<PAGE>
                                                                     EXHIBIT 4.5


                                                                       NO. GC-01


THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES LAWS OF ANY STATE.
THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE
APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN
FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED
TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE
SECURITIES LAWS.


                         QUESTCOR PHARMACEUTICALS, INC.

               WARRANT FOR THE PURCHASE OF SHARES OF COMMON STOCK


October 10, 2000                                                   ______ Shares


For Value Received, QUESTCOR PHARMACEUTICALS, INC. a California corporation (the
"Company"), with its principal office at 26118 Research Road, Hayward,
California 94545, hereby certifies that [INSERT NAME OF HOLDER] ("Holder"), or
its assigns is entitled, in consideration for Holder's participation as the
underwriter of the RiboGene Common Stock offering completed in June of 1998,
subject to the provisions of this Warrant, to purchase from the Company, at
any time before 5:00 p.m. (Pacific Standard Time) June 2, 2003
(the "Expiration Date"), the number of fully paid and nonassessable shares of
Common Stock of the Company set forth above, subject to adjustment as
hereinafter provided.

Holder may purchase such number of shares of Common Stock at a purchase price
per share (as appropriately adjusted pursuant to Section 6 hereof) of One Dollar
and Fifty-Four Cents ($1.5408) (the "Exercise Price"). The term "Common Stock"
shall mean the aforementioned Common Stock of the Company, together with any
other equity securities that may be issued by the Company in addition thereto or
in substitution therefor as provided herein.

The number of shares of Common Stock to be received upon the exercise of this
Warrant and the price to be paid for a share of Common Stock are subject to
adjustment from time to time as hereinafter set forth. The shares of Common
Stock deliverable upon such exercise, as adjusted from time to time, are
hereinafter sometimes referred to as "Warrant Shares."

<PAGE>
     SECTION 1.   EXERCISE OF WARRANT.

          (a)  Exercise Procedures. This Warrant may be exercised in whole or in
part, on any business day prior to the Expiration Date by presentation and
surrender hereof to the Company at its principal office at the address set forth
in the initial paragraph hereof (or at such other address as the Company may
hereafter notify Holder in writing) with the Purchase Form annexed hereto duly
executed. If this Warrant should be exercised in part only, the Company shall,
upon surrender of this Warrant, execute and deliver a new Warrant dated as of
the date hereof and evidencing the rights of Holder thereof to purchase the
balance of the Warrant Shares purchasable hereunder.  Upon receipt by the
Company of this Warrant and such Purchase Form, together with proper payment of
the Exercise Price, at the principal office of the Company, Holder shall be
deemed to be the holder of record of the Warrant Shares, notwithstanding that
the stock transfer books of the Company shall then be closed or that
certificates representing such Warrant Shares shall not then be actually
delivered to Holder.

          (b)  Cash or Net Exercise.  The Holder may elect to exercise this
Warrant by cash exercise or a net exercise as described below.

               (A)  In the case of a cash exercise, the Purchase Form delivered
under Section 1(a) shall be accompanied by proper payment of the Exercise Price
in lawful money of the United States of America, in cash or by certified check,
for the number of Warrant Shares specified in the Purchase Form.

               (B)  In the case of a net exercise, the Holder may elect to
exercise this Warrant and receive shares on a "net exercise" basis in an amount
equal to the value of this Warrant by delivery of a written request by the
Holder, the Purchase Form and surrender of this Warrant, in which event the
Company shall issue to Holder a number of shares computed using the following
formula:

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

     Where:    X =     the number of shares of Common Stock to be issued to
                       Holder.

               P =     the percentage of the Warrant being exercised.

               Y =     the number of shares of Common Stock issuable upon
                       exercise of this Warrant.

               A =     the Current Market Price (as determined pursuant to
                       Section 3) of one share of Common Stock.

               B =     Exercise Price.
<PAGE>
Provided, however, that no fractional shares shall be issuable upon such
exchange, and if the number of shares of Common Stock determined in accordance
with the foregoing formula is other than a whole number, the Company shall pay
Holder an amount by check, determined in accordance with the provisions of
Section 3.

     SECTION 2.  RESERVATION OF SHARES. The Company hereby agrees that at all
times there shall be reserved for issuance and delivery upon exercise of this
Warrant all shares of its Common Stock or other shares of capital stock of the
Company from time to time issuable upon exercise of this Warrant. All such
shares shall be duly authorized and, when issued upon such exercise in
accordance with the terms of this Warrant, shall be validly issued, fully paid
and nonassessable, free and clear of all liens, security interests, charges and
other encumbrances or restrictions on sale (other than as provided in the
Company's certificate of incorporation and any restrictions on sale set forth
herein or pursuant to applicable federal and state securities laws) and free and
clear of all preemptive rights.

     SECTION 3.  FRACTIONAL INTEREST. The Company will not issue a fractional
share of Common Stock upon exercise of a Warrant. Instead, the Company will
deliver its check for the current market value of the fractional share. The
current market value of a fraction of a share is determined as follows: multiply
the current market price of a full share by the fraction of a share and round
the result to the nearest cent.

The Current Market Price of a share of Common Stock for purposes of this Section
3 is the last reported sales price of the Common Stock on the last trading day
prior to the exercise date, as reported by the Nasdaq National Market, or the
primary national securities exchange on which the Common Stock is then quoted;
provided, however, that if the Common Stock is neither traded on the Nasdaq
National Market nor on a national securities exchange, the price referred to
above shall be the price reflected in the over-the counter market as reported by
the National Quotation Bureau, Inc. or any organization performing a similar
function.

     SECTION 4.  TRANSFERS; ASSIGNMENT OR LOSS OF WARRANT.

            (a)  Subject to the terms and conditions contained in Section 10
hereof, this Warrant and all rights hereunder are transferable in whole or in
part by Holder and any successor transferee; provided that prior to such
transfer Holder shall give thirty (30) days prior written notice of any such
transfer to the Company, and the Company shall have the right to acquire the
Warrant under the identical provisions contained in such notice by giving Holder
written notice within fifteen (15) days of receipt of such notice. The Company's
failure to respond to said notice within said fifteen (15) days shall be deemed
a waiver of this right of first refusal. The transfer shall be recorded on the
books of the Company upon receipt by the Company of the Transfer Notice annexed
hereto, at its principal offices and the payment to the Company of all transfer
taxes and other governmental charges imposed on such transfer.

            (b)  Holder shall not, without obtaining the prior written consent
of the
<PAGE>
Company, which consent shall not be unreasonably withheld, assign its interest
in this Warrant in whole or in part to any person or persons. Subject to the
provisions of Section 9, upon surrender of this Warrant to the Company or at
the office of its stock transfer agent or warrant agent, with the Assignment
Form annexed hereto duly executed and funds sufficient to pay any transfer tax,
the Company shall, without charge, execute and deliver a new Warrant or
Warrants in the name of the assignee or assignees named in such instrument of
assignment (any such assignee will then be a "Holder" for purposes of this
Warrant) and, if Holder's entire interest is not being assigned, in the name of
Holder, and this Warrant shall promptly be canceled.

          (c)  Upon receipt of evidence satisfactory to the Company of the
loss, theft, destruction or mutilation of this Warrant, and (in the case of
loss, theft or destruction) of indemnification satisfactory to the Company, and
upon surrender and cancellation of this Warrant, if mutilated, the Company
shall execute and deliver a new Warrant of like tenor and date. In the event
that this Warrant is lost, stolen, destroyed or mutilated, Holder shall pay all
reasonable attorneys' fees and expenses incurred by the Company in connection
with the replacement of this Warrant and the issuance of a new Warrant.

     SECTION 5. RIGHTS OF HOLDER. Holder shall not, by virtue hereof, be
entitled to any rights of a stockholder in the Company, either at law or
equity, and the rights of Holder are limited to those expressed in this
Warrant. Nothing contained in this Warrant shall be construed as conferring
upon Holder hereof the right to vote or to consent or to receive notice as a
stockholder of the Company on any matters or with respect to any rights
whatsoever as a stockholder of the Company. No dividends or interest shall be
payable or accrued in respect of this Warrant or the interest represented
hereby or the Warrant Shares purchasable hereunder until, and only to the
extent that, this Warrant shall have been exercised in accordance with its
terms.

     SECTION 6. ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES. The number
and kind of securities purchasable upon the exercise of this Warrant and the
Exercise Price shall be subject to adjustment from time to time upon the
beginning of certain events, as follows:

          (a) Adjustment for Change in Capital Stock. If at any time after the
date hereof the Company:

               (A) pays a dividend in Common Stock or makes a distribution on
its Common Stock in shares of its Common Stock;

               (B) subdivides its outstanding shares of Common Stock into a
greater number of shares;

               (C) combines its outstanding shares of Common Stock into a
smaller number of shares;

               (D) makes a distribution on its Common Stock in shares of its
capital


<PAGE>
stock other than Common Stock; or

               (E)  issues by reclassification of its Common Stock any shares of
its capital stock;

then the Exercise Price in effect immediately prior to such action shall be
adjusted so that Holder may receive upon exercise of this Warrant and payment of
the same aggregate consideration the number of shares of capital stock of the
Company which Holder would have owned immediately following such action if
Holder had exercised this Warrant immediately prior to such action.

The adjustment shall become effective immediately after the record date in the
case of a dividend or distribution and immediately after the effective date in
the case of a subdivision, combination or reclassification.

          (b)  Minimum Adjustment. No adjustment in the Exercise Price shall be
required pursuant to this Section 6 unless such adjustment would require an
increase or decrease of at least twenty-five cents ($.25) in such Exercise
Price; provided, however, that any adjustments which by reason of this
subsection are not required to be made, shall be carried forward and taken into
account in any subsequent adjustment. All calculations under this Section 6
shall be made to the nearest cent or to the nearest share, as the case may be.

          (c)  Deferral of Issuance or Payment. In any case in which an event
covered by this Section 6 shall require that an adjustment in the Exercise Price
be made effective as of a record date, the Company may elect to defer until the
occurrence of such event (i) issuing to Holder, if this Warrant is exercised
after such record date, the shares of Common Stock and other capital stock of
the Company, if any, issuable upon such exercise over and above the shares of
Common Stock or other capital stock of the Company, if any, issuable upon such
exercise on the basis of the Exercise Price in effect prior to such adjustment,
and (ii) paying to Holder by check any amount in lieu of the issuance of
fractional shares pursuant to Section 3.

          (d)  When No Adjustment Required. No adjustment shall be required for
a change in the par value or no par value of the Common Stock. To the extent
this Warrant becomes exercisable into cash, no adjustment shall be required
thereafter as to the cash, and interest will not accrue on the cash.

          (e)  Notice of Certain Actions. In the event that:

               (A)  the Company shall authorize the issuance to all holders of
its Common Stock of rights, warrants, options or convertible securities to
subscribe for or purchase shares of its Common Stock or of any other
subscription rights, warrants, options or convertible securities; or

               (B)  the Company shall authorize the distribution to all holders
of its
<PAGE>
Common Stock of evidences of its indebtedness or assets (other than dividends
paid in or distributions of the Company's capital stock for which the Exercise
Price shall have been adjusted pursuant to subsection (a) of this Section 6 or
cash dividends or cash distributions payable out of consolidated current or
retained earnings as shown on the books of the Company and paid in the ordinary
course of business); or

                 (C)  the Company shall authorize any capital reorganization or
reclassification of the Common Stock (other than a subdivision or combination of
the outstanding Common Stock and other than a change in par value of the Common
Stock) or of any consolidation or merger to which the Company is a party and for
which approval of any stockholders of the Company is required (other than a
consolidation or merger in which the Company is the continuing corporation and
that does not result in any reclassification or change of the Common Stock
outstanding), or of the conveyance or transfer of the properties and assets of
the Company as an entirety or substantially as an entirety; or

                 (D)  the Company is the subject of a voluntary or involuntary
dissolution, liquidation or winding-up procedure.

then the Company shall cause to be mailed by first-class mail to Holder, at
least ten (10) days prior to the applicable record or effective date hereinafter
specified, a notice stating (x) the date as of which the holders of Common Stock
of record to be entitled to receive any such rights, warrants or distributions
are to be determined, or (y) the date on which any such consolidation, merger,
conveyance, transfer, dissolution, liquidation or winding-up is expected to
become effective, 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 or other property, if any, deliverable upon such reorganization,
reclassification, consolidation, merger, conveyance, transfer, dissolution,
liquidation or winding-up; provided, however, that Holder shall make a best
efforts attempt to respond to such notice (to the extent any such response is
required or permitted hereunder or is reasonably requested by the Company) as
early as possible after the receipt thereof.

                 (E)  No Adjustment After Exercise of Warrant. No adjustments
shall be made under any Section herein in connection with the issuance of
Warrant Shares after exercise of this Warrant.

     SECTION 7.  NOTICE OF ADJUSTMENT. Upon any adjustment of the Exercise
Price or any increase or decrease in the number of shares of Common Stock
purchasable upon the exercise of this Warrant, the Company shall give written
notice thereof, by certified or registered mail, postage prepaid and return
receipt requested, addressed to the registered Holder at the address of such
Holder as shown on the books of the Company. The notice shall be 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.
<PAGE>
     SECTION 8.     RECLASSIFICATION, REORGANIZATION, CONSOLIDATION OR MERGER.
In the event of any reclassification, capital reorganization or other change of
outstanding shares of Common Stock of the Company (other than a subdivision or
combination of the outstanding Common Stock and other than a change in the par
value of the Common Stock) or in the event of any consolidation or merger of the
Company with or into another corporation (other than a merger in which the
Company is the continuing corporation and that does not result in any
reclassification, capital reorganization or other change of outstanding shares
of Common Stock of the class issuable upon exercise of this Warrant) or in the
event of any sale, lease, transfer or conveyance to another corporation of the
property and assets of the Company as an entirety or substantially as an
entirety, the Company shall, as a condition precedent to such transaction, cause
effective provisions to be made so that Holder shall have the right thereafter,
by exercising this Warrant, (in lieu of the shares of the Common Stock of the
Company immediately theretofore purchasable and receivable upon exercise of the
rights represented hereby) to purchase the kind and amount of shares of stock
and other securities and property (including cash) receivable upon such
reclassification, capital reorganization and other change, consolidation,
merger, sale or conveyance by a holder of the number of shares of Common Stock
that might have been received upon exercise of this Warrant immediately prior to
such reclassification, capital reorganization, change, consolidation, merger,
sale or conveyance; provided, however, that in the event (a) the value of the
stock, securities or other assets or property (determined in good faith by the
Board of Directors of the Company) issuable or payable with respect to one share
of the Common Stock of the Company immediately theretofore purchasable and
receivable upon the exercise of the rights represented hereby is in excess of
the Exercise Price hereof effective at the time of the merger (after giving
effect to any adjustment in such Exercise Price required to be made under the
terms of this Warrant), and (b) the securities received in such reorganization,
if any, are publicly traded, then this Warrant shall expire unless exercised
prior to the reorganization. Any such provision shall include provisions for
adjustments in respect of such shares of stock and other securities and property
that shall be as nearly equivalent as may be practicable to the adjustments
provided for in this Warrant. The foregoing provisions of this Section 8 shall
similarly apply to successive reclassifications, capital reorganizations and
changes of shares of Common Stock and to successive consolidations, mergers,
sales or conveyances. In the event that in connection with any such capital
reorganization or reclassification, consolidation, merger, sale or conveyance,
additional shares of Common Stock shall be issued in exchange, conversion,
substitution or payment, in whole or in part, for or of, a security of the
Company other than Common Stock, any such issue shall be treated as an issue of
Common Stock covered by the provisions of subsection (a) of Section 6.

     SECTION 9.      TRANSFER TO COMPLY WITH THE SECURITIES ACT OF 1933. This
Warrant may not be exercised and neither this Warrant nor any of the Warrant
Shares, nor any interest in either, may be offered, sold, assigned, pledged,
hypothecated, encumbered or in any other manner transferred or disposed of, in
whole or in part, except in compliance with applicable United States federal
and state securities or blue sky laws and the terms and conditions hereof. Each
Warrant shall bear a legend in substantially the same form as the legend set
forth on the first page of this Warrant. Each certificate for Warrant Shares
issued upon exercise of this Warrant, unless at the


<PAGE>
time of exercise such Warrant Shares are acquired pursuant to a registration
statement that has been declared effective under the Securities Act of 1933, as
amended (the "Securities Act"), and applicable blue sky laws, shall bear a
legend substantially in the following form:

    THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER
    THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE
    SECURITIES LAWS OF ANY STATE. THESE SECURITIES ARE SUBJECT TO
    RESTRICTIONS ON TRANSFERABILITY AND RESALE AND MAY NOT BE
    TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE
    APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR
    EXEMPTION THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN
    OPINION OF COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE
    ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS IN
    COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS.

Any certificate for any Warrants Shares issued at any time in exchange or
substitution for any certificate for any Warrant Shares bearing such legend
(except  a new certificate for any Warrant Shares issued after the acquisition
of such Warrant Shares pursuant to a registration statement that has been
declared effective under the Securities Act) shall also bear such legend
unless, in the opinion of counsel for the Company, the Warrant Shares
represented thereby need no longer be subject to the restriction contained
herein. The provisions of this Section 9 shall be binding upon all subsequent
holders of certificates for Warrant Shares bearing the above legend and all
subsequent holders of this Warrant, if any.

      SECTION 10. REPRESENTATIONS AND COVENANTS OF HOLDER.  This Warrant has
been entered into by the Company in reliance upon the following representations
and covenants of Holder, which by its execution hereof Holder hereby confirms:

         (a)  Investment Purpose.  The right to acquire Common Stock, and any
Common Stock issued upon exercise of Holder's rights contained herein, will be
acquired for investment and not with a view to the sale or distribution of any
part thereof, and Holder has no present intention of selling or engaging in any
public distribution of the same except pursuant to a registration or exemption.

         (b)  Private Issue.  Holder understands (i) that the Common Stock
issuable upon exercise of Holder's rights contained herein is not registered
under the Securities Act or qualified under applicable state securities laws on
the ground that the issuance contemplated by this Warrant will be exempt from
the registration and qualification requirements thereof, and (ii) that the
Company's reliance on such exemption is predicated on the representations set
forth in this Section 10.
<PAGE>
      (C)  Disposition of Holder's Rights.  In no event will Holder make a
disposition of any of its rights to acquire Common Stock, or of any Common Stock
issued upon exercise of such rights, unless and until (i) it shall have notified
the Company of the proposed disposition, and (ii) if requested by the Company,
it shall have furnished the Company with an opinion of counsel (which counsel
may either be inside or outside counsel to Holder) satisfactory to the Company
and its counsel to the effect that (A) appropriate action necessary for
compliance with the Securities Act has been taken, or (B) an exemption from the
registration requirements of the Securities Act is available. Notwithstanding
the foregoing, the restrictions imposed upon the transferability of any of its
rights to acquire Common Stock, or of any Common Stock issued on the exercise of
such rights do not apply to transfers from the beneficial owner of any of the
aforementioned securities to its nominee or from such nominee to its beneficial
owner, and shall terminate as to any particular share of Common Stock when (1)
such security shall have been effectively registered under the Act and sold by
the holder thereof in accordance with such registration, (2) such security shall
have been sold without registration in compliance with Rule 144 under the
Securities Act, or (3) a letter shall have been issued to Holder at its request
by the staff of the Securities and Exchange Commission or a ruling shall have
been issued to Holder at its request by such Commission stating that no action
shall be recommended by such staff or taken by such Commission, as the case may
be, if such security is transferred without registration under the Securities
Act in accordance with the conditions set forth in such letter or ruling, and
such letter or ruling specifies that no subsequent restrictions on transfer are
required. Whenever the restrictions imposed hereunder shall terminate, as
hereinabove provided, Holder or a holder of a share of Common Stock then
outstanding as to which such restrictions have terminated shall be entitled to
receive from the Company, without expense to such holder, one or more new
certificates for the Warrant or for such shares of Common Stock not bearing any
restrictive legend.

      (D)  Financial Risk.  Holder has such knowledge and experience in
financial and business matters as to be capable of evaluating the merits and
risks of its investment and has the ability to bear the economic risks of its
investment.

      (E)  Risk of No Registration.  Holder understands that if the Company does
not register with the Securities and Exchange Commission pursuant to Section 12
of the Securities Act, or file reports pursuant to Section 15(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act), or if a
registration statement covering the securities under the Securities Act is not
in effect when it desires to sell (i) the rights to purchase Common Stock
pursuant to this Warrant, or (ii) the Common Stock issued upon exercise of the
right to purchase, it may be required to hold such securities for an indefinite
period. Holder also understands that any sale of its rights of Holder to
purchase Common Stock, or of any Common Stock, which might be made by it in
reliance upon Rule 144 under the Securities Act may be made only in accordance
with the terms and conditions of that Rule.

      (F)  Accredited Investor.  Holder is an "accredited investor" within the
meaning of the Securities and Exchange Rule 501 of Regulation D, as presently in
effect.
<PAGE>
     SECTION 11.  REGISTRATION RIGHTS.

          (a)  If at any time the Company shall determine to register any of its
securities under the Securities Act either for its own account or the account of
a security holder or holders, other than the Company's initial public offering
of its Common Stock or a registration relating solely to employee benefit plans,
or a registration relating solely to a Rule 145 transaction, or a registration
on any registration form that does not permit secondary sales, then the Company
will:

               (A)  promptly give to Holder a written notice thereof; and

               (B)  use its best efforts to include in such registration (and
any related qualification under blue sky laws or other compliance), except as
set forth in Section 11(b) below, and in any underwriting involved therein, all
of the Warrant Shares specified in a written request or requests made by Holder
and received by the Company within ten (10) days after the written notice from
the Company described in clause (A) above is mailed or delivered by the Company.
Such written request may specify all or a part of the Warrant Shares.

          (b)  If the registration of which the Company gives notice to Holder
is for a registered public offering involving an underwriting, the Company shall
so advise Holder as a part of the written notice given pursuant to Section
11(a)(A). In such event, the right of Holder to registration pursuant to Section
11(a) shall be conditioned upon Holder's participation in such underwriting and
the inclusion of all or any part of the Warrant Shares specified in Holder's
notice in the underwriting to the extent provided herein. Holder shall (together
with the Company and the other holders of securities of the Company with
registration rights to participate therein distributing their securities through
such underwriting) enter into an underwriting agreement in customary form with
the representative of the underwriter or underwriters selected by the Company.

Notwithstanding any other provision of Sections 11(a) or (b), if the
representative of the underwriters advises the Company in writing that marketing
factors require a limitation on the number of shares to be underwritten, the
representative may (subject to the limitations set forth below) exclude all of
the Warrant Shares from, or limit the number of Warrant Shares to be included
in, the registration and underwriting. The Company shall so advise Holder and
other holders of securities requesting registration, and the number of shares
that are entitled to be included in the registration and underwriting shall be
allocated first to the Company for securities being sold for its own account and
thereafter the number of shares that are entitled to be included in the
registration shall be allocated among Holder and other holders requesting
inclusion of shares on a pro rata basis, subject to any prior agreements among
the Company and its other stockholders, but only to the extent that such other
agreements provide for additional limitations on the number of shares such other
stockholders or the Company will be entitled to include in the registration,
which agreements are in effect as of the date hereof. If Holder or any other
person does not agree to the terms of any such underwriting, Holder and any
other such person shall be excluded therefrom by written notice from the Company
or the underwriter. Any Warrant Shares or other securities excluded or withdrawn
from such underwriting shall also be withdrawn from such registration.
<PAGE>
          (c) As used herein, "Registration Expenses" shall mean all expenses
incurred by the Company in complying with this Section 11, including, without
limitation, all registration, qualification and filing fees; printing expenses;
fees and disbursements of counsel for the Company (and the fees and
disbursements of counsel for the Company in its capacity as counsel to Holder
and other holders hereunder; if Company counsel does not make itself available
for this purpose, the Company will pay the reasonable fees and disbursements of
one counsel for Holder and other holders as mutually agreed upon by all such
holders) and of the Company's independent accounting firm; blue sky fees and
expenses; and the expense of any special audits incident to or required by any
such registration (but excluding the compensation of regular employees of the
Company which shall be paid in any event by the Company). All Registration
Expenses in connection with any registration pursuant to Section 11(a) hereof
shall be borne by the Company; provided, however, that (A) any incremental
filing fees or other expenses incurred by the Company solely by reason of
Holder's exercise of registration rights pursuant to Section 11(a), and (B) any
underwriting discounts and commissions payable in connection with Holder's
exercise of registration rights pursuant to Section 11(a) shall be borne by
Holder.

          (d) The rights conferred upon Holder under this Section 11 may be
assigned by Holder to any permitted transferee of the Warrant Shares; provided
that such transfer complies with Section 9 hereof.

          (e) In the event any Warrant Shares are included in a registration
statement under Section 11(a):

               (A) To the extent permitted by law, the Company will indemnify
and hold harmless Holder, the partners, officers, directors and legal counsel of
Holder, any underwriter (as defined in the Securities Act) for Holder and each
person, if any, who controls Holder or such underwriter within the meaning of
the Securities Act or the Exchange Act, against any losses, claims, damages or
liabilities (joint or several) to which they may become subject under the
Securities Act, the Exchange Act or other federal or state law, insofar as such
losses, claims, damages or liabilities (or actions in respect thereof) arise out
of or are based upon any of the following statements, omissions or violations
(collectively a "Violation") by the Company: (i) any untrue statement or alleged
untrue statement of a material fact contained in such registration statement,
including any preliminary prospectus or final prospectus contained therein or
any amendments or supplements thereto, (ii) the omission or alleged omission to
state therein a material fact required to be stated therein, or necessary to
make the statements therein not misleading, or (iii) any violation or alleged
violation by the Company of the Securities Act, the Exchange Act, any state
securities law or any rule or regulation promulgated under the Securities Act,
the Exchange Act or any state securities law in connection with the offering
covered by such registration statement; and the Company will reimburse Holder
and each partner, officer or director, underwriter or controlling person for any
legal or other expenses reasonably incurred by them in connection with
investigating or defending any such loss, claim, damage, liability or action;
provided, however, that the indemnity agreement contained in this Section
11(e)(A) shall not apply



<PAGE>
to amounts paid in settlement of any such loss, claim, damage, liability or
action if such settlement is effected without the consent of the Company, which
consent shall not be unreasonably withheld, nor shall the Company be liable in
any such case for any such loss, claim, damage, liability or action to the
extent that it arises out of or is based upon a Violation which occurs in
reliance upon and in conformity with written information furnished expressly for
use in connection with such registration by Holder or such partner, officer,
director, underwriter or controlling person of Holder.

          (B)  To the extent permitted by law, Holder will indemnify and hold
harmless the Company, each of its directors, its officers and legal counsel and
each person, if any, who controls the Company within the meaning of the
Securities Act, any underwriter and any other person selling securities under
such registration statement or any of such other person's partners, directors or
officers or any person who controls such person, against any losses, claims,
damages or liabilities (joint or several) to which the Company or any such
director, officer, controlling person, underwriter or other such person, or
partner, director, officer or controlling person of such person may become
subject under the Securities Act, the Exchange Act or other federal or state
law, insofar as such losses, claims, damages or liabilities (or actions in
respect thereto) arise out of or are based upon any Violation, in each case to
the extent (and only to the extent) that such Violation occurs in reliance upon
and in conformity with written information furnished by Holder under an
instrument duly executed by Holder and stated to be specifically for use in
connection with such registration; and Holder will reimburse any legal or other
expenses reasonably incurred by the Company or any such director, officer,
controlling person, underwriter or other person, or partner, officer, director
or controlling person of such other person in connection with investigating or
defending any such loss, claim, damage, liability or action if it is judicially
determined that there was such a Violation; provided, however, that the
indemnity agreement contained in this Section 11(e)(B) shall not apply to
amounts paid in settlement of any such loss, claim, damage, liability or action
if such settlement is effected without the consent of Holder, which consent
shall not be unreasonably withheld; provided further, that in no event shall any
indemnity under this Section 11(e)(B) exceed the net proceeds from the offering
received by such Holder.

          (C)  Promptly after receipt by an indemnified party under this Section
11(e) of notice of the commencement of any action (including any governmental
action), such indemnified party will, if a claim in respect thereof is to be
made against any indemnifying party under this Section 11(e), deliver to the
indemnifying party a written notice of the commencement thereof and the
indemnifying party shall have the right to participate in, and, to the extent
the indemnifying party so desires, jointly with any other indemnifying party
similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party shall
have the right to retain its own counsel, with the fees and expenses to be paid
by the indemnifying party, if representation of such indemnified party by the
counsel retained by the indemnifying party would be inappropriate due to actual
or potential differing interests between such indemnified party and any other
party represented by such counsel in such proceeding. The failure to deliver
written notice to the indemnifying party within a reasonable time of the
commencement of any such action, if materially prejudicial to its ability to
<PAGE>
defend such action, shall relieve such indemnifying party of any liability to
the indemnified party under this Section 11(e), but the omission so to deliver
written notice to the indemnifying party will not relieve it of any liability
that it may have to any indemnified party otherwise than under this Section
11(e).

               (D)  If the indemnification provided for in this Section 11(e) is
held by a court of competent jurisdiction to be unavailable to an indemnified
party with respect to any losses, claims, damages or liabilities referred to
herein, the indemnifying party, in lieu of indemnifying such indemnified party
thereunder, shall to the extent permitted by applicable law contribute to the
amount paid or payable by such indemnified party as a result of such loss,
claim, damage or liability in such proportion as is appropriate to reflect the
relative fault of the indemnifying party on the one hand and of the indemnified
party on the other in connection with the Violation(s) that resulted in such
loss, claim, damage or liability, as well as any other relevant equitable
considerations. The relative fault of the indemnifying party and of the
indemnified party shall be determined by a court of law by reference to, among
other things, whether the untrue or alleged untrue statement of a material fact
or the omission to state a material fact relates to information supplied by the
indemnifying party or by the indemnified party and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission; provided, that in no event shall any contribution by
Holder hereunder exceed the proceeds from the offering received by Holder.

               (E)  The obligations of the Company and Holder under this
Section 11(e) shall survive completion of any offering of securities in a
registration statement pursuant to Section 11. No indemnifying party, in the
defense of any such claim or litigation, shall, except with the consent of each
indemnified party, consent to entry of any judgment or enter into any
settlement which does not include as an unconditional term thereof the giving
by the claimant or plaintiff to such indemnified party of a release from all
liability in respect to such claim or litigation.

     SECTION 12. SATURDAYS, SUNDAYS AND HOLIDAYS. If the last or appointed day
for the taking of any action or the expiration of any right required or granted
herein shall be a Saturday or a Sunday or shall be a legal holiday in the State
of California, then such action may be taken or such right may be exercised on
the next succeeding day not a Saturday, Sunday or legal holiday in the State of
California.

     SECTION 13. ISSUE TAX. The issuance of certificates for Common Stock upon
the exercise of the Warrant shall be made without charge to the holder of the
Warrant for any issue tax (other than any applicable income taxes) in respect
thereof; 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 issuance
and delivery of any certificates in a name other than that of the then Holder
of the Warrant being exercised.

     SECTION 14. MODIFICATION AND WAIVER. Neither this Warrant nor any term
hereof may be changed, waived, discharged or terminated other than by an
instrument in writing signed by

<PAGE>
the Company and by Holder.

     SECTION 15. NOTICES. Unless otherwise specified herein, any notice, request
or other document required or permitted to be given or delivered to Holder or
the Company shall be given in writing and shall be deemed effectively given (i)
upon personal delivery to the party to be notified, (ii) three (3) days after
deposit in the United States mail if sent by registered or certified mail,
postage prepaid, or (iii) one (1) day after deposit with an overnight courier,
specifying next day delivery, with written verification of receipt. All
communications shall be sent to Holder at its address as shown on the books of
the Company, or to the Company at the address indicated therefor in the first
paragraph of this Warrant.

     SECTION 16. DESCRIPTIVE HEADINGS AND GOVERNING LAW. The description
headings of the several sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant. This Warrant
shall be construed and enforced in accordance with, and the rights of the
parties shall be governed by, the laws of the State of California, without
regard to its conflicts of laws principles.

     SECTION 17. ATTORNEYS' FEES. In any litigation, arbitration or court
proceeding between the Company and Holder relating hereto, the prevailing party
shall be entitled to attorneys' fees and expenses and all costs of proceedings
incurred in enforcing this Warrant.

     SECTION 18. SURVIVAL. The representations, warranties, covenants and
conditions of the respective parties contained herein or made pursuant to this
Warrant shall survive the execution and delivery of this Warrant.

     SECTION 19. SEVERABILITY. In the event any one or more of the provisions of
this Warrant shall for any reason be held invalid, illegal or unenforceable, the
remaining provisions of this Warrant shall be unimpaired, and the invalid,
illegal or unenforceable provision shall be replaced by a mutually acceptable
valid, legal and enforceable provision, which comes closest to the intention of
the parties underlying the invalid, illegal or unenforceable provision.
<PAGE>
     IN WITNESS WHEREOF, the Company has duly caused this Warrant to be signed
by its duly authorized officer and to be dated as of March 13, 2000.

                                        COMPANY:

                                        QUESTCOR PHARMACEUTICALS, INC.

                                        By: /s/ CHARLES J. CASAMENTO
                                           ____________________________________
                                                  Charles J. Casamento
                                                  Chief Executive Officer

                                        HOLDER:



                                        By:____________________________________

                                        Print Name:____________________________

                                        Title:_________________________________








                                    WARRANT
                                 SIGNATURE PAGE


<PAGE>
                                 PURCHASE FORM

                                                        Dated ___________ , ____


The undersigned hereby irrevocably elects to exercise the within Warrant to
purchase _______ shares of Common Stock and hereby makes payment of $________ in
payment of the exercise price thereof, together with all applicable transfer
taxes, if any.

In exercising its rights to purchase the Common Stock of Questcor
Pharmaceuticals, Inc., the undersigned hereby confirms and acknowledges the
investment representations and warranties made in Section 10 of the Warrant.

Please issue a certificate or certificates representing said shares of Common
Stock in the name of the undersigned or in such other name as is specified
below.


                                              _________________________________
                                              (Name)

                                              _________________________________
                                              (Address)

                                              _________________________________


                                              HOLDER:




                                              By: _____________________________

                                              Print Name: _____________________

                                              Title: __________________________

<PAGE>
                                ASSIGNMENT FORM

                                                      Dated ___________, _______


FOR VALUE RECEIVED, [INSERT NAME OF HOLDER] hereby sells, assigns and
transfers unto ____________________________________________ (the "Assignee"),
(please type or print in block letters)
___________________________________________________________________________
                                (insert address)
its right to purchase up to _____ shares of Common Stock represented by this
Warrant and does hereby irrevocably constitute and appoint _________________
attorney, to transfer the same on the books of the Company, with full power of
substitution in the premises.







                                        By: _________________________________

                                        Print Name: _________________________

                                        Title: ______________________________


<PAGE>
                                TRANSFER NOTICE


     (To transfer or assign the foregoing Warrant, execute this form and supply
     required information. Do not use this form to purchase shares.)

FOR VALUE RECEIVED, the foregoing Warrant and all rights evidenced thereby are
hereby transferred and assigned to:

________________________________________________________________________________
                                 (Please Print)

whose address is _______________________________________________________________

________________________________________________________________________________

                                         Dated _________________________________

                                         Holder's Signature ____________________

                                         Holder's Address ______________________

                                         _______________________________________



Note: The signature to this Transfer Notice must correspond with the name as it
      appears on the face of the Warrant, without alteration or enlargement or
      any change whatever. Officers of corporations and those acting in a
      fiduciary or other representative capacity should file proper evidence of
      authority to assign the foregoing Warrant.