EXHIBIT 4.3

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, (THE "SECURITIES ACT") PURSUANT TO AN
EXEMPTION FROM REGISTRATION CONTAINED IN REGULATION S PROMULGATED UNDER THE
SECURITIES ACT, AND MAY NOT BE TRANSFERRED EXCEPT IN ACCORDANCE WITH THE
PROVISIONS OF REGULATION S, PURSUANT TO A REGISTRATION UNDER THE SECURITIES ACT
OR PURSUANT TO AN AVAILABLE EXEMPTION FROM REGISTRATION. NO HEDGING TRANSACTIONS
INVOLVING THESE SECURITIES MAY BE CONDUCTED EXCEPT IN COMPLIANCE WITH THE
SECURITIES ACT.


                              NEOTHERAPEUTICS, INC.

                                     WARRANT

                               Dated: May 1, 2000


         NeoTherapeutics, Inc., a Delaware corporation (the "Company"), hereby
certifies that, for value received, Royal Canadian Growth Fund, an Ontario
trust, or its registered assigns ("Holder"), is entitled, subject to the terms
set forth below, to purchase from the Company up to a total of 125,000 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")
at an exercise price equal to $17.50 per share (as adjusted from time to time as
provided in Section 7, the "Exercise Price"), at any time and from time to time
from and after the date hereof and through and including May 1, 2005 (the
"Expiration 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 or the Warrant Shares issued upon any exercise
hereof 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 or any Warrant Shares other than pursuant to an effective
registration 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 transferred securities 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 in Section 2(b) below) or a legend of similar import
on any Warrant Shares issued upon an




exercise hereof. 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 conformance with Section 2(a) in the Warrant Register, upon
surrender of this Warrant, with the Form of Assignment attached hereto duly
completed and signed, to the Company at the office specified in or pursuant to
Section 10. 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.

         3. DURATION AND EXERCISE OF WARRANT.

             (a) This Warrant shall be exercisable by the then registered
Holder on any business day before 5:00 P.M., California time, at any time and
from time to time on or after the date hereof to and including the Expiration
Date. At 5:00 P.M., California time on the Expiration Date, the portion of this
Warrant not exercised prior thereto shall be and become void and of no value.

             (b) Subject to Sections 2(c), and 4, 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 10 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 5 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 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


                                       2


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. 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) Prior to the exercise of this Warrant, the Holder shall
not be entitled to any rights as a stockholder of the Company with respect to
the Warrant Shares, including (without limitation) the right to vote such
shares, receive dividends or other distributions thereon or be notified of
stockholder meetings (except as otherwise set forth in Section 7(f) herein).

         4. PAYMENT OF TAXES. The Company will pay any 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.

         5. 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.

         6. 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 7). 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.

         7. CERTAIN ADJUSTMENTS. The Exercise Price and number of Warrant Shares
issuable upon exercise of this Warrant are subject to adjustment from time to
time as set forth in this Section 7.

             (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 and not the Common
Stock) payable in


                                       3


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 adjusted by
multiplying the Exercise Price in effect immediately before such event 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 the
denominator shall be the number of shares of Common Stock (excluding treasury
shares, if any) outstanding after such event. The number of Warrant shares
issuable upon exercise of this Warrant shall be adjusted upon such adjustment of
the Exercise Price by multiplying the number of Warrant shares issuable upon
exercise of this Warrant immediately prior to such adjustment by a fraction of
which the denominator shall be the number of shares of Common Stock (excluding
treasury shares, if any) outstanding before such event and the numerator 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, any
consolidation or merger of the Company with or into another person, the sale or
transfer of all or substantially all of the assets of the Company 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, consolidation, merger, sale,
transfer or share exchange, and the Holder shall be entitled upon such event 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, consolidation, merger, sale,
transfer or share exchange. The terms of any such consolidation, merger, sale,
transfer 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 7(b) upon any exercise following any such reclassification,
consolidation, merger, sale, transfer 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 7(a), and (b)), then in each such case the Exercise Price shall be
reduced by subtracting from the Exercise Price in effect immediately prior to
the record date fixed for determination of stockholders entitled to receive such
distribution the fair market value on 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.

             (d) All calculations under this Section 7 shall be made to the
nearest cent or the nearest 1/100th of a share, as the case may be.

             (e) If:


                                       4


                           (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 of
                                    the Company, 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.

         8. PAYMENT OF EXERCISE PRICE. The Holder shall pay the Exercise Price
in one of the following manners:

         (a) Cash exercise. The Holder shall deliver immediately available funds
by certified check or bank draft payable to the order of the Company or by wire
transfer to an account designated by the Company; 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:


                                       5


                                    Y (A-B)
                           X =      -------
                                        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.

         9. 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 9, 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.

         10. 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 2:00 p.m. (California 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 2:00 p.m. (California time) on any date and earlier than
11:59 p.m. (California time) on such date, (iii) the business day following the
date of mailing, if sent by nationally recognized overnight courier service, or
(iv) 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, with a copy to Latham & Watkins, 650 Town
Center Drive, Suite 2000, Costa Mesa, California 92626, attention Alan W.
Pettis, Esq., 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 10, with a copy to Heller, Ehrman, White & McAuliffe, LLP, 4250
Executive Square 7th Floor, La Jolla, California 92037, attention: Stephen C.
Ferruolo, Esq.

         11. WARRANT AGENT. The Company shall serve as warrant agent under this
Warrant. The Company may appoint a new warrant agent upon notice to the Holder
in accordance with Section 10. Any corporation into which the Company may be
merged or any corporation resulting from any consolidation to which the Company
shall be a party or any corporation to which the Company


                                       6


transfers substantially all of its corporate assets 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.

         12.      MISCELLANEOUS.

                  (a) This Warrant shall be binding on and inure to the benefit
of the parties hereto and their respective successors and permitted 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 12(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) This Warrant shall be governed by and construed and
enforced in accordance with the internal laws of the State of California without
regard to the principles of conflicts of law thereof.

                  (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.

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


                                       7


                          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 ("Common Stock"), $.001 par value per share, of
NeoTherapeutics, Inc. 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)






                               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 Warrant enclosed with
this Form of Assignment to purchase __________ shares of Common Stock of
NeoTherapeutics, Inc. to which the 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:


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