<PAGE>

                                  Exhibit 4.3

                                   EXHIBIT A
                                   ---------

     THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
     AS AMENDED (THE "SECURITIES ACT") OR UNDER THE SECURITIES LAWS OF ANY
     JURISDICTION AND MAY NOT BE TRANSFERRED, SOLD OR OTHERWISE DISPOSED OF
     UNLESS A REGISTRATION STATEMENT IS IN EFFECT UNDER THE SECURITIES ACT AND
     ANY APPLICABLE SECURITIES LAWS WITH RESPECT TO SUCH SECURITIES OR A WRITTEN
     OPINION OF COUNSEL REASONABLY ACCEPTABLE TO THE COMPANY IS PROVIDED TO THE
     COMPANY, TO THE EFFECT THAT NO REGISTRATION IS REQUIRED UNDER SUCH
     SECURITIES LAWS. THE SECURITIES MAY NOT BE SOLD OR OFFERED FOR SALE IN
     WHOLE OR IN PART NOR EXERCISED EXCEPT IN ACCORDANCE WITH THE PROVISIONS
     HEREOF.

                           OXIS INTERNATIONAL, INC.

                       WARRANT TO PURCHASE COMMON STOCK

     OXIS International, Inc., a Delaware corporation (the "Company"), hereby
     certifies that, for value received, ________________________ ("Investor"),
     the registered holder hereof, or its registered assigns, is entitled,
     subject to the terms set forth below, to purchase from the Company upon
     surrender of this Warrant, at any time or times after the date hereof, but
     not after 5:00 P.M., Portland, Oregon, USA time, on the Expiration Date (as
     defined herein), _____________fully paid nonassessable shares (the "Warrant
     Shares") of Common Stock (as defined herein) of the Company (as adjusted
     from time to time as provided in this Warrant) at an initial purchase price
     of US$______________ per share in lawful money of the United States of
     America.

     Section 1.   (a)  Definitions. The following words and terms as used in
                       -----------
     this Warrant shall have the following meanings:

          "Common Stock" means (a) the Company's Common Stock, par value $.001
          -------------
          and (b) any capital stock into which such Common Stock shall have been
          changed or any capital stock resulting from a reclassification of such
          Common Stock.

          "Expiration Date" means ______________, 2001 (one year after the
           ---------------
          Closing Date as defined in the Subscription Agreement)

          "Warrant Exercise Price" shall initially be US$_____________ per share
           ----------------------
     and shall be
<PAGE>

     adjusted and readjusted from time to time to the extent as provided in this
     Warrant.

          (b)    Other Definitional Provisions. (i) Except as otherwise
                 -----------------------------
     specified herein, all reference herein (A) to any person other than the
     Company, shall be deemed to include such person's successors and assigns,
     (B) to the Company shall be deemed to include the Company's successors and
     (C) to any applicable law defined or referred to herein, shall be deemed
     references to such applicable law as the same may have been or may be
     amended or supplemented from time to time.

          (ii)   When used in this Warrant, the words "herein," "hereof," and
     "hereunder," and words of similar import, shall refer to this Warrant as a
     whole and not to any provision of this Warrant, and the words "Section" and
     "Exhibit" shall refer to Sections of, and Exhibits to, this Warrant unless
     otherwise specified.

          (iii)  Whenever the context so requires the neuter gender includes the
     masculine or feminine, and the singular number includes the plural, and
     vice versa.

     Section 2.  Exercise of Warrant. (a) Subject to the terms and conditions
                 -------------------
hereof, this Warrant may be exercised, in whole or in part, at any time during
normal business hours on or after the opening of business on the date hereof and
prior to the close of business on the Expiration Date. The rights represented by
this Warrant may be exercised by the holder hereof then registered on the books
of the Company, in whole or from time to time in part (except that this Warrant
shall not be exercisable as to a fractional share) by (i) delivery of a written
notice, in the form of the Subscription Form attached as Exhibit A hereto, of
such holder's election to exercise this Warrant, which notice shall specify the
number of Warrant Shares to be purchased, (ii) payment to the Company of an
amount equal to the Warrant Exercise Price multiplied by the number of Warrant
Shares as to which the Warrant is being exercised (plus any applicable issue or
transfer taxes) in cash or by certified or official bank check, for the number
of Warrant Shares as to which this Warrant shall have been exercised, and (iii)
the surrender of this Warrant, properly endorsed, at the principal office of the
Company in Portland, Oregon (or at such other agency or office of the Company as
the Company may designate by notice to the holder hereof); provided, that if
such Warrant Shares are to be issued in any name other than that of the
registered holder of this Warrant, such issuance shall be deemed a transfer and
the provisions of Section 11 shall be applicable. In the event of any exercise
of the rights represented by this Warrant in compliance with this Section 2(a),
a certificate or certificates for the Warrant Shares so purchased, registered in
the name of, or as directed by, the holder, shall be delivered to, or as
directed by such holder within a reasonable time, not exceeding 15 days, after
such rights shall have been so exercised.

     (b)  Unless the rights represented by this Warrant shall have expired or
have been fully exercised, the Company shall issue a new Warrant identical in
all respects to the Warrant exercised except (x) it shall represent rights to
purchase the number of Warrant Shares purchasable immediately prior to such
exercise under the Warrant
<PAGE>

exercised, less the number of Warrant Shares with respect to which such Warrant
was exercised, and (y) the holder thereof shall be deemed to have become the
holder of record of such Warrant Shares immediately prior to the close of
business on the date on which the Warrant was surrendered and payment of the
amount due in respect of such exercise and any applicable taxes was made,
irrespective of the date of delivery of such share certificate, except that, if
the date of such surrender and payment is a date when the stock transfer books
of the Company are properly closed, such person shall be deemed to have become
the holder of such Warrant Shares at the opening of business on the next
succeeding date on which the stock transfer books are open.

     Section 3.  Covenants as to Common Stock. The Company covenants and agrees
                 ----------------------------
that all Warrant Shares which may be issued upon the exercise of the rights
represented by this Warrant will, upon issuance, be validly issued, fully paid
and nonassessable.

     Section 4.  Adjustment of Warrant Exercise Price Upon Stock Splits,
                 -------------------------------------------------------
Dividends, Distributions and Combinations; and Adjustment of Number of Shares.
-----------------------------------------------------------------------------
(a) In case the Company shall at any time subdivide its outstanding shares of
Common Stock into a greater number of shares or issue a stock dividend or make a
distribution with respect to outstanding shares of Common Stock payable in
Common Stock, the Warrant Exercise Price in effect immediately prior to such
subdivision or stock dividend or distribution shall be proportionately reduced
and conversely, in case the outstanding shares of Common Stock of the Company
shall be combined into a smaller number of shares, the Warrant Exercise Price in
effect immediately prior to such combination shall be proportionately increased
in each case by multiplying the then effective Warrant Exercise Price by a
fraction, the numerator of which shall be the number of shares of Common Stock
outstanding immediately prior to such action and the denominator of which shall
be the number of shares of Common Stock outstanding immediately after such
action, and the product so obtained shall thereafter be the Warrant Exercise
Price.

          (b)    Upon each adjustment of the Warrant Exercise Price as provided
above in this Section 4, the registered holder of this Warrant shall thereafter
be entitled to purchase, at the Warrant Exercise Price resulting from such
adjustment, the number of shares obtained by multiplying the Warrant Exercise
Price in effect immediately prior to such adjustment by the number of shares
purchasable pursuant hereto immediately prior to such adjustment and dividing
the product thereof by the Warrant Exercise Price after such adjustment.

     Section 5.  Notice of Adjustment of Warrant Exercise Price. Upon any
                 ----------------------------------------------
adjustment of the Warrant Exercise Price, the Company shall give notice thereof
to the registered holder of this Warrant, which notice shall state the Warrant
Exercise Price in effect after such adjustment and the increase, or decrease, if
any, in the number of shares purchasable at the Warrant Exercise Price upon the
exercise of this Warrant, setting forth in reasonable detail the method of
calculation and the facts upon which such calculation is based. In the event of
a merger, consolidation or reorganization of the Company with
<PAGE>

or into another corporation or corporations in which the Company is not the
surviving entity (other than a mere reincorporation transaction), a sale of all
or substantially all of the assets of the Company, or a transaction in which the
Company issues shares representing more than fifty percent (50%) of the voting
power in the Company immediately after giving effect to such transaction, the
Company shall give notice thereof to the registered holder of this Warrant at
least ten (10) business days prior to the consummation of such transaction.

     Section 6.  Computation of Adjustments. Upon each computation of an
                 --------------------------
adjustment in the Warrant Exercise Price and the number of shares which may be
subscribed for and purchased upon exercise of this Warrant, the Warrant Exercise
Price shall be computed to the nearest cent (i.e., fractions of .5 of a cent, or
greater, shall be rounded to the next highest cent) and the number of shares
which may be subscribed for and purchased upon exercise of this Warrant shall be
calculated to the nearest whole share (i.e., fractions of less than one half of
a share shall be disregarded and fractions of one half of a share, or greater,
shall be treated as being a whole share).

     Section 7.  No Change in Warrant Terms on Adjustment. Irrespective of any
                 ----------------------------------------
adjustment in the Warrant Exercise Price or the number of shares of Common Stock
issuable upon exercise hereof, this Warrant, whether theretofore or thereafter
issued or reissued, may continue to express the same price and number of shares
as are stated herein and the Warrant Exercise Price and such number of shares
specified herein shall be deemed to have been so adjusted.

     Section 8.  Taxes. The Company shall not be required to pay any tax or
                 -----
taxes attributable to the initial issuance of the Warrant Shares or any transfer
involved in the issue or delivery of any certificates for Warrant Shares of
Common Stock in a name other than that of the registered holder hereof or upon
any transfer of this Warrant.

     Section 9.  Warrant Holder Not Deemed a Shareholder. No holder, as such, of
                 ---------------------------------------
this Warrant shall be entitled to vote or receive dividends or be deemed the
holder of shares of the Company for any purpose, nor shall anything contained in
this Warrant be construed to confer upon the holder hereof, as such, any of the
rights of a shareholder of the Company or any right to vote, give or withhold
consent to any corporate action (whether any reorganization, issue of stock,
reclassification of stock, consolidation, merger, conveyance or otherwise),
receive notice of meetings, receive dividends or subscription rights, or
otherwise, prior to the issuance to the holder of this Warrant of the Warrant
Shares which it is then entitled to receive upon the due exercise of this
Warrant.

     Section 10. No Limitation on Corporate Action. No provisions of this
                 ---------------------------------
Warrant and no right or option granted or conferred hereunder shall in any way
limit, affect or abridge the exercise by the Company of any of its corporate
rights or powers to recapitalize, amend its Certificate of Incorporation,
reorganize, consolidate or merge with or into another corporation, or to
transfer all or any part of its property or assets, or the exercise of any other
of its corporate rights and powers.
<PAGE>

     Section 11. Transfer; Opinions of Counsel; Restrictive Legends.
                 --------------------------------------------------

          (a)    Prior to any sale, transfer or other disposition of this
Warrant or the Warrant Shares, the holder thereof will give ten (10) days'
notice to the Company of such holder's intention to effect such transfer. Each
such notice shall describe the manner and circumstances of the proposed transfer
and, if such transfer is not registered under the Securities Act of 1933, as
amended ("Securities Act"), shall be accompanied by an opinion, addressed to the
Company and reasonably satisfactory in form and substance to it, of counsel
(reasonably satisfactory to the Company) for such holder, stating whether, in
the opinion of such counsel, such transfer will be a transaction exempt from
registration under the Securities Act.

          (b)    If such sale, transfer or other disposition may in the opinion
of such counsel be effected without registration under the Securities Act, such
holder shall thereupon be entitled to the terms of the notice delivered by such
holder to the Company. If in the opinion of such counsel such transfer may not
be effected without registration under the Securities Act, such holder shall not
be entitled to so transfer this Warrant, or the Warrant Shares unless the
Company shall have filed a registration statement under the Securities Act
relating to such proposed transfer and such registration statement has become
effective under the Securities Act; provided, however, notwithstanding the
foregoing, the Company shall under no circumstances be obligated to file such a
registration statement relating to the transfer of this Warrant or the Warrant
Shares.

          (c)    Any Warrant Shares issued pursuant to the exercise of this
Warrant may bear one or more of the legends in similar form to the legend set
forth on this Warrant.

     Section 12. Exchange of Warrant. This Warrant is exchangeable upon the
                 -------------------
surrender hereof by the holder hereof at such office or agency of the Company,
for new Warrants of like tenor representing in the aggregate the right to
subscribe for and purchase the number of shares which may be subscribed for and
purchased hereunder from time to time after giving effect to all the provisions
hereof, each of such new Warrants to represent the right to subscribe for and
purchase such number of shares as shall be designated by said holder hereof at
the time of such surrender.

     Section 13. Lost, Stolen, Mutilated or Destroyed Warrant. If this Warrant
                 --------------------------------------------
is lost, stolen, mutilated or destroyed, the Company shall, on such terms as to
indemnity or otherwise as it may in its discretion impose (which shall, in the
case of a mutilated Warrant, include the surrender thereof), issue a new Warrant
of like denomination and tenor as the Warrant so lost, stolen, mutilated or
destroyed. Any such new Warrant shall constitute an original contractual
obligation of the Company, whether or not the allegedly lost, stolen, mutilated
or destroyed Warrant shall be at any time enforceable by anyone.

     Section 14. Representations of Holder. The holder of this Warrant, by the
                 -------------------------
acceptance hereof, represents that it is acquiring this Warrant for its own
account for investment and not with a view to, or sale in connection with, any
distribution hereof or
<PAGE>

of any of the shares of Common Stock or other securities issuable upon the
exercise thereof, nor with any present intention of distributing any of the
same. Investor represents that it is an "accredited investor" as such term is
defined under Regulation D of the Securities Act. Upon exercise of this Warrant,
the holder will confirm in writing, in form reasonably satisfactory to the
Company, the holder's investment intent.

     Section 15.  Notice. All notices and other communications under this
                  ------
Warrant shall (a) be in writing (which shall include communications by
telecopy), (b) be (i) sent by registered or certified mail, postage prepaid,
return receipt requested, by telecopier, or (ii) delivered by hand, (c) be given
at the following respective addresses and telecopier numbers and to the
attention of the following persons:

          (i)       if to the Company, to it at:

                    OXIS International, Inc.
                    Corporate Headquarters
                    6040 N. Cutter Circle, Suite 317
                    Portland, Oregon 97217-3935
                    Attention: Chief Financial Officer
                    Telephone: (503) 283-3911
                    Telecopier: (503) 283-4058

          (ii)      if to Investor, to it at the address set forth below
          Investor's signature on the signature page hereof.

or at such other address or telecopier number or to the attention of such other
person as the party to whom such information pertains may hereafter specify for
the purpose in a notice to the other specifically captioned "Notice of Change of
Address", and (d) be effective or deemed delivered or furnished (i) if given by
mail, on the fifth Business Day after such communication is deposited in the
mail, addressed as above provided, (ii) if given by telecopier, when such
communication is transmitted to the appropriate number determined as above
provided in this Section and the appropriate answer back is received or receipt
is otherwise acknowledged, and (iii) if given by hand delivery, when left at the
address of the addressee addressed as above provided, except that notices of a
change of address, telecopier or telephone number, shall not be deemed
furnished, until received.

     Section 16.  Miscellaneous. This Warrant and any term hereof may be
                  -------------
changed, waived, discharged, or terminated only by an instrument in writing
signed by the party or holder hereof against which enforcement of such change,
waiver, discharge or termination is sought. The headings in this Warrant are for
purposes of reference only and shall not limit or otherwise affect the meaning
hereof. This Warrant shall be governed by and interpreted under the laws of the
State of Oregon.  The courts sitting in the State of Oregon shall have the
exclusive jurisdiction over any dispute arising out of, or relating to, the
Warrant or the purchase of the Warrant Shares.
<PAGE>

     Section 17.  Date. The date of this Warrant is _________________________.
                  ----
This Warrant, in all events, shall be wholly void and of no effect after the
close of business on the Expiration Date, except that notwithstanding any other
provisions hereof, the provisions of Section 11 shall continue in full force and
effect after such date as to any Warrant Shares or other securities issued upon
the exercise of this Warrant.



                                        OXIS INTERNATIONAL, INC.

                                        By:________________________

                                        Name:______________________

                                        Title:_____________________



     ACCEPTED
     --------

     INVESTOR

     By:___________________________

     Name:_________________________

     Title:________________________

     Address:______________________

     ______________________________

     ______________________________
<PAGE>

                             EXHIBIT A TO WARRANT
                             --------------------

                               SUBSCRIPTION FORM

TO BE EXECUTED BY THE REGISTERED HOLDER IF SUCH REGISTERED HOLDER DESIRES TO
EXERCISE THIS WARRANT

                           OXIS INTERNATIONAL, INC.

     The undersigned hereby exercises the right to purchase Warrant Shares
covered by this Warrant according to the conditions thereof and herewith makes
payment of US $ __________________, the aggregate Warrant Exercise Price to
purchase _______ Warrant Shares.

    The undersigned represents that it is purchasing the Warrant Shares for its
own account for investment and not with a view to, or sale in connection with,
any distribution hereof, nor with any present intention of distributing the
same. The undersigned represents that it is an "accredited investor" as such
term is defined under Regulation D of the Securities Act of 1933, as amended
("Securities Act"). The Warrant Shares may not be sold, pledged, transferred,
hypothecated, or otherwise disposed of except pursuant to an effective
registration thereof under the Securities Act, or unless the Company shall have
received an opinion of counsel satisfactory to the Company that such
registration is not required.

                               INVESTOR:

     By:______________________________________

     Name:____________________________________

     Title:___________________________________

     Address:_________________________________

     _________________________________________

     _________________________________________

     Number of Warrant Shares Being Purchased:

     __________________________________________

Dated: ___________________, 200__.