<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