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                                                                     EXHIBIT 4.2

                             AVANIR PHARMACEUTICALS
                          CLASS A COMMON STOCK WARRANT

         THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933
         (THE "ACT") OR APPLICABLE STATE SECURITIES LAWS. THE WARRANT HAS BEEN
         ACQUIRED FOR INVESTMENT PURPOSES AND MAY NOT BE OFFERED FOR SALE, SOLD,
         TRANSFERRED, PLEDGED OR OTHERWISE ASSIGNED IN THE ABSENCE OF AN
         EFFECTIVE REGISTRATION STATEMENT FOR THIS WARRANT UNDER THE ACT OR
         APPLICABLE STATE SECURITIES LAWS, OR AN OPINION OF COUNSEL, REASONABLY
         SATISFACTORY TO THE COMPANY, THAT REGISTRATION IS NOT REQUIRED UNDER
         THE ACT OR APPLICABLE STATE SECURITIES LAWS. THESE SECURITIES AND THE
         SECURITIES ISSUABLE UPON EXERCISE OF THESE SECURITIES MAY BE PLEDGED IN
         CONNECTION WITH A BONA FIDE MARGIN ACCOUNT.

         This certifies that [________________] (the "Holder"), or assigns, for
value received, is entitled to purchase from Avanir Pharmaceuticals (the
"Company"), subject to the terms set forth below, a maximum of [__________]
fully-paid and nonassessable shares (subject to adjustment as provided herein)
of the Company's Class A Common Stock, no par value, (the "Warrant Shares") for
cash at a price of $2.23 per share (the "Exercise Price") (subject to adjustment
as provided herein) at any time or from time to time up to and including 8:00
p.m. (Pacific Time) on July 23, 2008 (the "Expiration Date") upon surrender to
the Company at its principal office (or at such other location as the Company
may advise the Holder in writing) of this Warrant properly endorsed with the
Form of Subscription attached hereto duly completed and signed and upon payment
of the aggregate Exercise Price for the number of shares for which this Warrant
is being exercised determined in accordance with the provisions hereof. The
Exercise Price is subject to adjustment as provided in Section 3 of this
Warrant. This Warrant is issued subject to the following terms and conditions:

         1.       Exercise, Issuance of Certificates. The Holder may exercise
this Warrant on or prior to the Expiration Date, at any time or from time to
time following, for all or any part of the Warrant Shares (but not for a
fraction of a share) which may be purchased hereunder, as that number may be
adjusted pursuant to Section 3 of this Warrant. The Company agrees that the
Warrant Shares purchased under this Warrant shall be and are deemed to be issued
to the Holder hereof as the record owner of such Warrant Shares as of the close
of business on the date on which this Warrant shall have been surrendered,
properly endorsed, the completed and executed Form of Subscription delivered,
and payment made for such Warrant Shares (such date, a "Date of Exercise").
Certificates for the Warrant Shares so purchased, together with any other
securities or property to which the Holder hereof is entitled upon such
exercise, shall be delivered to the Holder hereof by the Company at the
Company's expense as soon as practicable after the rights represented by this
Warrant have been so exercised, but in any event not later than the third
trading day following the Date of Exercise. In case of a purchase of less than
all the Warrant Shares which may be purchased under this Warrant, the Company
shall cancel this Warrant and execute and deliver to the Holder hereof within a
reasonable time a new Warrant or

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Warrants of like tenor for the balance of the Warrant Shares purchasable under
the Warrant surrendered upon such purchase. Each stock certificate so delivered
shall be registered in the name of such Holder and issued with or without
legends in accordance with the Securities Purchase Agreement pursuant to which
this Warrant was originally issued (the "Purchase Agreement").

                  (a)      If by the third trading day after a Date of Exercise
the Company fails to deliver the required number of Warrant Shares in the manner
required pursuant to Section 5(a), then the Holder will have the right to
rescind such exercise.

                  (b)      If by the third trading day after a Date of Exercise
the Company fails to deliver the required number of Warrant Shares in the manner
required pursuant to Section 5(a), and if after such third trading day and prior
to the receipt of such Warrant Shares, the Holder purchases (in an open market
transaction or otherwise) shares of Common Stock to deliver in satisfaction of a
sale by the 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 shares of Common Stock so purchased
exceeds (y) the amount obtained by multiplying (A) the number of Warrant Shares
that the Company was required to deliver to the Holder in connection with the
exercise at issue by (B) the closing bid price of the Common Stock at the time
of the obligation giving rise to such purchase obligation and (2) at the option
of the Holder, either reinstate the portion of the Warrant and equivalent number
of Warrant Shares for which such exercise was not honored or deliver to the
Holder the number of shares of Common Stock that would have been issued had the
Company timely complied with its exercise and delivery obligations hereunder.
The Holder shall provide the Company written notice indicating the amounts
payable to the Holder in respect of the Buy-In.

                  (c)      The Company's obligations to issue and deliver
Warrant Shares in accordance with the terms hereof are absolute and
unconditional, irrespective of any action or inaction by the Holder to enforce
the same, any waiver or consent with respect to any provision hereof, the
recovery of any judgment against any Person or any action to enforce the same,
or any setoff, counterclaim, recoupment, limitation or termination, or any
breach or alleged breach by the Holder or any other Person of any obligation to
the Company or any violation or alleged violation of law by the Holder or any
other Person, and irrespective of any other circumstance which might otherwise
limit such obligation of the Company to the Holder in connection with the
issuance of Warrant Shares. Nothing herein shall limit a Holder's right to
pursue any other remedies available to it hereunder, at law or in equity
including, without limitation, a decree of specific performance and/or
injunctive relief with respect to the Company's failure to timely deliver
certificates representing shares of Common Stock upon exercise of the Warrant as
required pursuant to the terms hereof.

                  (d)      Payment of Exercise Price. The Holder shall pay the
Exercise Price by cash or immediately available funds; provided, however, that
if a registration statement registering the Warrant Shares for resale under the
Securities Act of 1933 (a "Registration Statement") is not then effective
(excluding any permissible suspensions of the use of the related prospectus, as
set forth in the Purchase Agreement, pursuant to which this Warrant was issued),

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then the Holder may notify the Company in an Exercise Notice of its election to
utilize 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 prices for the five
                    Trading Days immediately prior to (but not including)
                    the Exercise Date.

                    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
commenced, on the date this Warrant was originally issued.

                  (e)      Limitation on Exercise. Notwithstanding anything to
the contrary contained herein, the number of shares of Common Stock that may be
acquired by the Holder upon any exercise of this Warrant (or otherwise in
respect hereof) shall be limited to the extent necessary to insure that,
following such exercise (or other issuance), the total number of shares of
Common Stock then beneficially owned by such Holder and its Affiliates and any
other Persons whose beneficial ownership of Common Stock would be aggregated
with the Holder's for purposes of Section 13(d) of the Exchange Act, does not
exceed 4.999% of the total number of issued and outstanding shares of Common
Stock (including for such purpose the shares of Common Stock issuable upon such
exercise). For such purposes, beneficial ownership shall be determined in
accordance with Section 13(d) of the Exchange Act and the rules and regulations
promulgated thereunder. Each delivery of an Exercise Notice hereunder will
constitute a representation by the Holder that it has evaluated the limitation
set forth in this paragraph and determined that issuance of the full number of
Warrant Shares requested in such Exercise Notice is permitted under this
paragraph. This provision shall not restrict the number of shares of Common
Stock which a Holder may receive or beneficially own in order to determine the
amount of securities or other consideration that such Holder may receive in the
event of a merger or other business combination or reclassification involving
the Company as contemplated in this Warrant. This restriction may not be waived.

         2.       Shares to be Fully Paid; Reservation of Shares. The Company
covenants and agrees that all Warrant Shares, will, upon issuance and, if
applicable, payment of the applicable Exercise Price, be duly authorized,
validly issued, fully paid and nonassessable, and free of all preemptive rights,
liens and encumbrances, except for restrictions on transfer provided for herein.
The Company shall at all times reserve and keep available out of its authorized
and

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unissued Class A Common Stock ("Common Stock"), solely for the purpose of
providing for the exercise of the rights to purchase all Warrant Shares granted
pursuant to this Warrant, such number of shares of Common Stock as shall, from
time to time, be sufficient therefor.

         3.       Adjustment of Exercise Price and Number of Shares. The
Exercise Price and the total number of Warrant Shares shall be subject to
adjustment from time to time upon the occurrence of certain events described in
this Section 3. Upon each adjustment of the Exercise Price, the Holder of this
Warrant shall thereafter be entitled to purchase, at the Exercise Price
resulting from such adjustment, the number of shares obtained by multiplying the
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 Exercise Price resulting from such
adjustment.

                  3.1.     Subdivision or Combination of Stock. In the event the
outstanding shares of the Company's Common Stock shall be increased by a stock
dividend payable in Common Stock, stock split, subdivision, or other similar
transaction occurring after the date hereof into a greater number of shares of
Common Stock, the Exercise Price in effect immediately prior to such subdivision
shall be proportionately reduced and the number of Warrant Shares issuable
hereunder proportionately increased. Conversely, in the event the outstanding
shares of the Company's Common Stock shall be decreased by reverse stock split,
combination, consolidation, or other similar transaction occurring after the
date hereof into a lesser number of shares of Common Stock, the Exercise Price
in effect immediately prior to such combination shall be proportionately
increased and the number of Warrant Shares issuable hereunder proportionately
decreased.

                  3.2.     Reclassification. If any reclassification of the
capital stock of the Company or any reorganization, consolidation, merger, or
any sale, lease, license, exchange or other transfer (in one transaction or a
series of related transactions) of all or substantially all, of the business
and/or assets of the Company (the "Reclassification Events") shall be effected
in such a way that holders of Common Stock shall be entitled to receive stock,
securities, or other assets or property, then, as a condition of such
Reclassification Event lawful and adequate provisions shall be made whereby the
Holder hereof shall thereafter have the right to purchase and receive (in lieu
of the shares of Common Stock of the Company immediately theretofore purchasable
and receivable upon the exercise of the rights represented hereby) such shares
of stock, securities, or other assets or property as may be issued or payable
with respect to or in exchange for a number of outstanding shares of such Common
Stock equal to the number of shares of such stock immediately theretofore
purchasable and receivable upon the exercise of the rights represented hereby.
In any Reclassification Event, appropriate provision shall be made with respect
to the rights and interests of the Holder of this Warrant to the end that the
provisions hereof (including, without limitation, provisions for adjustments of
the Exercise Price and of the number of Warrant Shares), shall thereafter be
applicable, as nearly as may be, in relation to any shares of stock, securities,
or assets thereafter deliverable upon the exercise hereof.

                  3.3.     Notice of Adjustment. Upon any adjustment of the
Exercise Price or any increase or decrease in the number of Warrant Shares, the
Company shall give written notice thereof, by first class mail postage prepaid,
addressed to the registered Holder of this Warrant at

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the address of such Holder as shown on the books of the Company. The notice
shall be prepared and signed by the Company's Chief Financial Officer and shall
state the Exercise Price resulting from such adjustment and the increase or
decrease, if any, in the number of shares purchasable at such 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.

         4.       No Voting or Dividend Rights. Nothing contained in this
Warrant shall be construed as conferring upon the holder hereof the right to
vote or to consent to receive notice as a shareholder of the Company on any
other matters or any rights whatsoever as a shareholder of the Company. No
dividends or interest shall be payable or accrued in respect of this Warrant or
the interest represented hereby or the shares purchasable hereunder until, and
only to the extent that, this Warrant shall have been exercised.

         5.       Compliance with Securities Act. The Holder of this Warrant, by
acceptance hereof, agrees that this Warrant is being acquired for their own
account and not for any other person or persons, for investment purposes and
that it will not offer, sell, or otherwise dispose of this Warrant except under
circumstances which will not result in a violation of the Securities Act of 1933
or any applicable state securities laws.

         6.       Modification and Waiver. This Warrant and any provision hereof
may be changed, waived, discharged, or terminated only by an instrument in
writing signed by the party against whom enforcement of the same is sought.

         7.       Redemption. Subject to the provisions of this Section 7, at
any time after the second anniversary of the date of this Warrant, if: (i) the
closing bid price of the Common Stock for 15 consecutive trading days is greater
than 200% of the Exercise Price (as the same may be adjusted pursuant to Section
3), (ii) the Warrant Shares are either registered for resale pursuant to an
effective registration statement naming the Holder as a selling stockholder
thereunder (and the prospectus thereunder is available for use by the Holder as
to all then available Warrant Shares) or freely transferable without volume
restrictions pursuant to Rule 144(k) promulgated under the Securities Act, and
(iii) the Company has fully honored, in accordance with the terms of this
Warrant, all Forms of Subscription delivered prior to 6:30 p.m. (New York City
time) on the Call Date (as defined below), then the Company may redeem the then
unexercised portion of this Warrant, at a price of $1.00 (the "Redemption
Price"). To exercise this right, the Company must deliver to the Holder an
irrevocable written notice (a "Call Notice") by over night express mail or
courier and facsimile transmission, indicating therein that this Warrant shall
be redeemed on the Call Date. If all of the conditions for such redemption are
satisfied from the period from the date of the Call Notice through and including
the Call Date, then this Warrant shall be cancelled at 6:30 p.m. (New York City
time) on the tenth trading day (the "Call Date") after the date of the Call
Notice and the Redemption Price shall thereafter be mailed by the Company to
such Holder at its address of record. The Company covenants and agrees that it
will honor all Forms of Subscription with respect to Warrant Shares that are
tendered from the time of delivery of the Call Notice through 6:30 p.m. (New
York City time) on the Call Date.

         8.       Notices. Any notice, request, or other document required or
permitted to be given or delivered to the Holder hereof or the Company shall be
delivered by hand or messenger or

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shall be sent by certified mail, postage prepaid, or by overnight courier to
each such Holder at its address as shown on the books of the Company or to the
Company at its principal place of business or such other address as either may
from time to time provide to the other. Each such notice or other communication
shall be treated as effective or having been given: (i) when delivered if
delivered personally, (ii) if sent by registered or certified mail, at the
earlier of its receipt or three business days after the same has been registered
or certified as aforesaid, (iii) if sent by overnight courier, on the next
business day after the same has been deposited with a nationally recognized
courier service, or (iv) the date of transmission, if such notice or
communication is delivered via facsimile prior to 5:00 p.m. (New York City time)
on a trading day at a facsimile number as either may from time to time provide
to the other and a confirming copy of such notice is sent the same day by first
class mail.

         9.       Governing Law. All 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. Each
party agrees that all legal proceedings concerning the interpretations,
enforcement and defense of this Warrant and the transactions herein contemplated
("Proceedings") (whether brought against a party hereto or its respective
Affiliates, employees or agents) shall be commenced exclusively in the state and
federal courts sitting in the City of New York, Borough of Manhattan (the "New
York Courts"). Each party hereto hereby irrevocably submits to the exclusive
jurisdiction of the New York Courts 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 Proceeding, any claim that it is not personally subject to the jurisdiction
of any New York Court, or that such Proceeding has been commenced in an improper
or inconvenient forum. Each party hereto hereby irrevocably waives personal
service of process and consents to process being served in any such Proceeding
by mailing a copy thereof via registered or certified mail or overnight delivery
(with evidence of delivery) to such party at the address in effect for notices
to it under this Warrant 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. Each party hereto hereby irrevocably waives, to the fullest extent
permitted by applicable law, any and all right to trial by jury in any legal
proceeding arising out of or relating to this Warrant or the transactions
contemplated hereby. If either party shall commence a Proceeding to enforce any
provisions of this Warrant, then the prevailing party in such Proceeding shall
be reimbursed by the other party for its attorney's fees and other costs and
expenses incurred with the investigation, preparation and prosecution of such
Proceeding.

         10.      Lost or Stolen Warrant. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction, or mutilation of
this Warrant and, in the case of any such loss, theft or destruction, upon
receipt of an indemnity reasonably satisfactory to the Company, or in the case
of any such mutilation, upon surrender and cancellation of such Warrant, the
Company, at its expense, will make and deliver a new Warrant, of like tenor, in
lieu of the lost, stolen, destroyed or mutilated Warrant.

         11.      Fractional Shares. No fractional shares shall be issued upon
exercise of this Warrant. The Company shall, in lieu of issuing any fractional
share, pay the Holder entitled to

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such fraction a sum in cash equal to such fraction (calculated to the nearest
1/100th of a share) multiplied by the then effective Exercise Price on the date
the Form of Subscription is received by the Company.

         12.      Acknowledgement. Upon the request of the Holder, the Company
will at any time during the period this Warrant is outstanding acknowledge in
writing, in form satisfactory to Holder, the continued validity of this Warrant
and the Company's obligations hereunder.

         13.      Successors and Assigns. This Warrant and the rights evidenced
hereby shall inure to the benefit of and be binding upon the successors of the
Company and the successors and assigns of the Holder. The provisions of this
Warrant are intended to be for the benefit of all Holders from time to time of
this Warrant, and shall be enforceable by any such Holder.

         14.      Severability of Provisions. 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 officer, thereunto duly authorized on this 23rd day of July,
2003.

                           Avanir Pharmaceuticals,
                           a California corporation

                           By:
                                 ------------------------------------------
                                 Gerald J. Yakatan, Ph.D.
                                 Chief Executive Officer

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                              FORM OF SUBSCRIPTION

(To be signed only upon exercise of Warrant)

To:      Avanir Pharmaceuticals

         The undersigned, the holder of the attached Class A Common Stock
Warrant, hereby elects to exercise the purchase right represented by such
Warrant for, and to purchase thereunder,___________(1) shares of Class A Common
Stock of Avanir Pharmaceuticals and, if such holder is not utilizing the
cashless exercise provisions set forth in the Warrant, herewith makes payment of
$_________ therefor.


         By its delivery of this Form of Subscription, the undersigned
represents and warrants to the Company that in giving effect to the exercise
evidenced hereby the Holder will not beneficially own in excess of the number of
shares of Common Stock (determined in accordance with Section 13(d) of the
Securities Exchange Act of 1934) permitted to be owned under Warrant to which
this notice relates.

The undersigned requests that certificates for such shares be issued in the name
of, and delivered to:___________________________________________________________
whose address is: _____________________________________________________________.

DATED:   _________

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

                           Name:________________________________________________

                           Title:_______________________________________________

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(1) Insert here the number of shares called for on the face of the Warrant (or,
in the case of a partial exercise, the portion thereof as to which the Warrant
is being exercised), in either case without making any adjustment for any stock
or other securities or property or cash which, pursuant to the adjustment
provisions of the Warrant, may be deliverable upon exercise.