited to the following:
 
          1. The tender price is $9.25 per Share, net to the seller in cash.
 
          2. The Offer is being made for all outstanding Shares.
 
          3. The Board of Directors of the Company unanimously has determined
     that the Offer and the Merger Agreement (as defined in the Offer to
     Purchase) are fair to, and in the best interests of, the stockholders of
     the Company, has approved the Offer, the Merger Agreement and the Merger
     and recommends that stockholders accept the Offer and tender their Shares
     pursuant to the Offer.
 
          4. The Offer and withdrawal rights will expire at 12:00 Midnight, New
     York City time, on Wednesday, December 21, 1994, unless the Offer is
     extended.
<PAGE>   2
 
          5. The Offer is conditioned upon, among other things, there being
     validly tendered and not withdrawn prior to the expiration of the Offer a
     number of Shares that constitutes at least a majority of Shares outstanding
     on a fully diluted basis (including Shares issuable upon exercise of
     outstanding employee and director stock options, but excluding Shares
     issuable upon exercise of outstanding warrants, rights or other securities
     to purchase or acquire Shares).
 
          6. Stockholders who tender Shares will not be obligated to pay
     brokerage fees or commissions, solicitation fees or, except as otherwise
     provided in Instruction 6 of the Letter of Transmittal, transfer taxes with
     respect to the purchase of Shares by Purchaser pursuant to the Offer.
 
     The Offer is made solely by the Offer to Purchase and the related Letter of
Transmittal and is being made to all holders of Shares. Purchaser is not aware
of any state where the making of the Offer is prohibited by administrative or
judicial action pursuant to any valid state statute. If Purchaser becomes aware
of any valid state statute prohibiting the making of the Offer or the acceptance
of Shares pursuant thereto, Purchaser will make a good faith effort to comply
with such state statute. If, after such good faith effort, Purchaser cannot
comply with such state statute, the Offer will not be made to (nor will tenders
be accepted from or on behalf of) the holders of Shares in such state. If any
jurisdiction where the securities, blue sky or other laws require the Offer to
be made by a licensed broker or dealer, the Offer shall be deemed to be made on
behalf of Purchaser by CS First Boston Corporation or one or more registered
brokers or dealers licensed under the laws of such jurisdiction.
 
     If you wish to have us tender any or all of your Shares, please complete,
execute and return to us the instruction form contained in this letter. An
envelope in which to return your instructions to us is enclosed. Your
instructions should be forwarded to us in ample time to permit us to submit a
tender on your behalf prior to the expiration of the Offer. If you authorize the
tender of your Shares, all such Shares will be tendered unless otherwise
specified on the instruction form set forth below.
 
                                        2
<PAGE>   3
 
                     INSTRUCTIONS WITH RESPECT TO THE OFFER
          TO PURCHASE FOR CASH ALL OUTSTANDING SHARES OF COMMON STOCK
                               OF SYNERGEN, INC.
 
     The undersigned acknowledge(s) receipt of your letter and the enclosed
Offer to Purchase, dated November 23, 1994, and the related Letter of
Transmittal (which together constitute the "Offer") in connection with the offer
by Amgen Acquistion Subsidiary, Inc., a Delaware corporation, and a wholly owned
subsidiary of Amgen Inc., a Delaware corporation, to purchase all outstanding
shares of Common Stock, par value $.01 per share (the "Shares"), of Synergen,
Inc., a Delaware corporation, including the associated preferred stock purchase
rights (unless the context requires otherwise, all references to "Shares" shall
include a reference to such rights).
 
     This will instruct you to tender the number of Shares indicated below (or,
if no number is indicated below, all Shares) that are held by you for the
account of the undersigned, upon the terms and subject to the conditions set
forth in the Offer.
 
                       Number of Shares to be Tendered:*
 
                                                                          Shares
Account Number:
Dated:                                                                     , 199
 
* Unless otherwise indicated, it will be assumed that all Shares held by us for
  your account are to be tendered.
 

                                   SIGN HERE
 


                         _____________________________
                                  Signature(s)
 


                         _____________________________
                          Please type or print name(s)
 


                         _____________________________
                          Please type or print address
 


                         _____________________________
                         Area Code and Telephone Number
 


                         _____________________________
                           Taxpayer Identification or
                             Social Security Number
 
                                        3

<PAGE>   1
 
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9
 
GUIDELINES FOR DETERMINING THE PROPER IDENTIFICATION NUMBER TO GIVE THE
PAYER--Social Security numbers have nine digits separated by two hyphens: i.e.,
000-00-0000. Employer identification numbers have nine digits separated by one
hyphen: i.e., 00-0000000. The table below will help determine the number to give
the payer.

<TABLE>
<CAPTION>
- --------------------------------------------------------------      ----------------------------------------------------------------
                                       GIVE THE                                                            GIVE THE EMPLOYER
FOR THIS TYPE OF ACCOUNT:              SOCIAL SECURITY              FOR THIS TYPE OF ACCOUNT:              IDENTIFICATION
                                       NUMBER OF --                                                        NUMBER OF --
- --------------------------------------------------------------      ----------------------------------------------------------------
 <S>                                   <C>                          <S>                                    <C>
 1. An individual's account            The individual                8. Sole proprietorship account        The owner(4)
                                                                                        
 2. Two or more individuals            The actual owner of           9. A valid trust, estate,             The legal entity (Do not 
    (joint account)                    the account or, if               or pension trust                   furnish the identifying  
                                       combined funds, the                                                 number of the personal   
                                       first individual on                                                 representative or trustee
                                       the account(1)                                                      unless the legal entity  
                                                                                                           itself is not designated 
 3. Husband and wife                   The actual owner of                                                 in the account title)(5) 
    (joint account)                    the account or, if  
                                       joint funds, either
                                       person.(1)                   10. Corporate account                  The corporation
                                                                   
 4. Custodian account of a minor       The minor(2)                 11. Association, club,                 The organization
    (Uniform Gift to Minors Act)                                        religious, charitable,   
                                                                        educational or other 
 5. a. The usual revocable savings     The grantor-trustee(1)           tax-exempt organization  
       trust account (grantor is
       also trustee)                                                12. Partnership account                The partnership
                                                                    
    b. So-called trust account that    The actual owner(1)         13. A broker or registered             The broker or nominee
       is not a legal or valid                                          nominee
       trust under State law
                                                                    14. Account with the                   The public entity
 6. Account in the name of             The ward, minor or               Department of Agriculture    
    guardian or committee for          incompetent person(3)            in the name of a public      
    a designated ward, minor,                                           entity (such as a State or   
    or incompetent person                                               local government, school            
                                                                        district or prison) that     
 7. Adult and minor                   The adult or, if the              receives agricultural             
    (joint account)                   minor is the only                 program payments
                                      contributor, the minor(1)                                                             
- --------------------------------------------------------------      ----------------------------------------------------------------
</TABLE>
                                                                          
(1)  List first and circle the name of the person whose number you furnish.

(2)  Circle the minor's name and furnish the minor's social security number.

(3)  Circle the ward's, minor's or incompetent person's name and furnish such
     person's social security number.

(4)  Show the name of the owner. Owner may use either owner's social security
     number or owner's employer identification number.

(5)  List first and circle the name of the valid trust, estate or pension trust.

NOTE:  If no name is circled when there is more than one name, the number will
       be considered to be that of the first name listed. 

<PAGE>   2
 
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                      NUMBER (TIN) ON SUBSTITUTE FORM W-9
             (SECTION REFERENCES ARE TO THE INTERNAL REVENUE CODE.)
                                     PAGE 2
 
NAME
If you are an individual, generally provide the name shown on your social
security card. However, if you have changed your last name, for instance, due to
marriage, without informing the Social Security Administration of the name
change, please enter your first name and both the last name shown on your social
security card and your new last name.
 
OBTAINING A NUMBER
If you don't have a taxpayer identification number ("TIN"), or if you do not
know your TIN, apply for one immediately. To apply, obtain Form SS-5,
Application for a Social Security Number Card, or Form SS-4, Application for
Employer Identification Number, at the local office of the Social Security
Administration or the Internal Revenue Service ("IRS").
 
PAYEES AND PAYMENTS EXEMPT FROM BACKUP WITHHOLDING
 
Payees specifically exempted from backup withholding on all payments include the
following:
 
  - A corporation.
  - An organization exempt from tax under section 501(a), or an individual
    retirement plan (IRA), or a custodial account under section 403(b)(7).
  - The United States or any of its agencies or instrumentalities.
  - A state, the District of Columbia, a possession of the United States, or any
    of their political subdivisions or instrumentalities.
  - A foreign government or any of its political subdivisions, agencies or
    instrumentalities.
  - An international organization or any of its agencies or instrumentalities.
  - A foreign central bank of issue.
  - A dealer in securities or commodities required to register in the U.S. or a
    possession of the U.S.
  - A futures commission merchant registered with the Commodity Futures Trading
    Commission.
  - A real estate investment trust.
  - An entity registered at all times during the tax year under the Investment
    Company Act of 1940.
  - A common trust fund operated by a bank under section 584(a).
  - A financial institution.
  - A middleman known in the investment community as a nominee or listed in the
    most recent publication of the American Society of Corporate Secretaries,
    Inc., Nominee List.
  - A trust exempt from tax under section 664 or described in section 4947.
 
Payments of dividends not generally subject to backup withholding also include
the following:
  - Payments to nonresident aliens subject to withholding under
    section 1441.
  - Payments to partnerships not engaged in a trade or business in the U.S. and
    that have at least one nonresident partner.
  - Payments made by certain foreign organizations.
Payments of interest generally not subject to backup withholding include the
following:
  - Payments of interest on obligations issued by individuals.
    Note: You may be subject to backup withholding if this interest is $600 or
    more and is paid in the course of the payer's trade or business and you have
    not provided your correct TIN to the payer.
  - Payments of tax-exempt interest (including exempt interest dividends under
    section 852).
  - Payments described in section 6049(b)(5) to nonresident aliens.
  - Payments on tax-free covenant bonds under section 1451.
  - Payments made by certain foreign organizations.
  - Mortgage interest paid by you.
 
Exempt payees described above should file Form W-9 to avoid possible erroneous
backup withholding. FILE THIS FORM WITH THE PAYER, FURNISH YOUR TAXPAYER
IDENTIFICATION NUMBER, WRITE "EXEMPT" ON THE FACE OF THE FORM, SIGN AND DATE THE
FORM AND RETURN IT TO THE PAYER.
 
Payments that are not subject to information reporting are also not subject to
backup withholding. For details, see sections 6041, 6041A(a), 6042, 6044, 6045,
6049, 6050A, and 6050N, and the regulations under those sections.
 
PRIVACY ACT NOTICE.--Section 6109 requires you to furnish your correct TIN to
persons who must file information returns with the IRS to report interest,
dividends, and certain other income paid to you, mortgage interest you paid, the
acquisition or abandonment of secured property, or contributions you made to an
IRA. The IRS uses the numbers for identification purposes and to help verify the
accuracy of tax returns. You must provide your TIN whether or not you are
qualified to file a tax return. Payers must generally withhold 31% of taxable
interest, dividend, and certain other payments to a payee who does not furnish a
TIN to a payor. Certain penalties may also apply.
 
PENALTIES
(1) FAILURE TO FURNISH TIN.--If you fail to furnish your correct TIN to a payer,
you are subject to a penalty of $50 for each such failure unless your failure is
due to reasonable cause and not to willful neglect.
(2) CIVIL PENALTY FOR FALSE INFORMATION WITH RESPECT TO WITHHOLDING.--If you
make a false statement with no reasonable basis which results in no imposition
of backup withholding, you are subject to a penalty of $500.
(3) CRIMINAL PENALTY FOR FALSIFYING INFORMATION.--Willfully falsifying
certifications or affirmations may subject you to criminal penalties including
fines and/or imprisonment.
 
                  FOR ADDITIONAL INFORMATION CONTACT YOUR TAX
                   CONSULTANT OR THE INTERNAL REVENUE SERVICE

<PAGE>   1
 
This announcement is neither an offer to purchase nor a solicitation of an offer
to sell Shares. The Offer is made solely by the Offer to Purchase dated
 November 23, 1994 and the related Letter of Transmittal, and is being made to
 all holders of Shares. Purchaser is not aware of any state where the making
   of the Offer is prohibited by administrative or judicial action pursuant
    to any valid state statute. If Purchaser becomes aware of any valid
    state statute prohibiting the making of the Offer or the acceptance of
     Shares pursuant thereto, Purchaser will make a good faith effort to
      comply with such state statute. If, after such good faith effort,
      Purchaser cannot comply with such state statute, the Offer will not
       be made to (nor will tenders be accepted from or on behalf of)
        the holders of Shares in such state. In any jurisdiction where
        the securities, blue sky or other laws require the offer to be
         made by a licensed broker or dealer, the Offer shall be deemed
         to be made on behalf of Purchaser by CS First Boston
          Corporation ("CS First Boston") or one or more registered
           brokers or dealers licensed under the laws of such
           jurisdiction.
 
                      Notice of Offer to Purchase for Cash
 
                     All Outstanding Shares of Common Stock
           (including the associated preferred stock purchase rights)
 
                                       of
 
                                 Synergen, Inc.
                                       at
 
                              $9.25 NET PER SHARE
 
                                       by
 
                       Amgen Acquisition Subsidiary, Inc.
                          a wholly owned subsidiary of
 
                                   Amgen Inc.
 
    Amgen Acquisition Subsidiary, Inc., a Delaware corporation ("Purchaser") and
a wholly owned subsidiary of Amgen Inc., a Delaware corporation ("Amgen"), is
offering to purchase all outstanding shares of Common Stock, par value $.01 per
share (the "Shares"), of Synergen, Inc., a Delaware corporation (the "Company"),
including the associated preferred stock purchase rights (unless the context
requires otherwise, all references to "Shares" shall include a reference to such
rights), at a price of $9.25 per Share, net to the seller in cash, without
interest thereon, upon the terms and subject to the conditions set forth in the
Offer to Purchase dated November 23, 1994 (the "Offer to Purchase") and in the
related Letter of Transmittal (which together constitute the "Offer"). Following
the Offer, Purchaser intends to effect the Merger described below.
 
         THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,
              NEW YORK CITY TIME, ON WEDNESDAY, DECEMBER 21, 1994,
                         UNLESS THE OFFER IS EXTENDED.
 
    THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS, THERE BEING VALIDLY
TENDERED AND NOT WITHDRAWN PRIOR TO THE EXPIRATION OF THE OFFER A NUMBER OF
SHARES THAT CONSTITUTES AT LEAST A MAJORITY OF THE SHARES OUTSTANDING ON A FULLY
DILUTED BASIS (INCLUDING SHARES ISSUABLE UPON EXERCISE OF OUTSTANDING EMPLOYEE
AND DIRECTOR STOCK OPTIONS, BUT EXCLUDING SHARES ISSUABLE UPON EXERCISE OF
OUTSTANDING WARRANTS, RIGHTS OR OTHER SECURITIES TO PURCHASE OR ACQUIRE SHARES).
<PAGE>   2
 
    The Offer is being made pursuant to an Agreement and Plan of Merger dated as
of November 17, 1994 (the "Merger Agreement") among Amgen, Purchaser and the
Company. The Merger Agreement provides that, among other things, as soon as
practicable after the purchase of the Shares pursuant to the Offer and the
satisfaction or waiver of the other conditions set forth in the Merger Agreement
and in accordance with relevant provisions of the General Corporation Law of the
State of Delaware ("Delaware Law"), Purchaser will be merged with and into the
Company (the "Merger"). Following consummation of the Merger, the Company will
continue as the surviving corporation (the "Surviving Corporation") and will be
a wholly owned subsidiary of Amgen. At the effective time of the Merger (the
'Effective Time"), each Share issued and outstanding immediately prior to the
Effective Time (other than Shares held in the treasury of the Company, or owned
by Purchaser, Amgen or any direct or indirect wholly owned subsidiary of
Purchaser, Amgen or the Company, and other than Shares held by stockholders who
shall have demanded and perfected appraisal rights, if any, under Delaware Law)
will be cancelled and converted automatically into the right to receive $9.25 in
cash, or any higher price that may he paid per Share in the Offer, without
interest.
 
    THE BOARD OF DIRECTORS OF THE COMPANY UNANIMOUSLY HAS DETERMINED THAT THE
OFFER AND THE MERGER ARE FAIR TO, AND IN THE BEST INTERESTS OF, THE COMPANY AND
ITS STOCKHOLDERS, HAS APPROVED THE OFFER, THE MERGER AGREEMENT AND THE MERGER
AND RECOMMENDS THAT HOLDERS OF SHARES OF THE COMPANY ACCEPT THE OFFER AND TENDER
THEIR SHARES PURSUANT TO THE OFFER.
 
    For purposes of the Offer, Purchaser will be deemed to have accepted for
payment (and thereby purchased) Shares validly tendered and not properly
withdrawn if and when Purchaser gives oral or written notice to American Stock
Transfer & Trust Company (the "Depositary") of Purchaser's acceptance for
payment of such Shares pursuant to the Offer. Upon the terms and subject to the
conditions of the Offer, payment for Shares accepted for payment pursuant to the
Offer will be made by deposit of the purchase price therefor with the
Depositary, which will act as agent for tendering stockholders for the purpose
of receiving payments from Purchaser and transmitting such payments to tendering
stockholders whose Shares have been accepted for payment. UNDER NO CIRCUMSTANCES
WILL INTEREST ON THE PURCHASE PRICE FOR THE SHARES BE PAID, REGARDLESS OF ANY
DELAY IN MAKING SUCH PAYMENT. In all cases, payment for Shares tendered and
accepted for payment pursuant to the Offer will be made only after timely
receipt by the Depositary of (i) the certificates evidencing such Shares (the
"Share Certificates") or timely confirmation (a "Book-Entry Confirmation") of a
book-entry transfer of such Shares into the Depositary's account at one of the
Book-Entry Transfer Facilities (as defined in Section 2 of the Offer to
Purchase) pursuant to the procedures set forth in Section 3 of the Offer to
Purchase, (ii) the Letter of Transmittal (or a facsimile thereof), properly
completed and duly executed, with any required signature guarantees or an
Agent's Message, as defined below, in connection with a book-entry transfer and
(iii) any other documents required under the Letter of Transmittal. The term
"Agent's Message" means a message, transmitted by a Book-Entry Transfer Facility
to, and received by, the Depositary and forming a part of a Book-Entry
Confirmation, which states that such Book-Entry Transfer Facility has received
an express acknowledgement from the participant in such Book-Entry Transfer
Facility tendering the Shares that are the subject of such Book-Entry
Confirmation, that such participant has received and agrees to be bound by the
terms of the Letter of Transmittal and that Purchaser may enforce such agreement
against such participant.
 
    Subject to the terms and conditions of the Merger Agreement, Purchaser
expressly reserves the right, at any time and from time to time, to extend the
period of time during which the Offer is open, including the occurrence of any
condition specified in Section 14 of the Offer to Purchase, by giving oral or
written notice of such extension to the Depositary. Any such extension will be
followed as promptly as practicable by public announcement thereof, such
announcement to be made not later than 9:00 a.m., New York City time, on the
next business day after the previously scheduled expiration date of the Offer.
During any such extension, all Shares previously tendered and not withdrawn will
remain subject to the Offer and to the rights of a tendering stockholder to
withdraw such stockholder's Shares.
 
    Tenders of Shares made pursuant to the Offer are irrevocable except that
such Shares may be withdrawn at any time prior to 12:00 Midnight, New York City
time, on Wednesday, December 21, 1994 (or the latest time and date at which the
Offer, if extended by Purchaser, shall expire) and, unless theretofore accepted
for payment by Purchaser pursuant to the Offer, may also be withdrawn at any
time after January 21, 1995. For the withdrawal to be effective, a written,
telegraphic, telex or facsimile transmission notice of withdrawal must be timely
received by the Depositary at its address set forth on the back cover page of
the Offer to Purchase. Any such notice of withdrawal must specify the name of
the person who tendered the Shares to be withdrawn, the number of Shares to be
withdrawn and the name of the registered holder of such Shares, if different
from that of the person who tendered such Shares. If Share Certificates
evidencing Shares to be withdrawn have been delivered or otherwise identified to
the Depositary, then, prior to the physical release of such Share Certificates,
the serial numbers shown on such Share Certificates must be submitted to the
Depositary and the signature(s) on the notice of withdrawal must be guaranteed
by an Eligible Institution (as defined in Section 3 of the Offer to Purchase),
unless such Shares have been tendered for the account of an Eligible
Institution. If Shares have been tendered pursuant to the procedures for
book-entry transfer as set forth in Section 3 of the Offer to Purchase, any
notice of withdrawal must specify the name and number of the account at the
Book-Entry Transfer Facility to be credited with the
<PAGE>   3
 
withdrawn Shares and must otherwise comply with such Book-Entry Transfer
Facility's procedures. All questions as to the form and validity (including the
time of receipt) of any notice of withdrawal will be determined by Purchaser, in
its sole discretion, whose determination will be final and binding.
 
    The information required to be disclosed by Rule 14d-6(e)(1)(vii) of the
General Rules and Regulations under the Securities Exchange Act of 1934, as
amended, is contained in the Offer to Purchase and is incorporated herein by
reference.
 
    The Company has provided Purchaser with the Company's stockholder list and
security position listings for the purpose of disseminating the Offer to holders
of Shares. The Offer to Purchase and the related Letter of Transmittal will be
mailed to record holders of Shares whose names appear on the Company's
stockholder list and will be furnished to brokers, dealers, commercial banks,
trust companies and similar persons whose names, or the names of whose nominees,
appear on the stockholder list or, if applicable, who are listed as participants
in a clearing agency's security position listing for subsequent transmittal to
beneficial owners of Shares.
 
    THE OFFER TO PURCHASE AND THE RELATED LETTER OF TRANSMITTAL CONTAIN
IMPORTANT INFORMATION WHICH SHOULD BE READ BEFORE ANY DECISION IS MADE WITH
RESPECT TO THE OFFER.
 
    Questions and requests for assistance or for copies of the Offer to Purchase
and the related Letter of Transmittal, and other tender offer materials may be
directed to the Information Agent or the Dealer Manager as set forth below, and
copies will be furnished promptly at Purchaser's expense. No fees or commissions
will be paid to brokers, dealers or other persons (other than the Dealer
Manager) for soliciting tenders of Shares pursuant to the Offer.
 
                    The Information Agent for the Offer is:
 
                             D. F. KING & CO., INC.
 
                                77 Water Street
                            New York, New York 10005
                         (212) 269-5550 (Call Collect)
                        (800) 628-8536 (Call Toll Free)
 
                        The Depositary for the Offer is:
 
                    AMERICAN STOCK TRANSFER & TRUST COMPANY
 
                        By Mail, Hand/Overnight Courier:
                                 40 Wall Street
                                   46th Floor
                               New York, New York
                                 (718) 921-8200
                        (800) 937-5449 (Call Toll Free)
 
                      The Dealer Manager for the Offer is:
 
                                CS First Boston
 
                               Park Avenue Plaza
                              55 East 52nd Street
                            New York, New York 10055
                         (212) 909-2000 (Call Collect)
 
November 23, 1994

<PAGE>   1
 
                           AMGEN TO ACQUIRE SYNERGEN
                              FOR $9.25 PER SHARE
 
<TABLE>
<S>                                <C>                     <C>
Amgen Contact:                     Amgen Contact:          Synergen Contact:
Sarah H. Crampton                  David Kaye              Susan Eustes
Director, Investor Relations,      Manager                 Director
Corporate Communications           Product Communications  Investor Relations
Amgen                              Amgen                   Synergen
(805) 447-1659                     (805) 447-6692          (303) 938-6242
</TABLE>
 
FOR IMMEDIATE RELEASE
 
THOUSAND OAKS, Calif., November 18, 1994 -- Amgen and Synergen today announced
that they have entered into a definitive agreement through which Amgen will
acquire Synergen.
 
Under the merger agreement, Amgen will commence a cash tender offer for all
outstanding shares of Synergen common stock for $9.25 per share. Any shares not
purchased in the offer will be acquired for the same price in cash, in a
second-step merger. Synergen currently has approximately 25,900,000 shares
outstanding.
 
In the merger, Amgen will acquire Synergen's product pipeline, which includes
Glial Derived Neurotrophic Factor (GDNF), Tumor Necrosis Factor binding protein
(TNFbp), Interleukin-1 receptor antagonist (IL-1ra), Nerve Growth Factor (NGF)
and Ciliary Neurotrophic Factor (CNTF). NGF and CNTF were being developed
jointly with Syntex (USA) Inc.
 
Upon completion of the merger, Amgen will direct one of the strongest and most
diversified inflammation and neurobiology research programs in the biotechnology
industry.
 
"This acquisition is a unique strategic fit between Synergen's capabilities and
product candidates in neurobiology and inflammation and Amgen's expanding
programs in these two medically important areas," said Gordon Binder, Amgen's
chairman and chief executive officer.
 
"The integration of Amgen and Synergen neurobiology and inflammation research
people and product candidates will expand and accelerate Amgen's programs in
these challenging therapeutic areas. We are particularly enthusiastic about
GDNF, a potential neurobiology product in pre-clinical studies, and TNFbp, now
in clinical trials. We are very pleased to have entered into this agreement with
Synergen."
 
                                   -- MORE --
<PAGE>   2
 
AMGEN TO ACQUIRE SYNERGEN FOR $9.25 PER SHARE
PAGE 2 OF 2
 
"Perhaps the most important aspect of this agreement, and the one that gives me
great personal satisfaction, is the potential opportunity for Amgen to do what
it does best, that is to provide very ill patients with medicines that can
improve both their health and the quality of their lives," Binder said.
 
Gregory Abbott, Synergen's president and chief executive officer, said, "The
merger represents an optimal strategic solution for Synergen's stockholders and
employees, one that builds on each company's outstanding scientific
capabilities. This combination of highly complementary research organizations
will propel the rapid development of Synergen's products for treating
neurological and inflammatory diseases."
 
The proposed acquisition is subject to the purchase of a majority of the
outstanding shares of Synergen common stock in the tender offer, clearance under
the Hart-Scott-Rodino Antitrust Improvements Act, and various other conditions.
The offer will begin no later than November 29, 1994 and will remain open for a
minimum of 20 business days. CS First Boston has been retained to act as
dealer/manager of the tender offer. Morgan Stanley provided financial advisory
services to Synergen's board of directors. Amgen and Synergen anticipate that
the acquisition will be completed by December 31, 1994.
 
Amgen anticipates that the acquisition will result in an immediate one-time
after-tax charge to earnings of approximately $130 million, or $0.93 per share
for the year, primarily associated with the write-off of in-process research and
development and other costs associated with the acquisition. The acquisition is
expected to reduce earnings by about $0.10 per share in 1995 and by $0.05 in
1996, as a result of increased research and development expenditures.
Thereafter, the acquisition should be neutral or beneficial to earnings.
 
Amgen (NASDAQ: AMGN), the world's largest biotechnology company, discovers,
develops, manufactures and markets human therapeutics based on advanced cellular
and molecular biology. With 1993 sales of more than $1.3 billion, Amgen has more
than 3,300 staff members and operations in 14 countries.
 
Synergen (NASDAQ: SYGN), is a biotechnology company in Boulder, Colorado engaged
in the discovery, development and manufacture of protein-based pharmaceuticals.
The company's research has been primarily concentrated in inflammation and
neurobiology.

<PAGE>   1
 
          AMGEN COMMENCES TENDER OFFER FOR SYNERGEN AT $9.25 PER SHARE
 
     Thousand Oaks, California -- November 23, 1984 -- Amgen Inc. announced that
its subsidiary, Amgen Acquisition Subsidiary, Inc. today commenced a cash tender
offer at $9.25 net per share for all outstanding shares of Common Stock, par
value $.01 per share, of Synergen, Inc. The offer and withdrawal rights will
expire at 12:00 midnight, New York City time on Wednesday, December 21, 1994,
unless extended.
 
     The offer is being made pursuant to a Merger Agreement among Amgen, Amgen
Acquisition and Synergen. The Board of Directors of Synergen, Inc. unanimously
has determined that the offer and the merger are fair to, and in the best
interests of Synergen and its stockholders, has approved the offer, the Merger
Agreement and the Merger and recommends that stockholders accept the offer and
tender their shares pursuant to the offer. Morgan Stanley & Co. Incorporated,
and Alex. Brown & Sons Incorporated, which acted as financial advisors to
Synergen, advised the Board of Directors of Synergen that the consideration to
be received by the stockholders of Synergen pursuant to each of the offer and
the merger is fair to the stockholders of Synergen, from a financial point of
view.
 
     The offer is conditioned upon, among other things, there being validly
tendered and not withdrawn prior to the expiration of the offer a number of
shares of Common Stock of Synergen constituting a majority of the shares of
Synergen's Common Stock then outstanding on a fully diluted basis (including
shares issuable upon exercise of outstanding employee and director stock options
but excluding shares issuable upon exercise of warrants, rights or other
securities to purchase or acquire shares of Common Stock). The Merger Agreement
provides that as soon as practicable after the purchase of the shares pursuant
to the offer and the satisfaction of the other conditions set forth in the
Merger Agreement, Amgen Acquisition will be merged into Synergen and each share
of Synergen's Common Stock outstanding immediately prior to the merger will be
converted into the right to receive $9.25 per share in cash, or any higher price
per share that may be paid pursuant to the offer, without interest.
 
     CS First Boston is acting as Dealer Manager for the offer and as financial
advisor as Amgen.
 
     Amgen (Nasdaq: AMGN), the largest biotechnology company, discovers,
develops, manufactures and markets human therapeutics based on advanced cellular
and molecular biology. With 1993 sales of more than $1.3 billion, Amgen has more
than 3,300 staff members and operations in 14 countries.
 
     Synergen (Nasdaq: SYGN) is a biotechnology company in Boulder, Colorado
engaged in the discovery, development and manufacture of protein-based
pharmaceuticals. Synergen's research has been primarily concentrated in
inflammation and neurobiology.
 
     For further information contact D.F. King & Co., Inc., toll free at (800)
628-8536.
 
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