NEOTHERAPEUTICS INC
8-K, 2000-04-21
COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH
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<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION


                             Washington, D.C. 20549



                                    FORM 8-K


                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(D) OF THE
                       SECURITIES AND EXCHANGE ACT OF 1934

                                  April 6, 2000
                Date of Report (Date of earliest event reported)




                              NEOTHERAPEUTICS, INC.

             (Exact name of registrant as specified in its charter)

<TABLE>
<CAPTION>
<S>                                                     <C>                                     <C>
                 DELAWARE                                      000-28782                              93-0979187
       (State or other Jurisdiction                     (Commission File Number)                    (IRS Employer
            of Incorporation)                                                                   Identification Number)

           157 TECHNOLOGY DRIVE                                                                         92618
            IRVINE, CALIFORNIA                                                                        (Zip Code)
 (Address of principal executive offices)
</TABLE>

                                 (949) 788-6700
              (Registrant's telephone number, including area code)

                                       N/A
          (Former Name or Former Address, if Changed Since Last Report)
<PAGE>   2
ITEM 5.  OTHER EVENTS.

On April 6, 2000, NeoTherapeutics, Inc. (the "Company") entered into a
Convertible Debenture Purchase Agreement (the "Purchase Agreement") with two
institutional investors for the issuance and sale of 5% subordinated convertible
debentures (the "Debentures") in the aggregate principal amount of $10,000,000,
warrants to purchase up to 4,000,000 shares of common stock over two years (the
"Class B Warrants") and 5-year warrants to purchase up to 315,000 shares of
common stock (the "Class A Warrants"), and a registration rights agreement (the
"Registration Rights Agreement") and a letter agreement regarding the issuance
of two additional tranches of Debentures and warrants (the "Letter Agreement",
and together with the Purchase Agreement, Registration Rights Agreement,
Debentures, Class A Warrants and Class B Warrants, the "Transaction Documents").
The Debentures bear interest at the rate of 5% per annum, payable upon
conversion or maturity, in cash or shares of common stock, and are convertible
into common stock at the option of the holder at $20.25 per share for the first
90 days after the closing. Thereafter, they are convertible at the option of the
holder at the lesser of $20.25 per share or 101% of the average of the ten
lowest closing bid prices of the common stock during the thirty trading days
preceding the conversion. Subject to certain conditions, the Debentures
automatically convert on the fifth anniversary of issuance. In the event that
the conversion price of the Debentures on a conversion date would be less than
$14, the Company has the option upon such conversion to issue the number of
shares that would be issuable at a conversion price of $14 and pay cash for the
number of additional shares of common stock that would otherwise be issuable at
the actual conversion price. In such event, the price per share that we would be
required to pay in lieu of issuing the additional shares will be equal to the
market value of a share of common stock at that time. In addition, if the
conversion price of the Debentures is less than $14, the Company has the right
upon three days notice to prepay the outstanding principal amount of the
Debentures with a 6% premium, provided that a holder may elect to convert the
Debentures during the three day notice period. The Debentures are subject to
mandatory prepayment of the outstanding principal amount plus a premium of at
least 20% upon the occurrence of certain events of default set forth in the
Debentures.

The Class B Warrants are exercisable for two years after the effectiveness of a
registration statement covering the resale of the shares of common stock
issuable upon exercise of the Class B Warrants, and may be redeemed by the
Company at the redemption price of $.05 per underlying share redeemed. The Class
B Warrants may be exercised by the holder within one day of delivery of a
redemption notice at an exercise price equal to the lesser of $33.75 per share
(subject to adjustment for stock splits, reverse stock splits and combinations)
and 97% of the closing bid price of the Company's common stock on the trading
day after the redemption notice is delivered. The Company may specify a floor
exercise price in the redemption notice of not more than 90% of the closing bid
price for the common stock on the trading day before the redemption notice is
delivered, and if the exercise price would be lower than the specified floor
price, the holder may either exercise the Class B Warrants at the specified
floor price or treat the redemption notice as null and void. The Class B
Warrants may also be exercised at the sole option of the holder at an exercise
price of $33.75 per share (subject to adjustment for stock splits, reverse stock
splits and combinations). The Company may not issue redemption notices (i) for a
number of underlying shares exceeding 15% of the average daily trading volume of
the common stock for the two trading days preceding delivery of the redemption
notice, or (ii) before the expiration of time for the exercise of the Class B
Warrants in response to a previous redemption notice. The Company's right to
deliver a redemption notice is subject to certain conditions set forth in Class
B Warrants. In addition, the number of shares issuable upon conversion of the
Debentures and exercise of the Class B Warrants in response to a redemption
notice cannot exceed 1,907,121 without stockholder approval.

The Class A Warrants are exercisable for five years at the exercise price of
$19.672 per share. The Class A Warrants vest and become exercisable (i) for an
aggregate of 115,000 shares for all Class A Warrants upon issuance, (ii) for an
additional 1 share for each 20 shares issued upon exercise of the Class B
Warrants, up to a maximum of 150,000 shares for all Class A Warrants, (iii) for
a number of additional shares equal to the difference between 50,000 shares and
1/20th of the number of shares subject to redemption notices issued by the
Company under the Class B Warrants, if redemption notices covering fewer than
1,000,000 shares are issued prior to the expiration of the Class B Warrants, and
(iv) for an additional 50,000 shares if the Class B Warrants are canceled
pursuant to the terms of the Registration Rights Agreement. Consequently, if the
Company issues redemption notices under the Class B Warrants covering in
aggregate at least 1,000,000 shares, the maximum vesting under the Class A
Warrants is 265,000 shares. The exercise price of the Class A Warrants is
subject to adjustment in the event of stock splits, reverse stock splits or
consolidations affecting the Company's common stock or distributions of
evidences of indebtedness or assets of the Company.
<PAGE>   3
The Letter Agreement provides for the issuance and sale of two additional
tranches of Debentures and warrants 5 and 10 months after April 6, 2000, each at
the option of either the Company or the investors. With respect to each tranche
there is a ten day period which the option can be exercised. The investors may
exercise their right to require the Company to sell the additional Debentures
and warrants only on the first day of each option period, and the Company may
exercise its right to require the investors to purchase the additional
Debentures and warrants only during the remaining nine days of the relevant
option period. Each additional tranche will consist of additional Debentures in
a principal amount of up to the lesser of $10,000,000 or 10% of the market
capitalization of the common stock on the date of issuance of the additional
debentures, and additional warrants to purchase up to 115,000 shares of
Company's common stock. The maximum principal amount of the additional
Debentures issued in each tranche will be reduced by the sum of (i) the
aggregate exercise prices paid upon exercise of Class B Warrants prior to the
issuance of the additional Debentures and (ii) the maximum aggregate exercise
price that would have been paid upon the exercise of any portion of the Class B
Warrants that has been redeemed prior to the issuance of the additional
Debentures. For the second tranche, no reduction will be made for exercises or
redemptions counted towards the reduction of the first tranche. In addition, if
the Class B Warrants are canceled in accordance with the Registration Rights
Agreement, the investors may only require the Company to sell up to $5,000,000
principal amount of additional Debentures in each tranche.

The additional Debentures will be identical in form to the original Debentures,
except that if the Company exercises the option to sell the additional
debentures, the maximum conversion price will be equal to 120% of the closing
bid price of the Company's common stock on the day the additional Debentures are
issued, and if the investors exercise the option to purchase the additional
debentures, the conversion price will be fixed at $20 per share, and will not
vary with the market value of the Company's common stock. The additional
warrants will be identical in form to the Class A Warrants, except that they
will have an exercise price equal to 125% of the closing bid price of the
Company's common stock on the day the additional warrants are issued, and the
additional warrants will be fully vested upon issuance. The obligation of the
investors to purchase the additional Debentures is subject to certain additional
conditions set forth in the Letter Agreement, including conditions relating to
the representations of the Company, compliance with prior agreement, the absence
of material adverse changes, the listing and tradability of the Company's common
stock and stockholder approval.

In connection with this financing, the Company paid a finder's fee to an
unrelated third party consisting of cash and warrants to purchase common stock
of the Company.

ITEM 7.  EXHIBITS.

<TABLE>
<CAPTION>
     Exhibits
     --------
<S>                 <C>
      4.1           Convertible Debenture Purchase Agreement dated as of April
                    6, 2000, by and among Registrant, Strong River Investments,
                    Inc. and Montrose Investments Ltd.

      4.2           Registration Rights Agreement dated as of April 6, 2000, by
                    and among Registrant, Strong River Investments, Inc. and
                    Montrose Investments Ltd.

      4.3           Form of 5% Subordinated Convertible Debenture issued by
                    Registrant, dated as of April 6, 2000

      4.4           Class A Warrant issued by Registrant to Montrose Investments
                    Ltd., dated as of April 6, 2000.

      4.5           Class A Warrant issued by Registrant to Strong River
                    Investments, Inc., dated as of April 6, 2000.

      4.6           Class B Warrant issued by Registrant to Montrose Investments
                    Ltd., dated as of April 6, 2000.

      4.7           Class B Warrant issued by Registrant to Strong River
                    Investments, Inc., dated as of April 6, 2000.

      4.8           Letter Agreement dated as of April 6, 2000, by and among
                    Registrant, Strong River Investments, Inc. and Montrose
                    Investments Ltd.

      99.1          Press Release dated April 10, 2000.
</TABLE>

                                       3
<PAGE>   4
                                   SIGNATURES


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


                                  NEOTHERAPEUTICS, INC.



Date: April 21, 2000              By:    /s/Samuel Gulko
                                         --------------------------------------
                                  Name:  Samuel Gulko
                                  Title: Chief Financial Officer

                                       4
<PAGE>   5
                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
     Exhibits       Description
     --------       -----------
<S>                 <C>
      4.1           Convertible Debenture Purchase Agreement dated as of April
                    6, 2000, by and among Registrant, Strong River Investments,
                    Inc. and Montrose Investments Ltd.

      4.2           Registration Rights Agreement dated as of April 6, 2000, by
                    and among Registrant, Strong River Investments, Inc. and
                    Montrose Investments Ltd.

      4.3           Form of 5% Subordinated Convertible Debenture issued by
                    Registrant, dated as of April 6, 2000

      4.4           Class A Warrant issued by Registrant to Montrose Investments
                    Ltd., dated as of April 6, 2000.

      4.5           Class A Warrant issued by Registrant to Strong River
                    Investments, Inc., dated as of April 6, 2000.

      4.6           Class B Warrant issued by Registrant to Montrose Investments
                    Ltd., dated as of April 6, 2000.

      4.7           Class B Warrant issued by Registrant to Strong River
                    Investments, Inc., dated as of April 6, 2000.

      4.8           Letter Agreement dated as of April 6, 2000, by and among
                    Registrant, Strong River Investments, Inc. and Montrose
                    Investments Ltd.

      99.1          Press Release dated April 10, 2000.
</TABLE>

<PAGE>   1
                                                                     EXHIBIT 4.1

                    CONVERTIBLE DEBENTURE PURCHASE AGREEMENT

                                      Among

                              NEOTHERAPEUTICS, INC.

                                       and

                         THE INVESTORS SIGNATORY HERETO




                            Dated as of April 6, 2000







<PAGE>   2


         CONVERTIBLE DEBENTURE PURCHASE AGREEMENT (this "Agreement"), dated as
of April 6, 2000, among NeoTherapeutics, Inc., a Delaware corporation (the
"Company"), and the investors signatory hereto on the date hereof (each such
investor is a "Purchaser" and all such investors are, collectively, the
"Purchasers").

         WHEREAS, subject to the terms and conditions set forth in this
Agreement, the Company desires to issue and sell to the Purchasers and the
Purchasers, severally and not jointly, desire to purchase from the Company an
aggregate principal amount of $10,000,000 of the Company's 5% Convertible
Debentures, due April 6, 2005, which shall be in the form of Exhibit A (the
"Debentures"), and which are convertible into shares of the Company's common
stock, $.001 par value per share (the "Common Stock"), and certain other
securities of the Company as more fully described in this Agreement.

         NOW, THEREFORE, IN CONSIDERATION of the mutual covenants contained in
this Agreement, and for other good and valuable consideration the receipt and
adequacy are hereby acknowledged, the Company and the Purchasers agree as
follows:

                                    ARTICLE I
                                PURCHASE AND SALE

         1.1      The Closing.

                  (a) The Closing. (i) Subject to the terms and conditions set
forth in this Agreement, the Company shall issue and sell to the Purchasers and
the Purchasers shall, severally and not jointly, purchase from the Company the
Debentures for an aggregate purchase price of $10,000,000. The closing of the
purchase and sale of the Debentures (the "Closing") shall take place at the
offices of Robinson Silverman Pearce Aronsohn & Berman LLP ("Robinson
Silverman"), 1290 Avenue of the Americas, New York, New York 10104, immediately
following the execution hereof or such later date as the parties shall agree.
The date of the Closing is hereinafter referred to as the "Closing Date."




         (ii) At the Closing, the parties shall deliver or shall cause to be
delivered the following: (A) the Company shall deliver to each Purchaser (1) the
Debentures in the aggregate principal amount of the purchase price indicated
below such Purchaser's name on the signature page to this Agreement, registered
in the name of such Purchaser, (2) a Common Stock purchase warrant, in the form
of Exhibit D, registered in the name of such Purchaser, pursuant to which such
Purchaser shall have the right at any time and from time to time thereafter
through the fifth anniversary of the Closing Date to acquire shares of Common
Stock upon the terms set forth therein (collectively, the "Class A Warrants"),
(3) a Common Stock purchase warrant, in the form of Exhibit E, registered in the
name of such Purchaser, pursuant to which such Purchaser shall have the right to
acquire shares of Common Stock upon the terms set forth therein (collectively,
the "Class B Warrants" and together with the Class A Warrants, the "Warrants"),
(4) the legal opinion of Latham & Watkins, outside counsel to the Company,
substantially in the form of Exhibit C, and (5) all other documents, instruments
and writings required to be delivered at or prior to the Closing by the Company
pursuant to this Agreement, including an executed Registration Rights Agreement,
dated the date hereof,


<PAGE>   3

among the Company and the Purchasers, in the form of Exhibit B (the
"Registration Rights Agreement"), the Transfer Agent Instructions, in the form
of Exhibit F, delivered to and acknowledged by the Company's transfer agent (the
"Transfer Agent Instructions") and the Letter Agreement, dated the date hereof,
among the Purchasers and the Company in the form of Exhibit G (the "Letter
Agreement"); and (B) each Purchaser shall deliver to the Company (1) the
purchase price indicated below such Purchaser's name on the signature page to
this Agreement in United States dollars in immediately available funds by wire
transfer to an account designated for such purpose prior to the Closing Date in
writing by the Company, and (2) all documents, instruments and writings required
to have been delivered at or prior to the Closing Date by such Purchaser
pursuant to this Agreement, including an executed Registration Rights Agreement
and Letter Agreement.

                  1.2 Certain Defined Terms. For purposes of this Agreement,
"Conversion Price," "Original Issue Date" and "Trading Day" shall have the
meanings set forth in the Debentures; "Business Day" shall mean any day except
Saturday, Sunday and any day which shall be a federal legal holiday or a day on
which banking institutions in the State of New York and the State of California
generally are authorized or required by law or other governmental action to
close. A "Person" means an individual or corporation, partnership, trust,
incorporated or unincorporated association, joint venture, limited liability
company, joint stock company, government (or an agency or subdivision thereof)
or other entity of any kind.


                                   ARTICLE II
                         REPRESENTATIONS AND WARRANTIES

         2.1 Representations and Warranties of the Company. The Company hereby
makes the following representations and warranties to the Purchasers:

                  (a) Organization and Qualification. The Company is a
corporation duly incorporated, validly existing and in good standing under the
laws of the State of Delaware with the requisite corporate power and authority
to own and use its properties and assets and to carry on its business as
currently conducted. The Company has no subsidiaries other than as set forth in
Schedule 2.1(a) (collectively the "Subsidiaries"). Each of the Subsidiaries is
an entity, duly organized, validly existing and in good standing under the laws
of the jurisdiction of its incorporation or organization (as applicable), with
the requisite corporate power and authority to own and use its properties and
assets and to carry on its business as currently conducted. Each of the Company
and the Subsidiaries is duly qualified to do business and is in good standing as
a foreign corporation or other entity in each jurisdiction in which the nature
of the business conducted or property owned by it makes such qualification
necessary, except where the failure to be so qualified or in good standing, as
the case may be, could not, individually or in the aggregate, (x) adversely
affect the legality, validity or enforceability of the Securities (as defined
below) or any of this Agreement, the Registration Rights Agreement, the Letter
Agreement, the Transfer Agent Instructions, the Debentures or the Warrants
(collectively, the "Transaction Documents"), (y) have or result in a material
adverse effect on the results of operations, assets, prospects, or condition
(financial or otherwise) of the Company and the Subsidiaries, taken as a whole,
or (z) adversely impair the Company's ability to perform fully on a timely basis
its obligations under any of the Transaction Documents (any of (x), (y) or (z),
a "Material Adverse Effect").
                                      -2-
<PAGE>   4
                  (b) Authorization; Enforcement. The Company has the requisite
corporate power and authority to enter into and to consummate the transactions
contemplated by each of the Transaction Documents and otherwise to carry out its
obligations thereunder. The execution and delivery of each of the Transaction
Documents by the Company and the consummation by it of the transactions
contemplated thereby have been duly authorized by all necessary corporate action
on the part of the Company and no further action is required by the Company.
Each of the Transaction Documents has been duly executed by the Company and,
when delivered (or filed, as the case may be) in accordance with the terms
hereof, will constitute the valid and binding obligation of the Company
enforceable against the Company in accordance with its terms. Neither the
Company nor any Subsidiary is in violation of any of the provisions of its
respective certificate of incorporation, by-laws or other charter or
organizational documents.

                  (c) Capitalization. The number of authorized, issued and
outstanding capital stock of the Company is set forth in Schedule 2.1(c). Except
as disclosed in Schedule 2.1(c), the Company owns all of the capital stock of
each Subsidiary. No securities of the Company or any Subsidiary are entitled to
preemptive or similar rights, nor is any holder of securities of the Company or
any Subsidiary entitled to preemptive or similar rights arising out of any
agreement or understanding with the Company or any Subsidiary by virtue of any
of the Transaction Documents. Except as disclosed in Schedule 2.1(c), there are
no outstanding options, warrants, script rights to subscribe to, calls or
commitments of any character whatsoever relating to, or securities, except as a
result of the purchase and sale of the Securities or rights or obligations
convertible into or exchangeable for, or giving any Person any right to
subscribe for or acquire, any shares of Common Stock, or contracts, commitments,
understandings, or arrangements by which the Company or any Subsidiary is or may
become bound to issue additional shares of Common Stock, or securities or rights
convertible or exchangeable into shares of Common Stock. To the knowledge of the
Company, except as specifically disclosed in the SEC Reports (as defined below)
or Schedule 2.1(c), no Person or group of related Persons beneficially owns (as
determined pursuant to Rule 13d-3 promulgated under the Securities Exchange Act
of 1934, as amended (the "Exchange Act")), or has the right to acquire by
agreement with or by obligation binding upon the Company, beneficial ownership
of in excess of 5% of the Common Stock.

                  (d) Issuance of the Securities. The Securities are duly
authorized and, when issued and paid for in accordance with the terms hereof,
will be duly and validly issued, fully paid and nonassessable, free and clear of
all liens, encumbrances and rights of first refusal of any kind (collectively,
"Liens"). The Company has reserved a number of duly authorized number of shares
of Common Stock for issuance hereunder upon conversion of the Debentures and
exercise of the Warrants that is not less than the sum of (i) 200% of the number
of shares of Common Stock which would be issuable upon conversion in full of the
Debentures, assuming such conversion occurred at the Conversion Price (as
defined in the Debenture) in effect on the Original Issue Date, the Debentures
remain outstanding for five years and all interest is paid in shares of Common
Stock and (ii) the maximum number of shares of Common Stock issuable upon
exercise in full of the Warrants and, in the case of the Class A Warrants,
assuming the maximum amount of Warrant Shares (as defined in the Warrants) has
vested thereunder (such number of shares of Common Stock as contemplated in
clauses (i)-(ii), the "Initial Minimum"). The shares of Common Stock issuable
upon conversion of the Debentures and upon exercise of the Warrants are referred
to herein as the "Underlying Shares." The Debentures, the Warrants and the
Underlying Shares are collectively referred to herein as, the "Securities."

                                      -3-
<PAGE>   5

                  (e) No Conflicts. The execution, delivery and performance of
the Transaction Documents by the Company and the consummation by the Company of
the transactions contemplated thereby do not and will not (i) conflict with or
violate any provision of the Company's or any Subsidiary's certificate of
incorporation, bylaws or other charter documents (each as amended through the
date hereof), or (ii) subject to obtaining the Required Approvals (as defined
below), conflict with, or constitute a default (or an event which with notice or
lapse of time or both would become a default) under, or give to others any
rights of termination, amendment, acceleration or cancellation (with or without
notice, lapse of time or both) of, any agreement, credit facility, debt or other
instrument (evidencing a Company or Subsidiary debt or otherwise) or other
understanding to which the Company or any Subsidiary is a party or by which any
property or asset of the Company or any Subsidiary is bound or affected, or
(iii) result in a violation of any law, rule, regulation, order, judgment,
injunction, decree or other restriction of any court or governmental authority
to which the Company or a Subsidiary is subject (including federal and state
securities laws and regulations), or by which any property or asset of the
Company or a Subsidiary is bound or affected; except in the case of each of
clauses (ii) and (iii), as could not, individually or in the aggregate, have or
result in a Material Adverse Effect. The business of the Company is not being
conducted in violation of any law, ordinance or regulation of any governmental
authority, except for violations which, individually or in the aggregate, could
not have or result in a Material Adverse Effect.

                  (f) Filings, Consents and Approvals. Neither the Company nor
any Subsidiary is required to obtain any consent, waiver, authorization or order
of, give any notice to, or make any filing or registration with, any court or
other federal, state, local or other governmental authority or other Person in
connection with the execution, delivery and performance by the Company of the
Transaction Documents, other than (i) the filings required pursuant to Section
3.10, (ii) the filing with the Securities and Exchange Commission (the
"Commission") of one or more registration statements meeting the requirements
set forth in the Registration Rights Agreement and covering the resale of the
Underlying Shares by the Purchasers (collectively, the "Underlying Shares
Registration Statement"), (iii) the application(s) to the Nasdaq National Market
("NASDAQ") for the listing of the Underlying Shares with the NASDAQ (and with
any other national securities exchange of market in which the Common Stock is
then listed) in the time and manner required thereby , (vi) applicable Blue Sky
filings, and (v) in all other cases where the failure to obtain such consent,
waiver, authorization or order, or to give such notice or make such filing or
registration could not have or result in, individually or in the aggregate, a
Material Adverse Effect (the items described in clauses (i)-(vi) are
collectively, the "Required Approvals").

                  (g) Litigation; Proceedings. Except as specified in the SEC
Reports or Schedule 2.1(g), there is no action, suit, notice of violation,
proceeding or investigation pending or, to the knowledge of the Company,
threatened against or affecting the Company or any of its Subsidiaries or any of
their respective properties before or by any court, governmental or
administrative agency or regulatory authority (federal, state, county, local or
foreign) which (i) adversely affects or challenges the legality, validity or
enforceability of any of the Transaction Documents or the Securities or (ii)
could, individually or in the aggregate, have or result in a Material Adverse
Effect.

                  (h) No Default or Violation. Neither the Company nor any
Subsidiary (i) is in default under or in violation of (and no event has occurred
which has not been waived which, with notice or lapse of time or both, would
result in a default by the Company or any Subsidiary under),

                                      -4-
<PAGE>   6
nor has the Company or any Subsidiary received notice of a claim that it is in
default under or that it is in violation of, any indenture, loan or credit
agreement or any other agreement or instrument to which it is a party or by
which it or any of its properties is bound (whether or not such default or
violation has been waived), (ii) is in violation of any order of any court,
arbitrator or governmental body, or (iii) is in violation of any statute, rule
or regulation of any governmental authority, except as could not individually or
in the aggregate, have or result in a Material Adverse Effect.

                  (i) Private Offering. Assuming the accuracy of the
representations and warranties of the Purchasers set forth in Sections
2.2(b)-(g), the offer, issuance and sale of the Securities to the Purchasers as
contemplated hereby are exempt from the registration requirements of the
Securities Act of 1933, as amended (the "Securities Act"). Neither the Company
nor any Person acting on its behalf has taken or is, to the knowledge of the
Company, contemplating taking any action which could subject the offering,
issuance or sale of the Securities to the registration requirements of the
Securities Act including soliciting any offer to buy or sell the Securities by
means of any form of general solicitation or advertising.

                  (j) SEC Reports; Financial Statements. The Company has filed
all reports required to be filed by it under the Securities Act of 1933, as
amended (the "Securities Act"), and the Exchange Act for the two years preceding
the date hereof (or such shorter period as the Company was required by law to
file such material) (the foregoing materials being collectively referred to
herein as the "SEC Reports" and, together with the Schedules to this Agreement
the "Disclosure Materials") on a timely basis or has received a valid extension
of such time of filing and has filed any such SEC Reports prior to the
expiration of any such extension. As of their respective dates, the SEC Reports
complied in all material respects with the requirements of the Securities Act
and the Exchange Act and the rules and regulations of the Commission promulgated
thereunder, and none of the SEC Reports, when filed, contained any untrue
statement of a material fact or omitted to state a material fact required to be
stated therein or necessary in order to make the statements therein, in light of
the circumstances under which they were made, not misleading. All material
agreements to which the Company is a party or to which the property or assets of
the Company are subject have been filed as exhibits to the SEC Reports. The
financial statements of the Company included in the SEC Reports comply in all
material respects with applicable accounting requirements and the rules and
regulations of the Commission with respect thereto as in effect at the time of
filing. Such financial statements have been prepared in accordance with
generally accepted accounting principles applied on a consistent basis during
the periods involved ("GAAP"), except as may be otherwise specified in such
financial statements or the notes thereto, and fairly present in all material
respects the financial position of the Company and its consolidated subsidiaries
as of and for the dates thereof and the results of operations and cash flows for
the periods then ended, subject, in the case of unaudited statements, to normal,
immaterial, year-end audit adjustments. Since September 30, 1999, except as
specifically disclosed in the SEC Reports, (a) there has been no event,
occurrence or development that has or that could result in a Material Adverse
Effect, (b) the Company has not incurred any liabilities (contingent or
otherwise) other than (x) liabilities incurred in the ordinary course of
business consistent with past practice and (y) liabilities not required to be
reflected in the Company's financial statements pursuant to GAAP or required to
be disclosed in filings made with the Commission, (c) the Company has not
altered its method of accounting or the identity of its auditors and (d) the
Company has not declared or made any payment or distribution of cash or other
property to its stockholders or officers or directors (other than in compliance
with existing Company stock or stock option plans and existing agreements and
terms of employment) with respect to its

                                      -5-
<PAGE>   7
capital stock, or purchased, redeemed (or made any agreements to purchase or
redeem) any shares of its capital stock.

                  (k) Investment Company. The Company is not, and is not an
Affiliate (as defined in Rule 405 under the Securities Act) of, an "investment
company" within the meaning of the Investment Company Act of 1940, as amended.

                  (l) Certain Fees. Except as are payable to Brighton Capital,
Ltd. by the Company, no fees or commissions will be payable by the Company to
any broker, financial advisor or consultant, finder, placement agent, investment
banker, bank or other person, with respect to the transactions contemplated by
this Agreement. The Purchasers shall have no obligation with respect to any fees
or with respect to any claims made by or on behalf of other Persons for fees of
a type contemplated in this Section that may be due in connection with the
transactions contemplated by this Agreement. The Company shall indemnify and
hold harmless the Purchasers, their employees, officers, directors, agents, and
partners, and its respective Affiliates, from and against all claims, losses,
damages, costs (including the costs of preparation and attorney's fees) and
expenses suffered in respect of any such claimed or existing fees, as such fees
and expenses are incurred.

                  (m) Form S-3 Eligibility. The Company is eligible to register
its Common Stock for resale under Form S-3 promulgated under the Securities Act.

                  (n) Seniority. Other than as set forth in Schedule 2.1(n), no
indebtedness of the Company is senior to the Debentures in right of payment,
whether with respect to interest or upon liquidation or dissolution, or
otherwise.

                  (o) Listing and Maintenance Requirements. The Company has not,
in the two years preceding the date hereof received notice (written or oral)
from the NASDAQ or any other stock exchange, market or trading facility on which
the Common Stock is or has been listed (or on which it has been quoted) to the
effect that the Company is not in compliance with the listing or maintenance
requirements of such exchange, market or trading facility. The Company is, and
has no reason to believe that it will not in the foreseeable future continue to
be, in compliance with all such listing and maintenance requirements.

                  (p) Patents and Trademarks. The Company and its Subsidiaries
have, or have rights to use, all patents, patent applications, trademarks,
trademark applications, service marks, trade names, copyrights, licenses and
rights (collectively, the "Intellectual Property Rights") which are necessary or
material for use in connection with their respective business as described in
the SEC Reports and as contemplated to be conducted, and which the failure to so
have would have a Material Adverse Effect. Neither the Company nor any
Subsidiary has received a written notice that the Intellectual Property Rights
used by the Company or its Subsidiaries violates or infringes upon the rights of
any Person, to the best knowledge of the Company. All such Intellectual Property
Rights are enforceable and there is no existing infringement by another Person
of any of the Intellectual Property Rights.

                  (q) Regulatory Permits. The Company and its Subsidiaries
possess all certificates, authorizations and permits issued by the appropriate
federal, state or foreign regulatory authorities necessary to conduct their
respective businesses as described in the SEC Reports, except


                                      -6-
<PAGE>   8
where the failure to possess such permits could not, individually or in the
aggregate, have or result in a Material Adverse Effect ("Material Permits"), and
neither the Company nor any such Subsidiary has received any notice of
proceedings relating to the revocation or modification of any Material Permit.

                  (r) Title. Except as set forth in Schedule 2.1(r), the Company
and the Subsidiaries have good and marketable title in fee simple to all real
property and personal property owned by them which is material to the business
of the Company and its Subsidiaries, in each case free and clear of all Liens,
except for Liens as do not materially affect the value of such property and do
not materially interfere with the use made and proposed to be made of such
property by the Company and its Subsidiaries. Any real property and facilities
held under lease by the Company and its Subsidiaries are held by them under
valid, subsisting and enforceable leases with such exceptions as are not
material and do not materially interfere with the use made and proposed to be
made of such property and buildings by the Company and its Subsidiaries.

                  (s) Disclosure. The Company confirms that it has not provided
the Purchasers or their agents or counsel with any information that constitutes
or might constitute material non-public information. The Company understands and
confirms that the Purchasers shall be relying on the foregoing representations
in effecting transactions in securities of the Company. All disclosure provided
to the Purchasers regarding the Company, its business and the transactions
contemplated hereby, including the Schedules to this Agreement, furnished by or
on behalf of the Company are true and correct and do 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.

         2.2 Representations and Warranties of the Purchasers. Each Purchaser
hereby for itself and for no other Purchaser, represents and warrants to the
Company as follows:

                  (a) Organization; Authority. Such Purchaser is an entity duly
organized, validly existing and in good standing under the laws of the
jurisdiction of its organization with the requisite corporate or partnership
power and authority to enter into and to consummate the transactions
contemplated by the Transaction Documents and otherwise to carry out its
obligations thereunder. The purchase by such Purchaser of the Securities
hereunder has been duly authorized by all necessary action on the part of such
Purchaser. Each of this Agreement, the Letter Agreement and the Registration
Rights Agreement has been duly executed by such Purchaser, and when delivered by
such Purchaser in accordance with the terms hereof, will constitute the valid
and legally binding obligation of such Purchaser, enforceable against it in
accordance with its terms.

                  (b) Investment Intent. Such Purchaser is acquiring the
Securities as principal for its own account for investment purposes only and not
with a view to or for distributing or reselling the Securities or any part
thereof. Such Purchaser has no present intention of selling or granting any
participation in, or otherwise distributing the Securities. Such Purchaser is
not party to any agreement or arrangement with any person to distribute any of
the Securities.

                  (c) Purchaser Status. At the time such Purchaser was offered
the Securities, it was, and at the date hereof it is, a "Qualified Institutional
Buyer" as defined in Rule 144A under the

                                      -7-
<PAGE>   9
Securities Act. Such Purchaser has not been formed solely for the purpose of
acquiring the Securities

                  (d) Experience of such Purchaser. Such Purchaser, either alone
or together with its representatives, has such knowledge, sophistication and
experience in business and financial matters so as to be capable of evaluating
the merits and risks of the prospective investment in the Securities, and has so
evaluated the merits and risks of such investment.

                  (e) Ability of such Purchaser to Bear Risk of Investment. Such
Purchaser is able to bear the economic risk of an investment in the Securities
and, at the present time, is able to afford a complete loss of such investment.

                  (f) Access to Information. Such Purchaser acknowledges that it
has reviewed the Disclosure Materials and has been afforded (i) the opportunity
to ask such questions as it has deemed necessary of, and to receive answers
from, representatives of the Company concerning the terms and conditions of the
offering of the Securities and the merits and risks of investing in the
Securities; (ii) access to information about the Company and the Company's
financial condition, results of operations, business, properties, management and
prospects sufficient to enable it to evaluate its investment; and (iii) the
opportunity to obtain such additional information which the Company possesses or
can acquire without unreasonable effort or expense that is necessary to make an
informed investment decision with respect to the investment. Neither such
inquiries nor any other investigation conducted by or on behalf of any Purchaser
or its representatives or counsel shall modify, amend or affect a Purchaser's
right to rely on the truth, accuracy and completeness of the Disclosure
Materials and the Company's representations and warranties contained in the
Transaction Documents.

                  (g) General Solicitation. Such Purchaser is not purchasing the
Securities as a result of or subsequent to any advertisement, article, notice or
other communication regarding the Securities published in any newspaper,
magazine or similar media or broadcast over television or radio or presented at
any seminar or any other general solicitation or general advertisement.

                  (h) Reliance. Such Purchaser understands and acknowledges that
(i) the Securities are being offered and sold to it without registration under
the Securities Act in a private placement that is exempt from the registration
provisions of the Securities Act and (ii) the availability of such exemption,
depends in part on, and the Company will rely upon the accuracy and truthfulness
of, the foregoing representations and such Purchaser hereby consents to such
reliance.

                  The Company acknowledges and agrees that no Purchaser makes or
has made any representations or warranties with respect to the transactions
contemplated hereby other than those specifically set forth in this Section 2.2.

                                   ARTICLE III
                         OTHER AGREEMENTS OF THE PARTIES

         3.1 Transfer Restrictions. (a) Securities may only be disposed of
pursuant to an effective registration statement under the Securities Act, to the
Company or pursuant to an available exemption from or in a transaction not
subject to the registration requirements of the Securities Act,

                                      -8-
<PAGE>   10
and in compliance with any applicable federal and state securities laws. In
connection with any transfer of Securities other than pursuant to an effective
registration statement or to the Company, except as otherwise set forth herein,
the Company may require the transferor thereof to provide to the Company an
opinion of counsel selected by the transferor, the form and substance of which
opinion shall be reasonably satisfactory to the Company, to the effect that such
transfer does not require registration under the Securities Act. Notwithstanding
the foregoing, the Company, without requiring a legal opinion as described in
the immediately preceding sentence, hereby consents to and agrees to register on
the books of the Company and with any transfer agent for the securities of the
Company any transfer of Securities by a Purchaser to an Affiliate of such
Purchaser or to one or more funds or managed accounts under common management
with such Purchaser, and any transfer among any such Affiliates or one or more
funds or managed accounts, provided (i) that the transferee certifies to the
Company that it is an "accredited investor" within the meaning of Rule 501(a)
under the Securities Act, (ii) that it is acquiring the Securities solely for
investment purposes (subject to the qualifications hereof), and (iii) that any
such transferee shall agree in writing to be bound by the terms of this
Agreement and shall have the rights of the Purchaser under this Agreement and
the Registration Rights Agreement.

                  (b) The Purchasers agree to the imprinting, so long as is
required by this Section 3.1(b), of the following legend on the Securities:

                  NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE
         SECURITIES ARE [CONVERTIBLE] [EXERCISABLE] HAVE BEEN REGISTERED WITH
         THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF
         ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND,
         ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE
         REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN
         AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE
         REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH
         APPLICABLE STATE SECURITIES LAWS.

                  Underlying Shares shall not contain the legend set forth above
nor any other legend at any time while an Underlying Shares Registration
Statement covering such Underlying Shares is effective under the Securities Act
or, in the event there is not an effective Registration Statement, covering such
Underlying Shares at such time if such legend is not required under applicable
requirements of the Securities Act (including judicial interpretations and
pronouncements issued by the staff of the Commission). The Company shall cause
its counsel to issue the legal opinion included in the Transfer Agent
Instructions to the Company's transfer agent on the day that such Underlying
Shares Registration Statement is declared effective by the Commission (the
"Effective Date"). The Company agrees that with respect to any Underlying Shares
that are issued with a legend in accordance with this Section 3.1(b), it will,
within three (3) Trading Days after request therefor by a Purchaser and the
surrender by such Purchaser of the certificate representing the applicable
Underlying Shares, provide such Purchaser with a certificate or certificates
representing such Underlying Shares, free from such legend at such time as such
legend would not have been required under this Section 3.1(b) had such issuance
occurred on the date of such request. The Company may not make any notation on
its records or give instructions to any transfer agent of the Company which


                                      -9-
<PAGE>   11
enlarge the restrictions of transfer set forth in this Section. Each Purchaser
will comply with the prospectus delivery requirements of the Securities Act as
applicable to it in connection with sales of Registrable Securities (as defined
in the Registration Rights Agreement) pursuant to an Underlying Shares
Registration Statement.

         3.2 Acknowledgment of Dilution. The Company acknowledges that the
issuance of the Underlying Shares upon (i) conversion of the Debentures in
accordance with the terms of the Debentures, and (ii) exercise of the Warrants
in accordance with their terms, will result in dilution of the outstanding
shares of Common Stock, which dilution may be substantial under certain market
conditions. The Company further acknowledges that its obligation to issue
Underlying Shares upon (x) conversion of the Debentures in accordance with the
terms of the Debentures, and (y) exercise of the Warrants in accordance with
their terms, is unconditional and absolute, subject to the limitations set forth
herein in the Debentures or pursuant to the Warrants, regardless of the effect
of any such dilution.

         3.3 Furnishing of Information. As long as the Purchasers own
Securities, the Company covenants to file timely (or obtain extensions in
respect thereof and file within the applicable grace period) all reports
required to be filed by the Company after the date hereof pursuant to the
Exchange Act. So long as the Purchasers own Securities, if the Company is not
required to file reports pursuant to such laws, it will prepare and furnish to
the Purchasers and make publicly available in accordance with Rule 144(c)
promulgated under the Securities Act such information as is required for the
Purchasers to sell the Securities under Rule 144 promulgated under the
Securities Act. The Company further covenants that it will take such further
action as any holder of Securities may reasonably request, all to the extent
required from time to time to enable such Person to sell Underlying Shares
without registration under the Securities Act within the limitation of the
exemptions provided by Rule 144 promulgated under the Securities Act, including
the legal opinion referenced above in this Section. Upon the request of any such
Person, the Company shall deliver to such Person a written certification of a
duly authorized officer as to whether it has complied with such requirements.

         3.4 Integration. The Company shall not, and shall use its best efforts
to ensure that, no Affiliate shall, sell, offer for sale or solicit offers to
buy or otherwise negotiate in respect of any security (as defined in Section 2
of the Securities Act) that would be integrated with the offer or sale of the
Securities in a manner that would require the registration under the Securities
Act of the sale of the Securities to the Purchasers or that would be integrated
with the offer or sale of the Securities for purposes of the rules and
regulations of the Nasdaq Stock Market.

         3.5 Increase in Authorized Shares. If on any date the Company would be,
if a notice of conversion or exercise (as the case may be) were to be delivered
on such date, precluded from issuing (a) 200% of the number of Underlying Shares
as would then be issuable upon a conversion in full of the Debentures, and (b)
the number of Underlying Shares issuable upon exercise in full of the Warrants
(the "Current Required Minimum"), in either case, due to the unavailability of a
sufficient number of authorized but unissued or reserved shares of Common Stock,
then the Board of Directors of the Company shall promptly (and in any case,
within 60 Business Days from such date) prepare and mail to the stockholders of
the Company proxy materials requesting authorization to amend the Company's
certificate of incorporation to increase the number of shares of Common Stock
which the Company is authorized to issue to at least such number of shares as is
reasonably

                                      -10-
<PAGE>   12
adequate to enable the Company to comply with its issuance, conversion, exercise
and reservation of shares obligations as set forth in this Agreement, the
Debentures and the Warrants (the sum of (x) the number of shares of Common Stock
then outstanding plus all shares of Common Stock issuable upon exercise of all
outstanding options, warrants and convertible instruments, and (y) the Current
Required Minimum, shall be a reasonable number). In connection therewith, the
Board of Directors shall (a) adopt proper resolutions authorizing such increase,
(b) recommend to and otherwise use its best efforts to promptly and duly obtain
stockholder approval to carry out such resolutions (and hold a special meeting
of the stockholders no later than the earlier to occur of the 60th day after
delivery of the proxy materials relating to such meeting and the 90th day after
request by a holder of Securities to issue the number of Underlying Shares in
accordance with the terms hereof) and (c) within five Business Days of obtaining
such stockholder authorization, file an appropriate amendment to the Company's
certificate of incorporation to evidence such increase.

         3.6 Reservation and Listing of Underlying Shares. (a) The Company shall
(i) in the time and manner required by the NASDAQ and such other national
securities exchange or, market or trading or quotation facility on which the
Common Stock is then listed for trading, prepare and file with the NASDAQ (and
such other national securities exchange or market or trading or quotation
facility on which the Common Stock is then listed for trading) an additional
shares listing application covering a number of shares of Common Stock which is
not less than the Initial Minimum, (ii) take all steps necessary to cause such
shares of Common Stock to be approved for listing in the NASDAQ (as well as on
any such other national securities exchange or market or trading or quotation
facility on which the Common Stock is then listed) as soon as possible
thereafter, and (iii) provide to the Purchasers evidence of such listing, and
the Company shall maintain the listing of its Common Stock thereon. If the
number of Underlying Shares issuable upon conversion in full of the then
outstanding Debentures and upon exercise of the then unexercised portion of the
Warrants exceeds 85% of the number of Underlying Shares previously listed on
account thereof with NASDAQ (and any such other required exchanges), then the
Company shall take the necessary actions to list immediately a number of
Underlying Shares as equals no less than the then Current Required Minimum with
respect thereto.

                  (b) The Company shall maintain a reserve of shares of Common
Stock for issuance upon conversion of the Debentures in full and upon exercise
in full of the Warrants in accordance with this Agreement, the Debentures and
the Warrants, respectively, in such amount as may be required to fulfill its
obligations in full under the Transaction Documents, which reserve shall equal
no less than the then Current Required Minimum.

         3.7 Conversion and Exercise Procedures. The Transfer Agent
Instructions, Conversion Notice (as defined in the Debentures) and Notice of
Exercise under the Warrants set forth the totality of the procedures with
respect to the conversion of the Debentures and exercise of the Warrants,
including the form of legal opinion, if necessary, that shall be rendered to the
Company's transfer agent and such other information and instructions as may be
reasonably necessary to enable the Purchasers to convert their Debentures and
exercise their Warrants as contemplated in the Debentures and the Warrants (as
applicable).

         3.8 Notice of Breaches. Each of the Company and the Purchasers shall
give prompt written notice to the other of any breach by it of any
representation, warranty or other agreement contained in any Transaction
Document, as well as any events or occurrences arising after the date

                                      -11-
<PAGE>   13
hereof which would reasonably be likely to cause any representation or warranty
or other agreement of such party, as the case may be, contained therein to be
incorrect or breached as of the Closing Date. However, no disclosure by a party
pursuant to this Section shall be deemed to cure any breach of any
representation, warranty or other agreement contained in any Transaction
Document.

         3.9 Right of First Refusal; Subsequent Registrations. (a) The Company
shall not, directly or indirectly, without the prior written consent of the
Purchasers (which shall not be unreasonably withheld), offer, sell, grant any
option to purchase, or otherwise dispose of (or announce any offer, sale, grant
or any option to purchase or other disposition) any of its or its Affiliates'
equity or equity-equivalent securities in a transaction intended to be exempt or
not subject to registration under the Securities Act (a "Subsequent Placement")
until the 310th day after the Closing Date (the "Threshold Date"), except (i)
the granting of options or warrants to employees, officers, directors,
consultants and other service providers , and the issuance of shares upon
exercise of options granted, under any stock option plan heretofore or
hereinafter duly adopted by the Company, (ii) shares of Common Stock issuable
upon exercise of currently outstanding options and warrants and upon conversion
of any currently outstanding convertible securities of the Company and , in each
case to the extent disclosed in Schedule 2.1(c) but not with respect to any
amendment or modification thereof, and convertible securities issued in
compliance with this Section 3.9(a), (iii) shares of Common Stock issuable upon
conversion of the Debentures and exercise of the Warrants in accordance with the
terms thereof, (iv) shares of Common Stock issuable in connection with a
Strategic Transaction (as defined below), (v) an underwritten public offering of
the Common Stock resulting in net proceeds to the Company in excess of
$10,000,000, (vi) warrants issuable to Brighton Capital, Ltd. in connection with
this transaction and the issuance of shares upon exercise thereof, (vii)
warrants to be issued by the Company to Kingsbridge Capital Limited to purchase
25,000 shares of Common Stock and the issuance of shares upon exercise thereof,
(viii) the granting of warrants to purchase up to 10,000 shares of Common Stock
in connection with equipment leasing or other debt financing transactions and
(ix) a single issuance of shares of Common Stock, at a discount of up to 10% of
the market price of the Common Stock at the time of such issuance and, in
connection therewith, the issuance of warrants to purchase Common Stock at a
price no less than 10% of the market price of the Common Stock at the time of
such issuance and the issuance of shares of Common Stock or warrants to purchase
Common Stock as payment of any placement fee, unless (A) the Company delivers to
each Purchaser a written notice (the "Subsequent Placement Notice") of its
intention to effect such Subsequent Placement, which Subsequent Placement Notice
shall describe in reasonable detail the proposed terms of such Subsequent
Placement, the amount of proceeds intended to be raised thereunder, the Person
with whom such Subsequent Placement shall be effected, and attached to which
shall be a term sheet or similar document relating thereto and (B) such
Purchaser shall not have notified the Company by 5:30 p.m. (New York City time)
on the second (2nd) Trading Day after its receipt of the Subsequent Placement
Notice of its willingness to cause such Purchaser to provide (or to cause its
sole designee to provide), subject to completion of mutually acceptable
documentation, financing to the Company on the same terms set forth in the
Subsequent Placement Notice. If the Purchasers shall fail to notify the Company
of their intention to enter into such negotiations within such time period, the
Company may effect the Subsequent Placement substantially upon the terms and to
the Persons (or Affiliates of such Persons) set forth in the Subsequent
Placement Notice; provided, that the Company shall provide the Purchasers with a
second Subsequent Placement Notice, and the Purchasers shall again have the
right of first refusal set forth above in this Section (a), if the Subsequent
Placement subject to the initial Subsequent Placement Notice shall not have been
consummated for any reason substantially on the terms set

                                      -12-
<PAGE>   14
forth in such Subsequent Placement Notice within thirty (30) Trading Days after
the date of the initial Subsequent Placement Notice with the Person (or an
Affiliate of such Person) identified in the Subsequent Placement Notice. The
rights of the Purchasers under this Section shall apply to each Subsequent
Placement contemplated by the Company or such Subsidiary, regardless of any
prior waivers or non-participation. If the Purchasers shall indicate a
willingness to provide financing in excess of the amount set forth in the
Subsequent Placement Notice, then each Purchaser shall be entitled to provide
financing pursuant to such Subsequent Placement Notice up to an amount equal to
such Purchaser's pro rata portion of the principal amount of Debentures
purchased by such Purchaser under this Agreement, but the Company shall not be
required to accept financing from the Purchasers in an amount less than or in
excess of the amount set forth in the Subsequent Placement Notice. For purposes
of this Section 3.9, a "Strategic Transaction" shall mean a transaction or
relationship in which the Company issues shares of Common Stock to an entity
which is, itself or through its subsidiaries, an operating company in a business
related to the business of the Company and in which the Company receives
material benefits in addition to the investment of funds, but shall not include
a transaction in which the Company is issuing securities primarily for the
purpose of raising capital or to an entity whose primary business is investing
in securities (such entity, a "Strategic Partner").

                  (b) Except for (x) Underlying Shares, (y) other "Registrable
Securities" (as such term is defined in the Registration Rights Agreement) to be
registered, and securities of the Company as set forth in Schedule 6(b) of the
Registration's Rights Agreement to be registered, in the Underlying Shares
Registration Statement in accordance with the Registration Rights Agreement, and
(z) Common Stock permitted to be issued pursuant to paragraph (a)(i) - (ix) of
Section 3.9 (a), the Company shall not, for a period of not less than 90 Trading
Days after the Effective Date, without the prior written consent of the
Purchasers (i) issue or sell any of its or any of its Affiliates' equity or
equity-equivalent securities pursuant to Regulation S promulgated under the
Securities Act, or (ii) file a registration statement for the issuance or resale
of any securities of the Company. Any days that a Purchaser, by action of the
Company or the Commission, is not permitted or unable to utilize the prospectus
or otherwise to sell Underlying Shares under the Underlying Shares Registration
Statement shall be added to such 90 Trading Day period for the purposes of this
Section.

                  (c) The rights of first refusal and limitations on
registration set forth in Sections 3.9(a) and (b) are intended to supercede and
replace any and all similar rights or limitations currently held by the
Purchasers and all such rights and limitations are hereby terminated.

         3.10 Certain Securities Laws Disclosures; Publicity. The Company shall:
(i) on the Closing Date, issue a press release acceptable to the Purchasers
disclosing the transactions contemplated hereby, (ii) file with the Commission a
Report on Form 8-K or Form 10-Q (as applicable) disclosing the transactions
contemplated hereby within ten (10) Business Days after the Closing Date, and
(iii) timely file with the Commission a Form D promulgated under the Securities
Act as required under Regulation D promulgated under the Securities Act and
provide a copy thereof to the Purchasers promptly after the filing thereof. The
Company shall, no less than two (2) Business Days prior to the filing of any
disclosure required by clauses (ii) and (iii) above, provide a copy thereof to
the Purchasers. The Company and the Purchasers shall consult with each other in
issuing any press releases or otherwise making public statements or filings and
other communications with the Commission or any regulatory agency or stock
market or trading facility

                                      -13-
<PAGE>   15
with respect to the transactions contemplated hereby and neither party shall
issue any such press release or otherwise make any such public statement,
filings or other communications pertaining to the transactions contemplated
hereby without the prior written consent of the other, which consent shall not
be unreasonably withheld or delayed, except that no prior consent shall be
required if such disclosure is required by law or such consent can not
reasonably be expected to be received prior to the time required to complete
such filing or make such statement in accordance with such applicable law, in
which such case the disclosing party shall provide the other party with prior
notice of such public statement, filing or other communication. Notwithstanding
the foregoing, the Company shall not publicly disclose the name of a Purchaser,
or include the name of a Purchaser in any filing with the Commission, or any
regulatory agency, trading facility or stock market without the prior written
consent of such Purchaser, except to the extent such disclosure is required by
law, in which case the Company shall provide such Purchaser with prior notice of
such disclosure.

         3.11 Transfer of Intellectual Property Rights. Except in connection
with the sale of all or substantially all of the assets of the Company, prior to
the 180th day after the Effective Date the Company shall not sell or otherwise
dispose of any Intellectual Property Rights or allow any of the Intellectual
Property Rights to become subject to any Liens, or fail to renew such
Intellectual Property Rights (if renewable and it would otherwise lapse if not
renewed), without the prior written consent of the Purchasers. Notwithstanding
the foregoing, the Company may license the right to promote and use its
Intellectual Property Rights to Strategic Partners in the ordinary course of its
business without the prior consent of the Purchasers.

         3.12 Use of Proceeds. The Company shall use the net proceeds from the
sale of Securities hereunder for working capital purposes and not to redeem any
Company equity or equity-equivalent securities, except as may be expressly
permitted by the Transaction Documents. Pending application of the proceeds of
this placement in the manner permitted hereby, the Company will invest such
proceeds in interest bearing accounts and/or short-term, investment grade
interest bearing securities.

         3.13 Reimbursement. If any Purchaser, other than by reason of its gross
negligence or willful misconduct, becomes involved in any capacity in any
action, proceeding or investigation brought by or against any Person, including
stockholders of the Company, in connection with or as a result of the
consummation of the transactions contemplated by Transaction Documents, the
Company will reimburse such Purchaser for its reasonable legal and other
expenses (including the cost of any investigation and preparation and travel in
connection therewith) incurred in connection therewith, as such expenses are
incurred. In addition, other than with respect to any matter in which any of the
Purchasers is a named party, the Company will pay such Purchaser the charges, as
reasonably determined by such Purchaser, for the time of any officers or
employees of such Purchaser devoted to appearing and preparing to appear as
witnesses, assisting in preparation for hearings, trials or pretrial matters, or
otherwise with respect to inquiries, hearings, trials, and other proceedings
relating to the subject matter of this Agreement. The reimbursement obligations
of the Company under this paragraph shall be in addition to any liability which
the Company may otherwise have, shall extend upon the same terms and conditions
to any Affiliates of the Purchasers who are actually named in such action,
proceeding or investigation, and partners, directors, agents, employees and
controlling persons (if any), as the case may be, of the Purchasers and any such
Affiliate, and shall be binding upon and inure to the benefit of any successors,
assigns, heirs and personal representatives of the Company, the Purchasers and
any such Affiliate and any such Person. The Company also agrees that neither the
Purchasers nor any such Affiliates, partners, directors,

                                      -14-
<PAGE>   16
agents, employees or controlling persons shall have any liability to the Company
or any Person asserting claims on behalf of or in right of the Company in
connection with or as a result of the consummation of the Transaction Documents
except to the extent that any losses, claims, damages, liabilities or expenses
incurred by the Company result from the gross negligence or willful misconduct
of the applicable Purchaser or entity in connection with the transactions
contemplated by this Agreement.

         3.14 Shareholders Rights Plan. In the event that a shareholders rights
plan is adopted by the Company, no claim will be made or enforced by the Company
or any other Person that any Purchaser is an "Acquiring Person" under any such
plan or in any way could be deemed to trigger the provisions of such plan by
virtue of receiving Underlying Shares under the Transaction Documents.

         3.15 Voting. During the period in which it owns Securities, each
Purchaser agrees to vote each voting security of the Company held by such
Purchaser as directed by the Company's management in all matters on which the
holder of such security is entitled to vote.


                                   ARTICLE IV
                                  MISCELLANEOUS

                  4.1 Fees and Expenses. At the Closing the Company shall
reimburse the Purchasers for their legal fees and expenses incurred in
connection with the preparation and negotiation of the Transaction Documents by
paying to Robinson Silverman $25,000 for the preparation and negotiation of the
Transaction Documents. The $25,000 may be deducted from the proceeds of the
Purchase Price payable to the Company and paid directly by the Purchasers to
Robinson Silverman. Other than the amounts contemplated in the immediately
preceding sentence, and except as otherwise set forth in the Registration Rights
Agreement, each party shall pay the fees and expenses of its advisers, counsel,
accountants and other experts, if any, and all other expenses incurred by such
party incident to the negotiation, preparation, execution, delivery and
performance of this Agreement. The Company shall pay all stamp and other taxes
and duties levied in connection with the issuance of the Securities.

                  4.2 Entire Agreement; Amendments. The Transaction Documents,
together with the Exhibits and Schedules thereto contain the entire
understanding of the parties with respect to the subject matter hereof and
supersede all prior agreements and understandings, oral or written, with respect
to such matters, which the parties acknowledge have been merged into such
documents, exhibits and schedules.

                  4.3 Notices. Any and all notices or other communications or
deliveries required or permitted to be provided hereunder shall be in writing
and shall be deemed given and effective on the earliest of (i) the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile telephone number specified in this Section prior to 8:00 p.m. (New
York City time) on a Business Day, (ii) the Business Day after the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile telephone number specified in this Agreement later than 8:00 p.m. (New
York City time) on any date and earlier than 11:59 p.m. (New York City time) on
such date, (iii) the Business Day following the date of mailing, if sent by

                                      -15-
<PAGE>   17
nationally recognized overnight courier service, or (iv) if sent other than by
the methods set forth in (i)-(iii) of this Section 4.3, upon actual receipt by
the party to whom such notice is required to be given. The address for such
notices and communications shall be as follows:

         If to the Company:              NeoTherapeutics, Inc.
                                         157 Technology Drive
                                         Irvine, CA 92618
                                         Facsimile No.: (949) 788-6706
                                         Attn: Chief Financial Officer

         With copies to:                 Latham & Watkins
                                         650 Town Center Drive, Suite 2000
                                         Costa Mesa, CA 92661-1925
                                         Facsimile No.: (714) 755-8290
                                         Attn: Alan W. Pettis, Esq.



                                      -16-
<PAGE>   18

         If to a Purchaser:              To the address
                                         set forth under such
                                         Purchaser's name on the
                                         signature pages hereto.

or such other address as may be designated in writing hereafter, in the same
manner, by such Person.

                  4.4 Amendments; Waivers. No provision of this Agreement may be
waived or amended except in a written instrument signed, in the case of an
amendment, by both the Company and the Purchasers or, in the case of a waiver,
by the party against whom enforcement of any such waiver is sought. No waiver of
any default with respect to any provision, condition or requirement of this
Agreement shall be deemed to be a continuing waiver in the future or a waiver of
any other provision, condition or requirement hereof, nor shall any delay or
omission of either party to exercise any right hereunder in any manner impair
the exercise of any such right accruing to it thereafter.


                  4.5 Headings. The headings herein are for convenience only, do
not constitute a part of this Agreement and shall not be deemed to limit or
affect any of the provisions hereof.

                  4.6 Successors and Assigns. This Agreement shall be binding
upon and inure to the benefit of the parties and their successors and permitted
assigns. The Company may not assign this Agreement or any rights or obligations
hereunder without the prior written consent of the Purchasers. Except as set
forth in Section 3.1(a), the Purchasers may not assign this Agreement or any of
the rights or obligations hereunder without the consent of the Company.

                  4.7 No Third-Party Beneficiaries. This Agreement is intended
for the benefit of the parties hereto and their respective successors and
permitted assigns and is not for the benefit of, nor may any provision hereof be
enforced by, any other Person.

                  4.8 Governing Law. The corporate laws of the State of Delaware
shall govern all issues concerning the relative rights of the Company and its
stockholders. All other questions concerning the construction, validity,
enforcement and interpretation of the Transaction Documents shall be governed by
and construed and enforced in accordance with the internal laws of the State of
New York, without regard to the principles of conflicts of law thereof. Each
party hereby irrevocably submits to the exclusive jurisdiction of the state and
federal courts sitting in the City of New York, borough of Manhattan, for the
adjudication of any dispute hereunder or in connection herewith or with any
transaction contemplated hereby or discussed herein (including with respect to
the enforcement of the any of the Transaction Documents), and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, that
such suit, action or proceeding is improper. Each party hereby irrevocably
waives personal service of process and consents to process being served in any
such suit, action or proceeding by mailing a copy thereof to such party at the
address in effect for notices to it under this Agreement and agrees that such
service shall constitute good and sufficient service of process and notice
thereof. Nothing contained herein shall be deemed to limit in any way any right
to serve process in any manner permitted by law.

                  4.9 Survival. The representations, warranties, agreements and
covenants contained herein shall survive the Closing, the delivery, exercise and
conversion (as the case may be) of the Warrants and the Debentures.

                                      -17-
<PAGE>   19

                  4.10 Execution. This Agreement may be executed in two or more
counterparts, all of which when taken together shall be considered one and the
same agreement and shall become effective when counterparts have been signed by
each party and delivered to the other party, it being understood that both
parties need not sign the same counterpart. In the event that any signature is
delivered by facsimile transmission, such signature shall create a valid and
binding obligation of the party executing (or on whose behalf such signature is
executed) the same with the same force and effect as if such facsimile signature
page were an original thereof.

                  4.11 Severability. In case any one or more of the provisions
of this Agreement shall be invalid or unenforceable in any respect, the validity
and enforceability of the remaining terms and provisions of this Agreement shall
not in any way be affecting or impaired thereby and the parties will attempt to
agree upon a valid and enforceable provision which shall be a reasonable
substitute therefor, and upon so agreeing, shall incorporate such substitute
provision in this Agreement.

                  4.12 Remedies. In addition to being entitled to exercise all
rights provided herein or granted by law, including recovery of damages, the
Purchasers will be entitled to specific performance of the obligations of the
Company under the Transaction Documents. Each of the Company and the Purchasers
agree that monetary damages may not be adequate compensation for any loss
incurred by reason of any breach of its obligations described in the foregoing
sentence and hereby agrees to waive in any action for specific performance of
any such obligation the defense that a remedy at law would be adequate.

                  4.13 Independent Nature of Purchasers' Obligations and Rights.
The obligations of each Purchaser under any Transaction Document is several and
not joint with the obligations of any other Purchaser, and no Purchaser shall be
responsible in any way for the performance of the obligations of any other
Purchaser under any Transaction Document. Nothing contained herein or in any
Transaction Document, and no action taken by any Purchaser pursuant thereto,
shall be deemed to constitute the Purchasers as a partnership, an association, a
joint venture or any other kind of entity, or create a presumption that the
Purchasers are in any way acting in concert with respect to such obligations or
the transactions contemplated by the Transaction Document. Each Purchaser shall
be entitled to independently protect and enforce its rights, including without
limitation the rights arising out of this Agreement or out of the Transaction
Documents, and it shall not be necessary for any other Purchaser to be joined as
an additional party in any proceeding for such purpose.


                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                             SIGNATURE PAGES FOLLOW]



                                      -18-
<PAGE>   20

                  IN WITNESS WHEREOF, the parties hereto have caused this
Convertible Debenture Purchase Agreement to be duly executed by their respective
authorized signatories as of the date first indicated above.

                                       NEOTHERAPEUTICS, INC.



                                       By:      /s/Samuel Gulko
                                         ----------------------------
                                       Name:       Samuel Gulko
                                       Title:      Chief Financial Officer


                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                      SIGNATURE PAGE FOR PURCHASER FOLLOWS]



<PAGE>   21
                 MONTROSE INVESTMENTS LTD.


                 By:    /s/Harlan B. Korenvaes
                      ----------------------------
                 Name:     Harlan B. Korenvaes
                 Title:    Authorized Signatory

                 Debentures Purchase Price:$5,000,000


                 Address for Notice:

                 Montrose Investments Ltd.
                 300 Crescent Court, Suite 700
                 Dallas, TX 75201
                 Facsimile: (214) 758-1221
                 Attn: Will Rose and Kim Rozman

                 With copies to:
                 Robinson Silverman Pearce Aronsohn & Berman LLP
                 1290 Avenue of the Americas
                 New York, NY  10104
                 Facsimile No.:  (212) 541-4630 and (212) 541-1432
                 Attn: Kenneth L. Henderson, Esq. and Eric L. Cohen, Esq.



<PAGE>   22



                 STRONG RIVER INVESTMENTS, INC.


                 By:  /s/ Kenneth L. Henderson
                      -------------------------
                 Name:    Kenneth L. Henderson
                 Title:   Attorney-in-fact

                  Debentures Purchase Price:         $5,000,000


                  Address for Notice:

                  Strong River Investments, Inc.
                  c/o Gonzalez-Ruiz 7 Aleman (BVI) Limited
                  Wickhams Cay I, Vanterpool Plaza
                  P.O. Box 873
                  Road Town, Tortolla, BVI

                  With copies to:
                  Robinson Silverman Pearce Aronsohn & Berman LLP
                  1290 Avenue of the Americas
                  New York, NY  10104
                  Facsimile No.:  (212) 541-4630 and (212) 541-1432
                  Attn: Kenneth L. Henderson, Esq. and Eric L. Cohen, Esq.



<PAGE>   1
                                                                     EXHIBIT 4.2


                          REGISTRATION RIGHTS AGREEMENT

         This Registration Rights Agreement (this "Agreement") is made and
entered into as of April 6, 2000, among NeoTherapeutics, Inc., a Delaware
corporation (the "Company"), and the investors signatory hereto (each such
investor is a "Purchaser" and all such investors are, collectively, the
"Purchasers").

         This Agreement is made pursuant to the Convertible Debenture Purchase
Agreement, dated as of the date hereof, among the Company and the Purchasers
(the "Purchase Agreement").

In consideration of the mutual covenants contained in the Purchase Agreement and
in this Agreement, the Company and the Purchasers hereby agree as follows:

1.       Definitions

         Capitalized terms used and not otherwise defined herein that are
defined in the Purchase Agreement shall have the meanings given such terms in
the Purchase Agreement. As used in this Agreement, the following terms shall
have the following meanings:

         "Advice" shall have meaning set forth in Section 6(e).

         "Affiliate" means, with respect to any Person, any other Person that
directly or indirectly controls or is controlled by or under common control with
such Person. For the purposes of this definition, "control," when used with
respect to any Person, means the possession, direct or indirect, of the power to
direct or cause the direction of the management and policies of such Person,
whether through the ownership of voting securities, by contract or otherwise;
and the terms of "affiliated," "controlling" and "controlled" have meanings
correlative to the foregoing.

         "Business Day" means any day except Saturday, Sunday and any day which
shall be a federal legal holiday or a day on which banking institutions in the
State of New York and the State of California generally are authorized or
required by law or other governmental action to close.

         "Class A Warrants" shall have the meaning set forth in the Purchase
Agreement.

         "Class B Warrants" shall have the meaning set forth in the Purchase
Agreement.

         "Closing Date" shall have the meaning set forth in the Purchase
Agreement.

         "Commission" means the Securities and Exchange Commission.

         "Common Stock" means the Company's common stock, $.001 par value per
share and any other securities into which such stock shall hereafter be
redistributed or recapitalized.
<PAGE>   2
         "Debentures" shall have the meaning set forth in the Purchase
Agreement.

         "Effectiveness Date" means the 90th day following the Closing Date.

         "Effectiveness Period" shall have the meaning set forth in Section
2(a).

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

         "Filing Date" means the 30th day following the Closing Date.

         "Holder" or "Holders" means the holder or holders, as the case may be,
from time to time of Registrable Securities.

         "Indemnified Party" shall have the meaning set forth in Section 5(c).

         "Indemnifying Party" shall have the meaning set forth in Section 5(c).

         "Losses" shall have the meaning set forth in Section 5(a).

         "Person" means an individual or a corporation, partnership, trust,
incorporated or unincorporated association, joint venture, limited liability
company, joint stock company, government (or an agency or political subdivision
thereof) or other entity of any kind.

         "Proceeding" means an action, claim, suit, investigation or proceeding
(including, without limitation, an investigation or partial proceeding, such as
a deposition), whether commenced or threatened.

         "Prospectus" means the prospectus included a Registration Statement
(including, without limitation, a prospectus that includes any information
previously omitted from a prospectus filed as part of an effective registration
statement in reliance upon Rule 430A promulgated under the Securities Act), as
amended or supplemented by any prospectus supplement, with respect to the terms
of the offering of any portion of the Registrable Securities covered by such
Registration Statement, and all other amendments and supplements to the
Prospectus, including post-effective amendments, and all material incorporated
by reference or deemed to be incorporated by reference in such Prospectus.

         "Registration Delay Payments" shall have the meaning set forth in
Section 2(e).

         "Registrable Securities" means the shares of Common Stock issuable upon
(i) conversion of the Debentures and (ii) exercise of the Warrants.

         "Registration Statement" means the registration statement and any
additional registration statement contemplated by Section 2(a) and 2(f),
including (in each case) the Prospectus, amendments and supplements to such
registration statement or Prospectus, including pre- and post-effective
amendments, all exhibits thereto, and all material incorporated by reference or
deemed to be incorporated by reference in such registration statement.
<PAGE>   3
         "Rule 144" means Rule 144 promulgated by the Commission pursuant to the
Securities Act, as such Rule may be amended from time to time, or any rule or
regulation hereafter adopted by the Commission to replace such Rule.

         "Rule 415" means Rule 415 promulgated by the Commission pursuant to the
Securities Act, as such Rule may be amended from time to time, or any rule or
regulation hereafter adopted by the Commission to replace such Rule.

         "Rule 424" means Rule 424 promulgated by the Commission pursuant to the
Securities Act, as such Rule may be amended from time to time, or any rule or
regulation hereafter adopted by the Commission to replace such Rule.

         "Securities Act" means the Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder.

         "Special Counsel" means one special counsel to the Holders for which
the Holders will be reimbursed by the Company pursuant to Section 4.

         "Transaction Documents" shall have the meaning set forth in the
Purchase Agreement.

         "Underwritten Registration or Underwritten Offering" means a
registration in connection with which securities of the Company are sold to an
underwriter for reoffering to the public pursuant to an effective registration
statement.

         "Warrants" means the Class A Warrants, the Class B Warrants and the
Common Stock purchase warrants, if any, issued to Brighton Capital, Ltd. in
connection with the transaction contemplated by the Purchase Agreement.

2.       Shelf Registration

         (a) On or prior to the Filing Date, the Company shall prepare and file
with the Commission a "Shelf" Registration Statement covering all Registrable
Securities for an offering to be made on a continuous basis pursuant to Rule
415, unless the Holders shall elect to effect an Underwritten Offering pursuant
to Section 2(c) hereof. The Registration Statement shall be on Form S-3 (except
if the Company is not then eligible to register for resale the Registrable
Securities on Form S-3, in which case such registration shall be on another
appropriate form in accordance herewith as the Holders may consent). The Company
shall use its best efforts to cause the Registration Statement to be declared
effective under the Securities Act as promptly as possible after the filing
thereof, but in any event prior to the Effectiveness Date, and shall use its
best efforts to keep such Registration Statement continuously effective under
the Securities Act until the date which is two (2) years after the date that
such Registration Statement is declared effective by the Commission or such
earlier date when all Registrable Securities covered by such Registration
Statement have been sold or may be sold without volume restrictions pursuant to
Rule 144(k) as determined by the counsel to the Company pursuant to a written
opinion letter to such effect, addressed and acceptable to the Company's
transfer agent (the "Effectiveness Period"), provided, that

                                      -3-
<PAGE>   4
the Company shall not be deemed to have used its best efforts to keep the
Registration Statement effective during the Effectiveness Period if it
voluntarily takes any action that would result in the Holders not being able to
sell the Registrable Securities covered by such Registration Statement during
the Effectiveness Period, unless such action is required under applicable law or
the Company has filed a post-effective amendment to the Registration Statement
and the Commission has not declared it effective.

         (b) The initial Registration Statement to be filed hereunder shall
include (but not be limited to) a number of shares of Common Stock equal to no
less than the sum of (i) 200% of the number of shares of Common Stock issuable
upon conversion in full of the outstanding principal amount of the Debentures,
assuming all interest is paid in shares of Common Stock, that the Debentures
remain outstanding for five years, and that such conversion occurred on the
Closing Date, the Filing Date or the Business Day immediately preceding the date
the Company files an acceleration request with the Commission relating to the
Registration Statement, whichever yields the lowest Conversion Price (as defined
in the Debentures) and (ii) the maximum number of shares of Common Stock
issuable upon exercise in full of the Warrants and, in the case of the Class A
Warrants, assuming the maximum amount of Warrant Shares (as defined in the
Warrants) has vested thereunder (the sum of (i) and (ii), the "Initial
Minimum").

         (c) If the Holders of a majority of the Registrable Securities then
outstanding so elect, an offering of Registrable Securities pursuant to a
Registration Statement may be effected in the form of an Underwritten Offering.
In such event, and, if the managing underwriters advise the Company and such
Holders in writing that in their opinion the amount of Registrable Securities
proposed to be sold in such Underwritten Offering exceeds the amount of
Registrable Securities which can be sold in such Underwritten Offering, there
shall be included in such Underwritten Offering the amount of such Registrable
Securities which in the opinion of such managing underwriters can be sold, and
such amount shall be allocated pro rata among the Holders proposing to sell
Registrable Securities in such Underwritten Offering.

         (d) If any of the Registrable Securities are to be sold in an
Underwritten Offering, the investment banker that will administer the offering
will be selected by the Holders of a majority of the Registrable Securities
included in such offering upon consultation with the Company. No Holder may
participate in any Underwritten Offering hereunder unless such Holder (i) agrees
to sell its Registrable Securities on the basis provided in any underwriting
agreements approved by the Persons entitled hereunder to approve such
arrangements and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents required
under the terms of such arrangements.

         (e) If (i) a Registration Statement is not filed on or before the
Filing Date (if the Company files such Registration Statement without affording
the Holder the opportunity to review and comment on the same as required by
Section 3(a) hereof, the Company shall not be deemed to have satisfied this
clause (i)), or (ii) the Company fails to file with the Commission a request to
accelerate in accordance with Rule 12d1-2 promulgated under the Exchange Act
within five (5) days of the date that the Company is notified (orally or in
writing, whichever is earlier) by the Commission that a Registration Statement
will not be "reviewed" or is not subject to further review, or (iii) a
Registration Statement filed hereunder is not declared effective by the
Commission on or before the 30th day following the Effectiveness Date, or (iv)
after a Registration Statement has been

                                      -4-
<PAGE>   5
declared effective by the Commission, such Registration Statement is either not
effective as to all Registrable Securities required to be covered thereby for
more than seven (7) consecutive days throughout the Effectiveness Period or the
Holders are not permitted for any reason to make sales for more than seven (7)
consecutive days thereunder throughout the Effectiveness Period, (v) an
amendment to the Registration Statement is not filed by the Company with the
Commission within ten (10) days of the Commission's notifying the Company that
such amendment is required in order for a Registration Statement to be declared
effective, or (vi) trading in the Common Stock shall be suspended from the
NASDAQ (as defined herein) or a Subsequent Market (as defined herein) for more
than (3) consecutive Business Days or six (6) Business Days (which need not be
consecutive days) in the aggregate (any such failure or breach being referred to
as an "Event," and for purposes of clauses (i) and (iii) the date on which such
Event occurs, or for purposes of clause (iv) the date on which such seven (7)
consecutive day period is exceeded, or for purposes of clause (ii) the date on
which such five (5) day period is exceeded, or for purposes of clause (v) the
date on which such ten (10) day period is exceeded, or for purposes of clause
(vi) either such third (3rd) Business Day or the date on which such six (6)
Business Day period is exceeded being referred to as "Event Date"), then, in any
such case, as partial relief for the damages suffered therefrom by the Holder
(which remedy shall not be exclusive of any other remedies available at law or
in equity), the Company shall on the Event Date and on each monthly anniversary
thereof until the triggering Event is cured, pay to the Holder an amount in
cash, as liquidated damages for the estimated cost to the Holders of not having
liquid securities in the time contemplated by the Transaction Documents and not
as a penalty, equal to 2% of the purchase price paid by such Holder pursuant to
the Purchase Agreement. The payments to which the Holders shall be entitled
pursuant to this Section are referred to herein as "Registration Delay
Payments." Registration Delay Payments shall be calculated on a cumulative basis
and paid within five (5) Business Days of the Event Date and each monthly
anniversary thereof. If the Company fails to make Registration Delay Payments in
a timely manner, such Registration Delay Payments shall bear interest at the
rate of 2.0% per month (or the maximum rate permitted by law), pro-rated for
partial months, until paid in full.

         (f) Notwithstanding anything to the contrary, if the Commission either
(i) refuses to declare effective or review a Registration Statement because
shares of Common Stock issuable upon exercise of the Class B Warrants (the
"Class B Shares") are included in such Registration Statement or (ii) deems a
portion of the offering of the Registrable Securities pursuant to the
Registration Statement to be a primary offering of Common Stock, then each of
the Company and the Holders shall have the unilateral right to terminate the
Class B Warrants without further liability of any kind with respect thereto, no
Registration Delay Payments shall apply with respect to the Company's failure to
register such shares of Common Stock and the Company will promptly file an
amendment to the Registration Statement removing the Class B Shares from the
Registration Statement. If the Company shall have filed the Registration
Statement on or prior to the Filing Date, upon receipt of written or oral
comments from the Commission relating to whether the inclusion of the Class B
Shares in the Registration Statement is permissible, if the Company reasonably
believes that the Registration Statement should be amended to remove the Class B
Shares, upon consent of the Purchasers (which consent shall not be unreasonably
withheld), the Company shall be entitled, between the 50th and 60th day
following the date of the filing of the Registration Statement, to terminate the
Class B Warrants without further liability of any kind with respect thereto and
to file an amendment to the Registration Statement removing the Class B Shares
from the Registration Statement and, upon the timely filing of such an
amendment, the "Effectiveness Date" shall be adjusted to mean the 60th day
following the date of the filing of such an amendment.

                                      -5-
<PAGE>   6
3.       Registration Procedures

         In connection with the Company's registration obligations hereunder,
the Company shall:

         (a) Prepare and file with the Commission on or prior to the Filing
Date, a Registration Statement on Form S-3 (or if the Company is not then
eligible to register for resale the Registrable Securities on Form S-3 such
registration shall be on another appropriate form in accordance herewith, or, in
connection with an Underwritten Offering hereunder, such other form agreed to by
the Company and the Holders) which shall contain the "Plan of Distribution"
attached hereto as Annex A (except if otherwise directed by the Holders), and
cause the Registration Statement to become effective and remain effective as
provided herein; provided, however, that not less than five (5) Business Days
prior to the filing of a Registration Statement or any related Prospectus (other
than a Prospectus filed pursuant to Rule 424) and not less than one (1) Business
Day prior to the filing of any amendment or supplement thereto (including any
document that would be incorporated or deemed to be incorporated therein by
reference), the Company shall, (i) furnish to the Holders, their Special Counsel
and any managing underwriters, copies of all such documents proposed to be
filed, which documents (other than those incorporated or deemed to be
incorporated by reference) will be subject to the review of such Holders, their
Special Counsel and such managing underwriters, and (ii) cause its officers and
directors, counsel and independent certified public accountants to respond to
such inquiries as shall be necessary, in the reasonable opinion of respective
counsel to such Holders and such underwriters, to conduct a reasonable
investigation within the meaning of the Securities Act. The Company shall not
file the Registration Statement or any such Prospectus or any amendments or
supplements thereto to which the Holders of a majority of the Registrable
Securities, their Special Counsel, or any managing underwriters, shall
reasonably object on a timely basis.

         (b)      (i) Prepare and file with the Commission such amendments,
including post-effective amendments, to the Registration Statement and the
Prospectus used in connection therewith as may be necessary to keep the
Registration Statement continuously effective as to the applicable Registrable
Securities for the Effectiveness Period and prepare and file with the Commission
such additional Registration Statements in order to register for resale under
the Securities Act all of the Registrable Securities; (ii) cause the related
Prospectus to be amended or supplemented by any required Prospectus supplement,
and as so supplemented or amended to be filed pursuant to Rule 424 (or any
similar provisions then in force); (iii) respond as promptly as reasonably
possible, and in any event within ten (10) days, to any comments received from
the Commission with respect to the Registration Statement or any amendment
thereto and as promptly as reasonably possible provide the Holders true and
complete copies of all correspondence from and to the Commission relating to the
Registration Statement; and (iv) comply in all material respects with the
provisions of the Securities Act and the Exchange Act with respect to the
disposition of all Registrable Securities covered by the Registration Statement
during the applicable period in accordance with the intended methods of
disposition by the Holders thereof set forth in the Registration Statement as so
amended or in such Prospectus as so supplemented.

         (c)      (i) File additional Registration Statements if the number of
Registrable Securities at any time exceeds 85% of the number of shares of Common
Stock then registered in a

                                      -6-
<PAGE>   7
Registration Statement. The Company shall have thirty (30) days to file such
additional Registration Statements after its receipt of notice of the
requirement thereof which the Holders may give at any time when the number of
Registrable Securities exceeds 85% of the number of shares of Common Stock then
registered in a Registration Statement hereunder. In such event, the
Registration Statement required to be filed by the Company shall include a
number of shares of Common Stock equal to no less than the Initial Minimum and
any other Registrable Securities not then registered in a Registration
Statement.

                  (ii) File such supplements or attach "stickers" to the
Registration Statement or Prospectus as and when required by the Commission to
evidence a material amount of resales by a Holder pursuant to a Prospectus. In
connection therewith, if such supplements or "stickers" are periodically
required by the Commission, the Company shall, within four (4) Business Days,
file such supplements or attach such "stickers" whenever a Holder has sold 50%
of the Registrable Securities covered by the then outstanding Prospectus (as
last supplemented or "stickered") in order to cover 100% of the number of the
outstanding Registrable Securities.

         (d) Notify the Holders of Registrable Securities to be sold, their
Special Counsel and any managing underwriters as promptly as reasonably possible
(and, in the case of (i)(A) below, not less than five (5) Business Days (or, in
the case of a supplement or "sticker" required to be filed or attached pursuant
to Section 3(c)(ii), within one (1) Business Day) prior to such filing) and (if
requested by any such Person) confirm such notice in writing no later than one
(1) Business Day following the day (i)(A) when a Prospectus or any Prospectus
supplement (other than a prospectus filed under Rule 424) or post-effective
amendment to the Registration Statement is proposed to be filed; (B) when the
Commission notifies the Company whether there will be a "review" of such
Registration Statement and whenever the Commission comments in writing on such
Registration Statement (the Company shall provide true and complete copies
thereof and all written responses thereto to each of the Holders); and (C) with
respect to the Registration Statement or any post-effective amendment, when the
same has become effective; (ii) of any request by the Commission or any other
Federal or state governmental authority for amendments or supplements to the
Registration Statement or Prospectus or for additional information; (iii) of the
issuance by the Commission of any stop order suspending the effectiveness of the
Registration Statement covering any or all of the Registrable Securities or the
initiation of any Proceedings for that purpose; (iv) and in the case of
Underwritten Offerings, if at any time any of the representations and warranties
of the Company contained in any agreement (including any underwriting agreement)
contemplated hereby ceases to be true and correct in all material respects; (v)
of the receipt by the Company of any notification with respect to the suspension
of the qualification or exemption from qualification of any of the Registrable
Securities for sale in any jurisdiction, or the initiation or threatening of any
Proceeding for such purpose; and (vi) of the occurrence of any event or passage
of time that makes the financial statements included in the Registration
Statement ineligible for inclusion therein or any statement made in the
Registration Statement or Prospectus or any document incorporated or deemed to
be incorporated therein by reference untrue in any material respect or that
requires any revisions to the Registration Statement, Prospectus or other
documents so that, in the case of the Registration Statement or the Prospectus,
as the case may be, it will not contain any untrue statement of a material fact
or omit to state any material fact required to be stated therein or necessary to
make the statements therein, in light of the circumstances under which they were
made, not misleading.

                                      -7-
<PAGE>   8
         (e) Use its best efforts to avoid the issuance of, or, if issued,
obtain the withdrawal of (i) any order suspending the effectiveness of the
Registration Statement, or (ii) any suspension of the qualification (or
exemption from qualification) of any of the Registrable Securities for sale in
any jurisdiction, at the earliest practicable moment.

         (f) If requested by any managing underwriter or the Holders of a
majority in interest of the Registrable Securities to be sold in connection with
an Underwritten Offering, (i) promptly incorporate in a Prospectus supplement or
post-effective amendment to the Registration Statement such information as such
managing underwriters and such Holders reasonably agree should be included
therein, and (ii) make all required filings of such Prospectus supplement or
such post-effective amendment as soon as practicable after the Company has
received notification of the matters to be incorporated in such Prospectus
supplement or post-effective amendment; provided, however, that the Company
shall not be required to take any action pursuant to this Section 3(f) that
would, in the opinion of counsel for the Company, violate applicable law or be
materially detrimental to the business prospects of the Company.

         (g) Furnish to each Holder, their Special Counsel and any managing
underwriters, without charge, at least one conformed copy of each Registration
Statement and each amendment thereto, including financial statements and
schedules, all documents incorporated or deemed to be incorporated therein by
reference, and all exhibits to the extent requested by such Person (including
those previously furnished or incorporated by reference) promptly after the
filing of such documents with the Commission.

         (h) Promptly deliver to each Holder, their Special Counsel, and any
underwriters, without charge, as many copies of the Prospectus or Prospectuses
(including each form of prospectus) and each amendment or supplement thereto as
such Persons may reasonably request; and the Company hereby consents to the use
of such Prospectus and each amendment or supplement thereto by each of the
selling Holders and any underwriters in connection with the offering and sale of
the Registrable Securities covered by such Prospectus and any amendment or
supplement thereto.


         (i) Prior to any public offering of Registrable Securities, use its
best efforts to register or qualify or cooperate with the selling Holders, any
underwriters and their Special Counsel in connection with the registration or
qualification (or exemption from such registration or qualification) of such
Registrable Securities for offer and sale under the securities or Blue Sky laws
of such jurisdictions within the United States as any Holder or underwriter
requests in writing, to keep each such registration or qualification (or
exemption therefrom) effective during the Effectiveness Period and to do any and
all other acts or things necessary or advisable to enable the disposition in
such jurisdictions of the Registrable Securities covered by a Registration
Statement; provided, however, that the Company shall not be required to qualify
generally to do business in any jurisdiction where it is not then so qualified
or to take any action that would subject it to general service of process in any
such jurisdiction where it is not then so subject or subject the Company to any
material tax in any such jurisdiction where it is not then so subject.

         (j) Cooperate with the Holders and any managing underwriters to
facilitate the timely preparation and delivery of certificates representing
Registrable Securities to be delivered to a transferee pursuant to a
Registration Statement, which certificates shall be free, to the extent

                                      -8-
<PAGE>   9
permitted by the Purchase Agreement and applicable federal and state securities
laws, of all restrictive legends, and to enable such Registrable Securities to
be in such denominations and registered in such names as any such managing
underwriters or Holders may request.

         (k) Upon the occurrence of any event contemplated by Section 3(d)(vi),
as promptly as reasonably possible, prepare a supplement or amendment, including
a post-effective amendment, to the Registration Statement or a supplement to the
related Prospectus or any document incorporated or deemed to be incorporated
therein by reference, and file any other required document so that, as
thereafter delivered, neither the Registration Statement nor such Prospectus
will contain an untrue statement of a material fact or omit to state a material
fact required to be stated therein or necessary to make the statements therein,
in light of the circumstances under which they were made, not misleading.


         (l) Use its best efforts to cause all Registrable Securities relating
to such Registration Statement to be listed on the Nasdaq National Market
("NASDAQ") or on any other stock market or trading facility on which the shares
of Common Stock are traded, listed or quoted (each a "Subsequent Market") as and
when required pursuant to the Purchase Agreement.

         (m) In the event of an Underwritten Offering, enter into such
agreements (including an underwriting agreement in form, scope and substance as
is customary in Underwritten Offerings) and take all such other actions in
connection therewith (including those reasonably requested by any managing
underwriters and the Holders of a majority of the Registrable Securities being
sold) in order to expedite or facilitate the disposition of such Registrable
Securities, which agreements and actions shall be subject to the reasonable
approval of counsel of the Company, (i) make such representations and warranties
to such Holders and such underwriters as are customarily made by issuers to
underwriters in underwritten public offerings, and confirm the same if and when
requested; (ii) in the case of an Underwritten Offering obtain and deliver
copies thereof to each Holder and the managing underwriters, if any, of opinions
of counsel to the Company and updates thereof addressed to each such
underwriter, in form, scope and substance reasonably satisfactory to any such
managing underwriters and Special Counsel to the selling Holders covering the
matters customarily covered in opinions requested in Underwritten Offerings and
such other matters as may be reasonably requested by such Special Counsel and
underwriters; (iii) in the case of an Underwritten Offering, if required by the
managing underwriters, at the time of delivery of any Registrable Securities
sold pursuant thereto, use its best reasonable efforts to obtain and deliver
copies to the Holders and the managing underwriters, if any, of "cold comfort"
letters and updates thereof from the independent certified public accountants of
the Company (and, if necessary, any other independent certified public
accountants of any subsidiary of the Company or of any business acquired by the
Company for which financial statements and financial data is, or is required to
be, included in the Registration Statement), addressed to the Company in form
and substance as are customary in connection with Underwritten Offerings; (iv)
if an underwriting agreement is entered into, the same shall contain
indemnification provisions and procedures no less favorable to the selling
Holders and the underwriters, if any, than those set forth in Section 5 (or such
other provisions and procedures acceptable to the managing underwriters, if any,
and holders of a majority of Registrable Securities participating in such
Underwritten Offering); and (v) deliver such documents and certificates as may
be reasonably requested by the Holders of a majority of the Registrable
Securities being sold, their Special Counsel and any managing underwriters to
evidence

                                      -9-
<PAGE>   10
the continued validity of the representations and warranties made pursuant to
Section 3(m)(i) above and to evidence compliance with any customary conditions
contained in the underwriting agreement or other agreement entered into by the
Company.

         (n) Make available for inspection by the selling Holders, any
representative of such Holders, any underwriter participating in any disposition
of Registrable Securities, and any attorney or accountant retained by such
selling Holders or underwriters, at the offices where normally kept, during
reasonable business hours and upon reasonable notice to the Company, all
financial and other records, pertinent corporate documents and properties of the
Company and its subsidiaries, and cause the officers, directors, agents and
employees of the Company and its subsidiaries to supply all information in each
case reasonably requested by any such Holder, representative, underwriter,
attorney or accountant in connection with the Registration Statement; provided,
however, that any information that is determined in good faith by the Company in
writing to be of a confidential nature at the time of delivery of such
information shall be kept confidential by such Persons, unless (i) disclosure of
such information is required by court or administrative order or is necessary to
respond to inquiries of regulatory authorities; (ii) disclosure of such
information, in the opinion of counsel to such Person, is required by law; (iii)
such information becomes generally available to the public other than as a
result of a disclosure or failure to safeguard by such Person; or (iv) such
information becomes available to such Person from a source other than the
Company and such source is not known by such Person to be bound by a
confidentiality agreement with the Company.

         (o) Comply with all applicable rules and regulations of the Commission.

         (p) The Company may require each selling Holder to furnish to the
Company such information regarding the distribution of such Registrable
Securities and the beneficial ownership of Common Stock held by such Holder as
is required by law to be disclosed in the Registration Statement, and the
Company may exclude from such registration the Registrable Securities of any
such Holder who unreasonably fails to furnish such information within a
reasonable time after receiving such request. If the Registration Statement
refers to any Holder by name or otherwise as the holder of any securities of the
Company, then such Holder shall have the right to require (if such reference to
such Holder by name or otherwise is not required by the Securities Act or any
similar Federal statute then in force) the deletion of the reference to such
Holder in any amendment or supplement to the Registration Statement filed or
prepared subsequent to the time that such reference ceases to be required.

         Each Holder agrees that, other than ordinary course brokerage
arrangements, in the event it enters into any arrangement with a broker-dealer
for the sale of any Registrable Securities through a block trade, special
offering, exchange distribution or secondary distribution or a purchase by a
broker or dealer, such Holder shall promptly deliver to the Company in writing
all applicable information required in order for the Company to be able to
timely file a supplement to the Prospectus pursuant to Rule 424(b) under the
Securities Act. Such information shall include a description of (i) the name of
such Holder and of the participating broker-dealer(s), (ii) the number of
Registrable Securities involved, (iii) the price at which such Registrable
Securities were or are to be sold, and (iv) the commissions paid or to be paid
or discounts or concessions allowed or to be allowed to such broker-dealer(s),
where applicable.

                                      -10-
<PAGE>   11
1.       Registration Expenses

         (a) All fees and expenses incident to the performance of or compliance
with this Agreement by the Company, except as and to the extent specified in
Section 4(b), shall be borne by the Company whether or not pursuant to an
Underwritten Offering and whether or not the Registration Statement is filed or
becomes effective and whether or not any Registrable Securities are sold
pursuant to the Registration Statement. The fees and expenses referred to in the
foregoing sentence shall include, without limitation, (i) all registration and
filing fees (including, without limitation, fees and expenses (A) with respect
to filings required to be made with the NASDAQ and any Subsequent Market on
which the Common Stock is then listed for trading, and (B) in compliance with
state securities or Blue Sky laws (including, without limitation, fees and
disbursements of counsel for the Holders in connection with Blue Sky
qualifications or exemptions of the Registrable Securities and determination of
the eligibility of the Registrable Securities for investment under the laws of
such jurisdictions as the managing underwriters, if any, or the Holders of a
majority of Registrable Securities may designate)), (ii) printing expenses
(including, without limitation, expenses of printing certificates for
Registrable Securities and of printing prospectuses if the printing of
prospectuses is requested by the managing underwriters, if any, or by the
holders of a majority of the Registrable Securities included in the Registration
Statement), (iii) messenger, telephone and delivery expenses of the Company,
(iv) fees and disbursements of counsel for the Company and Special Counsel for
the Holders (not to exceed $7,500), (v) Securities Act liability insurance, if
the Company so desires such insurance, and (vi) fees and expenses of all other
Persons retained by the Company in connection with the consummation of the
transactions contemplated by this Agreement. In addition, the Company shall be
responsible for all of its internal expenses incurred in connection with the
consummation of the transactions contemplated by this Agreement (including,
without limitation, all salaries and expenses of its officers and employees
performing legal or accounting duties), the expense of any annual audit, the
fees and expenses incurred in connection with the listing of the Registrable
Securities on any securities exchange as required hereunder.

         (b) If the Holders require an Underwritten Offering pursuant to the
terms hereof, the Company shall be responsible for all costs, fees and expenses
in connection therewith, except for the fees and disbursements of the
Underwriters (including any underwriting commissions and discounts) and their
legal counsel and accountants. By way of illustration which is not intended to
diminish from the provisions of Section 4(a), the Holders shall not be
responsible for, and the Company shall be required to pay the fees or
disbursements incurred by the Company (including by its legal counsel and
accountants) in connection with, the preparation and filing of a Registration
Statement and related Prospectus for such offering, the maintenance of such
Registration Statement in accordance with the terms hereof, the listing of the
Registrable Securities in accordance with the requirements hereof, and printing
expenses incurred to comply with the requirements hereof.

4.       Indemnification

         (a) Indemnification by the Company. The Company shall, notwithstanding
any termination of this Agreement, indemnify and hold harmless each Holder, the
officers, directors, agents (including any underwriters retained by such Holder
in connection with the offer and sale of Registrable Securities), investment
advisors and employees of each of them, each Person who controls any such Holder
(within the meaning of Section 15 of the Securities Act or Section 20 of the

                                      -11-
<PAGE>   12
Exchange Act) and the officers, directors, agents and employees of each such
controlling Person, to the fullest extent permitted by applicable law, from and
against any and all losses, claims, damages, liabilities, costs (including,
without limitation, costs of preparation and reasonable attorneys' fees) and
expenses (collectively, "Losses"), as incurred, arising out of or relating to
any untrue or alleged untrue statement of a material fact contained in the
Registration Statement, any Prospectus or any form of prospectus or in any
amendment or supplement thereto or in any preliminary prospectus, or arising out
of or relating to any omission or alleged omission of a material fact required
to be stated therein or necessary to make the statements therein (in the case of
any Prospectus or form of prospectus or supplement thereto, in light of the
circumstances under which they were made) not misleading, except to the extent,
but only to the extent, that (1) such untrue statements or omissions are based
solely upon information regarding such Holder furnished in writing to the
Company by such Holder expressly for use therein, or to the extent that such
information relates to such Holder or such Holder's proposed method of
distribution of Registrable Securities and was reviewed and expressly approved
in writing by such Holder expressly for use in the Registration Statement, such
Prospectus or such form of Prospectus or in any amendment or supplement thereto
or (2) in the case of an occurrence of an event of the type specified in Section
3(d)(ii)-(vi), the use by such Holder of an outdated or defective Prospectus
after the Company has notified such Holder in writing that the Prospectus is
outdated or defective and prior to the receipt by such Holder of the Advice
contemplated in Section 6(e). The Company shall notify the Holders promptly of
the institution, threat or assertion of any Proceeding of which the Company is
aware in connection with the transactions contemplated by this Agreement.

         (b) Indemnification by Holders. Each Holder shall, severally and not
jointly, indemnify and hold harmless the Company, its directors, officers,
agents and employees, each Person who controls the Company (within the meaning
of Section 15 of the Securities Act and Section 20 of the Exchange Act), and the
directors, officers, agents or employees of such controlling Persons, to the
fullest extent permitted by applicable law, from and against all Losses (as
determined by a court of competent jurisdiction in a final judgment not subject
to appeal or review) arising solely out of or based solely upon any untrue
statement of a material fact contained in the Registration Statement, any
Prospectus, or any form of prospectus, or in any amendment or supplement
thereto, or arising solely out of or based solely upon any omission of a
material fact required to be stated therein or necessary to make the statements
therein not misleading to the extent, but only to the extent, that such untrue
statement or omission is contained in any information so furnished in writing by
such Holder to the Company specifically for inclusion in the Registration
Statement or such Prospectus or to the extent that such information relates to
such Holder or such Holder's proposed method of distribution of Registrable
Securities and was reviewed and expressly approved in writing by such Holder
expressly for use in the Registration Statement, such Prospectus or such form of
Prospectus, or in any amendment or supplement thereto. In no event shall the
liability of any selling Holder hereunder be greater in amount than the dollar
amount of the net proceeds received by such Holder upon the sale of the
Registrable Securities giving rise to such indemnification obligation.

         (c) Conduct of Indemnification Proceedings. If any Proceeding shall be
brought or asserted against any Person entitled to indemnity hereunder (an
"Indemnified Party"), such Indemnified Party shall promptly notify the Person
from whom indemnity is sought (the "Indemnifying Party") in writing, and the
Indemnifying Party shall assume the defense thereof, including the employment of
counsel reasonably satisfactory to the Indemnified Party and the payment of all
fees and expenses incurred in connection with defense thereof; provided, that
the

                                      -12-
<PAGE>   13
failure of any Indemnified Party to give such notice shall not relieve the
Indemnifying Party of its obligations or liabilities pursuant to this Agreement,
except (and only) to the extent that it shall be finally determined by a court
of competent jurisdiction (which determination is not subject to appeal or
further review) that such failure shall have proximately and materially
adversely prejudiced the Indemnifying Party.

         An Indemnified Party shall have the right to employ separate counsel in
any such Proceeding and to participate in the defense thereof, but the fees and
expenses of such counsel shall be at the expense of such Indemnified Party or
Parties unless: (1) the Indemnifying Party has agreed in writing to pay such
fees and expenses; or (2) the Indemnifying Party shall have failed promptly to
assume the defense of such Proceeding and to employ counsel reasonably
satisfactory to such Indemnified Party in any such Proceeding; or (3) the named
parties to any such Proceeding (including any impleaded parties) include both
such Indemnified Party and the Indemnifying Party, and such Indemnified Party
shall have been advised by counsel that a conflict of interest is likely to
exist if the same counsel were to represent such Indemnified Party and the
Indemnifying Party (in which case, if such Indemnified Party notifies the
Indemnifying Party in writing that it elects to employ separate counsel at the
expense of the Indemnifying Party, the Indemnifying Party shall not have the
right to assume the defense thereof and such counsel shall be at the expense of
the Indemnifying Party). The Indemnifying Party shall not be liable for any
settlement of any such Proceeding effected without its written consent, which
consent shall not be unreasonably withheld. No Indemnifying Party shall, without
the prior written consent of the Indemnified Party, effect any settlement of any
pending Proceeding in respect of which any Indemnified Party is a party, unless
such settlement includes an unconditional release of such Indemnified Party from
all liability on claims that are the subject matter of such Proceeding.

         All fees and expenses of the Indemnified Party (including reasonable
fees and expenses to the extent incurred in connection with investigating or
preparing to defend such Proceeding in a manner not inconsistent with this
Section) shall be paid to the Indemnified Party, as incurred, within ten (10)
Business Days of written notice thereof to the Indemnifying Party (regardless of
whether it is ultimately determined that an Indemnified Party is not entitled to
indemnification hereunder; provided, that the Indemnifying Party may require
such Indemnified Party to undertake to reimburse all such fees and expenses to
the extent it is finally judicially determined that such Indemnified Party is
not entitled to indemnification hereunder).

         (d) Contribution. If a claim for indemnification under Section 5(a) or
5(b) is unavailable to an Indemnified Party (by reason of public policy or
otherwise), then each Indemnifying Party, in lieu of indemnifying such
Indemnified Party, shall contribute to the amount paid or payable by such
Indemnified Party as a result of such Losses, in such proportion as is
appropriate to reflect the relative fault of the Indemnifying Party and
Indemnified Party in connection with the actions, statements or omissions that
resulted in such Losses as well as any other relevant equitable considerations.
The relative fault of such Indemnifying Party and Indemnified Party shall be
determined by reference to, among other things, whether any action in question,
including any untrue or alleged untrue statement of a material fact or omission
or alleged omission of a material fact, has been taken or made by, or relates to
information supplied by, such Indemnifying Party or Indemnified Party, and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such action, statement or omission. The amount paid or
payable by a party as a result of any Losses shall be deemed to include, subject
to the limita-

                                      -13-
<PAGE>   14
tions set forth in Section 5(c), any reasonable attorneys' or other reasonable
fees or expenses incurred by such party in connection with any Proceeding to the
extent such party would have been indemnified for such fees or expenses if the
indemnification provided for in this Section was available to such party in
accordance with its terms.

         The parties hereto agree that it would not be just and equitable if
contribution pursuant to this Section 5(d) were determined by pro rata
allocation or by any other method of allocation that does not take into account
the equitable considerations referred to in the immediately preceding paragraph.
Notwithstanding the provisions of this Section 5(d), no Holder shall be required
to contribute, in the aggregate, any amount in excess of the amount by which the
proceeds actually received by such Holder from the sale of the Registrable
Securities subject to the Proceeding exceeds the amount of any damages that such
Holder has otherwise been required to pay by reason of such untrue or alleged
untrue statement or omission or alleged omission. No Person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
shall be entitled to contribution from any Person who was not guilty of such
fraudulent misrepresentation.

         The indemnity and contribution agreements contained in this Section are
in addition to any liability that the Indemnifying Parties may have to the
Indemnified Parties.

5.       Miscellaneous

         (a) Remedies. In the event of a breach by the Company or by a Holder,
of any of their obligations under this Agreement, each Holder or the Company, as
the case may be, in addition to being entitled to exercise all rights granted by
law and under this Agreement, including recovery of damages, will be entitled to
specific performance of its rights under this Agreement. The Company and each
Holder agree that monetary damages would not provide adequate compensation for
any losses incurred by reason of a breach by it of any of the provisions of this
Agreement and hereby further agrees that, in the event of any action for
specific performance in respect of such breach, it shall waive the defense that
a remedy at law would be adequate.

         (b) No Inconsistent Agreements. Neither the Company nor any of its
subsidiaries has entered, as of the date hereof, nor shall the Company or any of
its subsidiaries, on or after the date of this Agreement, enter into any
agreement with respect to its securities that is inconsistent with the rights
granted to the Holders in this Agreement or otherwise conflicts with the
provisions hereof. Except as and to the extent specified in Schedule 6(b)
hereto, neither the Company nor any of its subsidiaries has previously entered
into any agreement granting any registration rights with respect to any of its
securities to any Person that have not been satisfied in full. Without limiting
the generality of the foregoing, without the written consent of the Holders of a
majority of the then outstanding Registrable Securities, the Company shall not
grant to any Person the right to request the Company to register any securities
of the Company under the Securities Act unless the rights so granted are subject
in all respects to the prior rights in full of the Holders set forth herein, and
are not otherwise in conflict or inconsistent with the provisions of this
Agreement. Notwithstanding anything herein to the contrary, the parties agree
that the granting by the Company of registration rights in connection with a
fixed priced offering of its securities in a private placement transaction with
an aggregate sum of up to $30,000,000, or any offering of its securities that
occurs after the 240th Trading Day following the Closing Date will not violate
this provision.

                                      -14-
<PAGE>   15
         (c) No Piggyback on Registrations. Except as and to the extent
specified in Schedule 6(b) hereto, neither the Company nor any of its security
holders (other than the Holders in such capacity pursuant hereto) may include
securities of the Company in the Registration Statement other than the
Registrable Securities, and the Company shall not after the date hereof enter
into any agreement providing any such right to any of its security holders.

         (d) Compliance. Each Holder covenants and agrees that it will comply
with the prospectus delivery requirements of the Securities Act as applicable to
it in connection with sales of Registrable Securities pursuant to the
Registration Statement.

         (e) Discontinued Disposition. Each Holder agrees by its acquisition of
such Registrable Securities that, upon receipt of a notice from the Company of
the occurrence of any event of the kind described in Sections 3(d)(ii),
3(d)(iii), 3(d)(iv), 3(d)(v) or 3(d)(vi), such Holder will forthwith discontinue
disposition of such Registrable Securities under the Registration Statement
until such Holder's receipt of the copies of the supplemented Prospectus and/or
amended Registration Statement contemplated by Section 3(k), or until it is
advised in writing (the "Advice") by the Company that the use of the applicable
Prospectus may be resumed, and, in either case, has received copies of any
additional or supplemental filings that are incorporated or deemed to be
incorporated by reference in such Prospectus or Registration Statement. The
Company may provide appropriate stop orders to enforce the provisions of this
paragraph.

         (f) Piggy-Back Registrations. If at any time when there is not an
effective Registration Statement covering all of the Registrable Securities then
outstanding and the Company shall determine to prepare and file with the
Commission a registration statement relating to an offering for its own account
or the account of others under the Securities Act of any of its equity
securities, other than on Form S-4 or Form S-8 (each as promulgated under the
Securities Act) or their then equivalents relating to equity securities to be
issued solely in connection with any acquisition of any entity or business or
equity securities issuable in connection with stock option or other employee
benefit plans, then the Company shall send to each Holder of Registrable
Securities written notice of such determination and, if within twenty (20) days
after receipt of such notice, any such holder shall so request in writing, the
Company shall include in such registration statement all or any part of such
Registrable Securities such holder requests to be registered. If any
registration of the Company pursuant to this Section 6(f) is for a registered
public offering involving an underwriting, the right of any Holder to
registration shall be conditioned upon such Holder's entering into an
underwriting agreement and/or lock-up agreement in customary forms with the
representative of the underwriter or underwriters.

         (g) Amendments and Waivers. The provisions of this Agreement, including
the provisions of this sentence, may not be amended, modified or supplemented,
and waivers or consents to departures from the provisions hereof may not be
given, unless the same shall be in writing and signed by the Company and the
Holders of at least two-thirds of the then outstanding Registrable Securities.
Notwithstanding the foregoing, a waiver or consent to depart from the provisions
hereof with respect to a matter that relates exclusively to the rights of
Holders and that does not directly or indirectly affect the rights of other
Holders may be given by Holders of at least a majority of the Registrable
Securities to which such waiver or consent relates; provided, however, that the
provisions of this sentence may not be amended, modified, or supplemented except
in accordance with the provisions of the immediately preceding sentence.

                                      -15-
<PAGE>   16
         (h) Notices. Any and all notices or other communications or deliveries
required or permitted to be provided hereunder shall be in writing and shall be
deemed given and effective on the earliest of (i) the date of transmission, if
such notice or communication is delivered via facsimile at the facsimile
telephone number specified in this Section prior to 8:00 p.m. (New York City
time) on a Business Day, (ii) the Business Day after the date of transmission,
if such notice or communication is delivered via facsimile at the facsimile
telephone number specified in the Purchase Agreement later than 8:00 p.m. (New
York City time) on any date and earlier than 11:59 p.m. (New York City time) on
such date, (iii) the Business Day following the date of mailing, if sent by
nationally recognized overnight courier service, or (iv) if sent other than by
the methods set forth in (i)-(iii) of this section, upon actual receipt by the
party to whom such notice is required to be given. The address for such notices
and communications shall be as follows:

         If to the Company:         NeoTherapeutics, Inc.
                                    157 Technology Drive
                                    Irvine, California 92618
                                    Facsimile No.: (949) 788-6706
                                    Attn: Chief Financial Officer

         With copies to:            Latham & Watkins
                                    650 Town Center Drive, Suite 2000
                                    Costa Mesa, CA 92661-1925
                                    Facsimile No.: (714) 755-8290
                                    Attn: Alan W. Pettis, Esq.

         If to any other Person who is then the registered Holder:
To the address of such Holder as it appears in the stock transfer books of the
Company or such other address as may be designated in writing hereafter, in the
same manner, by such Person.

         (i) Successors and Assigns. This Agreement shall inure to the benefit
of and be binding upon the successors and permitted assigns of each of the
parties and shall inure to the benefit of each Holder. The Company may not
assign its rights or obligations hereunder without the prior written consent of
each Holder. Each Holder may assign their respective rights hereunder in the
manner and to the Persons as permitted under this Agreement and the Purchase
Agreement.

         (j) Counterparts. This Agreement may be executed in any number of
counterparts, each of which when so executed shall be deemed to be an original
and, all of which taken together shall constitute one and the same Agreement. In
the event that any signature is delivered by facsimile transmission, such
signature shall create a valid binding obligation of the party executing (or on
whose behalf such signature is executed) the same with the same force and effect
as if such facsimile signature were the original thereof.

         (k) Governing Law. This Agreement shall be governed by and construed
and enforced in accordance with the internal laws of the State of New York
without regard to the principles of conflicts of law thereof. Each party hereby
irrevocably submits to the exclusive jurisdiction of the state and federal
courts sitting in the City of New York, borough of Manhattan, for the
adjudication of any dispute hereunder or in connection herewith or with any
transaction

                                      -16-
<PAGE>   17
contemplated hereby or discussed herein (including with respect to the
enforcement of any of the Transaction Documents) and hereby irrevocably waives,
and agrees not to assert in any suit, action or proceeding, any claim that it is
not personally subject to the jurisdiction of any such court, that such suit,
action or proceeding is improper. Each party hereby irrevocably waives personal
service of process and consents to process being served in any such suit, action
or proceeding by mailing a copy thereof to such party at the address in effect
for notices to it under this Agreement and agrees that such service shall
constitute good and sufficient service of process and notice thereof. Nothing
contained herein shall be deemed to limit in any way any right to serve process
in any manner permitted by law.

         (l) Cumulative Remedies. The remedies provided herein are cumulative
and not exclusive of any remedies provided by law.

         (m) Severability. If any term, provision, covenant or restriction of
this Agreement is held by a court of competent jurisdiction to be invalid,
illegal, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions set forth herein shall remain in full force and
effect and shall in no way be affected, impaired or invalidated, and the parties
hereto shall use their reasonable efforts to find and employ an alternative
means to achieve the same or substantially the same result as that contemplated
by such term, provision, covenant or restriction. It is hereby stipulated and
declared to be the intention of the parties that they would have executed the
remaining terms, provisions, covenants and restrictions without including any of
such that may be hereafter declared invalid, illegal, void or unenforceable.

         (n) Headings. The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

         (o) Shares Held by the Company and its Affiliates. Whenever the consent
or approval of Holders of a specified percentage of Registrable Securities is
required hereunder, Registrable Securities held by the Company or its Affiliates
(other than any Holder or transferees or successors or assigns thereof if such
Holder is deemed to be an Affiliate solely by reason of its holdings of such
Registrable Securities) shall not be counted in determining whether such consent
or approval was given by the Holders of such required percentage.

         (p) Independent Nature of Purchasers' Obligations and Rights. The
obligations of each Purchaser hereunder is several and not joint with the
obligations of any other Purchaser hereunder, and neither Purchaser shall be
responsible in any way for the performance of the obligations of any other
Purchaser hereunder. Nothing contained herein or in any other agreement or
document delivered at any closing, and no action taken by any Purchaser pursuant
hereto or thereto, shall be deemed to constitute the Purchasers as a
partnership, an association, a joint venture or any other kind of entity, or
create a presumption that the Purchasers are in any way acting in concert with
respect to such obligations or the transactions contemplated by this Agreement.
Each Purchaser shall be entitled to protect and enforce its rights, including
without limitation the rights arising out of this Agreement, and it shall not be
necessary for any other Purchaser to be joined as an additional party in any
proceeding for such purpose.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                           SIGNATURE PAGES TO FOLLOW]

                                      -17-
<PAGE>   18
         IN WITNESS WHEREOF, the parties have executed this Registration Rights
Agreement as of the date first written above.


                                    NEOTHERAPEUTICS, INC.


                                    By: /s/Samuel Gulko
                                       -----------------------------------
                                           Samuel Gulko
                                           Chief Financial Officer


                                      -18-
<PAGE>   19
                               MONTROSE INVESTMENTS LTD.



                               By: /s/ Harlan B. Korenvaes
                                   -----------------------------
                                   Name: Harlan B. Korenvaes
                                   Title: Authorized Signatory

                               Address for Notice:

                               Montrose Investments Ltd.
                               300 Crescent Court, Suite 700
                               Dallas, TX 75201
                               Facsimile: (214) 758-1221
                               Attn: Will Rose
                                     Kim Rozman


                               With copies to:
                               Robinson Silverman Pearce Aronsohn &
                                 Berman LLP
                               1290 Avenue of the Americas
                               New York, NY  10104
                               Facsimile No.: (212) 541-4630 and (212) 541-1432
                               Attn: Kenneth L. Henderson, Esq.
                                     Eric L. Cohen, Esq.


                                      -19-
<PAGE>   20
                               STRONG RIVER INVESTMENTS, INC.



                               By: /s/ Kenneth L. Henderson
                                   -----------------------------
                                   Name: Kenneth L. Henderson
                                   Title: Attorney-in-fact



                               Address for Notice:

                               Strong River Investment, Inc.
                               c/o Gonzalez-Ruiz & Aleman (BVI) Limited
                               Wickhams Cay I, Vanterpool Plaza
                               P.O. Box 873
                               Road Town, Tortolla. BVI


                               With copies to:

                               Robinson Silverman Pearce Aronsohn &
                               Berman LLP
                               1290 Avenue of the Americas
                               New York, NY 10104
                               Facsimile No.:  (212) 541-4630 and (212) 541-1432
                               Attn:  Kenneth L. Henderson, Esq.
                               Eric L. Cohen, Esq.


                                      -20-
<PAGE>   21
                                                                         Annex A

                              PLAN OF DISTRIBUTION


         The Selling Stockholders and any of their pledgees, assignees and
successors-in-interest may, from time to time, sell any or all of their shares
of Common Stock on any stock exchange, market or trading facility on which the
shares are traded or in private transactions. These sales may be at fixed or
negotiated prices. The Selling Stockholders may use any one or more of the
following methods when selling shares:

- -        ordinary brokerage transactions and transactions in which the
         broker-dealer solicits purchasers;

- -        block trades in which the broker-dealer will attempt to sell the shares
         as agent but may position and resell a portion of the block as
         principal to facilitate the transaction;

- -        purchases by a broker-dealer as principal and resale by the
         broker-dealer for its account;

- -        an exchange distribution in accordance with the rules of the applicable
         exchange;

- -        privately negotiated transactions;

- -        short sales;

- -        broker-dealers may agree with the Selling Stockholders to sell a
         specified number of such shares at a stipulated price per share;

- -        a combination of any such methods of sale; and

- -        any other method permitted pursuant to applicable law.

         The Selling Stockholders may also sell shares under Rule 144 under the
Securities Act, if available, rather than under this prospectus.

         The Selling Stockholders may also engage in short sales against the
box, puts and calls and other transactions in securities of the Company or
derivatives of Company securities and may sell or deliver shares in connection
with these trades. The Selling Stockholders may pledge their shares to their
brokers under the margin provisions of customer agreements. If a Selling
Stockholder defaults on a margin loan, the broker may, from time to time, offer
and sell the pledged shares. The Selling Stockholders have advised the Company
that they have not entered into any agreements, understandings or arrangements
with any underwriters or broker-dealers regarding the sale of their shares other
than ordinary course brokerage arrangements, nor is there an underwriter or
coordinating broker acting in connection with the proposed sale of shares by the
Selling Stockholders.

         Broker-dealers engaged by the Selling Stockholders may arrange for
other brokers-dealers to participate in sales. Broker-dealers may receive
commissions or discounts from the Selling

                                      -21-
<PAGE>   22
Stockholders (or, if any broker-dealer acts as agent for the purchaser of
shares, from the purchaser) in amounts to be negotiated. The Selling
Stockholders do not expect these commissions and discounts to exceed what is
customary in the types of transactions involved.

         The Selling Stockholders and any broker-dealers or agents that are
involved in selling the shares may be deemed to be "underwriters" within the
meaning of the Securities Act in connection with such sales. In such event, any
commissions received by such broker-dealers or agents and any profit on the
resale of the shares purchased by them may be deemed to be underwriting
commissions or discounts under the Securities Act.

         The Company is required to pay all fees and expenses incident to the
registration of the shares, including fees and disbursements of counsel to the
Selling Stockholders. The Company has agreed to indemnify the Selling
Stockholders against certain losses, claims, damages and liabilities, including
liabilities under the Securities Act.

         Upon the Company being notified by a Selling Stockholder that any
material arrangement has been entered into with a broker-dealer for the sale of
shares through a block trade, special offering, exchange distribution or
secondary distribution or a purchase by a broker or dealer, a supplement to this
prospectus will be filed, if required, pursuant to Rule 424(b) under the
Securities Act, disclosing (i) the name of each such Selling Stockholder and of
the participating broker-dealer(s), (ii) the number of shares involved, (iii)
the price at which such shares were sold, (iv) the commissions paid or discounts
or concessions allowed to such broker-dealer(s), where applicable, (v) that such
broker-dealer(s) did not conduct any investigation to verify the information set
out or incorporated by reference in this prospectus, and (vi) other facts
material to the transaction. In addition, upon the Company being notified by a
Selling Stockholder that a donee or pledgee intends to sell more than 500
shares, a supplement to this prospectus will be filed.

         The Company has advised the Selling Stockholders that the
anti-manipulative provisions of Regulation M promulgated under the Exchange Act
may apply to their sales of the shares offered hereby.

                                      -22-

<PAGE>   1
                                                                     EXHIBIT 4.3

NEITHER THIS DEBENTURE NOR THE SECURITIES INTO WHICH THIS DEBENTURE IS
CONVERTIBLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES
ACT"), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN
AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE
SECURITIES LAWS.

No. 1                                                                 $1,000,000

                              NEOTHERAPEUTICS, INC.

                      5% SUBORDINATED CONVERTIBLE DEBENTURE

                                DUE APRIL 6, 2005

         THIS DEBENTURE is one of a series of duly authorized and issued
debentures of NeoTherapeutics, Inc., a Nevada corporation, having a principal
place of business at 157 Technology Drive, Irvine, CA 92618 (the "Company"),
designated as its 5% Subordinated Convertible Debentures, due April 6, 2005, in
the aggregate principal amount of Ten Million Dollars ($10,000,000) (the
"Debentures").

         FOR VALUE RECEIVED, the Company promises to pay to [ ], or its
registered assigns (the "Holder"), the principal sum of One Million Dollars
($1,000,000), on April 6, 2005 or such earlier date as the Debentures are
required or permitted to be repaid as provided hereunder (the "Maturity Date")
and to pay interest to the Holder on the aggregate unconverted and then
outstanding principal amount of this Debenture at the rate of 5% per annum,
payable on each Conversion Date (as defined in Section 4(a)(i)(C)) with respect
to the principal amount then converted and on the Maturity Date, in cash or
shares of Common Stock (as defined in Section 6). Subject to the terms and
conditions set forth herein, the decision whether to pay interest hereunder in
shares of Common Stock or cash shall be at the discretion of the Company. Not
less than ten Trading Days (as defined in Section 6) prior to each Conversion
Date, the Company shall provide the Holder with written notice of its election
to pay interest hereunder either in cash or shares of Common Stock pursuant to
the terms of Section 4(a)(i) (the Company may indicate in such notice that the
election contained in such notice shall continue for later periods until
revised). Failure to timely provide such written notice shall be deemed an
election by the Company to pay the interest on such Conversion Date in shares of
Common Stock pursuant to the terms of Section 4(a)(i). Interest shall be
calculated on the basis

                                                           Convertible Debenture
<PAGE>   2
on a 360-day year and shall accrue daily commencing on the Original Issue Date
(as defined in Section 6) until payment in full of the principal sum, together
with all accrued and unpaid interest and other amounts which may become due
hereunder, has been made. Interest hereunder will be paid to the Person (as
defined in Section 6) in whose name this Debenture is registered on the records
of the Company regarding registration and transfers of Debentures (the
"Debenture Register"). All overdue accrued and unpaid interest to be paid in
cash hereunder shall entail a late fee at the rate of 18% per annum (or such
lower maximum amount of interest permitted to be charged under applicable law)
to accrue daily, from the date such interest is due hereunder through and
including the date of payment, payable in cash.

         This Debenture is subject to the following additional provisions:

         Section 1. This Debenture is exchangeable for an equal aggregate
principal amount of Debentures of different authorized denominations, as
requested by the Holder surrendering the same. No service charge will be made
for the registration of such exchange.

         Section 2. This Debenture has been issued subject to certain investment
representations of the original Holder set forth in the Purchase Agreement (as
defined in Section 6) and may be transferred or exchanged only in compliance
with the Purchase Agreement. Prior to due presentment to the Company for
transfer of this Debenture, the Company and any agent of the Company may treat
the Person (as defined in Section 6) in whose name this Debenture is duly
registered on the Debenture Register as the owner hereof for the purpose of
receiving payment as herein provided and for all other purposes, whether or not
this Debenture is overdue, and neither the Company nor any such agent shall be
affected by notice to the contrary.

         Section 3. Events of Default.

                  (a) "Event of Default", wherever used herein, means any one of
the following events (whatever the reason and whether it shall be voluntary or
involuntary or effected by operation of law or pursuant to any judgment, decree
or order of any court, or any order, rule or regulation of any administrative or
governmental body):

                           (i) any default in the payment of the principal of,
         interest on or liquidated damages in respect of, any Debentures, free
         of any claim of subordination, as and when the same shall become due
         and payable (whether on a Conversion Date or the Maturity Date or by
         acceleration or otherwise);

                           (ii) the Company shall fail to observe or perform any
         other covenant, agreement or warranty contained in, or otherwise commit
         any breach of any of the Transaction Documents (as defined in Section
         6), and such failure or breach shall not have been remedied within five
         Business Days (as defined in Section 6) after the date on which written
         notice of such failure or breach shall have been received by the
         Company;

                           (iii) the Company or any of its subsidiaries shall
         commence, or there shall be commenced against the Company or any such
         subsidiary a case under any applicable


                                      -2-
                                                           Convertible Debenture
<PAGE>   3
         bankruptcy or insolvency laws as now or hereafter in effect or any
         successor thereto, or the Company commences any other proceeding under
         any reorganization, arrangement, adjustment of debt, relief of debtors,
         dissolution, insolvency or liquidation or similar law of any
         jurisdiction whether now or hereafter in effect relating to the Company
         or any subsidiary thereof or there is commenced against the Company or
         any subsidiary thereof any such bankruptcy, insolvency or other
         proceeding which remains undismissed for a period of 60 days; or the
         Company or any subsidiary thereof is adjudicated insolvent or bankrupt;
         or any order of relief or other order approving any such case or
         proceeding is entered; or the Company or any subsidiary thereof suffers
         any appointment of any custodian or the like for it or any substantial
         part of its property which continues undischarged or unstayed for a
         period of 60 days; or the Company or any subsidiary thereof makes a
         general assignment for the benefit of creditors; or the Company shall
         fail to pay, or shall state that it is unable to pay, or shall be
         unable to pay, its debts generally as they become due; or the Company
         or any subsidiary thereof shall call a meeting of its creditors with a
         view to arranging a composition, adjustment or restructuring of its
         debts; or the Company or any subsidiary thereof shall by any act or
         failure to act expressly indicate its consent to, approval of or
         acquiescence in any of the foregoing; or any corporate or other action
         is taken by the Company or any subsidiary thereof for the purpose of
         effecting any of the foregoing;

                           (iv) the Company shall default in any of its
         obligations under any mortgage, credit agreement or other facility,
         indenture agreement, factoring agreement or other instrument under
         which there may be issued, or by which there may be secured or
         evidenced any indebtedness for borrowed money or money due under any
         long term leasing or factoring arrangement of the Company in an amount
         exceeding one hundred thousand dollars ($100,000), whether such
         indebtedness now exists or shall hereafter be created and such default
         shall result in such indebtedness becoming or being declared due and
         payable prior to the date on which it would otherwise become due and
         payable;

                           (v) the Common Stock either be delisted from the
         Nasdaq National Market ("NASDAQ") or suspended from trading on the
         NASDAQ without resuming trading and/or being relisted thereon or listed
         on the New York Stock Exchange, American Stock Exchange or the Nasdaq
         SmallCap Market (each, a "Subsequent Market") or having such suspension
         lifted, in either case, for five consecutive Trading Days or ten
         Trading Days in the aggregate (which need not be consecutive Trading
         Days);

                           (vi) the Company shall be a party to any Change of
         Control Transaction (as defined in Section 6), shall agree to sell or
         dispose all or in excess of 33% of the fair market value of its assets
         in one or more transactions (whether or not such sale would constitute
         a Change of Control Transaction), or shall redeem or repurchase of
         shares of Common Stock or other equity securities of the Company for an
         aggregate of purchase prices in excess of $75,000 (other than
         redemptions of Underlying Shares (as defined in Section 6));



                                      -3-
                                                           Convertible Debenture
<PAGE>   4
                           (vii) an Underlying Shares Registration Statement (as
         defined in Section 6) shall not have been declared effective by the
         Commission (as defined in Section 6) on or prior to the 180th day after
         the Original Issue Date;

                           (viii) if, during the Effectiveness Period (as
         defined in the Registration Rights Agreement (as defined in Section
         6)), the effectiveness of the Underlying Shares Registration Statement
         lapses for any reason or the Holder shall not be permitted to resell
         Registrable Securities (as defined in the Registration Rights
         Agreement) under the Underlying Shares Registration Statement, in
         either case, for more than five consecutive Trading Days or an
         aggregate of ten Trading Days (which need not be consecutive Trading
         Days);

                           (ix) an Event (as defined in the Registration Rights
         Agreement) shall not have been cured to the satisfaction of the Holder
         prior to the expiration of thirty days from the Event Date (as defined
         in the Registration Rights Agreement) relating thereto unless no
         Registration Delay Payment (as defined in the Registration Rights
         Agreement) is due in respect to such Event, and excluding an Event
         resulting from a failure of an Underlying Shares Registration Statement
         to be declared effective by the Commission on or prior to the 180th day
         after the Original Issue Date, which shall be covered by Section
         3(a)(vii);

                           (x) the Company shall fail for any reason to deliver
         certificates to a Holder prior to the twelfth (12th) day after a
         Conversion Date pursuant to and in accordance with Section 4(b) or the
         Company shall provide notice to the Holder, including by way of public
         announcement, at any time, of its intention not to comply with requests
         for conversions of any Debentures in accordance with the terms hereof;
         or

                           (xi) the Company shall fail for any reason to deliver
         the payment in cash pursuant to a Buy-In (as defined herein) within
         seven (7) days after notice is deemed delivered hereunder.

                  (b) During the time that any portion of this Debenture remains
outstanding, if any Event of Default occurs and is continuing, the full
principal amount of this Debenture (and, at the Holder's option, all other
Debentures then held by such Holder), together with interest and other amounts
owing in respect thereof to the date of acceleration, shall become, immediately
due and payable in cash. The aggregate amount payable upon an Event of Default
shall be equal to the sum of (i) the Mandatory Prepayment Amount (as defined in
Section 6) plus (ii) the product of (A) the number of Underlying Shares issued
in respect of conversions hereunder within thirty (30) days of the date of a
declaration of an Event of Default and then held by the Holder and (B) the Per
Share Market Value (as defined in Section 6) on the date prepayment is due or
the date the full prepayment price is paid, whichever is greater. Interest shall
accrue on the prepayment amount hereunder from the seventh day after such amount
is due (being the date of an Event of Default) through the date of prepayment in
full thereof at the rate of 18% per annum (or such lesser maximum amount that is
permitted to be paid by applicable law), to accrue daily from the date such
payment is due hereunder through and including the date of payment. All
Debentures and Underlying Shares for which the full prepayment price hereunder
shall have been paid in accordance herewith shall promptly be


                                      -4-
                                                           Convertible Debenture
<PAGE>   5
surrendered to or as directed by the Company. The Holder need not provide and
the Company hereby waives any presentment, demand, protest or other notice of
any kind, and the Holder may immediately and without expiration of any grace
period enforce any and all of its rights and remedies hereunder and all other
remedies available to it under applicable law. Such declaration may be rescinded
and annulled by Holder at any time prior to payment hereunder. No such
rescission or annulment shall affect any subsequent Event of Default or impair
any right consequent thereon.

         Section 4. Conversion.

                  (a) (i) Conversion at Option of Holder. (A) This Debenture
shall be convertible into shares of Common Stock at the option of the Holder, in
whole or in part at any time and from time to time, after the Original Issue
Date (subject to the limitations on conversion set forth in Section 4(a)(iii)
hereof). The number of shares of Common Stock issuable upon a conversion
hereunder shall be determined by adding the sum of (i) the quotient obtained by
dividing (x) the outstanding principal amount of this Debenture to be converted
by (y) the Conversion Price (as defined herein), and (ii) the amount equal to
(I) the product of (x) the outstanding principal amount of this Debenture to be
converted and (y) the product of (1) the quotient obtained by dividing .05 by
360 and (2) the number of days for which such principal amount was outstanding,
divided by (II) the Conversion Price on the Conversion Date, provided, that if
the Company shall have timely elected to pay the interest due on a Conversion
Date in cash pursuant to the terms hereof, subsection (ii) shall not be used in
the calculation of the number of shares of Common Stock issuable upon a
conversion hereunder.

                           (B) Notwithstanding anything to the contrary
contained herein, if on any Conversion Date:

                           (1) the number of shares of Common Stock at the time
         authorized, unissued and unreserved for all purposes, or held as
         treasury stock, is insufficient to pay interest hereunder in shares of
         Common Stock;

                           (2) after the Interest Effectiveness Date (as defined
         in Section 6) such shares of Common Stock (x) are not registered for
         resale pursuant to an effective Underlying Shares Registration
         Statement and (y) may not be sold without volume restrictions pursuant
         to Rule 144(k) promulgated under the Securities Act (as defined in
         Section 6), as determined by counsel to the Company pursuant to a
         written opinion letter, addressed to the Company's transfer agent in
         the form and substance acceptable to the applicable Holder and such
         transfer agent;

                           (3) the Common Stock is not listed or quoted on the
         NASDAQ or on a Subsequent Market;

                           (4) the Company has failed to timely satisfy its
         conversion obligations hereunder; or


                                      -5-
                                                           Convertible Debenture
<PAGE>   6
                           (5) the issuance of such shares of Common Stock would
         result in a violation of Sections 4(a)(iii)(A) and (B),

                           then, at the option of the Holder, the Company, in
lieu of delivering shares of Common Stock pursuant to Section 4(a)(i)(A)(ii),
shall deliver, within three Trading Days of the applicable Conversion Date, an
amount in cash equal to the product of (a) the outstanding principal amount of
the Debentures to be converted on such Conversion Date and (b) the product of
(x) the quotient obtained by dividing .05 by 360 and (y) the number of days for
which such principal amount was outstanding.

         If shares of Common Stock are permitted by the Holder to be delivered
under the conditions described in clause (2) prior to the Effectiveness Date (as
defined in the Registration Rights Agreement) and thereafter an Underlying
Shares Registration Statement shall be declared effective by the Commission, the
Company shall, within three (3) Trading Days after the date of such declaration
of effectiveness, exchange such shares for shares of Common Stock that are free
of restrictive legends of any kind.

                           (C) The Holder shall effect conversions by
surrendering the Debentures (or such portions thereof) to be converted, together
with the form of conversion notice attached hereto as Exhibit A (a "Conversion
Notice") to the Company. Each Conversion Notice shall specify the principal
amount of Debentures to be converted and the date on which such conversion is to
be effected, which date may not be prior to the date such Conversion Notice is
deemed to have been delivered hereunder (a "Conversion Date"). If no Conversion
Date is specified in a Conversion Notice, the Conversion Date shall be the date
that such Conversion Notice is deemed delivered hereunder. Subject to Section
4(b), each Conversion Notice, once given, shall be irrevocable. If the Holder is
converting less than all of the principal amount represented by the Debenture(s)
tendered by the Holder with the Conversion Notice, or if a conversion hereunder
cannot be effected in full for any reason, the Company shall honor such
conversion to the extent permissible hereunder and shall promptly deliver to
such Holder (in the manner and within the time set forth in Section 4(b)) a new
Debenture for such principal amount as has not been converted.

                           (ii) Automatic Conversion. Subject to the provisions
in this paragraph, the principal amount of Debentures for which conversion
notices have not previously been received or for which prepayment has not been
made or required hereunder shall be automatically converted on the fifth
anniversary of the Original Issue Date (the "Automatic Conversion Date")
pursuant to Section 4(a)(i), at the Conversion Price on such date. The
conversion contemplated by this paragraph shall not occur if (a) (1) an
Underlying Securities Registration Statement is not then effective that names
the Holder as a selling stockholder thereunder and (2) the Holder is not
permitted to resell Underlying Shares pursuant to Rule 144(k) promulgated under
the Securities Act, without volume restrictions, as evidenced by an opinion
letter of counsel acceptable to the Holder and the transfer agent for the Common
Stock; or (b) there are not sufficient shares of Common Stock authorized and
reserved for issuance upon such conversion. Notwithstanding anything herein to
the contrary, the Automatic Conversion Date shall be extended (on a day-for-day
basis) for any Trading Days after the Effectiveness Date that the Holder is
unable to resell Underlying Shares due to (a) the Common Stock not being listed
for trading on the NASDAQ or any Subsequent Market, (b) the


                                      -6-
                                                           Convertible Debenture
<PAGE>   7
failure of an Underlying Securities Registration Statement to be declared
effective by the Commission or, if so declared, to remain effective during the
Effectiveness Period as to all Underlying Shares, or (c) the suspension of the
Holder's right to resell Underlying Shares thereunder. Notwithstanding anything
to the contrary contained herein, a conversion pursuant to this Section shall
not be subject to the provisions of Section 4(a)(iii)(A).

                  (iii) Certain Conversion Restrictions.

                        (A) A Holder may not convert Debentures or receive
shares of Common Stock as payment of interest hereunder to the extent such
conversion or receipt of such interest payment would result in the Holder,
together with any affiliate thereof, beneficially owning (as determined in
accordance with Section 13(d) of the Exchange Act (as defined in Section 6) and
the rules promulgated thereunder) in excess of 9.999% of the then issued and
outstanding shares of Common Stock, including shares issuable upon conversion
of, and payment of interest on, the Debentures held by such Holder after
application of this Section. Since the Holder will not be obligated to report to
the Company the number of shares of Common Stock it may hold at the time of a
conversion hereunder, unless the conversion at issue would result in the
issuance of shares of Common Stock in excess of 9.999% of the then outstanding
shares of Common Stock without regard to any other shares which may be
beneficially owned by the Holder or an affiliate thereof, the Holder shall have
the authority and obligation to determine whether the restriction contained in
this Section will limit any particular conversion hereunder and to the extent
that the Holder determines that the limitation contained in this Section
applies, the determination of which portion of the principal amount of
Debentures are convertible shall be the responsibility and obligation of the
Holder. If the Holder has delivered a Conversion Notice for a principal amount
of Debentures that, without regard to any other shares that the Holder or its
affiliates may beneficially own, would result in the issuance in excess of the
permitted amount hereunder, the Company shall notify the Holder of this fact and
shall honor the conversion for the maximum principal amount permitted to be
converted on such Conversion Date in accordance with the periods described in
Section 4(b) and, at the option of the Holder, either retain any principal
amount tendered for conversion in excess of the permitted amount hereunder for
future conversions or return such excess principal amount to the Holder. The
provisions of this Section may be waived by a Holder (but only as to itself and
not to any other Holder) upon not less than 61 days prior notice to the Company.
Other Holders shall be unaffected by any such waiver.

                        (B) If the Common Stock is then listed for trading on
the NASDAQ or the Nasdaq SmallCap Market and the Company has not obtained the
Shareholder Approval (as defined below), then the Company is precluded from
issuing in excess of 1,907,121 shares of Common Stock (the "Issuable Maximum")
upon conversion of the Debentures and as payment of interest thereon and
exercise of the Class B Warrants (as defined in the Purchase Agreement) in
response to a Call Notice (as defined in the Class B Warrants). The Issuable
Maximum equals 19.999% of the number of shares of Common Stock outstanding
immediately prior to the closing of transactions set forth in the Purchase
Agreement. Accordingly, if on any Conversion Date (A) the Common Stock is listed
for trading on the NASDAQ or the Nasdaq SmallCap Market and (B) the Company
shall not have previously obtained the vote of shareholders (the "Shareholder
Approval"), if any, as may be required by the applicable rules and regulations
of


                                      -7-
                                                           Convertible Debenture
<PAGE>   8
the Nasdaq Stock Market (or any successor entity) applicable to approve the
issuance of a number of shares of Common Stock in excess of the Issuable Maximum
at a price below the market price of the Common Stock, then the Company shall
issue to the Holder requesting a conversion a number of shares of Common Stock
equal to the lesser of (x) the number of shares of Common Stock issuable upon
such conversion at the Conversion Price and (y) the Issuable Maximum less all
shares of Common Stock previously issued upon conversion of the Debentures and
as payment of interest thereon and all shares of Common Stock previously issued
upon any exercise of the Class B Warrants in response to a Call Notice. With
respect to the principal amount of Debentures tendered for conversion at issue
for which a conversion in accordance with the Conversion Price would, when
aggregated with all shares of Common Stock previously issued on account of
conversions of Debentures and payment of interest thereon and upon exercise of
Class B Warrants in response to a Call Notice (the "Excess Principal"), result
in the issuance of a number of shares of Common Stock in excess of the Issuable
Maximum, the converting Holder shall have the option to require the Company to
either (1) use its best efforts to obtain the Shareholder Approval applicable to
such issuance as soon as is possible, but in any event not later than the 60th
day after such request, or (2) pay cash to the converting Holder in an amount
equal to the Mandatory Prepayment Amount for the Excess Principal. If the
converting Holder shall have elected the first option pursuant to the
immediately preceding sentence and the Company shall have failed to obtain the
Shareholder Approval on or prior to the 60th day after such request, then within
three days of such 60th day, the Company shall pay cash to the converting Holder
an amount equal to the Mandatory Prepayment Amount for the Excess Principal. If
the Company fails to pay the Mandatory Prepayment Amount in full pursuant to
this Section within seven days of the date payable, the Company will pay
interest thereon at a rate of 18% per annum (or such lesser maximum amount that
is permitted to be paid by applicable law) to the converting Holder, accruing
daily from the Conversion Date until such amount, plus all such interest
thereon, is paid in full. In the event there is more than one holder of
Debentures, the Issuable Maximum applicable to each Debenture shall be
determined pro rata by reference to the percentage of the principal amount of
such Debenture and $10,000,000, provided that if one or more Debentures shall
have been redeemed or converted without having been issued its pro rata
allocated portion of the Issuable Maximum such unissued shares shall be
allocated pro rata to the remaining Holders. It is understood and agreed that
shares of Common Stock delivered to and held by the Holder or one of its
affiliates on account of conversion hereunder may not cast votes on the matter
of Shareholder Approval. Shares delivered on account of conversion hereunder and
not held by the Holder or its affiliates may cast votes on the matter of
Shareholder Approval.

                  (b) (i) Not later than three Trading Days after any Conversion
Date, the Company will deliver to the Holder (i) a certificate or certificates
which shall be free of restrictive legends and trading restrictions (other than
those required by Section 3.1(b) of the Purchase Agreement) representing the
number of shares of Common Stock being acquired upon the conversion of
Debentures (subject to the limitations set forth in Section 4(a)(iii) hereof),
(ii) Debentures in a principal amount equal to the principal amount of
Debentures not converted, and (iii) a bank check in the amount of accrued and
unpaid interest (if the Company has timely elected or is required to pay accrued
interest in cash) and the Floor Prepayment Price (as defined in Section
4(c)(i)(B)) (if applicable), provided, that the Company shall not be obligated
to issue certificates evidencing the shares of Common Stock issuable upon
conversion of the principal amount of Debentures until Debentures are delivered
for conversion to the Company, or the Holder notifies the


                                      -8-
                                                           Convertible Debenture
<PAGE>   9
Company that such Debentures have been lost, stolen or destroyed and provides a
bond (or other adequate security) reasonably satisfactory to the Company to
indemnify the Company from any loss incurred by it in connection therewith. The
Company shall, upon request of the Holder, if available, use its best efforts to
deliver any certificate or certificates required to be delivered by the Company
under this Section electronically through the Depository Trust Corporation or
another established clearing corporation performing similar functions. If in the
case of any Conversion Notice such certificate or certificates are not delivered
to or as directed by the applicable Holder by the third Trading Day after a
Conversion Date, the Holder shall be entitled by written notice to the Company
at any time on or before its receipt of such certificate or certificates
thereafter, to rescind such conversion, in which event the Company shall
immediately return the certificates representing the principal amount of
Debentures tendered for conversion.

                      (ii) If the Company fails to deliver to the Holder such
certificate or certificates pursuant to Section 4(b)(i) by the third Trading Day
after the Conversion Date, the Company shall pay to such Holder, in cash, as
liquidated damages and not as a penalty, $5,000 for each Trading Day after such
third Trading Day until such certificates are delivered. Nothing herein shall
limit a Holder's right to pursue actual damages or declare an Event of Default
pursuant to Section 3 herein for the Company's failure to deliver certificates
representing shares of Common Stock upon conversion within the period specified
herein and such Holder shall have the right to pursue all remedies available to
it at law or in equity including, without limitation, a decree of specific
performance and/or injunctive relief. The exercise of any such rights shall not
prohibit the Holders from seeking to enforce damages pursuant to any other
Section hereof or under applicable law. Further, if the Company shall not have
delivered any cash due in respect of conversions of Debentures or as payment of
interest thereon by the third Trading Day after the Conversion Date, the Holder
may, by notice to the Company, require the Company to issue shares of Common
Stock pursuant to Section 4(c), except that for such purpose the Conversion
Price applicable thereto shall be the lesser of the Conversion Price on the
Conversion Date and the Conversion Price on the date of such Holder demand. Any
such shares will be subject to the provisions of this Section.

                      (iii) In addition to any other rights available to the
Holder, if the Company fails to deliver to the Holder such certificate or
certificates pursuant to Section 4(b)(i) by the third Trading Day after the
Conversion Date, and if after such third Trading Day the Holder purchases (in an
open market transaction or otherwise) Common Stock to deliver in satisfaction of
a sale by such Holder of the Underlying Shares which the Holder anticipated
receiving upon such conversion (a "Buy-In"), then the Company shall (A) pay in
cash to the Holder (in addition to any remedies available to or elected by the
Holder) the amount by which (x) the Holder's total purchase price (including
brokerage commissions, if any) for the Common Stock so purchased exceeds (y) the
product of (1) the aggregate number of shares of Common Stock that such Holder
anticipated receiving from the conversion at issue multiplied by (2) the market
price of the Common Stock at the time of the sale giving rise to such purchase
obligation and (B) at the option of the Holder, either reissue Debentures in
principal amount equal to the principal amount of the attempted conversion or
deliver to the Holder the number of shares of Common Stock that would have been
issued had the Company timely complied with its delivery requirements under
Section 4(b)(i). For example, if the Holder purchases Common Stock having a
total purchase price of $11,000 to cover a Buy-In with respect to an attempted
conversion of Debentures with respect to which the market price of the


                                      -9-
                                                           Convertible Debenture
<PAGE>   10
Underlying Shares on the date of conversion was a total of $10,000 under clause
(A) of the immediately preceding sentence, the Company shall be required to pay
the Holder $1,000. The Holder shall provide the Company written notice
indicating the amounts payable to the Holder in respect of the Buy-In.
Notwithstanding anything contained herein to the contrary, if a Holder requires
the Company to make payment in respect of a Buy-In for the failure to timely
deliver certificates hereunder and the Company timely pays in full such payment,
the Company shall not be required to pay such Holder liquidated damages under
Section 4(b)(ii) in respect of the certificates resulting in such Buy-In.

                  (c) (i)(A) The conversion price (the "Conversion Price") in
effect on any Conversion Date occurring on or prior to the 90th day following
the Original Issue Date shall be $20.25 (the "Initial Conversion Price"),
provided, that for any Conversion Date occurring after the 90th day following
the Original Issue Date, the Conversion Price shall be the lesser of (A) the
Initial Conversion Price and (B) 101% of the average of the ten lowest Per Share
Market Values during the thirty Trading Days immediately preceding the
applicable Conversion Date (which may include Trading Days prior to the Original
Issue Date), provided, however, that such thirty Trading Day period shall be
extended for the number of Trading Days during such period in which (A) trading
in the Common Stock is suspended by the NASDAQ or a Subsequent Market on which
the Common Stock is then listed, or (B) after the date declared effective by the
Commission, the Underlying Shares Registration Statement is not effective, or
(C) after the date declared effective by the Commission, the Prospectus included
in the Underlying Shares Registration Statement may not be used by the Holder
for the resale of Underlying Shares.

                      (B) If on any Conversion Date, the Conversion Price shall
be lower than $14.00 (which number shall be subject to equitable adjustments for
stock splits, recombinations and similar events) (such Conversion Price, the
"Floor Price" and a Conversion Date on which such condition is met, a "Record
Date"), then the Company will have the right, exercisable by delivery of a
written notice to the Holders delivered no later than twenty Trading Days prior
to the Record Date (the "Company Notice"), which notice shall remain in effect
until a subsequent such notice is provided by the Company to the Holders, to
elect to honor the conversion at issue by either: (x) issuing the number of
shares of Common Stock issuable at the actual Conversion Price pursuant to
Section 4(c)(i)(A), or (y) issue the number of shares of Common Stock issuable
upon the conversion at issue, as if the conversion price applicable to such
conversion was equal to the Floor Price and pay cash, no later than the third
Trading Day following the applicable Conversion Date, to the Holder, in an
amount equal to the product of (A) the average of the Per Share Market Values
for the five Trading Days preceding the Conversion Date for such conversion and
(B) the number of shares of Common Stock otherwise issuable at the actual
Conversion Price then in effect less the number of shares of Common Stock
issuable upon such conversion at the Floor Price (the "Floor Prepayment Price").
Failure by the Company to timely deliver the Company Notice to the Holder
pursuant to the terms of this Section shall result conclusively be deemed an
election by the Company under subsection (x) hereunder. Failure by the Company
to pay any portion of the Floor Prepayment Price by the third Trading Day
following the applicable Conversion Date shall result in the invalidation ab
initio of the unpaid portion of such optional prepayment. In such event, the
Company shall, at the option of the Holder, either, (i) not later than three
Trading Days from receipt of Holder's request for such election, return to the
Holder all of the principal amount of Debentures for which such Floor


                                      -10-
                                                           Convertible Debenture
<PAGE>   11
Prepayment Price has not been paid in full (the "Unpaid Prepayment Debentures")
or (ii) convert all or any portion of the Unpaid Prepayment Debentures in which
event the applicable Conversion Price shall be the lower of the Per Share Market
Value Conversion Price calculated on the date the Floor Prepayment Price was
originally due and the Per Share Market Value Conversion Price as of the
Holder's written demand for conversion. If the Holder elects option (ii) above,
the Company shall within three Trading Days of its receipt of such election
deliver to the Holder the shares of Common Stock issuable upon conversion of the
Unpaid Prepayment Debentures subject to such Holder conversion demand and
otherwise perform its obligations hereunder with respect thereto.

                      (ii) If the Company, at any time while any Debentures are
outstanding, (a) shall pay a stock dividend or otherwise make a distribution or
distributions on shares of its Common Stock or any other equity or equity
equivalent securities payable in shares of Common Stock, (b) subdivide
outstanding shares of Common Stock into a larger number of shares, (c) combine
(including by way of reverse stock split) outstanding shares of Common Stock
into a smaller number of shares, or (d) issue by reclassification of shares of
the Common Stock any shares of capital stock of the Company, then the Initial
Conversion Price shall be multiplied by a fraction of which the numerator shall
be the number of shares of Common Stock (excluding treasury shares, if any)
outstanding before such event and of which the denominator shall be the number
of shares of Common Stock outstanding after such event. Any adjustment made
pursuant to this Section shall become effective immediately after the record
date for the determination of stockholders entitled to receive such dividend or
distribution and shall become effective immediately after the effective date in
the case of a subdivision, combination or re-classification.

                      (iii) If the Company, at any time while Debentures are
outstanding, shall distribute to all holders of Common Stock (and not to
Holders) evidences of its indebtedness or assets or rights or warrants to
subscribe for or purchase any security other than with respect to rights granted
pursuant to a stockholders rights plan adopted by the Company, then in each such
case the Initial Conversion Price shall be adjusted by multiplying the Initial
Conversion Price in effect immediately prior to the record date fixed for
determination of stockholders entitled to receive such distribution by a
fraction of which the denominator shall be the Per Share Market Value determined
as of the record date mentioned above, and of which the numerator shall be such
Per Share Market Value on such record date less the then fair market value at
such record date of the portion of such assets or evidence of indebtedness so
distributed applicable to one outstanding share of the Common Stock as
determined by the Board of Directors in good faith. In either case the
adjustments shall be described in a statement provided to the Holders of the
portion of assets or evidences of indebtedness so distributed or such
subscription rights applicable to one share of Common Stock. Such adjustment
shall be made whenever any such distribution is made and shall become effective
immediately after the record date mentioned above.

                      (iv) In case of any reclassification of the Common Stock
or any compulsory share exchange pursuant to which the Common Stock is converted
into other securities, cash or property, the Holders shall have the right
thereafter to, at their option, (A) convert the then outstanding principal
amount, together with all accrued but unpaid interest and any other amounts then
owing hereunder in respect of this Debenture only into the shares of stock and
other securities, cash and property receivable upon or deemed to be held by
holders of the Common Stock following


                                      -11-
                                                           Convertible Debenture
<PAGE>   12
such reclassification or share exchange, and the Holders of the Debentures shall
be entitled upon such event to receive such amount of securities, cash or
property as the shares of the Common Stock of the Company into which the then
outstanding principal amount, together with all accrued but unpaid interest and
any other amounts then owing hereunder in respect of this Debenture could have
been converted immediately prior to such reclassification or share exchange
would have been entitled or (B) require the Company to prepay the aggregate of
its outstanding principal amount of Debentures, plus all interest and other
amounts due and payable thereon, at a price determined in accordance with
Section 3(b). The entire prepayment price shall be paid in cash. This provision
shall similarly apply to successive reclassifications or share exchanges.

                      (v) All calculations under this Section 4 shall be made to
the nearest cent or the nearest 1/100th of a share, as the case may be. No
adjustments in either the Conversion Price or the Initial Conversion Price shall
be required if such adjustment is less than $0.01, provided, however, that any
adjustments which by reason of this Section are not required to be made shall be
carried forward and taken into account in any subsequent adjustment.

                      (vi) Whenever the Initial Conversion Price is adjusted
pursuant to Section 4(c)(ii) or (iii), the Company shall promptly mail to each
Holder a notice setting forth the Initial Conversion Price after such adjustment
and setting forth a brief statement of the facts requiring such adjustment.

                      (vii) If (A) the Company shall declare a dividend (or any
other distribution) on the Common Stock; (B) the Company shall declare a special
nonrecurring cash dividend on or a redemption of the Common Stock; (C) the
Company shall authorize the granting to all holders of the Common Stock rights
or warrants to subscribe for or purchase any shares of capital stock of any
class or of any rights; (D) the approval of any stockholders of the Company
shall be required in connection with any reclassification of the Common Stock,
any consolidation or merger to which the Company is a party, any sale or
transfer of all or substantially all of the assets of the Company, of any
compulsory share exchange whereby the Common Stock is converted into other
securities, cash or property; (E) the Company shall authorize the voluntary or
involuntary dissolution, liquidation or winding up of the affairs of the
Company; then, in each case, the Company shall cause to be filed at each office
or agency maintained for the purpose of conversion of the Debentures, and shall
cause to be mailed to the Holders at their last addresses as they shall appear
upon the stock books of the Company, at least 20 calendar days prior to the
applicable record or effective date hereinafter specified, a notice stating (x)
the date on which a record is to be taken for the purpose of such dividend,
distribution, redemption, rights or warrants, or if a record is not to be taken,
the date as of which the holders of the Common Stock of record to be entitled to
such dividend, distributions, redemption, rights or warrants are to be
determined or (y) the date on which such reclassification, consolidation,
merger, sale, transfer or share exchange is expected to become effective or
close, and the date as of which it is expected that holders of the Common Stock
of record shall be entitled to exchange their shares of the Common Stock for
securities, cash or other property deliverable upon such reclassification,
consolidation, merger, sale, transfer or share exchange, provided, that the
failure to mail such notice or any defect therein or in the mailing thereof
shall not affect the validity of the corporate action required to be specified
in such notice. Holders are entitled


                                      -12-
                                                           Convertible Debenture
<PAGE>   13
to convert Debentures during the 20-day period commencing the date of such
notice to the effective date of the event triggering such notice.

                      (viii) In case of the closing of any (1) merger or
consolidation of the Company with or into another Person, or (2) sale by the
Company of more than one-half of the assets of the Company (on a market value
basis) in one or a series of related transactions, a Holder shall have the right
to (A) if permitted under Section 3(b) hereof, exercise its rights of prepayment
under Section 3(b) with respect to such event, or (B) convert its aggregate
principal amount of Debentures then outstanding into the shares of stock and
other securities, cash and property receivable upon or deemed to be held by
holders of Common Stock following such merger, consolidation or sale, and such
Holder shall be entitled upon conversion of the Debentures to receive such
amount of securities, cash and property as the shares of Common Stock into which
such aggregate principal amount of Debentures could have been converted
immediately prior to such merger, consolidation or sales would have been
entitled. The terms of any such merger, sale or consolidation shall include such
terms so as to continue to give the Holders the right to receive the securities,
cash and property set forth in this Section upon any conversion or redemption
following such event. This provision shall similarly apply to successive such
events.

                  (d) The Company covenants that it will at all times reserve
and keep available out of its authorized and unissued shares of Common Stock
solely for the purpose of issuance upon conversion of the Debentures and payment
of interest on the Debentures, each as herein provided, free from preemptive
rights or any other actual contingent purchase rights of persons other than the
Holders, not less than such number of shares of the Common Stock as shall
(subject to any additional requirements of the Company as to reservation of such
shares set forth in the Purchase Agreement) be issuable (taking into account the
adjustments and restrictions of Section 4(b)) upon the conversion of the
outstanding principal amount of the Debentures and payment of interest
hereunder. The Company covenants that all shares of Common Stock that shall be
so issuable shall, upon issue, be duly and validly authorized, issued and fully
paid, nonassessable and, if the Underlying Shares Registration Statement has
been declared effective under the Securities Act, registered for public sale in
accordance with such Underlying Shares Registration Statement.

                  (e) Upon a conversion hereunder the Company shall not be
required to issue stock certificates representing fractions of shares of the
Common Stock, but may if otherwise permitted, make a cash payment in respect of
any final fraction of a share based on the Per Share Market Value at such time.
If the Company elects not, or is unable, to make such a cash payment, the Holder
shall be entitled to receive, in lieu of the final fraction of a share, one
whole share of Common Stock.

                  (f) The issuance of certificates for shares of the Common
Stock on conversion of the Debentures shall be made without charge to the
Holders thereof for any documentary stamp or similar taxes that may be payable
in respect of the issue or delivery of such certificate, provided that the
Company shall not be required to pay any tax that may be payable in respect of
any transfer involved in the issuance and delivery of any such certificate upon
conversion in a name other than that of the Holder of such Debentures so
converted and the Company shall not be required to issue or deliver such
certificates unless or until the person or persons requesting the issuance
thereof shall


                                      -13-
                                                           Convertible Debenture
<PAGE>   14
have paid to the Company the amount of such tax or shall have established to the
satisfaction of the Company that such tax has been paid.

                  (g) Any and all notices or other communications or deliveries
to be provided by the Holders of the Debentures hereunder, including, without
limitation, any Conversion Notice, shall be in writing and delivered personally,
by facsimile, sent by a nationally recognized overnight courier service or sent
by certified or registered mail, postage prepaid, addressed to the Company, at
157 Technology Drive, Irvine, CA 92618, Facsimile No.: (949) 788-6706, attention
Chief Financial Officer, or such other address or facsimile number as the
Company may specify for such purposes by notice to the Holders delivered in
accordance with this Section, with a copy to Latham & Watkins, 650 Town Center
Drive, Suite 2000, Costa Mesa, CA 92661-1925 (facsimile number (714) 755-8290),
attention Alan W. Pettis, Esq. Any and all notices or other communications or
deliveries to be provided by the Company hereunder shall be in writing and
delivered personally, by facsimile, sent by a nationally recognized overnight
courier service or sent by certified or registered mail, postage prepaid,
addressed to each Holder of the Debentures at the facsimile telephone number or
address of such Holder appearing on the books of the Company, or if no such
facsimile telephone number or address appears, at the principal place of
business of the holder. Any notice or other communication or deliveries
hereunder shall be deemed given and effective on the earliest of (i) the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile telephone number specified in this Section prior to 6:30 p.m. (New
York City time), (ii) the date after the date of transmission, if such notice or
communication is delivered via facsimile at the facsimile telephone number
specified in this Section later than 6:30 p.m. (New York City time) on any date
and earlier than 11:59 p.m. (New York City time) on such date, (iii) four days
after deposit in the United States mail, (iv) the Business Day following the
date of mailing, if sent by nationally recognized overnight courier service, or
(v) upon actual receipt by the party to whom such notice is required to be
given.

         Section 5. Optional Prepayment.

                  (a) During the time that any portion of this Debenture remains
outstanding, the Company shall have the right, exercisable on any Trading Day in
which the Conversion Price shall be less than $14.00 (which number shall be
subject to equitable adjustments for stock splits, recombinations and similar
events), in accordance with the terms hereof and upon three Trading Days' prior
written notice to the Holders to be prepaid (an "Optional Prepayment Notice"),
to prepay all or any portion of the outstanding principal amount of the
Debentures which has not previously been repaid or for which Conversion Notices
have not previously been delivered. The prepayment price applicable to
prepayments under this Section 5(a) shall equal the Optional Prepayment Price
(as defined in Section 6) and shall be paid in cash. Any such prepayment shall
be free of any claim of subordination. The Holders shall have the right to
tender, and the Company shall honor, Conversion Notices delivered on or prior to
the expiration of the third Trading Day after receipt by the Holders of an
Optional Prepayment Notice for such Debentures (the third Trading Day after
receipt by the Holders of an Optional Prepayment Notice is referred to herein as
the "Optional Prepayment Date").



                                      -14-
                                                           Convertible Debenture
<PAGE>   15
                  (b) The Company shall not be entitled to deliver an Optional
Prepayment Notice to the Holder (and, if after delivery thereof and prior to the
Optional Prepayment Date, any of the following conditions shall cease to be met,
such notice, at the option of the Holders, shall be deemed no longer effective)
if: (i) the number of shares of Common Stock at the time authorized, unissued
and unreserved for all purposes is insufficient to satisfy the Company's
conversion obligations of the aggregate principal amount of Debentures then
outstanding, or (ii) there is neither an effective Underlying Shares
Registration Statement under which the Holders can resell all of the issued
Underlying Shares and all of the Underlying Shares as are issuable upon
conversion in full of the principal amount of Debentures subject to an Optional
Prepayment Notice nor may all of such issued and issuable Underlying Shares be
sold by the Holders subject to such prepayment without volume restrictions
pursuant to Rule 144 promulgated under the Securities Act, as determined by
counsel to the Company pursuant to a written opinion letter, addressed to the
Company's transfer agent in the form and substance acceptable to the Holders and
such transfer agent, or (iii) the Common Stock is not then listed for trading on
the NASDAQ or on a Subsequent Market.

                  (c) If any portion of the Optional Prepayment Price shall not
be paid by the Company by the second (2nd) Business Day following the Optional
Prepayment Date, the Optional Prepayment Price shall bear interest at the rate
of 18% per annum (or such lesser maximum amount that is permitted to be paid by
applicable law) to accrue daily from the date such interest is due hereunder
through and including the date of payment (which amount shall be paid as
liquidated damages and not as a penalty). In addition, if any portion of the
Optional Prepayment Price remains unpaid through the expiration of the Optional
Prepayment Date, the Holder subject to such prepayment may elect by written
notice to the Company to either (x) demand conversion in accordance with the
formula and the time period therefor set forth in Section 4 of any portion of
the principal amount of Debentures for which the Optional Prepayment Price, plus
accrued interest thereon, has not been paid in full (the "Unpaid Prepayment
Principal Amount"), in which event the applicable Per Share Market Value shall
be the lower of the Per Share Market Value calculated on the Optional Prepayment
Date and the Per Share Market Value as of the Holder's written demand for
conversion, or (y) invalidate ab initio such optional prepayment,
notwithstanding anything herein contained to the contrary. If the Holder elects
option (x) above, the Company shall, within three Trading Days after such
election is deemed delivered hereunder, deliver to the Holder the shares of
Common Stock issuable upon conversion of the Unpaid Prepayment Principal Amount
subject to such conversion demand and otherwise perform its obligations
hereunder with respect thereto. If the Holder elects option (y) above, the
Company shall promptly, and in any event not later than three Trading Days from
receipt of notice of such election, return to the Holder new Debentures for the
full Unpaid Prepayment Principal Amount and shall no longer have any prepayment
rights under this Debenture. If, upon an election under option (x) above, the
Company fails to deliver certificates representing the shares of Common Stock
issuable upon conversion of the Unpaid Prepayment Principal Amount within the
time period set forth in this Section, the Company shall pay to the Holder in
cash, as liquidated damages and not as a penalty, $5,000 per day until the
Company delivers such certificates to the Holder.

         Section 6. Definitions. For the purposes hereof, the following terms
shall have the following meanings:



                                      -15-
                                                           Convertible Debenture
<PAGE>   16
                  "Business Day" means any day except Saturday, Sunday and any
day which shall be a legal holiday or a day on which banking institutions in the
State of New York or the State of California are authorized or required by law
or other government action to close.

                  "Change of Control Transaction" means the occurrence of any of
(i) an acquisition after the date hereof by an individual or legal entity or
"group" (as described in Rule 13d-5(b)(1) promulgated under the Exchange Act) of
effective control (whether through legal or beneficial ownership of capital
stock of the Company, by contract or otherwise) of in excess of 33% of the
voting securities of the Company, (ii) a replacement at one time or over time of
more than one-half of the members of the Company's board of directors which is
not approved by a majority of those individuals who are members of the board of
directors on the date hereof (or by those individuals who are serving as members
of the board of directors on any date whose nomination to the board of directors
was approved by a majority of the members of the board of directors who are
members on the date hereof), (iii) the merger or consolidation of the Company
with or into another entity that is not wholly-owned by the Company upon the
completion of which the stockholders of the Company, immediately before such
merger or consolidation, own or control less than 2/3 of the voting securities
of the surviving entity, or sale of 50% or more of the assets of the Company in
one or a series of related transactions, or (iv) the execution by the Company of
an agreement to which the Company is a party or by which it is bound, providing
for any of the events set forth above in (i), (ii) or (iii).

                  "Commission" means the Securities and Exchange Commission.

                  "Common Stock" means the common stock, $.001 par value per
share, of the Company and stock of any other class into which such shares may
hereafter have been reclassified or changed.

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

                  "Interest Effectiveness Date" means the earlier to occur of
(x) the Effectiveness Date (as defined in the Registration Rights Agreement) and
(y) the date that an Underlying Shares Registration Statement is declared
effective by the Commission.

                  "Mandatory Prepayment Amount" for any Debentures shall equal
the sum of (i) the greater of (A) 120% of the principal amount of Debentures to
be prepaid, plus all accrued and unpaid interest thereon, and (B) the principal
amount of Debentures to be prepaid, plus all accrued and unpaid interest
thereon, divided by the Conversion Price on (x) the date the Mandatory
Prepayment Amount is demanded or otherwise due or (y) the date the Mandatory
Prepayment Amount is paid in full, whichever is less, multiplied by the Per
Share Market Value on (x) the date the Mandatory Prepayment Amount is demanded
or otherwise due or (y) the date the Mandatory Prepayment Amount is paid in
full, whichever is greater, and (ii) all other amounts, costs, expenses and
liquidated damages due in respect of such Debentures.



                                      -16-
                                                           Convertible Debenture
<PAGE>   17
                  "Optional Prepayment Price" shall equal the sum of (i) 106% of
the principal amount of Debentures to be prepaid, plus all accrued and unpaid
interest thereon, and (ii) all other amounts, expenses, costs and liquidated
damages due in respect of such Debentures.

                  "Original Issue Date" shall mean the date of the first
issuance of the Debentures regardless of the number of transfers of any
Debenture and regardless of the number of instruments which may be issued to
evidence such Debenture.

                  "Per Share Market Value" means on any particular date (a) the
closing bid price per share of Common Stock on such date on the NASDAQ or on
such Subsequent Market on which the shares of Common Stock are then listed or
quoted, or if there is no such price on such date, then the closing bid price on
the NASDAQ or on such Subsequent Market on the date nearest preceding such date,
or (b) if the shares of Common Stock are not then listed or quoted on the NASDAQ
or a Subsequent Market, the closing bid price for a share of Common Stock in the
over-the-counter market, as reported by the National Quotation Bureau
Incorporated or similar organization or agency succeeding to its functions of
reporting prices) at the close of business on such date, or (c) if the shares of
Common Stock are not then reported by the National Quotation Bureau Incorporated
(or similar organization or agency succeeding to its functions of reporting
prices), then the average of the "Pink Sheet" quotes for the relevant conversion
period, as determined in good faith by the Holder, or (d) if the shares of
Common Stock are not then publicly traded the fair market value of a share of
Common Stock as determined by an Appraiser selected in good faith by the Holders
of a majority in interest of the principal amount of Debentures then
outstanding.

                  "Person" means a corporation, an association, a partnership,
an organization, a business, an individual, a government or political
subdivision thereof or a governmental agency.

                  "Purchase Agreement" means the Convertible Debenture Purchase
Agreement, dated as of the Original Issue Date, to which the Company and the
original Holder are parties, as amended, modified or supplemented from time to
time in accordance with its terms.

                  "Registration Rights Agreement" means the Registration Rights
Agreement, dated as of the Original Issue Date, to which the Company and the
original Holder are parties, as amended, modified or supplemented from time to
time in accordance with its terms.

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

                  "Trading Day" means (a) a day on which the shares of Common
Stock are traded on the NASDAQ or on such Subsequent Market on which the shares
of Common Stock are then listed or quoted, or (b) if the shares of Common Stock
are not listed on the NASDAQ or a Subsequent Market, a day on which the shares
of Common Stock are traded in the over-the-counter market, as reported by the
OTC Bulletin Board, or (c) if the shares of Common Stock are not quoted on the
OTC Bulletin Board, a day on which the shares of Common Stock are quoted in the
over-the-counter market as reported by the National Quotation Bureau
Incorporated (or any similar organization or agency succeeding its functions of
reporting prices); provided, however, that in the event that the shares of
Common Stock are not listed or quoted as set forth in (a), (b) and (c) hereof,
then Trading


                                      -17-
                                                           Convertible Debenture
<PAGE>   18
Day shall mean any day except Saturday, Sunday and any day which shall be a
legal holiday or a day on which banking institutions in the State of New York
are authorized or required by law or other government action to close.

                  "Transaction Documents" shall have the meaning set forth in
the Purchase Agreement.

                  "Underlying Shares" means the shares of Common Stock issuable
upon conversion of Debentures or as payment of interest in accordance with the
terms hereof.

                  "Underlying Shares Registration Statement" means a
registration statement meeting the requirements set forth in the Registration
Rights Agreement, covering among other things the resale of the Underlying
Shares and naming the Holder as a "selling stockholder" thereunder.

         Section 7. Except as expressly provided herein, no provision of this
Debenture shall alter or impair the obligation of the Company, which is absolute
and unconditional, to pay the principal of, interest and liquidated damages (if
any) on, this Debenture at the time, place, and rate, and in the coin or
currency, herein prescribed. This Debenture is a direct obligation of the
Company. This Debenture ranks pari passu with all other Debentures now or
hereafter issued under the terms set forth herein. As long as there are
Debentures outstanding, the Company shall not and shall cause it subsidiaries
not to, without the consent of the Holders, (i) amend its certificate of
incorporation, bylaws or other charter documents so as to adversely affect any
rights of the Holders; (ii) repay, repurchase or offer to repay, repurchase or
otherwise acquire shares of its Common Stock or other equity securities other
than as to the Underlying Shares to the extent permitted or required under the
Transaction Documents; or (iii) enter into any agreement with respect to any of
the foregoing. The Company may only voluntarily prepay the outstanding principal
amount on the Debentures in accordance with Section 5 hereof.

         Section 8. This Debenture shall not entitle the Holder to any of the
rights of a stockholder of the Company, including without limitation, the right
to vote, to receive dividends and other distributions, or to receive any notice
of, or to attend, meetings of stockholders or any other proceedings of the
Company, unless and to the extent converted into shares of Common Stock in
accordance with the terms hereof.

         Section 9. If this Debenture shall be mutilated, lost, stolen or
destroyed, the Company shall execute and deliver, in exchange and substitution
for and upon cancellation of a mutilated Debenture, or in lieu of or in
substitution for a lost, stolen or destroyed debenture, a new Debenture for the
principal amount of this Debenture so mutilated, lost, stolen or destroyed but
only upon receipt of evidence of such loss, theft or destruction of such
Debenture, and of the ownership hereof, and indemnity, if requested, all
reasonably satisfactory to the Company.

         Section 10. This Debenture is subordinate to all bank debt of the
Company outstanding as of the Original Issue Date and set forth in Schedule
2.1(n) to the Purchase Agreement or at any time thereafter.



                                      -18-
                                                           Convertible Debenture
<PAGE>   19
         Section 11. This Debenture shall be governed by and construed in
accordance with the laws of the State of New York, without giving effect to
conflicts of laws thereof. The Company and the Holder hereby irrevocably submits
to the exclusive jurisdiction of the state and federal courts sitting in the
City of New York, Borough of Manhattan, for the adjudication of any dispute
hereunder or in connection herewith or with any transaction contemplated hereby
or discussed herein, and hereby irrevocably waives, and agrees not to assert in
any suit, action or proceeding, any claim that it is not personally subject to
the jurisdiction of any such court, or that such suit, action or proceeding is
improper. Each of the Company and the Holder hereby irrevocably waives personal
service of process and consents to process being served in any such suit, action
or proceeding by receiving a copy thereof sent to the Company at the address in
effect for notices to it under this instrument and agrees that such service
shall constitute good and sufficient service of process and notice thereof.
Nothing contained herein shall be deemed to limit in any way any right to serve
process in any manner permitted by law.

         Section 12. Any waiver by the Company or the Holder of a breach of any
provision of this Debenture shall not operate as or be construed to be a waiver
of any other breach of such provision or of any breach of any other provision of
this Debenture. The failure of the Company or the Holder to insist upon strict
adherence to any term of this Debenture on one or more occasions shall not be
considered a waiver or deprive that party of the right thereafter to insist upon
strict adherence to that term or any other term of this Debenture. Any waiver
must be in writing.

         Section 13. If any provision of this Debenture is invalid, illegal or
unenforceable, the balance of this Debenture shall remain in effect, and if any
provision is inapplicable to any person or circumstance, it shall nevertheless
remain applicable to all other persons and circumstances. If it shall be found
that any interest or other amount deemed interest due hereunder shall violate
applicable laws governing usury, the applicable rate of interest due hereunder
shall automatically be lowered to equal the maximum permitted rate of interest.

         Section 14. Whenever any payment or other obligation hereunder shall be
due on a day other than a Business Day, such payment shall be made on the next
succeeding Business Day.

                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                             SIGNATURE PAGE FOLLOWS]



                                      -19-
                                                           Convertible Debenture
<PAGE>   20
                  IN WITNESS WHEREOF, the Company has caused this Convertible
Debenture to be duly executed by a duly authorized officer as of the date first
above indicated.

                                                     NEOTHERAPEUTICS, INC.

                                                     By:________________________
                                                        Name:
                                                        Title:

Attest:



By:______________________________
  Name:
  Title:

                                                           Convertible Debenture
<PAGE>   21
                                    EXHIBIT A

                              NOTICE OF CONVERSION

(To be Executed by the Registered Holder
in order to Convert the Debenture)

The undersigned hereby elects to convert the attached Debenture into shares of
common stock, $.001 par value per share (the "Common Stock"), of
NeoTherapeutics, Inc. (the "Company") according to the conditions hereof, as of
the date written below. If shares are to be issued in the name of a person other
than undersigned, the undersigned will pay all transfer taxes payable with
respect thereto and is delivering herewith such certificates and opinions as
reasonably requested by the Company in accordance therewith. No fee will be
charged to the holder for any conversion, except for such transfer taxes, if
any.

Conversion calculations:

                                  ______________________________________________
                                  Date to Effect Conversion

                                  ______________________________________________
                                  Principal Amount of Debentures to be Converted

                                  ______________________________________________
                                  Number of shares of Common Stock to be Issued

                                  ______________________________________________
                                  Applicable Conversion Price

                                  ______________________________________________
                                  Signature

                                  ______________________________________________
                                  Name

                                  ______________________________________________
                                  Address

                                                           Convertible Debenture

<PAGE>   1
                                                                     EXHIBIT 4.4

NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE
EXEMPTION FROM THE REGISTRATION REQUIREMENTS THEREUNDER AND IN COMPLIANCE WITH
APPLICABLE STATE SECURITIES OR BLUE SKY LAWS.

                              NEOTHERAPEUTICS, INC.

                                 CLASS A WARRANT

Warrant No. A-1                                             Dated: April 6, 2000


         NeoTherapeutics, Inc., a Delaware corporation (the "Company"), hereby
certifies that, for value received, Montrose Investments Ltd., or its registered
assigns ("Holder"), is entitled, subject to the terms set forth below, to
purchase from the Company up to a total of 157,500 shares of common stock, $.001
par value per share (the "Common Stock"), of the Company (each such share, a
"Warrant Share" and all such shares, the "Warrant Shares") at an exercise price
equal to $19.672 per share (as adjusted from time to time as provided in Section
9, the "Exercise Price"), at any time and from time to time from and after the
date hereof and through and including April 6, 2005 (the "Termination Date"),
and subject to the following terms and conditions:

                  1.       Registration of Warrant. The Company shall register
this Warrant, upon records to be maintained by the Company for that purpose (the
"Warrant Register"), in the name of the record Holder hereof from time to time.
The Company may deem and treat the registered Holder of this Warrant as the
absolute owner hereof for the purpose of any exercise hereof or any distribution
to the Holder, and for all other purposes, and the Company shall not be affected
by notice to the contrary.

                  2.       Registration of Transfers and Exchanges.

                           (a) This Warrant may only be transferred pursuant to
an effective registration statement under the Securities Act, to the Company or
pursuant to an available exemption from or in a transaction not subject to the
registration requirements of the Securities Act. In connection with any transfer
of this Warrant other than pursuant to an effective registration


                                                                 Class A Warrant
<PAGE>   2
statement or to the Company, the Company may require the transferor thereof to
provide to the Company an opinion of counsel selected by the transferor, the
form and substance of which opinion shall be reasonably satisfactory to the
Company, to the effect that such transfer does not require registration of such
Warrant under the Securities Act. Holder agrees to the imprinting, so long as is
required by this Section 2(a), of a legend substantially similar to that first
above written on any New Warrant (as defined below). Any such transferee shall
agree in writing to be bound by the terms of this Warrant and shall have the
rights of Holder under this Warrant.

                           (b) The Company shall register the transfer of any
portion of this Warrant in the Warrant Register, upon surrender of this Warrant,
with the Form of Assignment attached hereto duly completed and signed, to the
Transfer Agent or to the Company at the office specified in or pursuant to
Section 3(b). Upon any such registration or transfer, a new warrant to purchase
Common Stock, in substantially the form of this Warrant (any such new warrant, a
"New Warrant"), evidencing the portion of this Warrant so transferred shall be
issued to the transferee and a New Warrant evidencing the remaining portion of
this Warrant not so transferred, if any, shall be issued to the transferring
Holder. The acceptance of the New Warrant by the transferee thereof shall be
deemed the acceptance of such transferee of all of the rights and obligations of
a holder of a Warrant.

                           (c) This Warrant is exchangeable, upon the surrender
hereof by the Holder to the office of the Company specified in or pursuant to
Section 3(b) for one or more New Warrants, evidencing in the aggregate the right
to purchase the number of Warrant Shares which may then be purchased hereunder.
Any such New Warrant will be dated the date of such exchange.

                  3.       Duration, Exercise and Vesting of Warrants.

                           (a) This Warrant shall be exercisable by the
registered Holder on any business day before 8:00 P.M., New York City time, at
any time and from time to time on or after the date hereof to and including the
Termination Date. At 8:00 P.M., New York City time on the Termination Date, the
portion of this Warrant not exercised prior thereto shall be and become void and
of no value. Prior to the Termination Date, the Company may not call or
otherwise redeem this Warrant without the prior written consent of the Holder.

                           (b) Subject to Sections 2(b), 6 and 10, upon
surrender of this Warrant, with the Form of Election to Purchase attached hereto
duly completed and signed, to the Company at its address for notice set forth in
Section 13 and upon payment of the Exercise Price multiplied by the number of
Warrant Shares that the Holder intends to purchase hereunder, in the manner
provided hereunder, all as specified by the Holder in the Form of Election to
Purchase, the Company shall promptly (but in no event later than 3 business days
after the Date of Exercise (as defined herein)) issue or cause to be issued and
cause to be delivered to or upon the written order of the Holder and in such
name or names as the Holder may designate, a certificate for the Warrant Shares
issuable upon such exercise, free of restrictive legends except (i) either in
the event that a registration statement covering the resale of the Warrant
Shares and naming the Holder as a selling stockholder thereunder is not then
effective or the Warrant Shares are not freely transferable without volume
restrictions pursuant to Rule 144(k) promulgated under the Securities Act of
1933, as amended (the "Securities Act"), or (ii) if this Warrant shall have been
issued pursuant to a written agreement


                                      -2-
                                                                 Class A Warrant
<PAGE>   3
between the original Holder and the Company, as required by such agreement. Any
person so designated by the Holder to receive Warrant Shares shall be deemed to
have become holder of record of such Warrant Shares as of the Date of Exercise
of this Warrant.

                           A "Date of Exercise" means the date on which the
Company shall have received (i) this Warrant (or any New Warrant, as
applicable), with the Form of Election to Purchase attached hereto (or attached
to such New Warrant) appropriately completed and duly signed, and (ii) payment
of the Exercise Price for the number of Warrant Shares so indicated by the
holder hereof to be purchased.

                           (c)      This Warrant shall be exercisable, either in
its entirety or, from time to time, for a portion of the number of Warrant
Shares which have vested pursuant to Section 3(d). If less than all of the
Warrant Shares which may be purchased under this Warrant are exercised at any
time, the Company shall issue or cause to be issued, at its expense, a New
Warrant evidencing the right to purchase the remaining number of Warrant Shares
for which no exercise has been evidenced by this Warrant.

                           (d)      (i) On the date hereof, 57,500 Warrant
                                    Shares shall vest on the date hereof;

                                    (ii) Upon each exercise by the Holder
                                    pursuant to Section 3(a) of the Class B
                                    Warrant of even date hereof, issued by the
                                    Company in the name of the Holder (the
                                    "Class B Warrant"), this Warrant shall vest
                                    with respect to 1/20th of the Warrant Shares
                                    so exercised under the Class B Warrant,
                                    provided, that no more than 75,000 Warrant
                                    Shares shall be permitted to vest under this
                                    subsection 3(d)(ii);

                                    (iii) If, on or prior to the Expiration Date
                                    (as defined in the Class B Warrant), the
                                    Company has failed to deliver one or more
                                    Call Notices (as defined in the Class B
                                    Warrant) pursuant to Section 3(a) of the
                                    Class B Warrant for a minimum of 500,000
                                    Warrant Shares (as defined in the Class B
                                    Warrant), then on the Expiration Date, this
                                    Warrant shall vest with respect to a number
                                    of Warrant Shares equal to the difference
                                    between (i) 25,000 and (ii) 1/20th of the
                                    number of Warrant Shares called pursuant to
                                    Section 3(a) of the Redeemable Warrant; and

                                    (iv) If the Class B Warrant shall be
                                    canceled pursuant to Section 2(f) of the
                                    Registration Rights Agreement of even date
                                    herewith to which the Company and the
                                    original holder are parties, then, on the
                                    date of such cancellation, this Warrant
                                    shall vest with respect to 25,000 Warrant
                                    Shares.


                                      -3-
                                                                 Class A Warrant
<PAGE>   4
                  4. Piggyback Registration Rights. During the Effectiveness
Period (as defined in the Registration Rights Agreement, of even date herewith,
between the Company and the original Holder), the Company may not file any
registration statement with the Securities and Exchange Commission (other than
registration statements of the Company filed on Form S-8 or Form S-4, each as
promulgated under the Securities Act, pursuant to which the Company is
registering securities pursuant to a Company employee benefit plan or pursuant
to a merger, acquisition or similar transaction including supplements thereto,
but not additionally filed registration statements in respect of such
securities) at any time when there is not an effective registration statement
covering the resale of the Warrant Shares and naming the Holder as a selling
stockholder thereunder, unless the Company provides the Holder with not less
than 20 days notice of its intention to file such registration statement and
provides the Holder the option to include any or all of the applicable Warrant
Shares therein. The piggyback registration rights granted to the Holder pursuant
to this Section shall continue until all of the Holder's Warrant Shares have
been sold in accordance with an effective registration statement or upon the
expiration of the Effective Period. The Company will pay all registration
expenses in connection therewith.

                  5. [intentionally left blank]

                  6. Payment of Taxes. The Company will pay all documentary
stamp taxes attributable to the issuance of Warrant Shares upon the exercise of
this Warrant; provided, however, that the Company shall not be required to pay
any tax which may be payable in respect of any transfer involved in the
registration of any certificates for Warrant Shares or Warrants in a name other
than that of the Holder. The Holder shall be responsible for all other tax
liability that may arise as a result of holding or transferring this Warrant or
receiving Warrant Shares upon exercise hereof.

                  7. Replacement of Warrant. If this Warrant is mutilated, lost,
stolen or destroyed, the Company shall issue or cause to be issued in exchange
and substitution for and upon cancellation hereof, or in lieu of and
substitution for this Warrant, a New Warrant, but only upon receipt of evidence
reasonably satisfactory to the Company of such loss, theft or destruction and
indemnity, if requested, satisfactory to it. Applicants for a New Warrant under
such circumstances shall also comply with such other reasonable regulations and
procedures and pay such other reasonable charges as the Company may prescribe.

                  8. Reservation of Warrant Shares. The Company covenants that
it will at all times reserve and keep available out of the aggregate of its
authorized but unissued Common Stock, solely for the purpose of enabling it to
issue Warrant Shares upon exercise of this Warrant as herein provided, the
number of Warrant Shares which are then issuable and deliverable upon the
exercise of this entire Warrant, free from preemptive rights or any other actual
contingent purchase rights of persons other than the Holder (taking into account
the adjustments and restrictions of Section 9). The Company covenants that all
Warrant Shares that shall be so issuable and deliverable shall, upon issuance
and the payment of the applicable Exercise Price in accordance with the terms
hereof, be duly and validly authorized, issued and fully paid and nonassessable.


                                      -4-
                                                                 Class A Warrant
<PAGE>   5
                  9. Certain Adjustments.

                  (a) If the Company, at any time while this Warrant is
outstanding, (i) shall pay a stock dividend (except scheduled dividends paid on
outstanding preferred stock as of the date hereof which contain a stated
dividend rate) or otherwise make a distribution or distributions on shares of
its Common Stock or on any other class of capital stock payable in shares of
Common Stock, (ii) subdivide outstanding shares of Common Stock into a larger
number of shares, or (iii) combine outstanding shares of Common Stock into a
smaller number of shares, the Exercise Price shall be multiplied by a fraction
of which the numerator shall be the number of shares of Common Stock (excluding
treasury shares, if any) outstanding before such event and of which the
denominator shall be the number of shares of Common Stock (excluding treasury
shares, if any) outstanding after such event. Any adjustment made pursuant to
this Section shall become effective immediately after the record date for the
determination of stockholders entitled to receive such dividend or distribution
and shall become effective immediately after the effective date in the case of a
subdivision or combination, and shall apply to successive subdivisions and
combinations.

                  (b) In case of any reclassification of the Common Stock or any
compulsory share exchange pursuant to which the Common Stock is converted into
other securities, cash or property, then the Holder shall have the right
thereafter to exercise this Warrant only into the shares of stock and other
securities and property receivable upon or deemed to be held by holders of
Common Stock following such reclassification or share exchange, and the Holder
shall be entitled upon such exercise to receive such amount of securities or
property equal to the amount of Warrant Shares such Holder would have been
entitled to had such Holder exercised this Warrant immediately prior to such
reclassification or share exchange. The terms of any such reclassification or
share exchange shall include such terms so as to continue to give to the Holder
the right to receive the securities or property set forth in this Section 9(b)
upon any exercise following any such reclassification or share exchange.

                  (c) If the Company, at any time while this Warrant is
outstanding, shall distribute to all holders of Common Stock (and not to holders
of this Warrant) evidences of its indebtedness or assets or rights or warrants
to subscribe for or purchase any security (excluding those referred to in
Sections 9(a), (b) and (d)) and other than with respect to rights granted
pursuant to a stockholders rights plan adopted by the Company, then in each such
case the Exercise Price shall be determined by multiplying the Exercise Price in
effect immediately prior to the record date fixed for determination of
stockholders entitled to receive such distribution by a fraction of which the
denominator shall be the Exercise Price determined as of the record date
mentioned above, and of which the numerator shall be such Exercise Price on such
record date less the then fair market value at such record date of the portion
of such assets or evidence of indebtedness so distributed applicable to one
outstanding share of Common Stock as determined by the Company's independent
certified public accountants that regularly examines the financial statements of
the Company (an "Appraiser").



                                      -5-
                                                                 Class A Warrant
<PAGE>   6
                  (d) In case of the closing of any (1) merger or consolidation
of the Company with or into another Person, or (2) sale by the Company of more
than one-half of the assets of the Company (on a book value basis) in one or a
series of related transactions, or (3) tender or other offer or exchange
(whether by the Company or another Person) pursuant to which holders of Common
Stock are permitted to tender or exchange their shares for other securities,
stock, cash or property of the Company or another Person; then the Holder shall
have the right thereafter to (A) exercise this Warrant for the shares of stock
and other securities, cash and property receivable upon or deemed to be held by
holders of Common Stock following such merger, consolidation or sale, and the
Holder shall be entitled upon exercise of this Warrant to receive such amount of
securities, cash and property as the Common Stock for which this Warrant could
have been exercised immediately prior to such merger, consolidation or sales
would have been entitled, or (B) in the event of an exchange or tender offer or
other transaction contemplated by clause (3) of this Section, tender or exchange
this Warrant for such securities, stock, cash and other property receivable upon
or deemed to be held by holders of Common Stock that have tendered or exchanged
their shares of Common Stock following such tender or exchange, and the Holder
shall be entitled upon such exchange or tender to receive such amount of
securities, cash and property as the shares of Common Stock for which this
Warrant could have been exercised immediately prior to such tender or exchange
would have been entitled as would have been issued. The terms of any such
merger, sale, consolidation, tender or exchange shall include such terms so as
continue to give the Holder the right to receive the securities, cash and
property set forth in this Section upon any conversion or redemption following
such event. This provision shall similarly apply to successive such events.

                  (e) For the purposes of this Section 9, the following clauses
shall also be applicable:

                      (i) Record Date. In case the Company shall take a record
of the holders of its Common Stock for the purpose of entitling them (A) to
receive a dividend or other distribution payable in Common Stock or in
securities convertible or exchangeable into shares of Common Stock, or (B) to
subscribe for or purchase Common Stock or securities convertible or exchangeable
into shares of Common Stock, then such record date shall be deemed to be the
date of the issue or sale of the shares of Common Stock deemed to have been
issued or sold upon the declaration of such dividend or the making of such other
distribution or the date of the granting of such right of subscription or
purchase, as the case may be.

                      (ii) Treasury Shares. The number of shares of Common Stock
outstanding at any given time shall not include shares owned or held by or for
the account of the Company, and the disposition of any such shares shall be
considered an issue or sale of Common Stock.

                  (f) All calculations under this Section 9 shall be made to the
nearest cent or the nearest 1/100th of a share, as the case may be.

                  (g) Whenever the Exercise Price is adjusted pursuant to
Section 9(c) above, the Holder, after receipt of the determination by the
Appraiser, shall have the right to select an additional appraiser (which shall
be a nationally recognized accounting firm), in which case the


                                      -6-
                                                                 Class A Warrant
<PAGE>   7
adjustment shall be equal to the average of the adjustments recommended by each
of the Appraiser and such appraiser. The Holder shall promptly mail or cause to
be mailed to the Company, a notice setting forth the Exercise Price after such
adjustment and setting forth a brief statement of the facts requiring such
adjustment. Such adjustment shall become effective immediately after the record
date mentioned above.

         (h)      If:

                  (i)      the Company shall declare a dividend (or any other
                           distribution) on its Common Stock; or

                  (ii)     the Company shall declare a special nonrecurring cash
                           dividend on or a redemption of its Common Stock; or

                  (iii)    the Company shall authorize the granting to all
                           holders of the Common Stock rights or warrants to
                           subscribe for or purchase any shares of capital stock
                           of any class or of any rights; or

                  (iv)     the approval of any stockholders of the Company shall
                           be required in connection with any reclassification
                           of the Common Stock, any consolidation or merger to
                           which the Company is a party, any sale or transfer of
                           all or substantially all of the assets of the
                           Company, or any compulsory share exchange whereby the
                           Common Stock is converted into other securities, cash
                           or property; or

                  (v)      the Company shall authorize the voluntary
                           dissolution, liquidation or winding up of the affairs
                           of the Company,

then the Company shall cause to be mailed to each Holder at their last addresses
as they shall appear upon the Warrant Register, at least 30 calendar days prior
to the applicable record or effective date hereinafter specified, a notice
stating (x) the date on which a record is to be taken for the purpose of such
dividend, distribution, redemption, rights or warrants, or if a record is not to
be taken, the date as of which the holders of Common Stock of record to be
entitled to such dividend, distributions, redemption, rights or warrants are to
be determined or (y) the date on which such reclassification, consolidation,
merger, sale, transfer or share exchange is expected to become effective or
close, and the date as of which it is expected that holders of Common Stock of
record shall be entitled to exchange their shares of Common Stock for
securities, cash or other property deliverable upon such reclassification,
consolidation, merger, sale, transfer, share exchange, dissolution, liquidation
or winding up; provided, however, that the failure to mail such notice or any
defect therein or in the mailing thereof shall not affect the validity of the
corporate action required to be specified in such notice.


                                      -7-
                                                                 Class A Warrant
<PAGE>   8
                  10. Payment of Exercise Price. The Holder shall pay the
Exercise Price in one of the following manners:

                           (a) Cash Exercise. The Holder may deliver immediately
available funds; or

                           (b) Cashless Exercise. The Holder may surrender this
Warrant to the Company together with a notice of cashless exercise, in which
event the Company shall issue to the Holder the number of Warrant Shares
determined as follows:

                               X = Y [(A-B)/A]
         where:
                               X = the number of Warrant Shares to be issued
         to the Holder.

                               Y = the number of Warrant Shares with
                               respect to which this Warrant is being
                               exercised.

                               A = the average of the closing sale prices
                               of the Common Stock for the five (5) trading
                               days immediately prior to (but not
                               including) the Date of Exercise.

                               B = the Exercise Price.

For purposes of Rule 144 promulgated under the Securities Act, it is intended,
understood and acknowledged that the Warrant Shares issued in a cashless
exercise transaction shall be deemed to have been acquired by the Holder, and
the holding period for the Warrant Shares shall be deemed to have been
commenced, on the issue date.

         11. Certain Exercise Restrictions. A Holder may not exercise this
Warrant to the extent such exercise would result in the Holder, together with
any affiliate thereof, beneficially owning (as determined in accordance with
Section 13(d) of the Securities Exchange Act of 1934, as amended and the rules
promulgated thereunder) in excess of 9.999% of the then issued and outstanding
shares of Common Stock, including shares of Common Stock issuable upon such
exercise and held by such Holder after application of this Section. Since the
Holder will not be obligated to report to the Company the number of shares of
Common Stock it may hold at the time of an exercise hereunder, unless the
exercise at issue would result in the issuance of shares of Common Stock in
excess of 9.999% of the then outstanding shares of Common Stock without regard
to any other shares which may be beneficially owned by the Holder or an
affiliate thereof, the Holder shall have the authority and obligation to
determine whether the restriction contained in this Section will limit any
particular exercise hereunder and to the extent that the Holder determines that
the limitation contained in this Section applies, the determination of which
portion of this Warrant is exercisable shall be the responsibility and
obligation of the Holder. If the Holder has delivered a Form of Election to
Purchase for a number of Warrant Shares that, without regard to any other shares
that the Holder or


                                      -8-
                                                                 Class A Warrant
<PAGE>   9
its affiliates may beneficially own, would result in the issuance in excess of
the permitted amount hereunder, the Company shall notify the Holder of this fact
and shall honor the exercise for the maximum portion of this Warrant permitted
to be exercised on such Date of Exercise in accordance with the periods
described herein and, at the option of the Holder, either keep the portion of
the Warrant tendered for exercise in excess of the permitted amount hereunder
for future exercises or return such excess portion of the Warrant to the Holder.
The provisions of this Section may be waived by a Holder (but only as to itself
and not to any other Holder) upon not less than 61 days prior notice to the
Company. Other Holders shall be unaffected by any such waiver.

                  12. Fractional Shares. The Company shall not be required to
issue or cause to be issued fractional Warrant Shares on the exercise of this
Warrant. The number of full Warrant Shares which shall be issuable upon the
exercise of this Warrant shall be computed on the basis of the aggregate number
of Warrant Shares purchasable on exercise of this Warrant so presented. If any
fraction of a Warrant Share would, except for the provisions of this Section, be
issuable on the exercise of this Warrant, the Company shall pay an amount in
cash equal to the Exercise Price multiplied by such fraction.

                  13. Notices. Any and all notices or other communications or
deliveries hereunder shall be in writing and shall be deemed given and effective
on the earliest of (i) the date of transmission, if such notice or communication
is delivered via facsimile at the facsimile telephone number specified in this
Section prior to 8:00 p.m. (New York City time) on a business day, (ii) the
business day after the date of transmission, if such notice or communication is
delivered via facsimile at the facsimile telephone number specified in this
Section later than 8:00 p.m. (New York City time) on any date and earlier than
11:59 p.m. (New York City time) on such date, (iii) the business day following
the date of mailing, if sent by nationally recognized overnight courier service,
or (iv) if sent other than by the methods set forth in (i)-(iii) of this
section, upon actual receipt by the party to whom such notice is required to be
given. The addresses for such communications shall be: (i) if to the Company, to
157 Technology Drive, Irvine, CA 92618, Attention: Chief Financial Officer, or
to Facsimile No. (949) 788-6706, or (ii) if to the Holder, to the Holder at the
address or facsimile number appearing on the Warrant Register or such other
address or facsimile number as the Holder may provide to the Company in
accordance with this Section.

                  14. Warrant Agent. The Company shall serve as warrant agent
under this Warrant. Upon thirty (30) days' notice to the Holder, the Company may
appoint a new warrant agent. Any corporation into which the Company or any new
warrant agent may be merged or any corporation resulting from any consolidation
to which the Company or any new warrant agent shall be a party or any
corporation to which the Company or any new warrant agent transfers
substantially all of its corporate trust or shareholders services business shall
be a successor warrant agent under this Warrant without any further act. Any
such successor warrant agent shall promptly cause notice of its succession as
warrant agent to be mailed (by first class mail, postage prepaid) to the Holder
at the Holder's last address as shown on the Warrant Register.


                                      -9-
                                                                 Class A Warrant
<PAGE>   10
                  15.      Miscellaneous.

                           (a) This Warrant shall be binding on and inure to the
benefit of the parties hereto and their respective successors and assigns. This
Warrant may be amended only in writing signed by the Company and the Holder and
their successors and assigns.

                           (b) Subject to Section 15(a), above, nothing in this
Warrant shall be construed to give to any person or corporation other than the
Company and the Holder any legal or equitable right, remedy or cause under this
Warrant. This Warrant shall inure to the sole and exclusive benefit of the
Company and the Holder.

                           (c) The corporate laws of the State of Delaware shall
govern all issues concerning the relative rights of the Company and its
stockholders. All other questions concerning the construction, validity,
enforcement and interpretation of this Warrant shall be governed by and
construed and enforced in accordance with the internal laws of the State of New
York, without regard to the principles of conflicts of law thereof. The Company
and the Holder hereby irrevocably submit to the exclusive jurisdiction of the
state and federal courts sitting in the City of New York, borough of Manhattan,
for the adjudication of any dispute hereunder or in connection herewith or with
any transaction contemplated hereby or discussed herein, and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, or that
such suit, action or proceeding is improper. Each of the Company and the Holder
hereby irrevocably waives personal service of process and consents to process
being served in any such suit, action or proceeding by receiving a copy thereof
sent to the Company at the address in effect for notices to it under this
instrument and agrees that such service shall constitute good and sufficient
service of process and notice thereof. Nothing contained herein shall be deemed
to limit in any way any right to serve process in any manner permitted by law.

                           (d) The headings herein are for convenience only, do
not constitute a part of this Warrant and shall not be deemed to limit or affect
any of the provisions hereof.

                           (e) In case any one or more of the provisions of this
Warrant shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall not
in any way be affected or impaired thereby and the parties will attempt in good
faith to agree upon a valid and enforceable provision which shall be a
commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                             SIGNATURE PAGE FOLLOWS]



                                      -10-
                                                                 Class A Warrant
<PAGE>   11
                  IN WITNESS WHEREOF, the Company has caused this Warrant to be
duly executed by its authorized officer as of the date first indicated above.

                                    NEOTHERAPEUTICS, INC.

                                    By:      /s/Samuel Gulko
                                       -------------------------------
                                       Name:  Samuel Gulko
                                       Title: Chief Financial Officer


                                                                 Class A Warrant
<PAGE>   12
                          FORM OF ELECTION TO PURCHASE

(To be executed by the Holder to exercise the right to purchase shares of Common
Stock under the foregoing Warrant)

To NeoTherapeutics, Inc.:

         In accordance with the Warrant enclosed with this Form of Election to
Purchase, the undersigned hereby irrevocably elects to purchase _____________
shares of common stock, $.001 par value per share, of NeoTherapeutics, Inc. (the
"Common Stock") and , if such Holder is not utilizing the cashless exercise
provisions set forth in this Warrant, encloses herewith $________ in cash,
certified or official bank check or checks, which sum represents the aggregate
Exercise Price (as defined in the Warrant) for the number of shares of Common
Stock to which this Form of Election to Purchase relates, together with any
applicable taxes payable by the undersigned pursuant to the Warrant.

         The undersigned requests that certificates for the shares of Common
Stock issuable upon this exercise be issued in the name of

                                                PLEASE INSERT SOCIAL SECURITY OR
                                                TAX IDENTIFICATION NUMBER

                                                ________________________________

________________________________________________________________________________
                         (Please print name and address)

         If the number of shares of Common Stock issuable upon this exercise
shall not be all of the shares of Common Stock which the undersigned is entitled
to purchase in accordance with the enclosed Warrant, the undersigned requests
that a New Warrant (as defined in the Warrant) evidencing the right to purchase
the shares of Common Stock not issuable pursuant to the exercise evidenced
hereby be issued in the name of and delivered to:

________________________________________________________________________________
                         (Please print name and address)

Dated:            ,               Name of Holder:
     _____________ _____


                                  (Print)______________________________________

                                  (By:)_______________________________________
                                  (Name:)
                                  (Title:)_____________________________________
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of the
                                  Warrant)

                                                                 Class A Warrant
<PAGE>   13
                               FORM OF ASSIGNMENT

           [To be completed and signed only upon transfer of Warrant]

         FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto ________________________________ the right represented by the within
Warrant to purchase ____________ shares of Common Stock of NeoTherapeutics, Inc.
to which the within Warrant relates and appoints ________________ attorney to
transfer said right on the books of NeoTherapeutics, Inc. with full power of
substitution in the premises.

Dated:

__________________, ______


                                             ___________________________________
                                            (Signature must conform in all
                                             respects to name of holder as
                                             specified on the face of the
                                             Warrant)


                                             ___________________________________
                                             Address of Transferee
                                             ___________________________________

                                             ___________________________________

                                             ___________________________________



In the presence of:


____________________________


                                                                 Class A Warrant

<PAGE>   1

                                                                     EXHIBIT 4.5

NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE
EXEMPTION FROM THE REGISTRATION REQUIREMENTS THEREUNDER AND IN COMPLIANCE WITH
APPLICABLE STATE SECURITIES OR BLUE SKY LAWS.


                              NEOTHERAPEUTICS, INC.

                                 CLASS A WARRANT

Warrant No. A-2                                           Dated: April 6, 2000


         NeoTherapeutics, Inc., a Delaware corporation (the "Company"), hereby
certifies that, for value received, Strong River Investments, Inc., or its
registered assigns ("Holder"), is entitled, subject to the terms set forth
below, to purchase from the Company up to a total of 157,500 shares of common
stock, $.001 par value per share (the "Common Stock"), of the Company (each such
share, a "Warrant Share" and all such shares, the "Warrant Shares") at an
exercise price equal to $19.672 per share (as adjusted from time to time as
provided in Section 9, the "Exercise Price"), at any time and from time to time
from and after the date hereof and through and including April 6, 2005 (the
"Termination Date"), and subject to the following terms and conditions:

                  1. Registration of Warrant. The Company shall register this
Warrant, upon records to be maintained by the Company for that purpose (the
"Warrant Register"), in the name of the record Holder hereof from time to time.
The Company may deem and treat the registered Holder of this Warrant as the
absolute owner hereof for the purpose of any exercise hereof or any distribution
to the Holder, and for all other purposes, and the Company shall not be affected
by notice to the contrary.

                  2. Registration of Transfers and Exchanges.

                        (a) This Warrant may only be transferred pursuant to an
effective registration statement under the Securities Act, to the Company or
pursuant to an available exemption from or in a transaction not subject to the
registration requirements of the Securities Act. In connection with any transfer
of this Warrant other than pursuant to an effective registration statement or to
the Company, the Company may require the transferor thereof to provide to the


                                                                 Class A Warrant
<PAGE>   2
Company an opinion of counsel selected by the transferor, the form and substance
of which opinion shall be reasonably satisfactory to the Company, to the effect
that such transfer does not require registration of such Warrant under the
Securities Act. Holder agrees to the imprinting, so long as is required by this
Section 2(a), of a legend substantially similar to that first above written on
any New Warrant (as defined below). Any such transferee shall agree in writing
to be bound by the terms of this Warrant and shall have the rights of Holder
under this Warrant.

                        (b) The Company shall register the transfer of any
portion of this Warrant in the Warrant Register, upon surrender of this Warrant,
with the Form of Assignment attached hereto duly completed and signed, to the
Transfer Agent or to the Company at the office specified in or pursuant to
Section 3(b). Upon any such registration or transfer, a new warrant to purchase
Common Stock, in substantially the form of this Warrant (any such new warrant, a
"New Warrant"), evidencing the portion of this Warrant so transferred shall be
issued to the transferee and a New Warrant evidencing the remaining portion of
this Warrant not so transferred, if any, shall be issued to the transferring
Holder. The acceptance of the New Warrant by the transferee thereof shall be
deemed the acceptance of such transferee of all of the rights and obligations of
a holder of a Warrant.

                        (c) This Warrant is exchangeable, upon the surrender
hereof by the Holder to the office of the Company specified in or pursuant to
Section 3(b) for one or more New Warrants, evidencing in the aggregate the right
to purchase the number of Warrant Shares which may then be purchased hereunder.
Any such New Warrant will be dated the date of such exchange.

                  3. Duration, Exercise and Vesting of Warrants.

                        (a) This Warrant shall be exercisable by the registered
Holder on any business day before 8:00 P.M., New York City time, at any time and
from time to time on or after the date hereof to and including the Termination
Date. At 8:00 P.M., New York City time on the Termination Date, the portion of
this Warrant not exercised prior thereto shall be and become void and of no
value. Prior to the Termination Date, the Company may not call or otherwise
redeem this Warrant without the prior written consent of the Holder.

                        (b) Subject to Sections 2(b), 6 and 10, upon surrender
of this Warrant, with the Form of Election to Purchase attached hereto duly
completed and signed, to the Company at its address for notice set forth in
Section 13 and upon payment of the Exercise Price multiplied by the number of
Warrant Shares that the Holder intends to purchase hereunder, in the manner
provided hereunder, all as specified by the Holder in the Form of Election to
Purchase, the Company shall promptly (but in no event later than 3 business days
after the Date of Exercise (as defined herein)) issue or cause to be issued and
cause to be delivered to or upon the written order of the Holder and in such
name or names as the Holder may designate, a certificate for the Warrant Shares
issuable upon such exercise, free of restrictive legends except (i) either in
the event that a registration statement covering the resale of the Warrant
Shares and naming the Holder as a selling stockholder thereunder is not then
effective or the Warrant Shares are not freely transferable without volume
restrictions pursuant to Rule 144(k) promulgated under the Securities Act of
1933, as amended (the "Securities Act"), or (ii) if this Warrant shall have been
issued pursuant to a written agreement between the original Holder and the
Company, as required by such agreement. Any person so

                                   -2-                          Class A Warrant
<PAGE>   3
designated by the Holder to receive Warrant Shares shall be deemed to have
become holder of record of such Warrant Shares as of the Date of Exercise of
this Warrant.

                        A "Date of Exercise" means the date on which the Company
shall have received (i) this Warrant (or any New Warrant, as applicable), with
the Form of Election to Purchase attached hereto (or attached to such New
Warrant) appropriately completed and duly signed, and (ii) payment of the
Exercise Price for the number of Warrant Shares so indicated by the holder
hereof to be purchased.

                        (c) This Warrant shall be exercisable, either in its
entirety or, from time to time, for a portion of the number of Warrant Shares
which have vested pursuant to Section 3(d). If less than all of the Warrant
Shares which may be purchased under this Warrant are exercised at any time, the
Company shall issue or cause to be issued, at its expense, a New Warrant
evidencing the right to purchase the remaining number of Warrant Shares for
which no exercise has been evidenced by this Warrant.

                         (d)      (i) On the date hereof, 57,500 Warrant Shares
                                  shall vest on the date hereof;

                                  (ii) Upon each exercise by the Holder pursuant
                                  to Section 3(a) of the Class B Warrant of even
                                  date hereof, issued by the Company in the name
                                  of the Holder (the "Class B Warrant"), this
                                  Warrant shall vest with respect to 1/20th of
                                  the Warrant Shares so exercised under the
                                  Class B Warrant, provided, that no more than
                                  75,000 Warrant Shares shall be permitted to
                                  vest under this subsection 3(d)(ii);

                                  (iii) If, on or prior to the Expiration Date
                                  (as defined in the Class B Warrant), the
                                  Company has failed to deliver one or more Call
                                  Notices (as defined in the Class B Warrant)
                                  pursuant to Section 3(a) of the Class B
                                  Warrant for a minimum of 500,000 Warrant
                                  Shares (as defined in the Class B Warrant),
                                  then on the Expiration Date, this Warrant
                                  shall vest with respect to a number of Warrant
                                  Shares equal to the difference between (i)
                                  25,000 and (ii) 1/20th of the number of
                                  Warrant Shares called pursuant to Section 3(a)
                                  of the Redeemable Warrant; and

                                  (iv) If the Class B Warrant shall be canceled
                                  pursuant to Section 2(f) of the Registration
                                  Rights Agreement of even date herewith to
                                  which the Company and the original holder are
                                  parties, then, on the date of such
                                  cancellation, this Warrant shall vest with
                                  respect to 25,000 Warrant Shares.

                  4. Piggyback Registration Rights. During the Effectiveness
Period (as defined in the Registration Rights Agreement, of even date herewith,
between the Company and the original

                                     -3-                       Class A Warrant
<PAGE>   4
Holder), the Company may not file any registration statement with the Securities
and Exchange Commission (other than registration statements of the Company filed
on Form S-8 or Form S-4, each as promulgated under the Securities Act, pursuant
to which the Company is registering securities pursuant to a Company employee
benefit plan or pursuant to a merger, acquisition or similar transaction
including supplements thereto, but not additionally filed registration
statements in respect of such securities) at any time when there is not an
effective registration statement covering the resale of the Warrant Shares and
naming the Holder as a selling stockholder thereunder, unless the Company
provides the Holder with not less than 20 days notice of its intention to file
such registration statement and provides the Holder the option to include any or
all of the applicable Warrant Shares therein. The piggyback registration rights
granted to the Holder pursuant to this Section shall continue until all of the
Holder's Warrant Shares have been sold in accordance with an effective
registration statement or upon the expiration of the Effective Period. The
Company will pay all registration expenses in connection therewith.

                  5. [intentionally left blank]

                  6. Payment of Taxes. The Company will pay all documentary
stamp taxes attributable to the issuance of Warrant Shares upon the exercise of
this Warrant; provided, however, that the Company shall not be required to pay
any tax which may be payable in respect of any transfer involved in the
registration of any certificates for Warrant Shares or Warrants in a name other
than that of the Holder. The Holder shall be responsible for all other tax
liability that may arise as a result of holding or transferring this Warrant or
receiving Warrant Shares upon exercise hereof.

                  7. Replacement of Warrant. If this Warrant is mutilated, lost,
stolen or destroyed, the Company shall issue or cause to be issued in exchange
and substitution for and upon cancellation hereof, or in lieu of and
substitution for this Warrant, a New Warrant, but only upon receipt of evidence
reasonably satisfactory to the Company of such loss, theft or destruction and
indemnity, if requested, satisfactory to it. Applicants for a New Warrant under
such circumstances shall also comply with such other reasonable regulations and
procedures and pay such other reasonable charges as the Company may prescribe.

                  8. Reservation of Warrant Shares. The Company covenants that
it will at all times reserve and keep available out of the aggregate of its
authorized but unissued Common Stock, solely for the purpose of enabling it to
issue Warrant Shares upon exercise of this Warrant as herein provided, the
number of Warrant Shares which are then issuable and deliverable upon the
exercise of this entire Warrant, free from preemptive rights or any other actual
contingent purchase rights of persons other than the Holder (taking into account
the adjustments and restrictions of Section 9). The Company covenants that all
Warrant Shares that shall be so issuable and deliverable shall, upon issuance
and the payment of the applicable Exercise Price in accordance with the terms
hereof, be duly and validly authorized, issued and fully paid and nonassessable.

                                       -4-                      Class A Warrant
<PAGE>   5
                  9. Certain Adjustments.

                  (a) If the Company, at any time while this Warrant is
outstanding, (i) shall pay a stock dividend (except scheduled dividends paid on
outstanding preferred stock as of the date hereof which contain a stated
dividend rate) or otherwise make a distribution or distributions on shares of
its Common Stock or on any other class of capital stock payable in shares of
Common Stock, (ii) subdivide outstanding shares of Common Stock into a larger
number of shares, or (iii) combine outstanding shares of Common Stock into a
smaller number of shares, the Exercise Price shall be multiplied by a fraction
of which the numerator shall be the number of shares of Common Stock (excluding
treasury shares, if any) outstanding before such event and of which the
denominator shall be the number of shares of Common Stock (excluding treasury
shares, if any) outstanding after such event. Any adjustment made pursuant to
this Section shall become effective immediately after the record date for the
determination of stockholders entitled to receive such dividend or distribution
and shall become effective immediately after the effective date in the case of a
subdivision or combination, and shall apply to successive subdivisions and
combinations.

                        (b) In case of any reclassification of the Common Stock
or any compulsory share exchange pursuant to which the Common Stock is converted
into other securities, cash or property, then the Holder shall have the right
thereafter to exercise this Warrant only into the shares of stock and other
securities and property receivable upon or deemed to be held by holders of
Common Stock following such reclassification or share exchange, and the Holder
shall be entitled upon such exercise to receive such amount of securities or
property equal to the amount of Warrant Shares such Holder would have been
entitled to had such Holder exercised this Warrant immediately prior to such
reclassification or share exchange. The terms of any such reclassification or
share exchange shall include such terms so as to continue to give to the Holder
the right to receive the securities or property set forth in this Section 9(b)
upon any exercise following any such reclassification or share exchange.

                        (c) If the Company, at any time while this Warrant is
outstanding, shall distribute to all holders of Common Stock (and not to holders
of this Warrant) evidences of its indebtedness or assets or rights or warrants
to subscribe for or purchase any security (excluding those referred to in
Sections 9(a), (b) and (d)) and other than with respect to rights granted
pursuant to a stockholders rights plan adopted by the Company, then in each such
case the Exercise Price shall be determined by multiplying the Exercise Price in
effect immediately prior to the record date fixed for determination of
stockholders entitled to receive such distribution by a fraction of which the
denominator shall be the Exercise Price determined as of the record date
mentioned above, and of which the numerator shall be such Exercise Price on such
record date less the then fair market value at such record date of the portion
of such assets or evidence of indebtedness so distributed applicable to one
outstanding share of Common Stock as determined by the Company's independent
certified public accountants that regularly examines the financial statements of
the Company (an "Appraiser").

                                      -5-                      Class A Warrant
<PAGE>   6
                        (d) In case of the closing of any (1) merger or
consolidation of the Company with or into another Person, or (2) sale by the
Company of more than one-half of the assets of the Company (on a book value
basis) in one or a series of related transactions, or (3) tender or other offer
or exchange (whether by the Company or another Person) pursuant to which holders
of Common Stock are permitted to tender or exchange their shares for other
securities, stock, cash or property of the Company or another Person; then the
Holder shall have the right thereafter to (A) exercise this Warrant for the
shares of stock and other securities, cash and property receivable upon or
deemed to be held by holders of Common Stock following such merger,
consolidation or sale, and the Holder shall be entitled upon exercise of this
Warrant to receive such amount of securities, cash and property as the Common
Stock for which this Warrant could have been exercised immediately prior to such
merger, consolidation or sales would have been entitled, or (B) in the event of
an exchange or tender offer or other transaction contemplated by clause (3) of
this Section, tender or exchange this Warrant for such securities, stock, cash
and other property receivable upon or deemed to be held by holders of Common
Stock that have tendered or exchanged their shares of Common Stock following
such tender or exchange, and the Holder shall be entitled upon such exchange or
tender to receive such amount of securities, cash and property as the shares of
Common Stock for which this Warrant could have been exercised immediately prior
to such tender or exchange would have been entitled as would have been issued.
The terms of any such merger, sale, consolidation, tender or exchange shall
include such terms so as continue to give the Holder the right to receive the
securities, cash and property set forth in this Section upon any conversion or
redemption following such event. This provision shall similarly apply to
successive such events.

                        (e) For the purposes of this Section 9, the following
clauses shall also be applicable:

                              (i) Record Date. In case the Company shall take a
record of the holders of its Common Stock for the purpose of entitling them (A)
to receive a dividend or other distribution payable in Common Stock or in
securities convertible or exchangeable into shares of Common Stock, or (B) to
subscribe for or purchase Common Stock or securities convertible or exchangeable
into shares of Common Stock, then such record date shall be deemed to be the
date of the issue or sale of the shares of Common Stock deemed to have been
issued or sold upon the declaration of such dividend or the making of such other
distribution or the date of the granting of such right of subscription or
purchase, as the case may be.

                              (ii) Treasury Shares. The number of shares of
Common Stock outstanding at any given time shall not include shares owned or
held by or for the account of the Company, and the disposition of any such
shares shall be considered an issue or sale of Common Stock.

                        (f) All calculations under this Section 9 shall be made
to the nearest cent or the nearest 1/100th of a share, as the case may be.

                        (g) Whenever the Exercise Price is adjusted pursuant to
Section 9(c) above, the Holder, after receipt of the determination by the
Appraiser, shall have the right to select an additional appraiser (which shall
be a nationally recognized accounting firm), in which case the


                                      -6-                       Class A Warrant
<PAGE>   7
adjustment shall be equal to the average of the adjustments recommended by each
of the Appraiser and such appraiser. The Holder shall promptly mail or cause to
be mailed to the Company, a notice setting forth the Exercise Price after such
adjustment and setting forth a brief statement of the facts requiring such
adjustment. Such adjustment shall become effective immediately after the record
date mentioned above.

                        (h) If:

                                    (i)      the Company shall declare a
                                             dividend (or any other
                                             distribution) on its Common Stock;
                                             or

                                    (ii)     the Company shall declare a special
                                             nonrecurring cash dividend on or a
                                             redemption of its Common Stock; or

                                    (iii)    the Company shall authorize the
                                             granting to all holders of the
                                             Common Stock rights or warrants to
                                             subscribe for or purchase any
                                             shares of capital stock of any
                                             class or of any rights; or

                                    (iv)     the approval of any stockholders of
                                             the Company shall be required in
                                             connection with any
                                             reclassification of the Common
                                             Stock, any consolidation or merger
                                             to which the Company is a party,
                                             any sale or transfer of all or
                                             substantially all of the assets of
                                             the Company, or any compulsory
                                             share exchange whereby the Common
                                             Stock is converted into other
                                             securities, cash or property; or

                                    (v)      the Company shall authorize the
                                             voluntary dissolution, liquidation
                                             or winding up of the affairs of the
                                             Company,

then the Company shall cause to be mailed to each Holder at their last addresses
as they shall appear upon the Warrant Register, at least 30 calendar days prior
to the applicable record or effective date hereinafter specified, a notice
stating (x) the date on which a record is to be taken for the purpose of such
dividend, distribution, redemption, rights or warrants, or if a record is not to
be taken, the date as of which the holders of Common Stock of record to be
entitled to such dividend, distributions, redemption, rights or warrants are to
be determined or (y) the date on which such reclassification, consolidation,
merger, sale, transfer or share exchange is expected to become effective or
close, and the date as of which it is expected that holders of Common Stock of
record shall be entitled to exchange their shares of Common Stock for
securities, cash or other property deliverable upon such reclassification,
consolidation, merger, sale, transfer, share exchange, dissolution, liquidation
or winding up; provided, however, that the failure to mail such notice or any
defect therein or in the mailing thereof shall not affect the validity of the
corporate action required to be specified in such notice.


                                      -7-                      Class A Warrant
<PAGE>   8
                  10. Payment of Exercise Price. The Holder shall pay the
Exercise Price in one of the following manners:

                        (a) Cash Exercise. The Holder may deliver immediately
available funds; or

                        (b) Cashless Exercise. The Holder may surrender this
Warrant to the Company together with a notice of cashless exercise, in which
event the Company shall issue to the Holder the number of Warrant Shares
determined as follows:

                            X = Y [(A-B)/A]
         where:
                            X = the number of Warrant Shares to be issued
         to the Holder.

                            Y = the number of Warrant Shares with respect to
                            which this Warrant is being exercised.

                            A = the average of the closing sale prices of the
                            Common Stock for the five (5) trading days
                            immediately prior to (but not including) the Date of
                            Exercise.

                            B = the Exercise Price.

For purposes of Rule 144 promulgated under the Securities Act, it is intended,
understood and acknowledged that the Warrant Shares issued in a cashless
exercise transaction shall be deemed to have been acquired by the Holder, and
the holding period for the Warrant Shares shall be deemed to have been
commenced, on the issue date.

         11. Certain Exercise Restrictions. A Holder may not exercise this
Warrant to the extent such exercise would result in the Holder, together with
any affiliate thereof, beneficially owning (as determined in accordance with
Section 13(d) of the Securities Exchange Act of 1934, as amended and the rules
promulgated thereunder) in excess of 9.999% of the then issued and outstanding
shares of Common Stock, including shares of Common Stock issuable upon such
exercise and held by such Holder after application of this Section. Since the
Holder will not be obligated to report to the Company the number of shares of
Common Stock it may hold at the time of an exercise hereunder, unless the
exercise at issue would result in the issuance of shares of Common Stock in
excess of 9.999% of the then outstanding shares of Common Stock without regard
to any other shares which may be beneficially owned by the Holder or an
affiliate thereof, the Holder shall have the authority and obligation to
determine whether the restriction contained in this Section will limit any
particular exercise hereunder and to the extent that the Holder determines that
the limitation contained in this Section applies, the determination of which
portion of this Warrant is exercisable shall be the responsibility and
obligation of the Holder. If the Holder has delivered a Form of Election to
Purchase for a number of Warrant Shares that, without regard to any other shares
that the Holder or

                                      -8-                      Class A Warrant
<PAGE>   9
its affiliates may beneficially own, would result in the issuance in excess of
the permitted amount hereunder, the Company shall notify the Holder of this fact
and shall honor the exercise for the maximum portion of this Warrant permitted
to be exercised on such Date of Exercise in accordance with the periods
described herein and, at the option of the Holder, either keep the portion of
the Warrant tendered for exercise in excess of the permitted amount hereunder
for future exercises or return such excess portion of the Warrant to the Holder.
The provisions of this Section may be waived by a Holder (but only as to itself
and not to any other Holder) upon not less than 61 days prior notice to the
Company. Other Holders shall be unaffected by any such waiver.

                  12. Fractional Shares. The Company shall not be required to
issue or cause to be issued fractional Warrant Shares on the exercise of this
Warrant. The number of full Warrant Shares which shall be issuable upon the
exercise of this Warrant shall be computed on the basis of the aggregate number
of Warrant Shares purchasable on exercise of this Warrant so presented. If any
fraction of a Warrant Share would, except for the provisions of this Section, be
issuable on the exercise of this Warrant, the Company shall pay an amount in
cash equal to the Exercise Price multiplied by such fraction.

                  13. Notices. Any and all notices or other communications or
deliveries hereunder shall be in writing and shall be deemed given and effective
on the earliest of (i) the date of transmission, if such notice or communication
is delivered via facsimile at the facsimile telephone number specified in this
Section prior to 8:00 p.m. (New York City time) on a business day, (ii) the
business day after the date of transmission, if such notice or communication is
delivered via facsimile at the facsimile telephone number specified in this
Section later than 8:00 p.m. (New York City time) on any date and earlier than
11:59 p.m. (New York City time) on such date, (iii) the business day following
the date of mailing, if sent by nationally recognized overnight courier service,
or (iv) if sent other than by the methods set forth in (i)-(iii) of this
section, upon actual receipt by the party to whom such notice is required to be
given. The addresses for such communications shall be: (i) if to the Company, to
157 Technology Drive, Irvine, CA 92618, Attention: Chief Financial Officer, or
to Facsimile No. (949) 788-6706, or (ii) if to the Holder, to the Holder at the
address or facsimile number appearing on the Warrant Register or such other
address or facsimile number as the Holder may provide to the Company in
accordance with this Section.

                  14. Warrant Agent. The Company shall serve as warrant agent
under this Warrant. Upon thirty (30) days' notice to the Holder, the Company may
appoint a new warrant agent. Any corporation into which the Company or any new
warrant agent may be merged or any corporation resulting from any consolidation
to which the Company or any new warrant agent shall be a party or any
corporation to which the Company or any new warrant agent transfers
substantially all of its corporate trust or shareholders services business shall
be a successor warrant agent under this Warrant without any further act. Any
such successor warrant agent shall promptly cause notice of its succession as
warrant agent to be mailed (by first class mail, postage prepaid) to the Holder
at the Holder's last address as shown on the Warrant Register.


                                      -9-                      Class A Warrant
<PAGE>   10
                  15. Miscellaneous.

                        (a) This Warrant shall be binding on and inure to the
benefit of the parties hereto and their respective successors and assigns. This
Warrant may be amended only in writing signed by the Company and the Holder and
their successors and assigns.

                        (b) Subject to Section 15(a), above, nothing in this
Warrant shall be construed to give to any person or corporation other than the
Company and the Holder any legal or equitable right, remedy or cause under this
Warrant. This Warrant shall inure to the sole and exclusive benefit of the
Company and the Holder.

                        (c) The corporate laws of the State of Delaware shall
govern all issues concerning the relative rights of the Company and its
stockholders. All other questions concerning the construction, validity,
enforcement and interpretation of this Warrant shall be governed by and
construed and enforced in accordance with the internal laws of the State of New
York, without regard to the principles of conflicts of law thereof. The Company
and the Holder hereby irrevocably submit to the exclusive jurisdiction of the
state and federal courts sitting in the City of New York, borough of Manhattan,
for the adjudication of any dispute hereunder or in connection herewith or with
any transaction contemplated hereby or discussed herein, and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, or that
such suit, action or proceeding is improper. Each of the Company and the Holder
hereby irrevocably waives personal service of process and consents to process
being served in any such suit, action or proceeding by receiving a copy thereof
sent to the Company at the address in effect for notices to it under this
instrument and agrees that such service shall constitute good and sufficient
service of process and notice thereof. Nothing contained herein shall be deemed
to limit in any way any right to serve process in any manner permitted by law.

                        (d) The headings herein are for convenience only, do not
constitute a part of this Warrant and shall not be deemed to limit or affect any
of the provisions hereof.

                        (e) In case any one or more of the provisions of this
Warrant shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall not
in any way be affected or impaired thereby and the parties will attempt in good
faith to agree upon a valid and enforceable provision which shall be a
commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.



                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                             SIGNATURE PAGE FOLLOWS]


                                      -10-                     Class A Warrant
<PAGE>   11
                  IN WITNESS WHEREOF, the Company has caused this Warrant to be
duly executed by its authorized officer as of the date first indicated above.


                                    NEOTHERAPEUTICS, INC.

                                    By:         /s/Samuel Gulko
                                        ------------------------------------
                                    Name:       Samuel Gulko
                                    Title:      Chief Financial Officer
<PAGE>   12
                          FORM OF ELECTION TO PURCHASE

(To be executed by the Holder to exercise the right to purchase shares of Common
Stock under the foregoing Warrant)

To NeoTherapeutics, Inc.:

         In accordance with the Warrant enclosed with this Form of Election to
Purchase, the undersigned hereby irrevocably elects to purchase
shares of common stock, $.001 par value per share, of NeoTherapeutics, Inc. (the
"Common Stock") and , if such Holder is not utilizing the cashless exercise
provisions set forth in this Warrant, encloses herewith $         in cash,
certified or official bank check or checks, which sum represents the aggregate
Exercise Price (as defined in the Warrant) for the number of shares of Common
Stock to which this Form of Election to Purchase relates, together with any
applicable taxes payable by the undersigned pursuant to the Warrant.

         The undersigned requests that certificates for the shares of Common
Stock issuable upon this exercise be issued in the name of

                                           PLEASE INSERT SOCIAL SECURITY OR
                                           TAX IDENTIFICATION NUMBER

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

- --------------------------------------------------------------------------------
                         (Please print name and address)


         If the number of shares of Common Stock issuable upon this exercise
shall not be all of the shares of Common Stock which the undersigned is entitled
to purchase in accordance with the enclosed Warrant, the undersigned requests
that a New Warrant (as defined in the Warrant) evidencing the right to purchase
the shares of Common Stock not issuable pursuant to the exercise evidenced
hereby be issued in the name of and delivered to:


- --------------------------------------------------------------------------------
                         (Please print name and address)

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

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

Dated:            ,                       Name of Holder:
      ------------------

                                          (Print)
                                                -------------------------------
                                           (By:)
                                                -------------------------------
                                           (Name:)
                                           (Title:)
                                           (Signature must conform in all
                                           respects to name of holder as
                                           specified on the face of the Warrant)

                                                                Class A Warrant
<PAGE>   13
                               FORM OF ASSIGNMENT

           [To be completed and signed only upon transfer of Warrant]

         FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto                  the right represented by the within Warrant to purchase
             shares of Common Stock of NeoTherapeutics, Inc. to which the within
Warrant relates and appoints                  attorney to transfer said right on
the books of NeoTherapeutics, Inc. with full power of substitution in the
premises.

Dated:

- ---------------, ----


                                      ---------------------------------------
                                      (Signature must conform in all respects to
                                      name of holder as specified on the face
                                      of the Warrant)


                                      ---------------------------------------
                                      Address of Transferee

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

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



In the presence of:


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

                                                                Class A Warrant

<PAGE>   1


                                                                     EXHIBIT 4.6



NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE
EXEMPTION FROM THE REGISTRATION REQUIREMENTS THEREUNDER AND IN COMPLIANCE WITH
APPLICABLE STATE SECURITIES OR BLUE SKY LAWS.


                              NEOTHERAPEUTICS, INC.

                                 CLASS B WARRANT

Warrant No. B-1                                            Dated: April 6, 2000


         NeoTherapeutics, Inc., a Delaware corporation (the "Company"), hereby
certifies that, for value received, Montrose Investments Ltd., or its registered
assigns (the "Holder"), is entitled, subject to the terms and conditions set
forth herein, to purchase from the Company up to a total of 2,000,000 shares of
common stock, $.001 par value per share (the "Common Stock"), of the Company
(each such share, a "Warrant Share" and all such shares, the "Warrant Shares").
Certain terms used herein are defined in Exhibit A attached hereto:

                  1. Registration of Warrant. The Company shall register this
Warrant, upon records to be maintained by the Company for that purpose (the
"Warrant Register") in the name of the record Holder hereof from time to time.
The Company may deem and treat the registered Holder of this Warrant as the
absolute owner hereof for the purpose of any exercise hereof or any distribution
to the Holder, and for all other purposes, and the Company shall not be affected
by notice to the contrary.

                  2. Registration of Transfers and Exchanges.

                        (a) This Warrant may only be transferred pursuant to an
effective registration statement under the Securities Act, to the Company or
pursuant to an available exemption from or in a transaction not subject to the
registration requirements of the Securities Act. In connection with any transfer
of this Warrant other than pursuant to an effective registration

                                                                 Class B Warrant
<PAGE>   2
statement or to the Company, the Company may require the transferor thereof to
provide to the Company an opinion of counsel selected by the transferor, the
form and substance of which opinion shall be reasonably satisfactory to the
Company, to the effect that such transfer does not require registration of such
Warrant under the Securities Act. Holder agrees to the imprinting, so long as is
required by this Section 2(a), of a legend substantially similar to that first
above written on any New Warrant (as defined below). Any such transferee shall
agree in writing to be bound by the terms of this Warrant and shall have the
rights of Holder under this Warrant. The Company shall register the transfer of
any portion of this Warrant in the Warrant Register, upon surrender of this
Warrant, with the Form of Assignment attached hereto duly completed and signed,
to the Transfer Agent or to the Company at its address for notice set forth in
Section 11. Upon any such registration or transfer, a new warrant to purchase
Common Stock, in substantially the form of this Warrant (any such new warrant, a
"New Warrant"), evidencing the portion of this Warrant so transferred shall be
issued to the transferee and a New Warrant evidencing the remaining portion of
this Warrant not so transferred, if any, shall be issued to the transferring
Holder. The acceptance of the New Warrant by the transferee thereof shall be
deemed the acceptance of such transferee of all of the rights and obligations of
a holder of a Warrant.

                        (b) This Warrant is exchangeable, upon the surrender
hereof by the Holder to the Company at its address for notice set forth in
Section 11 for one or more New Warrants, evidencing in the aggregate the right
to purchase the number of Warrant Shares which may then be purchased hereunder.
Any such New Warrant will be dated the date of such exchange.

                  3. Duration, Exercise and Redemption of Warrants.

                        (a) Company Call Option.

                   (i) Subject to the terms and conditions set forth herein,
prior to 2:30 p.m. (New York City time) on any Trading Day (as defined in
Exhibit A) during the period between the Effective Date (as defined in Exhibit
A) and the Trading Day immediately following the second year anniversary of the
Effective Date (the "Expiration Date"), the Company may deliver written notices
to the Holder (each, a "Call Notice" and the Trading Day a Call Notice is
delivered, a "Delivery Date"), of the Company's election to call, for a price of
$.0005 per Warrant Share, a portion of this Warrant as further described herein;
provided that such price shall be adjusted to reflect any adjustment in the
number of Warrant Shares issuable hereunder, so that the maximum aggregate
redemption price shall continue to be $1,000. Notwithstanding anything to the
contrary set forth in this Warrant: (1) a Call Notice may not apply to a number
of Warrant Shares in excess of 15% of the average trading volume of the Common
Stock for the two Trading Days immediately preceding the Delivery Date, (2) no
Call Notice may be delivered until the expiration of the Call Expiration Time
(as defined below) for the immediately preceding Call Notice, (3) a Call Notice
may indicate that if the Exercise Price (as defined herein) applicable to an
exercise of this Warrant pursuant to such Call Notice shall be lower than a
dollar amount designated by the Company in such Call Notice (such dollar amount,
a "Floor Price"), then, at the option of the

                                      -2-                       Class B Warrant
<PAGE>   3
Holder: (A) the Exercise Price shall, exclusively for the purpose of such Call
Notice, equal the Floor Price or (B) such Call Notice shall be null and void ab
initio, provided, that a Floor Price must be less than 90% of the Per Share
Market Value on the Trading Day preceding the Delivery Date and (4) no Call
Notice may be delivered unless the conditions set forth in Section 3(a)(iii)
have been either satisfied by the Company or waived by the Holder.

                  (ii) The portion of this Warrant subject to a Call Notice will
be canceled and of no further effect from and after 5:30 p.m. (New York City
time) on the Trading Day following Delivery Date (the "Call Expiration Time"),
unless between the Delivery Date and the Call Expiration Time the Holder
notifies the Company in writing that it will exercise this Warrant to acquire
the number of Warrant Shares subject to such Call Notice at the Exercise Price
per share set forth in Section 3(c). Such exercise shall be in accordance with
Section 3(b)(ii).

                  (iii) The right of the Company to deliver a Call Notice is
subject to the satisfaction or waiver by the Holder, at or before the applicable
Call Expiration Time, of each of the following conditions (and, if after
delivery thereof and on the applicable Exercise Date, any of the following
conditions shall cease to be met, such Call Notice, at the option of the Holder,
shall be null and void ab initio):

                           (a)      The representations and warranties of the
                                    Company contained in the Purchase Agreement
                                    shall be true and correct as of each of the
                                    applicable Delivery Date and Call Expiration
                                    Time, as though first made on and as of such
                                    Delivery Date and Call Expiration Time
                                    (other than representations and warranties
                                    which relate to a specific date (which shall
                                    not include representations and warranties
                                    relating to the "date hereof") which
                                    representations and warranties shall be true
                                    as of such specific date);

                           (b)      The Company shall have performed, satisfied
                                    and complied in all material respects with
                                    all covenants (including timely delivery of
                                    Warrant Shares in accordance with Section
                                    3(a)), agreements and conditions of the
                                    Transaction Documents (as defined in the
                                    Purchase Agreement) to be performed,
                                    satisfied or complied with by the Company at
                                    or prior to the applicable Delivery Date and
                                    Call Expiration Time;

                           (c)      The Underlying Shares Registration Statement
                                    (as defined in Exhibit A) shall be effective
                                    on the Delivery Date, not subject to any
                                    stop order or suspension;

                           (d)      No statute, rule, regulation, executive
                                    order, decree, ruling or injunction shall
                                    have been enacted, entered, promulgated or


                                      -3-                        Class B Warrant
<PAGE>   4
                                    endorsed by any court or governmental
                                    authority of competent jurisdiction and in
                                    force on the Delivery Date which prohibits
                                    the consummation of any of the transactions
                                    contemplated by the Transaction Documents;

                           (e)      Since the Closing Date (as defined in the
                                    Purchase Agreement), no event or series of
                                    events which reasonably would be expected to
                                    have or result in a Material Adverse Effect
                                    (as defined in the Purchase Agreement) and
                                    no Change of Control Transaction (as defined
                                    in Exhibit A) shall have occurred;

                           (f)      Since the Closing Date, trading in the
                                    Common Stock shall not have been suspended
                                    by the Securities and Exchange Commission
                                    for a period in excess of five consecutive
                                    Trading Days or ten Trading Days in the
                                    aggregate (which need not be consecutive
                                    Trading Days), except for any suspensions of
                                    trading of not more than one Trading Day
                                    solely to permit dissemination of material
                                    information regarding the Company;

                           (g)      On the Delivery Date, the Common Stock shall
                                    be trading on the Nasdaq Small Cap Market
                                    ("NASDAQ"), or on the Nasdaq National
                                    Market, New York Stock Exchange or American
                                    Stock Exchange (each, a "Subsequent
                                    Market");

                           (h)      No approval of the shareholders of the
                                    Company shall be required under the rules of
                                    the Nasdaq Stock Market or any other
                                    Subsequent Market on which the Common Stock
                                    is traded or listed for trading in order to
                                    issue the number of Warrant Shares indicated
                                    in the applicable Call Notice at the
                                    Exercise Price;

                           (i)      For the five Trading Days immediately
                                    preceding the applicable Delivery Date, the
                                    average daily trading volume of the Common
                                    Stock on the NASDAQ as reported by Bloomberg
                                    L.P., shall be at least 20,000 shares and
                                    the average of the Per Share Market Values
                                    (as defined in Exhibit A) for such five
                                    Trading Days shall be at least $5.00; and

                           (j)      The Call Notice at issue would not result in
                                    a violation of Section 3(e).

                           (b)      Exercise By Holder.


                                      -4-                        Class B Warrant
<PAGE>   5
                  (i) At any time on and after the Effective Date (and in the
case of an election to purchase which is not in response to a Call Notice, if
earlier, the 90th day after the date of this Warrant) and prior to 5:30 p.m.
(New York City time) on the Expiration Date, the Holder shall be entitled to
purchase all or a portion of the Warrant Shares which have not been previously
issued and with respect to which this Warrant has not been previously redeemed
or canceled in accordance with the terms hereof.

                  (ii) The Holder may purchase Warrant Shares hereunder by
delivering to the Company, at its address for notice set forth in Section 11, a
completed Form of Election to Purchase in the form attached hereto, together
with the payment of the Exercise Price multiplied by the number of Warrant
Shares indicated therein. An "Exercise Date" means the date of the delivery
(which may be made via facsimile) of the Form of Election to Purchase and
applicable Exercise Price.

                  (iii) After the end of the week in which the Company receives
one or more Forms of Election to Purchase and the applicable Exercise Price, the
Company shall promptly (but in no event later than three Trading Days following
the end of such week) issue or cause to be issued and cause to be delivered to
or upon the written order of the Holder and in such name or names as the Holder
may designate, a certificate for the Warrant Shares issuable upon such exercise,
free of restrictive legends except as required by the Purchase Agreement,
provided, that, if in any week the Company shall receive one or more Forms of
Election to Purchase for the purchase of in excess of 30,000 Warrant Shares, the
Company shall issue such certificate no later than the third Trading Day
following the date of the delivery of the applicable Form of Election to
Purchase which resulted in the purchase of in excess of 30,000 Warrant Shares.

                           (A)      If the Company fails to deliver to the
                                    Holder the certificate or certificates
                                    pursuant to this Section within the time
                                    specified in above, the Holder shall be
                                    entitled by written notice to the Company at
                                    any time on or before its receipt of such
                                    certificate or certificates thereafter, to
                                    rescind such exercise.

                           (B)      In addition to the rights set forth in (A)
                                    above, if the Company fails to deliver to
                                    the Holder such certificate or certificates
                                    pursuant to this Section within the time
                                    specified in above, and if after such time
                                    the Holder purchases (in an open market
                                    transaction or otherwise) Common Stock to
                                    deliver in satisfaction of a sale by such
                                    Holder of the Warrant Shares which the
                                    Holder anticipated receiving upon such
                                    exercise (a "Buy-In"), then the Company
                                    shall (1) pay in cash to the Holder the
                                    amount by which (x) the Holder's total
                                    purchase price (including brokerage
                                    commissions, if any) for the Common Stock so
                                    purchased exceeds (y) the product of (i) the
                                    aggregate number of Warrant Shares that such
                                    Holder anticipated receiving from the
                                    exercise at issue multiplied by (ii) the Per
                                    Share Market

                                      -5-                        Class B Warrant
<PAGE>   6
                                    Value on the Exercise Date and (2) at the
                                    option of the Holder, either rescind the
                                    exercise at issue or deliver to the Holder
                                    the number of Warrant Shares that would have
                                    been issued had the Company timely complied
                                    with its delivery requirements under this
                                    Section. For example, if the Holder
                                    purchases Common Stock having a total
                                    purchase price of $11,000 to cover a Buy-In
                                    with respect to an attempted exercise with
                                    respect to which the Per Share Market Value
                                    on the Exercise Date was a total of $10,000,
                                    the Company shall be required to pay the
                                    Holder $1,000. The Holder shall provide the
                                    Company written notice indicating the
                                    amounts payable to the Holder in respect of
                                    the Buy-In.

                           (c) Exercise Price.

                  The "Exercise Price" applicable to an exercise following a
Call Notice under Section 3(a) shall equal the lower of (i) $33.75(subject to
equitable adjustment for stock splits, reverse splits, combinations and other
similar events) and (ii) 97% of the Per Share Market Value on the Trading Day
immediately following the applicable Delivery Date. The Exercise Price
applicable to an exercise pursuant to Section 3(b)(i) that is not in response to
a Call Notice shall equal $33.75 (subject to equitable adjustment for stock
splits, reverse splits, combinations and other similar events). The Exercise
Price shall be subject to adjustment in accordance with Section 8.

                           (d) Redemption at Option of Company.

                  On and after the 6th month anniversary of the Effective Date,
the Company may redeem all or any portion of this Warrant which has not been
previously exercised and for which no Form of Election to Purchase shall been
received by delivery to the Holder of a notice of such redemption, together with
the redemption price equal to $.05 per Warrant Share to be redeemed, payable by
the third Trading Day following the delivery of such notice by the Company;
provided that the redemption price shall be adjusted to reflect any adjustment
in the number of Warrant Shares issuable hereunder, so that the maximum
aggregate redemption price shall continue to be $100,000. Interest shall accrue
on the unpaid portion of such redemption price at the rate of 10% per annum
beginning on such third Trading Day.

                           (e) Certain Exercise Restrictions.

                  (i) The Company may not issue Warrant Shares upon exercise of
this Warrant, in response to a Call Notice in excess of the product of (x) 50%
and (y) 19.9999% of the shares of Common Stock outstanding on the Closing Date,
less an amount equal to the aggregate number of shares of Common Stock issued
(A) upon conversion of the Company's 5% Subordinated Convertible Debentures
originally issued to the Holder, and (B) upon any exercise of this Warrant, in
response to a Call Notice unless the Company shall have obtained the approval of
the

                                      -6-                        Class B Warrant
<PAGE>   7
stockholders of the Company as required under the rules of the Nasdaq Stock
Market or such other exchange or trading facility on which the Common Stock is
traded or listed for trading for such issuance. In the event of any subdivision,
transfer or exchange of this Warrant, the limitation contained in this Section
3(e)(i) shall be appropriately adjusted to ensure that in no event shall the
Company issue, upon any exercise of this Warrant in response to a Call Notice,
in excess of the product of (x) 50% and (y) 19.999% of the shares of Common
Stock outstanding on the Closing Date, less an amount equal to the aggregate
number of shares of Common Stock issued (A) upon conversion of the Company's 5%
Subordinated Convertible Debentures originally issued to the Holder, and (B)
upon any exercise of this Warrant, in response to a Call Notice unless the
Company shall have obtained the approval of the stockholders of the Company as
required under the rules of the Nasdaq Stock Market or such other exchange or
trading facility on which the Common Stock is traded or listed for trading for
such issuance.

                  (ii) A Holder may not exercise this Warrant to the extent such
exercise would result in the Holder, together with any affiliate thereof,
beneficially owning (as determined in accordance with Section 13(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act") and the rules
promulgated thereunder) in excess of 9.999% of the then issued and outstanding
shares of Common Stock, including shares issuable upon such exercise and held by
such Holder after application of this Section. Since the Holder will not be
obligated to report to the Company the number of shares of Common Stock it may
hold at the time of an exercise hereunder, unless the exercise at issue would
result in the issuance of shares of Common Stock in excess of 9.999% of the then
outstanding shares of Common Stock without regard to any other shares which may
be beneficially owned by the Holder or an affiliate thereof, the Holder shall
have the authority and obligation to determine whether the restriction contained
in this Section will limit any particular exercise hereunder and to the extent
that the Holder determines that the limitation contained in this Section
applies, the determination of which portion of this Warrant is exercisable shall
be the responsibility and obligation of the Holder. If the Holder has delivered
a Form of Election to Purchase for a number of Warrant Shares that, without
regard to any other shares that the Holder or its affiliates may beneficially
own, would result in the issuance in excess of the permitted amount hereunder,
the Company shall notify the Holder of this fact and shall honor the exercise
for the maximum portion of this Warrant permitted to be exercised on such Date
of Exercise in accordance with the periods described herein and, at the option
of the Holder, either keep the portion of the Warrant tendered for exercise in
excess of the permitted amount hereunder for future exercises or return such
excess portion of the Warrant to the Holder. The provisions of this Section may
be waived by a Holder (but only as to itself and not to any other Holder) upon
not less than 61 days prior notice to the Company.

                  4. Piggyback Registration Rights. During the Effectiveness
Period (as defined in the Registration Rights Agreement, of even date herewith,
between the Company and the original Holder), the Company may not file any
registration statement with the Securities and Exchange Commission (other than
registration statements of the Company filed on Form S-8 or Form S-4, each as
promulgated under the Securities Act, pursuant to which the Company is
registering securities pursuant to a Company employee benefit plan or pursuant
to a merger,

                                      -7-                        Class B Warrant
<PAGE>   8
acquisition or similar transaction including supplements thereto, but not
additionally filed registration statements in respect of such securities) at any
time when there is not an effective registration statement covering the resale
of the Warrant Shares and naming the Holder as a selling stockholder thereunder,
unless the Company provides the Holder with not less than 20 days notice of its
intention to file such registration statement and provides the Holder the option
to include any or all of the applicable Warrant Shares therein. The piggyback
registration rights granted to the Holder pursuant to this Section shall
continue until all of the Holder's Warrant Shares have been sold in accordance
with an effective registration statement or upon the expiration of the Effective
Period. The Company will pay all registration expenses in connection therewith.

                  5. Payment of Taxes. The Company will pay all documentary
stamp taxes attributable to the issuance of Warrant Shares upon the exercise of
this Warrant; provided, however, that the Company shall not be required to pay
any tax which may be payable in respect of any transfer involved in the
registration of any certificates for Warrant Shares or Warrants in a name other
than that of the Holder. The Holder shall be responsible for all other tax
liability that may arise as a result of holding or transferring this Warrant or
receiving Warrant Shares upon exercise hereof.

                  6. Replacement of Warrant. If this Warrant is mutilated, lost,
stolen or destroyed, the Company shall issue or cause to be issued in exchange
and substitution for and upon cancellation hereof, or in lieu of and
substitution for this Warrant, a New Warrant, but only upon receipt of evidence
reasonably satisfactory to the Company of such loss, theft or destruction and
indemnity, if requested, satisfactory to it. Applicants for a New Warrant under
such circumstances shall also comply with such other reasonable regulations and
procedures and pay such other reasonable charges as the Company may prescribe.

                  7. Reservation of Warrant Shares. The Company covenants that
it will at all times reserve and keep available out of the aggregate of its
authorized but unissued Common Stock, solely for the purpose of enabling it to
issue Warrant Shares upon exercise of this Warrant as herein provided, the
number of Warrant Shares which are then issuable and deliverable upon the
exercise of this entire Warrant, free from preemptive rights or any other actual
contingent purchase rights of persons other than the Holder (taking into account
the adjustments and restrictions of Section 8). The Company covenants that all
Warrant Shares that shall be so issuable and deliverable shall, upon issuance
and the payment of the applicable Exercise Price in accordance with the terms
hereof, be duly and validly authorized, issued and fully paid and nonassessable.

                  8. Certain Adjustments.

                        (a) In case of any reclassification of the Common Stock
or any compulsory share exchange pursuant to which the Common Stock is converted
into other securities, cash or property, then the Holder shall have the right
thereafter to exercise this Warrant only into the shares of stock and other
securities and property receivable upon or deemed to be

                                      -8-                        Class B Warrant
<PAGE>   9
held by holders of Common Stock following such reclassification or share
exchange, and the Holder shall be entitled upon such exercise to receive such
amount of securities or property equal to the amount of Warrant Shares such
Holder would have been entitled to had such Holder exercised this Warrant
immediately prior to such reclassification or share exchange.

                        (b) In case of the closing of any (1) merger or
consolidation of the Company with or into another Person, or (2) sale by the
Company of more than one-half of the assets of the Company (on a book value
basis) in one or a series of related transactions, or (3) tender or other offer
or exchange (whether by the Company or another Person) pursuant to which holders
of Common Stock are permitted to tender or exchange their shares for other
securities, stock, cash or property of the Company or another Person; then the
Holder shall have the right thereafter to (A) exercise this Warrant for the
shares of stock and other securities, cash and property receivable upon or
deemed to be held by holders of Common Stock following such merger,
consolidation or sale, and the Holder shall be entitled upon exercise of this
Warrant to receive such amount of securities, cash and property as the Common
Stock for which this Warrant could have been exercised immediately prior to such
merger, consolidation or sales would have been entitled, or (B) in the event of
an exchange or tender offer or other transaction contemplated by clause (3) of
this Section, tender or exchange this Warrant for such securities, stock, cash
and other property receivable upon or deemed to be held by holders of Common
Stock that have tendered or exchanged their shares of Common Stock following
such tender or exchange, and the Holder shall be entitled upon such exchange or
tender to receive such amount of securities, cash and property as the shares of
Common Stock for which this Warrant could have been exercised immediately prior
to such tender or exchange would have been entitled as would have been issued.
The terms of any such merger, sale, consolidation, tender or exchange shall
include such terms so as continue to give the Holder the right to receive the
securities, cash and property set forth in this Section upon any conversion or
redemption following such event. This provision shall similarly apply to
successive such events.

                        (c) All calculations under this Section 8 shall be made
to the nearest cent or the nearest 1/100th of a share, as the case may be.

                        (d) If (i) the Company shall declare a dividend (or any
other distribution) on its Common Stock; or (ii) the Company shall declare a
special nonrecurring cash dividend on or a redemption of its Common Stock; or
(iii) the Company shall authorize the granting to all holders of the Common
Stock rights or warrants to subscribe for or purchase any shares of capital
stock of any class or of any rights; or (iv) the approval of any stockholders of
the Company shall be required in connection with any reclassification of the
Common Stock, any consolidation or merger to which the Company is a party, any
sale or transfer of all or substantially all of the assets of the Company, or
any compulsory share exchange whereby the Common Stock is converted into other
securities, cash or property; or (v) the Company shall authorize the voluntary
dissolution, liquidation or winding up of the affairs of the Company, then the
Company shall cause to be mailed to each Holder at their last addresses as they
shall appear upon the Warrant Register, at least 30 calendar days prior to the
applicable record or effective date

                                      -9-                        Class B Warrant
<PAGE>   10
hereinafter specified, a notice stating (x) the date on which a record is to be
taken for the purpose of such dividend, distribution, redemption, rights or
warrants, or if a record is not to be taken, the date as of which the holders of
Common Stock of record to be entitled to such dividend, distributions,
redemption, rights or warrants are to be determined or (y) the date on which
such reclassification, consolidation, merger, sale, transfer or share exchange
is expected to become effective or close, and the date as of which it is
expected that holders of Common Stock of record shall be entitled to exchange
their shares of Common Stock for securities, cash or other property deliverable
upon such reclassification, consolidation, merger, sale, transfer, share
exchange, dissolution, liquidation or winding up, provided, that the failure to
mail such notice or any defect therein or in the mailing thereof shall not
affect the validity of the corporate action required to be specified in such
notice.

                  9. Payment of Exercise Price. The Holder shall pay the
Exercise Price for Warrant Shares purchased hereunder by delivery of immediately
available funds.

                  10. Fractional Shares. The Company shall not be required to
issue or cause to be issued fractional Warrant Shares on the exercise of this
Warrant. The number of full Warrant Shares which shall be issuable upon the
exercise of this Warrant shall be computed on the basis of the aggregate number
of Warrant Shares purchasable on exercise of this Warrant so presented. If any
fraction of a Warrant Share would, except for the provisions of this Section, be
issuable on the exercise of this Warrant, the Company shall pay an amount in
cash equal to the Exercise Price multiplied by such fraction.

                  11. Notices. Any and all notices or other communications or
deliveries hereunder shall be in writing and shall be deemed given and effective
on the earliest of (i) the date of transmission, if such notice or communication
is delivered via facsimile at the facsimile telephone number specified in this
Section prior to 8:00 p.m. (New York City time) on a business day, (ii) the
business day after the date of transmission, if such notice or communication is
delivered via facsimile at the facsimile telephone number specified in this
Section later than 8:00 p.m. (New York City time) on any date and earlier than
11:59 p.m. (New York City time) on such date, (iii) the business day following
the date of mailing, if sent by nationally recognized overnight courier service,
or (iv) if sent other than by the methods set forth in (i)-(iii) of this
section, upon actual receipt by the party to whom such notice is required to be
given. The addresses for such communications shall be: (i) if to the Company, to
157 Technology Drive, Irvine, CA 92618, Attention: Chief Financial Officer, or
to Facsimile No. (949) 788-6706, or (ii) if to the Holder, to the Holder at the
address or facsimile number appearing on the Warrant Register or such other
address or facsimile number as the Holder may provide to the Company in
accordance with this Section.

                  12. Warrant Agent. The Company shall serve as warrant agent
under this Warrant. Upon thirty (30) days' notice to the Holder, the Company may
appoint a new warrant agent. Any corporation into which the Company or any new
warrant agent may be merged or any corporation resulting from any consolidation
to which the Company or any new warrant agent

                                      -10-                       Class B Warrant
<PAGE>   11
shall be a party or any corporation to which the Company or any new warrant
agent transfers substantially all of its corporate trust or shareholders
services business shall be a successor warrant agent under this Warrant without
any further act. Any such successor warrant agent shall promptly cause notice of
its succession as warrant agent to be mailed (by first class mail, postage
prepaid) to the Holder at the Holder's last address as shown on the Warrant
Register.

                  13. Miscellaneous.

                        (a) This Warrant shall be binding on and inure to the
benefit of the parties hereto and their respective successors and assigns. This
Warrant may be amended only in writing signed by the Company and the Holder and
their successors and assigns.

                        (b) Subject to Section 13(a), above, nothing in this
Warrant shall be construed to give to any person or corporation other than the
Company and the Holder any legal or equitable right, remedy or cause under this
Warrant. This Warrant shall inure to the sole and exclusive benefit of the
Company and the Holder.

                        (c) The corporate laws of the State of Delaware shall
govern all issues concerning the relative rights of the Company and its
stockholders. All other questions concerning the construction, validity,
enforcement and interpretation of this Warrant shall be governed by and
construed and enforced in accordance with the internal laws of the State of New
York, without regard to the principles of conflicts of law thereof. The Company
and the Holder hereby irrevocably submit to the exclusive jurisdiction of the
state and federal courts sitting in the City of New York, borough of Manhattan,
for the adjudication of any dispute hereunder or in connection herewith or with
any transaction contemplated hereby or discussed herein, and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, or that
such suit, action or proceeding is improper. Each of the Company and the Holder
hereby irrevocably waives personal service of process and consents to process
being served in any such suit, action or proceeding by receiving a copy thereof
sent to the Company at the address in effect for notices to it under this
instrument and agrees that such service shall constitute good and sufficient
service of process and notice thereof. Nothing contained herein shall be deemed
to limit in any way any right to serve process in any manner permitted by law.

                        (d) The headings herein are for convenience only, do not
constitute a part of this Warrant and shall not be deemed to limit or affect any
of the provisions hereof.

                        (e) In case any one or more of the provisions of this
Warrant shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall not
in any way be affected or impaired thereby and the parties will attempt in good
faith to agree upon a valid and enforceable provision which shall be a
commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                             SIGNATURE PAGE FOLLOWS]



                                      -11-                       Class B Warrant
<PAGE>   12
                  IN WITNESS WHEREOF, the Company has caused this Warrant to be
duly executed by its authorized officer as of the date first indicated above.


                                    NEOTHERAPEUTICS, INC.

                                    By:              /s/Samuel Gulko
                                        --------------------------------------
                                        Name:       Samuel Gulko
                                        Title:      Chief Financial Officer
<PAGE>   13
                          FORM OF ELECTION TO PURCHASE

(To be executed by the Holder to exercise the right to purchase shares of Common
Stock under the foregoing Warrant)

To NeoTherapeutics, Inc.:

         In accordance with the Warrant enclosed with this Form of Election to
Purchase, the undersigned hereby irrevocably elects to purchase
shares of common stock, $.001 par value per share, of NeoTherapeutics, Inc. (the
"Common Stock") and , if such Holder is not utilizing the cashless exercise
provisions set forth in this Warrant, encloses herewith $              in cash,
certified or official bank check or checks, which sum represents the aggregate
Exercise Price (as defined in the Warrant) for the number of shares of Common
Stock to which this Form of Election to Purchase relates, together with any
applicable taxes payable by the undersigned pursuant to the Warrant.

         The undersigned requests that certificates for the shares of Common
Stock issuable upon this exercise be issued in the name of

PLEASE INSERT SOCIAL SECURITY OR TAX IDENTIFICATION NUMBER

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

- --------------------------------------------------------------------------------
                         (Please print name and address)



         If the number of shares of Common Stock issuable upon this exercise
shall not be all of the shares of Common Stock which the undersigned is entitled
to purchase in accordance with the enclosed Warrant, the undersigned requests
that a New Warrant (as defined in the Warrant) evidencing the right to purchase
the shares of Common Stock not issuable pursuant to the exercise evidenced
hereby be issued in the name of and delivered to:


- --------------------------------------------------------------------------------
                         (Please print name and address)

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

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

Dated:            ,                Name of Holder:
      ------------

(Print)
       ------------------------------------------------------------------------
(By:)
      -------------------------------------------------------------------------
(Name:)
(Title:)

                                    (Signature must conform in all respects to
                                    name of holder as specified on the face of
                                    the Warrant)

                                                                 Class B Warrant
<PAGE>   14
                               FORM OF ASSIGNMENT

           [To be completed and signed only upon transfer of Warrant]

         FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto                    the right represented by the within Warrant to purchase
             shares of Common Stock of NeoTherapeutics, Inc. to which the within
Warrant relates and appoints                  attorney to transfer said right on
the books of NeoTherapeutics Inc. with full power of substitution in the
premises.

Dated:

- ---------------, ----


                                    ---------------------------------------
                                    (Signature must conform in all respects to
                                    name of holder as specified on the face of
                                    the Warrant)


                                    ---------------------------------------
                                    Address of Transferee

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

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



In the presence of:


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


                                                                 Class B Warrant
<PAGE>   15
                                                                       EXHIBIT A


         (i) "Business Day" means any day except Saturday, Sunday and any day
which shall be a federal legal holiday or a day on which banking institutions in
the State of New York and the State of California are authorized or required by
law or other governmental action to close.

         (ii) "Change of Control Transaction" means the occurrence of any of (i)
an acquisition after the date hereof by an individual or legal entity or "group"
(as described in Rule 13d-5(b)(1) promulgated under the Exchange Act) of
effective control (whether through legal or beneficial ownership of capital
stock of the Company, by contract or otherwise) of in excess of 33% of the
voting securities of the Company, (ii) a replacement at one time or over time of
more than one-half of the members of the Company's board of directors which is
not approved by a majority of those individuals who are members of the board of
directors on the date hereof (or by those individuals who are serving as members
of the board of directors on any date whose nomination to the board of directors
was approved by a majority of the members of the board of directors who are
members on the date hereof), (iii) the merger or consolidation of the Company
with or into another entity that is not wholly-owned by the Company upon the
completion of which the stockholders of the Company immediately before such
merger or consolidation own or control less than 2/3 of the voting securities of
the surviving entity or sale of 50% or more of the assets of the Company in one
or a series of related transactions, or (i) the execution by the Company of an
agreement to which the Company is a party or by which it is bound, providing for
any of the events set forth above in (i), (ii) or (iii).

         (iii) "Commission" means the Securities and Exchange Commission.

         (iv) "Effective Date" means the date the Underlying Shares Registration
Statement is declared effective by the Commission.

         (v) "Per Share Market Value" means on any particular date (a) the
closing bid price per share of Common Stock on such date on the NASDAQ or on
such Subsequent Market on which the shares of Common Stock are then listed or
quoted, or if there is no such price on such date, then the closing bid price on
the NASDAQ or on such Subsequent Market on the date nearest preceding such date,
or (b) if the shares of Common Stock are not then listed or quoted on the NASDAQ
or a Subsequent Market, the closing bid price for a share of Common Stock in the
over-the-counter market, as reported by the National Quotation Bureau
Incorporated or similar organization or agency succeeding to its functions of
reporting prices) at the close of business on such date, or (c) if the shares of
Common Stock are not then reported by the National Quotation Bureau Incorporated
(or similar organization or agency succeeding to its functions of reporting
prices), then the average of the "Pink Sheet" quotes for the relevant conversion
period, as determined in good faith by the Holder, or (d) if the shares of
Common Stock are not then publicly traded the fair market value of a share of
Common Stock as determined by an Appraiser selected in good faith by the Holders
of a majority in interest of the Warrants then outstanding.

         (vi) "Purchase Agreement" means the Convertible Debenture Purchase
Agreement dated as of the date hereof, to which the Company and the original
Holder hereof are parties.


                                                                 Class B Warrant
<PAGE>   16
         (vii) "Trading Day" means (a) a day on which the shares of Common Stock
are traded on the NASDAQ or on such Subsequent Market on which the shares of
Common Stock are then listed or quoted, or (b) if the shares of Common Stock are
not listed on the NASDAQ or a Subsequent Market, a day on which the shares of
Common Stock are traded in the over-the-counter market, as reported by the OTC
Bulletin Board, or (c) if the shares of Common Stock are not quoted on the OTC
Bulletin Board, a day on which the shares of Common Stock are quoted in the
over-the-counter market as reported by the National Quotation Bureau
Incorporated (or any similar organization or agency succeeding its functions of
reporting prices); provided, however, that in the event that the shares of
Common Stock are not listed or quoted as set forth in (a), (b) and (c) hereof,
then Trading Day shall mean a Business Day.

         (viii) "Underlying Shares Registration Statement" shall have the
meaning set forth in the Purchase Agreement.


                                                                 Class B Warrant

<PAGE>   1
                                                                     EXHIBIT 4.7



NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR
THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE
EXEMPTION FROM THE REGISTRATION REQUIREMENTS THEREUNDER AND IN COMPLIANCE WITH
APPLICABLE STATE SECURITIES OR BLUE SKY LAWS.


                              NEOTHERAPEUTICS, INC.

                                 CLASS B WARRANT

Warrant No. B-2                                           Dated: April 6, 2000


      NeoTherapeutics, Inc., a Delaware corporation (the "Company"), hereby
certifies that, for value received, Strong River Investments, Inc., or its
registered assigns (the "Holder"), is entitled, subject to the terms and
conditions set forth herein, to purchase from the Company up to a total of
2,000,000 shares of common stock, $.001 par value per share (the "Common
Stock"), of the Company (each such share, a "Warrant Share" and all such shares,
the "Warrant Shares"). Certain terms used herein are defined in Exhibit A
attached hereto:

            1. Registration of Warrant. The Company shall register this Warrant,
upon records to be maintained by the Company for that purpose (the "Warrant
Register") in the name of the record Holder hereof from time to time. The
Company may deem and treat the registered Holder of this Warrant as the absolute
owner hereof for the purpose of any exercise hereof or any distribution to the
Holder, and for all other purposes, and the Company shall not be affected by
notice to the contrary.

            2. Registration of Transfers and Exchanges.

                  (a) This Warrant may only be transferred pursuant to an
effective registration statement under the Securities Act, to the Company or
pursuant to an available exemption from or in a transaction not subject to the
registration requirements of the Securities Act. In connection with any transfer
of this Warrant other than pursuant to an effective registration


                                                                 Class B Warrant
<PAGE>   2
statement or to the Company, the Company may require the transferor thereof to
provide to the Company an opinion of counsel selected by the transferor, the
form and substance of which opinion shall be reasonably satisfactory to the
Company, to the effect that such transfer does not require registration of such
Warrant under the Securities Act. Holder agrees to the imprinting, so long as is
required by this Section 2(a), of a legend substantially similar to that first
above written on any New Warrant (as defined below). Any such transferee shall
agree in writing to be bound by the terms of this Warrant and shall have the
rights of Holder under this Warrant. The Company shall register the transfer of
any portion of this Warrant in the Warrant Register, upon surrender of this
Warrant, with the Form of Assignment attached hereto duly completed and signed,
to the Transfer Agent or to the Company at its address for notice set forth in
Section 11. Upon any such registration or transfer, a new warrant to purchase
Common Stock, in substantially the form of this Warrant (any such new warrant, a
"New Warrant"), evidencing the portion of this Warrant so transferred shall be
issued to the transferee and a New Warrant evidencing the remaining portion of
this Warrant not so transferred, if any, shall be issued to the transferring
Holder. The acceptance of the New Warrant by the transferee thereof shall be
deemed the acceptance of such transferee of all of the rights and obligations of
a holder of a Warrant.

                  (b) This Warrant is exchangeable, upon the surrender hereof by
the Holder to the Company at its address for notice set forth in Section 11 for
one or more New Warrants, evidencing in the aggregate the right to purchase the
number of Warrant Shares which may then be purchased hereunder. Any such New
Warrant will be dated the date of such exchange.

            3. Duration, Exercise and Redemption of Warrants.

                  (a)   Company Call Option.

             (i) Subject to the terms and conditions set forth herein, prior to
2:30 p.m. (New York City time) on any Trading Day (as defined in Exhibit A)
during the period between the Effective Date (as defined in Exhibit A) and the
Trading Day immediately following the second year anniversary of the Effective
Date (the "Expiration Date"), the Company may deliver written notices to the
Holder (each, a "Call Notice" and the Trading Day a Call Notice is delivered, a
"Delivery Date"), of the Company's election to call, for a price of $.0005 per
Warrant Share, a portion of this Warrant as further described herein; provided
that such price shall be adjusted to reflect any adjustment in the number of
Warrant Shares issuable hereunder, so that the maximum aggregate redemption
price shall continue to be $1,000. Notwithstanding anything to the contrary set
forth in this Warrant: (1) a Call Notice may not apply to a number of Warrant
Shares in excess of 15% of the average trading volume of the Common Stock for
the two Trading Days immediately preceding the Delivery Date, (2) no Call Notice
may be delivered until the expiration of the Call Expiration Time (as defined
below) for the immediately preceding Call Notice, (3) a Call Notice may indicate
that if the Exercise Price (as defined herein) applicable to an exercise of this
Warrant pursuant to such Call Notice shall be lower than a dollar amount
designated by the Company in such Call Notice (such dollar amount, a "Floor
Price"), then, at the option of the





                                      -2-
                                                                 Class B Warrant
<PAGE>   3
Holder: (A) the Exercise Price shall, exclusively for the purpose of such Call
Notice, equal the Floor Price or (B) such Call Notice shall be null and void ab
initio, provided, that a Floor Price must be less than 90% of the Per Share
Market Value on the Trading Day preceding the Delivery Date and (4) no Call
Notice may be delivered unless the conditions set forth in Section 3(a)(iii)
have been either satisfied by the Company or waived by the Holder.

            (ii) The portion of this Warrant subject to a Call Notice will be
canceled and of no further effect from and after 5:30 p.m. (New York City time)
on the Trading Day following Delivery Date (the "Call Expiration Time"), unless
between the Delivery Date and the Call Expiration Time the Holder notifies the
Company in writing that it will exercise this Warrant to acquire the number of
Warrant Shares subject to such Call Notice at the Exercise Price per share set
forth in Section 3(c). Such exercise shall be in accordance with Section
3(b)(ii).

            (iii) The right of the Company to deliver a Call Notice is subject
to the satisfaction or waiver by the Holder, at or before the applicable Call
Expiration Time, of each of the following conditions (and, if after delivery
thereof and on the applicable Exercise Date, any of the following conditions
shall cease to be met, such Call Notice, at the option of the Holder, shall be
null and void ab initio):


                  (a)   The representations and warranties of the Company
                        contained in the Purchase Agreement shall be true and
                        correct as of each of the applicable Delivery Date
                        and Call Expiration Time, as though first made on and
                        as of such Delivery Date and Call Expiration Time
                        (other than representations and warranties which
                        relate to a specific date (which shall not include
                        representations and warranties relating to the "date
                        hereof") which representations and warranties shall
                        be true as of such specific date);

                  (b)   The Company shall have performed, satisfied and
                        complied in all material respects with all covenants
                        (including timely delivery of Warrant Shares in
                        accordance with Section 3(a)), agreements and
                        conditions of the Transaction Documents (as defined
                        in the Purchase Agreement) to be performed, satisfied
                        or complied with by the Company at or prior to the
                        applicable Delivery Date and Call Expiration Time;

                  (c)   The Underlying Shares Registration Statement (as defined
                        in Exhibit A) shall be effective on the Delivery Date,
                        not subject to any stop order or suspension;

                  (d)   No statute, rule, regulation, executive order, decree,
                        ruling or injunction shall have been enacted, entered,
                        promulgated or




                                      -3-
                                                                 Class B Warrant
<PAGE>   4
                        endorsed by any court or governmental authority of
                        competent jurisdiction and in force on the Delivery Date
                        which prohibits the consummation of any of the
                        transactions contemplated by the Transaction Documents;

                  (e)   Since the Closing Date (as defined in the Purchase
                        Agreement), no event or series of events which
                        reasonably would be expected to have or result in a
                        Material Adverse Effect (as defined in the Purchase
                        Agreement) and no Change of Control Transaction (as
                        defined in Exhibit A) shall have occurred;

                  (f)   Since the Closing Date, trading in the Common Stock
                        shall not have been suspended by the Securities and
                        Exchange Commission for a period in excess of five
                        consecutive Trading Days or ten Trading Days in the
                        aggregate (which need not be consecutive Trading
                        Days), except for any suspensions of trading of not
                        more than one Trading Day solely to permit
                        dissemination of material information regarding the
                        Company;

                  (g)   On the Delivery Date, the Common Stock shall be trading
                        on the Nasdaq Small Cap Market ("NASDAQ"), or on the
                        Nasdaq National Market, New York Stock Exchange or
                        American Stock Exchange (each, a "Subsequent Market");

                  (h)   No approval of the shareholders of the Company shall be
                        required under the rules of the Nasdaq Stock Market or
                        any other Subsequent Market on which the Common Stock is
                        traded or listed for trading in order to issue the
                        number of Warrant Shares indicated in the applicable
                        Call Notice at the Exercise Price;

                  (i)   For the five Trading Days immediately preceding the
                        applicable Delivery Date, the average daily trading
                        volume of the Common Stock on the NASDAQ as reported by
                        Bloomberg L.P., shall be at least 20,000 shares and the
                        average of the Per Share Market Values (as defined in
                        Exhibit A) for such five Trading Days shall be at least
                        $5.00; and

                  (j)   The Call Notice at issue would not result in a violation
                        of Section 3(e).

                  (b)   Exercise By Holder.




                                      -4-
                                                                 Class B Warrant
<PAGE>   5
            (i) At any time on and after the Effective Date (and in the case of
an election to purchase which is not in response to a Call Notice, if earlier,
the 90th day after the date of this Warrant) and prior to 5:30 p.m. (New York
City time) on the Expiration Date, the Holder shall be entitled to purchase all
or a portion of the Warrant Shares which have not been previously issued and
with respect to which this Warrant has not been previously redeemed or canceled
in accordance with the terms hereof.

            (ii) The Holder may purchase Warrant Shares hereunder by delivering
to the Company, at its address for notice set forth in Section 11, a completed
Form of Election to Purchase in the form attached hereto, together with the
payment of the Exercise Price multiplied by the number of Warrant Shares
indicated therein. An "Exercise Date" means the date of the delivery (which may
be made via facsimile) of the Form of Election to Purchase and applicable
Exercise Price.

            (iii) After the end of the week in which the Company receives one or
more Forms of Election to Purchase and the applicable Exercise Price, the
Company shall promptly (but in no event later than three Trading Days following
the end of such week) issue or cause to be issued and cause to be delivered to
or upon the written order of the Holder and in such name or names as the Holder
may designate, a certificate for the Warrant Shares issuable upon such exercise,
free of restrictive legends except as required by the Purchase Agreement,
provided, that, if in any week the Company shall receive one or more Forms of
Election to Purchase for the purchase of in excess of 30,000 Warrant Shares, the
Company shall issue such certificate no later than the third Trading Day
following the date of the delivery of the applicable Form of Election to
Purchase which resulted in the purchase of in excess of 30,000 Warrant Shares.

                  (A)   If the Company fails to deliver to the Holder the
                        certificate or certificates pursuant to this Section
                        within the time specified in above, the Holder shall be
                        entitled by written notice to the Company at any time on
                        or before its receipt of such certificate or
                        certificates thereafter, to rescind such exercise.

                  (B)   In addition to the rights set forth in (A) above, if
                        the Company fails to deliver to the Holder such
                        certificate or certificates pursuant to this Section
                        within the time specified in above, and if after such
                        time the Holder purchases (in an open market
                        transaction or otherwise) Common Stock to deliver in
                        satisfaction of a sale by such Holder of the Warrant
                        Shares which the Holder anticipated receiving upon
                        such exercise (a "Buy-In"), then the Company shall
                        (1) pay in cash to the Holder  the amount by which
                        (x) the Holder's total purchase price (including
                        brokerage commissions, if any) for the Common Stock
                        so purchased exceeds (y) the product of (i) the
                        aggregate number of Warrant Shares that such Holder
                        anticipated receiving from the exercise at issue
                        multiplied by (ii) the Per Share Market





                                      -5-
                                                                 Class B Warrant
<PAGE>   6
                           Value on the Exercise Date and (2) at the option of
                           the Holder, either rescind the exercise at issue or
                           deliver to the Holder the number of Warrant Shares
                           that would have been issued had the Company timely
                           complied with its delivery requirements under this
                           Section. For example, if the Holder purchases Common
                           Stock having a total purchase price of $11,000 to
                           cover a Buy-In with respect to an attempted exercise
                           with respect to which the Per Share Market Value on
                           the Exercise Date was a total of $10,000, the Company
                           shall be required to pay the Holder $1,000. The
                           Holder shall provide the Company written notice
                           indicating the amounts payable to the Holder in
                           respect of the Buy-In.

                  (c)      Exercise Price.

            The "Exercise Price" applicable to an exercise following a Call
Notice under Section 3(a) shall equal the lower of (i) $33.75(subject to
equitable adjustment for stock splits, reverse splits, combinations and other
similar events) and (ii) 97% of the Per Share Market Value on the Trading Day
immediately following the applicable Delivery Date. The Exercise Price
applicable to an exercise pursuant to Section 3(b)(i) that is not in response to
a Call Notice shall equal $33.75 (subject to equitable adjustment for stock
splits, reverse splits, combinations and other similar events). The Exercise
Price shall be subject to adjustment in accordance with Section 8.

                  (d) Redemption at Option of Company.

            On and after the 6th month anniversary of the Effective Date, the
Company may redeem all or any portion of this Warrant which has not been
previously exercised and for which no Form of Election to Purchase shall been
received by delivery to the Holder of a notice of such redemption, together with
the redemption price equal to $.05 per Warrant Share to be redeemed, payable by
the third Trading Day following the delivery of such notice by the Company;
provided that the redemption price shall be adjusted to reflect any adjustment
in the number of Warrant Shares issuable hereunder, so that the maximum
aggregate redemption price shall continue to be $100,000. Interest shall accrue
on the unpaid portion of such redemption price at the rate of 10% per annum
beginning on such third Trading Day.

                  (e)   Certain Exercise Restrictions.

            (i) The Company may not issue Warrant Shares upon exercise of this
Warrant, in response to a Call Notice in excess of the product of (x) 50% and
(y)19.9999% of the shares of Common Stock outstanding on the Closing Date, less
an amount equal to the aggregate number of shares of Common Stock issued (A)
upon conversion of the Company's 5% Subordinated Convertible Debentures
originally issued to the Holder, and (B) upon any exercise of this Warrant, in
response to a Call Notice unless the Company shall have obtained the approval of
the





                                      -6-
                                                                 Class B Warrant
<PAGE>   7
stockholders of the Company as required under the rules of the Nasdaq Stock
Market or such other exchange or trading facility on which the Common Stock is
traded or listed for trading for such issuance. In the event of any subdivision,
transfer or exchange of this Warrant, the limitation contained in this Section
3(e)(i) shall be appropriately adjusted to ensure that in no event shall the
Company issue, upon any exercise of this Warrant in response to a Call Notice,
in excess of the product of (x) 50% and (y) 19.999% of the shares of Common
Stock outstanding on the Closing Date, less an amount equal to the aggregate
number of shares of Common Stock issued (A) upon conversion of the Company's 5%
Subordinated Convertible Debentures originally issued to the Holder, and (B)
upon any exercise of this Warrant, in response to a Call Notice unless the
Company shall have obtained the approval of the stockholders of the Company as
required under the rules of the Nasdaq Stock Market or such other exchange or
trading facility on which the Common Stock is traded or listed for trading for
such issuance.

            (ii) A Holder may not exercise this Warrant to the extent such
exercise would result in the Holder, together with any affiliate thereof,
beneficially owning (as determined in accordance with Section 13(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act") and the rules
promulgated thereunder) in excess of 9.999% of the then issued and outstanding
shares of Common Stock, including shares issuable upon such exercise and held by
such Holder after application of this Section. Since the Holder will not be
obligated to report to the Company the number of shares of Common Stock it may
hold at the time of an exercise hereunder, unless the exercise at issue would
result in the issuance of shares of Common Stock in excess of 9.999% of the then
outstanding shares of Common Stock without regard to any other shares which may
be beneficially owned by the Holder or an affiliate thereof, the Holder shall
have the authority and obligation to determine whether the restriction contained
in this Section will limit any particular exercise hereunder and to the extent
that the Holder determines that the limitation contained in this Section
applies, the determination of which portion of this Warrant is exercisable shall
be the responsibility and obligation of the Holder. If the Holder has delivered
a Form of Election to Purchase for a number of Warrant Shares that, without
regard to any other shares that the Holder or its affiliates may beneficially
own, would result in the issuance in excess of the permitted amount hereunder,
the Company shall notify the Holder of this fact and shall honor the exercise
for the maximum portion of this Warrant permitted to be exercised on such Date
of Exercise in accordance with the periods described herein and, at the option
of the Holder, either keep the portion of the Warrant tendered for exercise in
excess of the permitted amount hereunder for future exercises or return such
excess portion of the Warrant to the Holder. The provisions of this Section may
be waived by a Holder (but only as to itself and not to any other Holder) upon
not less than 61 days prior notice to the Company.

            4. Piggyback Registration Rights. During the Effectiveness Period
(as defined in the Registration Rights Agreement, of even date herewith, between
the Company and the original Holder), the Company may not file any registration
statement with the Securities and Exchange Commission (other than registration
statements of the Company filed on Form S-8 or Form S-4, each as promulgated
under the Securities Act, pursuant to which the Company is registering
securities pursuant to a Company employee benefit plan or pursuant to a merger,






                                      -7-
                                                                 Class B Warrant
<PAGE>   8
acquisition or similar transaction including supplements thereto, but not
additionally filed registration statements in respect of such securities) at any
time when there is not an effective registration statement covering the resale
of the Warrant Shares and naming the Holder as a selling stockholder thereunder,
unless the Company provides the Holder with not less than 20 days notice of its
intention to file such registration statement and provides the Holder the option
to include any or all of the applicable Warrant Shares therein. The piggyback
registration rights granted to the Holder pursuant to this Section shall
continue until all of the Holder's Warrant Shares have been sold in accordance
with an effective registration statement or upon the expiration of the Effective
Period. The Company will pay all registration expenses in connection therewith.

            5. Payment of Taxes. The Company will pay all documentary stamp
taxes attributable to the issuance of Warrant Shares upon the exercise of this
Warrant; provided, however, that the Company shall not be required to pay any
tax which may be payable in respect of any transfer involved in the registration
of any certificates for Warrant Shares or Warrants in a name other than that of
the Holder. The Holder shall be responsible for all other tax liability that may
arise as a result of holding or transferring this Warrant or receiving Warrant
Shares upon exercise hereof.

            6. Replacement of Warrant. If this Warrant is mutilated, lost,
stolen or destroyed, the Company shall issue or cause to be issued in exchange
and substitution for and upon cancellation hereof, or in lieu of and
substitution for this Warrant, a New Warrant, but only upon receipt of evidence
reasonably satisfactory to the Company of such loss, theft or destruction and
indemnity, if requested, satisfactory to it. Applicants for a New Warrant under
such circumstances shall also comply with such other reasonable regulations and
procedures and pay such other reasonable charges as the Company may prescribe.

            7. Reservation of Warrant Shares. The Company covenants that it will
at all times reserve and keep available out of the aggregate of its authorized
but unissued Common Stock, solely for the purpose of enabling it to issue
Warrant Shares upon exercise of this Warrant as herein provided, the number of
Warrant Shares which are then issuable and deliverable upon the exercise of this
entire Warrant, free from preemptive rights or any other actual contingent
purchase rights of persons other than the Holder (taking into account the
adjustments and restrictions of Section 8). The Company covenants that all
Warrant Shares that shall be so issuable and deliverable shall, upon issuance
and the payment of the applicable Exercise Price in accordance with the terms
hereof, be duly and validly authorized, issued and fully paid and nonassessable.

            8.    Certain Adjustments.

                  (a) In case of any reclassification of the Common Stock or any
compulsory share exchange pursuant to which the Common Stock is converted into
other securities, cash or property, then the Holder shall have the right
thereafter to exercise this Warrant only into the shares of stock and other
securities and property receivable upon or deemed to be





                                      -8-
                                                                 Class B Warrant
<PAGE>   9
held by holders of Common Stock following such reclassification or share
exchange, and the Holder shall be entitled upon such exercise to receive such
amount of securities or property equal to the amount of Warrant Shares such
Holder would have been entitled to had such Holder exercised this Warrant
immediately prior to such reclassification or share exchange.

                  (b) In case of the closing of any (1) merger or consolidation
of the Company with or into another Person, or (2) sale by the Company of more
than one-half of the assets of the Company (on a book value basis) in one or a
series of related transactions, or (3) tender or other offer or exchange
(whether by the Company or another Person) pursuant to which holders of Common
Stock are permitted to tender or exchange their shares for other securities,
stock, cash or property of the Company or another Person; then the Holder shall
have the right thereafter to (A) exercise this Warrant for the shares of stock
and other securities, cash and property receivable upon or deemed to be held by
holders of Common Stock following such merger, consolidation or sale, and the
Holder shall be entitled upon exercise of this Warrant to receive such amount of
securities, cash and property as the Common Stock for which this Warrant could
have been exercised immediately prior to such merger, consolidation or sales
would have been entitled, or (B) in the event of an exchange or tender offer or
other transaction contemplated by clause (3) of this Section, tender or exchange
this Warrant for such securities, stock, cash and other property receivable upon
or deemed to be held by holders of Common Stock that have tendered or exchanged
their shares of Common Stock following such tender or exchange, and the Holder
shall be entitled upon such exchange or tender to receive such amount of
securities, cash and property as the shares of Common Stock for which this
Warrant could have been exercised immediately prior to such tender or exchange
would have been entitled as would have been issued. The terms of any such
merger, sale, consolidation, tender or exchange shall include such terms so as
continue to give the Holder the right to receive the securities, cash and
property set forth in this Section upon any conversion or redemption following
such event. This provision shall similarly apply to successive such events.

                  (c) All calculations under this Section 8 shall be made to the
nearest cent or the nearest 1/100th of a share, as the case may be.

                  (d) If (i) the Company shall declare a dividend (or any other
distribution) on its Common Stock; or (ii) the Company shall declare a special
nonrecurring cash dividend on or a redemption of its Common Stock; or (iii) the
Company shall authorize the granting to all holders of the Common Stock rights
or warrants to subscribe for or purchase any shares of capital stock of any
class or of any rights; or (iv) the approval of any stockholders of the Company
shall be required in connection with any reclassification of the Common Stock,
any consolidation or merger to which the Company is a party, any sale or
transfer of all or substantially all of the assets of the Company, or any
compulsory share exchange whereby the Common Stock is converted into other
securities, cash or property; or (v) the Company shall authorize the voluntary
dissolution, liquidation or winding up of the affairs of the Company, then the
Company shall cause to be mailed to each Holder at their last addresses as they
shall appear upon the Warrant Register, at least 30 calendar days prior to the
applicable record or effective date





                                      -9-
                                                                 Class B Warrant
<PAGE>   10
hereinafter specified, a notice stating (x) the date on which a record is to be
taken for the purpose of such dividend, distribution, redemption, rights or
warrants, or if a record is not to be taken, the date as of which the holders of
Common Stock of record to be entitled to such dividend, distributions,
redemption, rights or warrants are to be determined or (y) the date on which
such reclassification, consolidation, merger, sale, transfer or share exchange
is expected to become effective or close, and the date as of which it is
expected that holders of Common Stock of record shall be entitled to exchange
their shares of Common Stock for securities, cash or other property deliverable
upon such reclassification, consolidation, merger, sale, transfer, share
exchange, dissolution, liquidation or winding up, provided, that the failure to
mail such notice or any defect therein or in the mailing thereof shall not
affect the validity of the corporate action required to be specified in such
notice.

            9. Payment of Exercise Price. The Holder shall pay the Exercise
Price for Warrant Shares purchased hereunder by delivery of immediately
available funds.

            10. Fractional Shares. The Company shall not be required to issue or
cause to be issued fractional Warrant Shares on the exercise of this Warrant.
The number of full Warrant Shares which shall be issuable upon the exercise of
this Warrant shall be computed on the basis of the aggregate number of Warrant
Shares purchasable on exercise of this Warrant so presented. If any fraction of
a Warrant Share would, except for the provisions of this Section, be issuable on
the exercise of this Warrant, the Company shall pay an amount in cash equal to
the Exercise Price multiplied by such fraction.

            11. Notices. Any and all notices or other communications or
deliveries hereunder shall be in writing and shall be deemed given and effective
on the earliest of (i) the date of transmission, if such notice or communication
is delivered via facsimile at the facsimile telephone number specified in this
Section prior to 8:00 p.m. (New York City time) on a business day, (ii) the
business day after the date of transmission, if such notice or communication is
delivered via facsimile at the facsimile telephone number specified in this
Section later than 8:00 p.m. (New York City time) on any date and earlier than
11:59 p.m. (New York City time) on such date, (iii) the business day following
the date of mailing, if sent by nationally recognized overnight courier service,
or (iv) if sent other than by the methods set forth in (i)-(iii) of this
section, upon actual receipt by the party to whom such notice is required to be
given. The addresses for such communications shall be: (i) if to the Company, to
157 Technology Drive, Irvine, CA 92618, Attention: Chief Financial Officer, or
to Facsimile No. (949) 788-6706, or (ii) if to the Holder, to the Holder at the
address or facsimile number appearing on the Warrant Register or such other
address or facsimile number as the Holder may provide to the Company in
accordance with this Section.

            12. Warrant Agent. The Company shall serve as warrant agent under
this Warrant. Upon thirty (30) days' notice to the Holder, the Company may
appoint a new warrant agent. Any corporation into which the Company or any new
warrant agent may be merged or any corporation resulting from any consolidation
to which the Company or any new warrant agent





                                      -10-
                                                                 Class B Warrant
<PAGE>   11
shall be a party or any corporation to which the Company or any new warrant
agent transfers substantially all of its corporate trust or shareholders
services business shall be a successor warrant agent under this Warrant without
any further act. Any such successor warrant agent shall promptly cause notice of
its succession as warrant agent to be mailed (by first class mail, postage
prepaid) to the Holder at the Holder's last address as shown on the Warrant
Register.

            13.   Miscellaneous.

                  (a) This Warrant shall be binding on and inure to the benefit
of the parties hereto and their respective successors and assigns. This Warrant
may be amended only in writing signed by the Company and the Holder and their
successors and assigns.

                  (b) Subject to Section 13(a), above, nothing in this Warrant
shall be construed to give to any person or corporation other than the Company
and the Holder any legal or equitable right, remedy or cause under this Warrant.
This Warrant shall inure to the sole and exclusive benefit of the Company and
the Holder.

                  (c) The corporate laws of the State of Delaware shall govern
all issues concerning the relative rights of the Company and its stockholders.
All other questions concerning the construction, validity, enforcement and
interpretation of this Warrant shall be governed by and construed and enforced
in accordance with the internal laws of the State of New York, without regard to
the principles of conflicts of law thereof. The Company and the Holder hereby
irrevocably submit to the exclusive jurisdiction of the state and federal courts
sitting in the City of New York, borough of Manhattan, for the adjudication of
any dispute hereunder or in connection herewith or with any transaction
contemplated hereby or discussed herein, and hereby irrevocably waives, and
agrees not to assert in any suit, action or proceeding, any claim that it is not
personally subject to the jurisdiction of any such court, or that such suit,
action or proceeding is improper. Each of the Company and the Holder hereby
irrevocably waives personal service of process and consents to process being
served in any such suit, action or proceeding by receiving a copy thereof sent
to the Company at the address in effect for notices to it under this instrument
and agrees that such service shall constitute good and sufficient service of
process and notice thereof. Nothing contained herein shall be deemed to limit in
any way any right to serve process in any manner permitted by law.

                  (d) The headings herein are for convenience only, do not
constitute a part of this Warrant and shall not be deemed to limit or affect any
of the provisions hereof.

                  (e) In case any one or more of the provisions of this Warrant
shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall not
in any way be affected or impaired thereby and the parties will attempt in good
faith to agree upon a valid and enforceable provision which shall be a
commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.

                 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                            SIGNATURE PAGE FOLLOWS]


                                                                 Class B Warrant

                                      -11-
<PAGE>   12
            IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed by its authorized officer as of the date first indicated above.


                                            NEOTHERAPEUTICS, INC.

                                            By: /s/ Samuel Gulko
                                                ------------------------------
                                                Name: Samuel Gulko
                                                Title: Chief Financial Officer
<PAGE>   13
                          FORM OF ELECTION TO PURCHASE

(To be executed by the Holder to exercise the right to purchase shares of Common
Stock under the foregoing Warrant)

To NeoTherapeutics, Inc.:

      In accordance with the Warrant enclosed with this Form of Election to
Purchase, the undersigned hereby irrevocably elects to purchase _____________
shares of common stock, $.001 par value per share, of NeoTherapeutics, Inc. (the
"Common Stock") and , if such Holder is not utilizing the cashless exercise
provisions set forth in this Warrant, encloses herewith $________ in cash,
certified or official bank check or checks, which sum represents the aggregate
Exercise Price (as defined in the Warrant) for the number of shares of Common
Stock to which this Form of Election to Purchase relates, together with any
applicable taxes payable by the undersigned pursuant to the Warrant.

      The undersigned requests that certificates for the shares of Common Stock
issuable upon this exercise be issued in the name of

PLEASE INSERT SOCIAL SECURITY OR TAX IDENTIFICATION NUMBER

________________________________________________________________________________

________________________________________________________________________________
                         (Please print name and address)

________________________________________________________________________________

________________________________________________________________________________


      If the number of shares of Common Stock issuable upon this exercise shall
not be all of the shares of Common Stock which the undersigned is entitled to
purchase in accordance with the enclosed Warrant, the undersigned requests that
a New Warrant (as defined in the Warrant) evidencing the right to purchase the
shares of Common Stock not issuable pursuant to the exercise evidenced hereby be
issued in the name of and delivered to:

________________________________________________________________________________
                         (Please print name and address)

________________________________________________________________________________

________________________________________________________________________________


Dated: ___________, _____                   Name of Holder:


(Print) ________________________________________________________________________

(By:) __________________________________________________________________________
Name:)
(Title:)
                                          (Signature must conform in all
                                          respects to name of holder as
                                          specified on the face of the
                                          Warrant)

                                                                 Class B Warrant
<PAGE>   14
                               FORM OF ASSIGNMENT

          [To be completed and signed only upon transfer of Warrant]

      FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto ________________________________ the right represented by the within
Warrant to purchase ____________ shares of Common Stock of NeoTherapeutics, Inc.
to which the within Warrant relates and appoints ________________ attorney to
transfer said right on the books of NeoTherapeutics Inc. with full power of
substitution in the premises.

Dated:

______________,____


                              ______________________________________

                              (Signature must conform in all respects to name
                              of holder as specified on the face of the
                              Warrant)

                              ______________________________________
                              Address of Transferee

                              ______________________________________

                              ______________________________________



In the presence of:


___________________


                                                                 Class B Warrant
<PAGE>   15
                                                                       EXHIBIT A


      (i) "Business Day" means any day except Saturday, Sunday and any day which
shall be a federal legal holiday or a day on which banking institutions in the
State of New York and the State of California are authorized or required by law
or other governmental action to close.

      (ii) "Change of Control Transaction" means the occurrence of any of (i) an
acquisition after the date hereof by an individual or legal entity or "group"
(as described in Rule 13d-5(b)(1) promulgated under the Exchange Act) of
effective control (whether through legal or beneficial ownership of capital
stock of the Company, by contract or otherwise) of in excess of 33% of the
voting securities of the Company, (ii) a replacement at one time or over time of
more than one-half of the members of the Company's board of directors which is
not approved by a majority of those individuals who are members of the board of
directors on the date hereof (or by those individuals who are serving as members
of the board of directors on any date whose nomination to the board of directors
was approved by a majority of the members of the board of directors who are
members on the date hereof), (iii) the merger or consolidation of the Company
with or into another entity that is not wholly-owned by the Company upon the
completion of which the stockholders of the Company immediately before such
merger or consolidation own or control less than 2/3 of the voting securities of
the surviving entity or sale of 50% or more of the assets of the Company in one
or a series of related transactions, or (i) the execution by the Company of an
agreement to which the Company is a party or by which it is bound, providing for
any of the events set forth above in (i), (ii) or (iii).

      (iii) "Commission" means the Securities and Exchange Commission.

      (iv) "Effective Date" means the date the Underlying Shares Registration
Statement is declared effective by the Commission.

      (v) "Per Share Market Value" means on any particular date (a) the closing
bid price per share of Common Stock on such date on the NASDAQ or on such
Subsequent Market on which the shares of Common Stock are then listed or quoted,
or if there is no such price on such date, then the closing bid price on the
NASDAQ or on such Subsequent Market on the date nearest preceding such date, or
(b) if the shares of Common Stock are not then listed or quoted on the NASDAQ or
a Subsequent Market, the closing bid price for a share of Common Stock in the
over-the-counter market, as reported by the National Quotation Bureau
Incorporated or similar organization or agency succeeding to its functions of
reporting prices) at the close of business on such date, or (c) if the shares of
Common Stock are not then reported by the National Quotation Bureau Incorporated
(or similar organization or agency succeeding to its functions of reporting
prices), then the average of the "Pink Sheet" quotes for the relevant conversion
period, as determined in good faith by the Holder, or (d) if the shares of
Common Stock are not then publicly traded the fair market value of a share of
Common Stock as determined by an Appraiser selected in good faith by the Holders
of a majority in interest of the Warrants then outstanding.

      (vi) "Purchase Agreement" means the Convertible Debenture Purchase
Agreement dated as of the date hereof, to which the Company and the original
Holder hereof are parties.

                                                                 Class B Warrant
<PAGE>   16
      (vii) "Trading Day" means (a) a day on which the shares of Common Stock
are traded on the NASDAQ or on such Subsequent Market on which the shares of
Common Stock are then listed or quoted, or (b) if the shares of Common Stock are
not listed on the NASDAQ or a Subsequent Market, a day on which the shares of
Common Stock are traded in the over-the-counter market, as reported by the OTC
Bulletin Board, or (c) if the shares of Common Stock are not quoted on the OTC
Bulletin Board, a day on which the shares of Common Stock are quoted in the
over-the-counter market as reported by the National Quotation Bureau
Incorporated (or any similar organization or agency succeeding its functions of
reporting prices); provided, however, that in the event that the shares of
Common Stock are not listed or quoted as set forth in (a), (b) and (c) hereof,
then Trading Day shall mean a Business Day.

      (viii) "Underlying Shares Registration Statement" shall have the meaning
set forth in the Purchase Agreement.

                                                                 Class B Warrant

<PAGE>   1
                                                                     EXHIBIT 4.8

                         STRONG RIVER INVESTMENTS, INC.
                   C/O GONZALEZ-RUIZ & ALEMAN (BVI) LIMITED
                        WICKHAMS CAY I, VANTERPOOL PLAZA
                                  P.O. BOX 873
                           ROAD TOWN, TORTOLLA. B.V.I.


                            MONTROSE INVESTMENTS LTD.
                          300 CRESCENT COURT, SUITE 700
                                DALLAS, TX 75201


                                                                   April 6, 2000

NeoTherapeutics, Inc.
157 Technology Drive
Irvine, CA 92618
Attention: President

      Re:   NeoTherapeutics, Inc.  (the "Company").

Gentlemen:

            Reference is made to the Convertible Debenture Purchase Agreement
(the "Purchase Agreement"), of even date hereof, between the Company and the
undersigned (the "Purchasers"), pursuant to which the Company will issue and
sell to the Purchasers: (i) an aggregate principal amount of $10,000,000 of the
Company's 5% Convertible Debentures, due April 6, 2005 (the "Initial
Debentures"), (ii) Common Stock purchase warrants, each in the form of Exhibit D
to the Purchase Agreement, pursuant to which the holder thereof shall have the
right, under certain circumstances described therein, to acquire shares of
Common Stock upon the terms set forth therein (the "Initial Warrants") and (iii)
certain additional Common Stock purchase warrants, each in the form of Exhibit E
to the Purchase Agreement (the "Class B Warrants"), for an aggregate purchase
price of $10,000,000. Capitalized terms used and not otherwise defined in this
letter that are defined in the Purchase Agreement shall have the meanings set
forth in the Purchase Agreement. The Initial Warrants and the Initial Debentures
are sometimes collectively referred to herein as the "Initial Securities."

            The Purchasers shall, severally and not jointly, commit, subject to
and upon the terms and conditions hereof, to purchase from the Company, and the
Company shall sell to the Purchasers (A) on the First Additional Closing Date
(as defined herein): (i) up to $10,000,000 principal amount of the Company's 5%
Convertible Debentures, due five years from the date of

                                                                     Side Letter
<PAGE>   2
their issuance (the "First Additional Debentures"), and (ii) additional Initial
Warrants pursuant to which the holders thereof shall have the right at any time
and from time to time thereafter through the fifth anniversary of the First
Additional Closing (as defined herein) to acquire an aggregate of up to 115,000
shares of Common Stock (the "First Additional Warrants" and together with the
First Additional Debentures, the "First Additional Securities"), for an
aggregate purchase price of up to 10% of the market capitalization of the Common
Stock on the First Additional Closing Date, not to exceed $10,000,000 (the
"First Additional Purchase Price"), provided, that each Purchaser's portion of
the First Additional Purchase Price (and the First Additional Securities
issuable therefor) shall be reduced by the sum of (I) the aggregate amount of
the Exercise Prices (as defined in the Class B Warrants) paid by such Purchaser
pursuant to exercises of the Class B Warrant issued to it, on or prior to the
First Additional Closing Date and (II) the maximum aggregate amount of Exercise
Prices that could have been payable upon exercise of the portion, if any, of the
Class B Warrant issued to such Purchaser that is redeemed by the Company on or
prior to the First Additional Closing Date (the "Cash Amount") and (B) on the
Second Additional Closing Date (as defined herein): (i) up to $10,000,000
principal amount of the Company's 5% Convertible Debentures, due five years from
the date of their issuance (the "Second Additional Debentures" and together with
the First Additional Debentures, the "Additional Debentures"), and (ii)
additional Initial Warrants pursuant to which the holders thereof shall have the
right at any time and from time to time thereafter through the fifth anniversary
of the Second Additional Closing (as defined herein) to acquire an aggregate of
up to 115,000 shares of Common Stock (the "Second Additional Warrants" and
together with the First Additional Warrants, the "Additional Warrants") (the
Second Additional Debentures and the Second Additional Warrants are
collectively, the "Second Additional Securities"), for an aggregate purchase
price of up to 10% of the market capitalization of the Common Stock on the
Second Additional Closing Date, not to exceed $10,000,000 (the "Second
Additional Purchase Price"), provided, that each Purchaser's portion of the
Second Additional Purchase Price (and the Second Additional Securities issuable
therefor) shall be reduced by the sum of (I) the aggregate amount of the
Exercise Prices paid by such Purchaser pursuant to exercises of the Class B
Warrant issued to it, during the period between the First Additional Closing
Date and the Second Additional Closing Date, (II) the maximum aggregate amount
of Exercise Prices that could have been payable upon exercise of the portion, if
any, of the Class B Warrant issued to such Purchaser that is redeemed by the
Company during the period between the First Additional Closing Date and the
Second Additional Closing Date and (C) if the Cash Amount exceeds $10,000,000,
the difference between the Cash Amount and $10,000,000.

            The commitment of the Purchasers set forth in this letter is subject
to the terms, conditions and qualifications set forth below:

            1. Form of Additional Debentures. The Additional Debentures shall be
identical to the Initial Debentures, mutatis mutandis, except that the Initial
Conversion Price (as defined in the Initial Debentures) applicable to (i) the
First Additional Debentures, shall be equal to 120% of the Per Share Market
Value on the First Additional Closing Date and (ii) the Second Additional

                                                                     Side Letter

                                      -2-
<PAGE>   3
Debentures, shall be equal to 120% of the Per Share Market Value on the Second
Additional Closing Date.

            2. Form of Additional Warrants. The Additional Warrants shall be
identical to the Initial Warrants, except that Section 3(d) shall be deleted and
the Exercise Price (as defined in the Initial Warrants) applicable to (i) the
First Additional Warrants, shall be equal to 125% of the average of the Per
Share Market Value for the five (5) Trading Days immediately preceding the First
Additional Closing Date and (ii) the Second Additional Warrants, shall be equal
to 125% of the average of the Per Share Market Value for the five (5) Trading
Days immediately preceding the Second Additional Closing Date.

            3. First Additional Documentation. In order to effectuate a purchase
and sale of the First Additional Securities, prior to their issuance, the
Company and the Purchasers shall enter into the following agreements: (a) a
securities purchase agreement identical to the Purchase Agreement, mutatis
mutandis (provided, that Section 3.9 relating to rights of first refusal and
registration lock-up shall be deleted) and shall include updated Schedules (the
"First Additional Purchase Agreement") and (b) a registration rights agreement
identical to the Registration Rights Agreement, mutatis mutandis and shall
include updated Schedules (the "First Additional Registration Rights Agreement",
and together with the First Additional Purchase Agreement and the First
Additional Warrants, collectively the "First Additional Transaction Documents").
The Purchasers shall prepare the First Additional Transaction Documents.

            4. Second Additional Documentation. In order to effectuate a
purchase and sale of the Second Additional Securities, prior to their issuance,
the Company and the Purchasers shall enter into the following agreements: (a) a
securities purchase agreement identical to the Purchase Agreement, mutatis
mutandis (provided, that the Threshold Date (as defined in the Purchase
Agreement) shall equal the date the registration statement filed pursuant to the
Second Additional Registration Rights Agreement (as defined herein) is declared
effective by the Commission) and shall include updated Schedules (the "Second
Additional Purchase Agreement") and (b) a registration rights agreement
identical to the Registration Rights Agreement, mutatis mutandis and shall
include updated Schedules (the "Second Additional Registration Rights
Agreement", and together with the Second Additional Purchase Agreement and the
Second Additional Warrants, collectively the "Second Additional Transaction
Documents"). The Purchasers shall prepare the Second Additional Transaction
Documents.

            5. The First Additional Closing. (i) The Purchasers and the Company
shall each have the right to deliver a written notice to the other (the "First
Additional Financing Notice") requiring such other party to either sell or buy
(severally and not jointly), as the case may be, the First Additional Securities
for the First Additional Purchase Price. Notwithstanding anything herein to the
contrary, upon the delivery of a First Additional Financing Notice by a
Purchaser to the Company: (x) the Conversion Price (as defined in the Initial
Debentures) applicable to the First Additional Debentures to be sold to such
Purchaser, shall be equal to $20.00 and (y) if the Class B Warrants shall be
canceled pursuant to Section 2(f) of the Registration Rights Agreement, then


                                                                     Side Letter

                                      -3-
<PAGE>   4
such Purchaser's portion of the aggregate First Additional Purchase Price (and
the First Additional Securities issuable therefor) shall not exceed $2,500,000.
The First Additional Financing Notice may be delivered by (i) a Purchaser,
between 2:30 p.m. (New York City time) on September 3, 2000 and 4:30 p.m. (New
York City time) on September 4, 2000 and (ii) the Company, between 4:30 p.m.
(New York City time) on September 4, 2000 and 4:30 p.m. (New York City time) on
September 13, 2000, or as otherwise agreed to by the parties hereto. At the
First Additional Closing each Purchaser shall (subject to the terms and
conditions herein) purchase such portion of the First Additional Securities as
equals such Purchaser's pro-rata portion of the Initial Securities issued and
sold at the Closing. The closing of the purchase and sale of the First
Additional Securities (the "First Additional Closing") shall take place at the
offices of Robinson Silverman,1290 Avenue of the Americas, New York, New York
10104, on the fifth (5th) Business Day after the First Additional Financing
Notice is received by the Purchasers or the Company, as the case may be, or on
such other date as otherwise agreed to by the parties hereto, provided, that in
no case shall the First Additional Closing take place unless and until all of
the conditions listed in Section 7 of this letter shall have been satisfied by
the Company or waived by the Purchasers. The date of the First Additional
Closing is hereinafter referred to as the "First Additional Closing Date."
Notwithstanding anything to the contrary contained in this letter, each
Purchaser may, prior to the First Additional Closing Date, designate an
Affiliate thereof to acquire all or any portion of the First Additional
Securities.

            (ii) At the First Additional Closing, the parties shall deliver or
shall cause to be delivered the following: (a) the Company shall deliver to (x)
each Purchaser or its designated Affiliate: (1) the First Additional Debentures
in the aggregate principal amount equal to portion of the First Additional
Purchase Price paid by such Purchaser, registered in the name of such Purchaser
or its designated Affiliate, (2) a First Additional Warrant registered in the
name of such Purchaser or its designated Affiliate, entitling the holder thereof
to purchase such portion of the aggregate shares of Common Stock underlying the
First Additional Warrants as equals such Purchaser's pro-rata portion of the
aggregate First Additional Purchase Price paid, (3) a legal opinion in form and
substance acceptable to the Purchasers and (4) executed First Additional
Transaction Documents and the Transfer Agent Instructions relating to the First
Additional Securities, and (y) Robinson Silverman, up to $25,000 for the legal
fees and expenses incurred by the Purchasers to prepare the First Additional
Transaction Documents, which amount shall be deducted by the Purchasers from the
First Additional Purchase Price and shall be paid directly to Robinson Silverman
and (b) each Purchaser shall deliver to the Company (1) its pro rata portion of
the First Additional Purchase Price, in United States dollars in immediately
available funds by wire transfer to an account designated in writing by the
Company for such purpose prior to the First Additional Closing Date and (2) the
executed First Additional Transaction Documents.

            6. The Second Additional Closing. (i) The Purchasers and the Company
shall each have the right to deliver a written notice to the other (the "Second
Additional Financing Notice") requiring such other party to either sell or buy
(severally and not jointly), as the case may be, the Second Additional
Securities for the Second Additional Purchase Price. Notwithstanding anything
herein to the contrary, upon the delivery of a Second Additional Financing
Notice by a Purchaser to the Company: (x) the Conversion Price applicable to the
Second Additional Debentures to be sold to such Purchaser, shall be equal to
$20.00 and (y) if the Class B Warrants shall be canceled pursuant to Section
2(f) of the Registration Rights Agreement, then such Purchaser's portion of

                                                                     Side Letter




                                      -4-
<PAGE>   5
the aggregate Second Additional Purchase Price (and the Second Additional
Securities issuable therefor) shall not exceed $2,500,000. The Second Additional
Financing Notice may be delivered by (i) a Purchaser, between 4:30 p.m. (New
York City time) on January 31, 2001 and 4:30 p.m. (New York City time) on
February 1, 2001 and (ii) the Company, between 4:30 p.m. (New York City time) on
February 1, 2001 and 4:30 p.m. (New York City time) on February 9, 2001, or as
otherwise agreed to by the parties hereto. At the Second Additional Closing (as
defined herein) each Purchaser shall (subject to the terms and conditions
herein) purchase such portion of the Second Additional Securities as equals such
Purchaser's pro-rata portion of the Initial Securities issued and sold at the
Closing. The closing of the purchase and sale of the Second Additional
Securities (the "Second Additional Closing") shall take place at the offices of
Robinson Silverman,1290 Avenue of the Americas, New York, New York 10104, on the
fifth (5th) Business Day after the Second Additional Financing Notice is
received by the Purchasers or the Company, as the case may be, or on such other
date as otherwise agreed to by the parties hereto, provided, that in no case
shall the Second Additional Closing take place unless and until all of the
conditions listed in Section 8 of this letter shall have been satisfied by the
Company or waived by the Purchasers. The date of the Second Additional Closing
is hereinafter referred to as the "Second Additional Closing Date."
Notwithstanding anything to the contrary contained in this letter, each
Purchaser may, prior to the Second Additional Closing Date, designate an
Affiliate thereof to acquire all or any portion of the Second Additional
Securities.

            (ii) At the Second Additional Closing, the parties shall deliver or
shall cause to be delivered the following: (a) the Company shall deliver to (x)
each Purchaser or its designated Affiliate: (1) the Second Additional Debentures
in the aggregate principal amount equal to portion of the Second Additional
Purchase Price paid by such Purchaser, registered in the name of such Purchaser
or its designated Affiliate, (2) a Second Additional Warrant registered in the
name of such Purchaser or its designated Affiliate, entitling the holder thereof
to purchase such portion of the aggregate shares of Common Stock underlying the
Second Additional Warrants as equals such Purchaser's pro-rata portion of the
aggregate Second Additional Purchase Price paid, (3) a legal opinion in form and
substance acceptable to the Purchasers and (4) executed Second Additional
Transaction Documents and the Transfer Agent Instructions relating to the Second
Additional Securities, and (y) Robinson Silverman, up to $25,000 for the legal
fees and expenses incurred by the Purchasers to prepare the Second Additional
Transaction Documents, which amount shall be deducted by the Purchasers from the
Second Additional Purchase Price and shall be paid directly to Robinson
Silverman and (b) each Purchaser shall deliver to the Company (1) its pro rata
portion of the Second Additional Purchase Price, in United States dollars in
immediately available funds by wire transfer to an account designated in writing
by the Company for such purpose prior to the Second Additional Closing Date and
(2) the executed Second Additional Transaction Documents.

            7. Conditions precedent to the First Additional Closing.
Notwithstanding anything to the contrary contained in this letter, the
commitment of a Purchaser to purchase acquire the First Additional Securities is
subject to the satisfaction or waiver by the Purchasers of each of the following
conditions:

            a. Closing of Initial Securities.  The Closing shall have occurred;

                                                                     Side Letter

                                      -5-
<PAGE>   6
            b. Accuracy of the Company's Representations and Warranties. The
representations and warranties of the Company contained in the Purchase
Agreement shall be true and correct as of the date when made and as of the First
Additional Closing Date as though made on and as of the First Additional Closing
Date (other than representations and warranties which relate to a specific date
(which shall not include representations and warranties relating to the "date
hereof") which representations and warranties shall be true as of such specific
date);

            c. Performance by the Company. The Company shall have performed,
satisfied and complied with all covenants, agreements and conditions required by
the Transaction Documents to be performed, satisfied or complied with by the
Company between the Closing Date and the First Additional Closing Date and no
Event (as defined in the Registration Rights Agreement ) shall have occurred
which has not been cured to the satisfaction of the Purchasers;

            d. Underlying Shares Registration Statement. The Underlying Shares
Registration Statement shall have been declared effective under the Securities
Act by the Commission for a period equal to no less than one month preceding the
First Additional Closing Date and shall have remained effective at all times,
not subject to any actual or threatened stop order or subject to any actual or
threatened suspension at any time prior to the First Additional Closing Date,
for more than five consecutive Trading Days or an aggregate of ten Trading Days
(which need not be consecutive Trading Days);

            e. No Injunction. Since the Closing Date, no statute, rule,
regulation, executive order, decree, ruling or injunction shall have been
enacted, entered, promulgated, amended, modified or endorsed by any court of
governmental authority of competent jurisdiction or governmental authority,
stock market or trading facility which prohibits the consummation of any of the
transactions contemplated by the First Additional Transaction Documents or makes
impracticable the transactions contemplated thereby;

            f. Adverse Changes.  Since the Closing Date, no event or series of
events which reasonably would be expected to have or result in a Material
Adverse Effect shall have occurred;

            g. No Suspensions of Trading in Common Stock. Since the Closing
Date, the trading in the Common Stock shall not have been suspended by the
Commission or on the NASDAQ for more than five consecutive Trading Days or an
aggregate of ten Trading Days (which need not be consecutive Trading Days);

            h. Listing of Common Stock. On the First Additional Closing Date,
the Common Stock shall be traded on the NASDAQ and, since the Closing Date, the
Common Stock shall not have been delisted therefrom for more than five
consecutive Trading Days or an aggregate of ten Trading Days (which need not be
consecutive Trading Days);

                                                                     Side Letter

                                      -6-
<PAGE>   7
            i. Shares of Common Stock. The Company shall have duly reserved the
number of shares of Common Stock as required by the First Additional Transaction
Documents to be reserved for issuance upon exercise of the First Additional
Warrants and conversion of the First Additional Debentures;

            j. Performance of Exercise and Conversion Obligations. The Company
shall have timely complied with its exercise, conversion and delivery
requirements under the Initial Warrants and Initial Debentures;

            k. Shareholder Approval. The Company shall have obtained the
approval of its shareholders to issue in excess of 20% of its Common Stock at a
price which is lower than the greater of the book or market value of the Common
Stock in connection with the Closing, the First Additional Closing and the
Second Additional Closing, as required under the rules of the Nasdaq Stock
Market or such other exchange or trading facility or which the Common Stock is
the traded or listed for trading; and

            l. Deliveries pursuant to First Additional Transaction Documents. At
the First Additional Closing, the Company shall deliver the First Additional
Securities and executed First Additional Transaction Documents and Transfer
Agent Instructions relating to the First Additional Securities in the forms
contemplated by this letter.

            8. Conditions precedent to the Second Additional Closing.
Notwithstanding anything to the contrary contained in this letter, the
commitment of a Purchaser to purchase acquire the Second Additional Securities
is subject to the satisfaction or waiver by the Purchasers of each of the
following conditions:

            a. Closing of Initial Securities.  The Closing shall have occurred;

            b. Accuracy of the Company's Representations and Warranties. The
representations and warranties of the Company contained in the Purchase
Agreement shall be true and correct as of the date when made and as of the
Second Additional Closing Date as though made on and as of the Second Additional
Closing Date (other than representations and warranties which relate to a
specific date (which shall not include representations and warranties relating
to the "date hereof") which representations and warranties shall be true as of
such specific date);

            c. Performance by the Company. The Company shall have performed,
satisfied and complied with all covenants, agreements and conditions required by
the Transaction Documents and the First Additional Transaction Documents to be
performed, satisfied or complied with by the Company between the Closing Date
and the Second Additional Closing Date and no Event shall have occurred which
has not been cured to the satisfaction of the Purchasers;

            d. Second Underlying Shares Registration Statement. The registration
statement filed pursuant to the First Additional Registration Rights Agreement
shall have been

                                                                     Side Letter


                                      -7-
<PAGE>   8
declared effective under the Securities Act by the Commission for a period equal
to no less than one month preceding the Second Additional Closing Date and shall
have remained effective at all times, not subject to any actual or threatened
stop order or subject to any actual or threatened suspension at any time prior
to the Second Additional Closing Date for more than five consecutive Trading
Days or an aggregate of ten Trading Days (which need not be consecutive Trading
Days);

            e. No Injunction. Since the Closing Date, no statute, rule,
regulation, executive order, decree, ruling or injunction shall have been
enacted, entered, promulgated, amended, modified or endorsed by any court of
governmental authority of competent jurisdiction or governmental authority,
stock market or trading facility which prohibits the consummation of any of the
transactions contemplated by the Second Additional Transaction Documents or
makes impracticable the transactions contemplated thereby;

            f. Adverse Changes. Since the Closing Date, no event or series of
events which, in the sole opinion of the Purchasers, could have or result in a
Material Adverse Effect shall have occurred;

            g. No Suspensions of Trading in Common Stock. Since the Closing
Date, the trading in the Common Stock shall not have been suspended by the
Commission or on the NASDAQ for more than five consecutive Trading Days or an
aggregate of ten Trading Days (which need not be consecutive Trading Days);

            h. Listing of Common Stock. On the Second Additional Closing Date,
the Common Stock shall be traded on the NASDAQ and, since the Closing Date, the
Common Stock shall not have been delisted therefrom for more than five
consecutive Trading Days or an aggregate of ten Trading Days (which need not be
consecutive Trading Days);

            i. Shares of Common Stock. The Company shall have duly reserved the
number of shares of Common Stock as required by the Second Additional
Transaction Documents to be reserved for issuance upon exercise of the Second
Additional Warrants and conversion of the Second Additional Debentures;

            j. Performance of Conversion and Exercise Obligations. The Company
shall have timely complied with its exercise, conversion and delivery
requirements under the First Additional Warrants and the First Additional
Debentures; and

            k. Deliveries pursuant to Second Additional Transaction Documents.
At the Second Additional Closing, the Company shall deliver the Second
Additional Securities and executed Second Additional Transaction Documents and
Transfer Agent Instructions relating to the Second Additional Securities in the
forms contemplated by this letter.

            9. Independent Nature of Purchasers' Obligations and Rights. The
obligations of each Purchaser hereunder is several and not joint with the
obligations of any other Purchaser

                                                                     Side Letter



                                      -8-
<PAGE>   9
hereunder, and neither Purchaser shall be responsible in any way for the
performance of the obligations of any other Purchaser hereunder. Nothing
contained herein or in any other agreement or document delivered at any closing,
and no action taken by any Purchaser pursuant hereto or thereto, shall be deemed
to constitute the Purchasers as a partnership, an association, a joint venture
or any other kind of entity, or create a presumption that the Purchasers are in
any way acting in concert with respect to such obligations or the transactions
contemplated by this Agreement. Each Purchaser shall be entitled to protect and
enforce its rights, including, without limitation, the rights arising out of
this letter or out of the either the First Additional Transaction Documents or
the Second Additional Transaction Documents, if any, and it shall not be
necessary for any other Purchaser to be joined as an additional party in any
proceeding for such purpose.

            10. Governing Law. This letter shall be governed by and construed
and enforced in accordance with the internal laws of the State of New York,
without regard to the principles of conflicts of law thereof.

            11. Execution. This letter may be executed in two or more
counterparts, all of which when taken together shall be considered one and the
same agreement and shall become effective when counterparts have been signed by
each party and delivered to the other party, it being understood that both
parties need not sign the same counterpart. In the event that any signature is
delivered by facsimile transmission, such signature shall create a valid and
binding obligation of the party executing (or on whose behalf such signature is
executed) the same with the same force and effect as if such facsimile signature
page were an original thereof.

                                                                     Side Letter


                                      -9-
<PAGE>   10
            Please indicate your agreement with the foregoing by executing a
countersigned copy of this letter and returning the same to our attention,
whereupon effective immediately thereafter this letter shall become a legally
valid and binding agreement between the Purchasers and the Company.


            We look forward to our continuing relationship.

            Sincerely,

            Strong River Investments, Inc.


             By:  /s/ Kenneth L. Henderson
                  --------------------------------
                  Name:  Kenneth L. Henderson
                  Title: Attorney-in-fact

            Montrose Investments Ltd.


             By:  /s/ Harlan B. Korenvaes
                  --------------------------------
                  Name:  Harlan B. Korenvaes
                  Title: Authorized Signatory



Agreed and accepted
April 6, 2000

NeoTherapeutics, Inc.


By:   /s/ Samuel Gulko
      Name:  Samuel Gulko
      Title: Chief Financial Officer

                                                                     Side Letter



                                      -10-


<PAGE>   1
                                                                    EXHIBIT 99.1

                                                           FOR IMMEDIATE RELEASE

         NEOTHERAPEUTICS OBTAINS MAJOR FINANCING FOR CLINICAL STUDIES OF
                     NEOTROFIN(TM) FOR ALZHEIMER'S DISEASE

IRVINE, California - April 10, 2000--NeoTherapeutics, Inc. (Nasdaq: NEOT, NEOTW)
announced today the closing of a major financing transaction with two investor
groups who have previously invested with the Company. In conjunction with this
new financing, the investors have also eliminated the remaining reset provision
of a previous financing. The new transaction consists of an initial tranche at
the closing of $10 million in 5% subordinated convertible debentures due April
6, 2005. In addition, subject to certain conditions, the investors have agreed
to fund two future tranches of up to $10 million each and redeemable warrants to
purchase up to 4 million shares of common stock over a two-year period (the "B"
warrants). The "B" warrants can be redeemed in part by the Company as frequently
as several times per week and when called for redemption can be exercised by the
investors at 97% of the per share closing market price (i.e. a discount of 3%)
and are exercisable at the sole option of the investors at the price of $33.75
per share. Based on the current market price, the "B" warrants could potentially
generate approximately $69 million of equity financing. The number of "B"
warrants that are exercisable at each redemption are subject to average daily
volume restrictions.

The debentures are convertible into common stock at $20.25 per share for the
first 90 days after the closing. Thereafter, they are convertible at the lesser
of $20.25 per share or 101% of the market price of the common stock as
determined under the agreement. The two additional tranches of convertible
debentures of up to $10 million each, 5 and 10 months after the closing, are at
the option of either the Company or the investor. If at the option of the
Company, the tranches are under similar terms and conditions as the initial
tranche. If at the option of the investor, the two tranches are at the fixed
conversion price of $20 per share. The amount available under the two additional
tranches will be reduced pro-rata to the extent that the investors have
exercised or the Company has redeemed the "B" warrants to purchase common stock.
The investors also received five-year warrants to purchase up to 265,000 shares
of common stock (the "A" warrants). The "A" warrants are exercisable at $19.672
per share.

In connection with this financing, the investors, who are the same investors who
purchased $10 million in common stock on November 19, 1999, as well as other
financings, have agreed to eliminate the second reset available to them under
the November 1999 agreement. Accordingly, under the terms of that agreement, the
investors received an additional 43,383 shares of common stock under the terms
of the first reset provision which, when combined with their original purchase
at 108% of the market price, made the effective purchase price equal to
approximately 103% of the market price at that time.

"This financing, assuming completion of all segments, should allow
NeoTherapeutics to complete the existing Phase 2 clinical development program
for our lead product candidate, NEOTROFIN(TM) for Alzheimer's disease", stated
Sam Gulko, NeoTherapeutics' Chief Financial Officer. "Now we can devote



<PAGE>   2

NeoTherapeutics Obtains Major Financing for Clinical Stucies of NEOTROFIN(TM)
April 10, 2000
Page 2


financial and human resources towards developing NEOTROFIN(TM) for possible
treatment of other neurodegenerative conditions, as well as the expansion of our
functional genomics company, NeoGene Technologies, Inc. This is NeoTherapeutics'
fourth round of financing with these institutional investors, and our mutual
confidence has encouraged us to expand our relationship. We are very pleased
that this financing has been arranged so that we receive funds over time,
consistent with our needs, and that the agreement includes incremental pricing
consistent with the performance of NeoTherapeutics' stock as progress continues
in the clinical studies of NEOTROFIN(TM). Finally, this financing agreement
represents a significant advancement in NeoTherapeutics' ongoing efforts to
provide effective treatments to patients suffering from neurodegenerative
diseases."

NEOTROFIN(TM) is being developed for nerve repair and regeneration, with
Alzheimer's disease as its first clinical indication. Pre-clinical studies have
demonstrated that NEOTROFIN(TM) causes the production of multiple natural nerve
growth (neurotrophic) factors and restores function in animal models of
cognitive decline, aging, neuroprotection, and spinal cord injury. Human
clinical studies have demonstrated positive effects of NEOTROFIN(TM) on memory
and behavioral function in patients with Alzheimer's disease.

According to figures from the Alzheimer's Association, Alzheimer's disease
presently affects over 4 million people in the U.S. and approximately 12 million
patients worldwide, with associated health care costs of $80-$100 billion per
year. Drugs such as Aricept(R), developed by Eisai and marketed by both Eisai
and Pfizer, and the soon to be marketed Exelon(R), developed by Novartis, have
been approved for the treatment of symptoms of mild to moderate Alzheimer's
disease.

NeoTherapeutics' research program is focused on designing and developing small
molecules capable of treating a range of neurological diseases and conditions
such as Alzheimer's and Parkinson's diseases, stroke, and spinal cord injury.
Additional compounds in NeoTherapeutics' product pipeline address other health
issues such as migraine and depression. NeoGene Technologies, Inc.,
NeoTherapeutics' subsidiary, is a functional genomics company engaged in the
development of a broad platform of enabling technology called receptor-targeted
drug design. NeoGene Technologies is using this technology to search for natural
and synthetic compounds that can potentially be developed as drugs for treating
various diseases. For additional Company information, visit the NeoTherapeutics
web site at www.neotherapeutics.com.

This press release contains forward-looking statements regarding future events
and the future performance of NeoTherapeutics that involve risks and
uncertainties that could cause actual results to differ materially. These risks
are described in further detail in the Company's reports filed with the
Securities and Exchange Commission.


CONTACTS:
Investment Community:                            Media:
Carol Gruetter                                   Kelly Finley
NeoTherapeutics, Inc.                            Halsted Communications, Inc.
Tel: (949) 788-6700                              Tel: (800) 600-7111 x.233
e-mail: [email protected]                 (323) 225-1835
                                                 e-mail:  [email protected]

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