<PAGE>   1
                                                                     EXHIBIT 4.5

CONFIDENTIAL TREATMENT--EDITED COPY

                       AMENDMENT NO. 1 TO OPTION AGREEMENT

                                 March 21, 2001


UBS AG, London Branch
c/o UBS Warburg LLC
[****]
[****]

Dear Sirs:

        Reference is hereby made to the Option Agreement, dated February 16,
2001 (the "Option Agreement"), between SciClone Pharmaceuticals, Inc. (the
"Company") and you. Capitalized terms not defined herein have the meanings
ascribed to them in the Option Agreement.

        The Company and you hereby agree to amend the terms of the Option
Agreement as follows:

        (a) the terms of the option shall have the terms set forth in the form
of zero coupon convertible note attached hereto as Annex I;

        (b) zero coupon convertible note has an aggregate principal amount of
$2,365,217 and convertible initially into 276,530 fully paid and non-assessable
shares of the Company's Common Stock, no par value, upon your exercise of the
option on or prior to March 21, 2006.

        (c) the amount of a payment you agree to make in consideration of the
purchase of the Option pursuant to Section 1 (a) of the Agreement shall be
$360,000, instead of $900,000 initially agreed.

        In all respects not inconsistent with the terms and provisions of this
Amendment, the Option Agreement shall continue to be in full force and effect in
accordance with the terms and conditions thereof, and is hereby ratified,
adopted approved and confirmed. From and after the date hereof, each reference
to the Option Agreement in any other instrument or document shall be deemed a
reference to the Option Agreement as amended hereby, unless the context
otherwise requires.


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CONFIDENTIAL TREATMENT--EDITED COPY

        This Amendment may be executed by the parties hereto in any number of
counterparts, each of which shall be deemed to be an original, but all such
respective counterparts shall together constitute one and the same instrument.

                                         Very truly yours,

                                         SciClone Pharmaceuticals, Inc.


                                         By:
                                             -----------------------------------
                                             Name:  Donald R. Sellers
                                             Title: President and
                                                    Chief Executive Officer

Accepted as of the date hereof:

UBS AG, London Branch

By:
   -----------------------------------
   Name:
   Title:


By:
   -----------------------------------
   Name:
   Title:


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CONFIDENTIAL TREATMENT--EDITED COPY

        THIS SECURITY AND THE COMMON STOCK ISSUABLE UPON ITS CONVERSION HAVE NOT
BEEN REGISTERED UNDER THE U.S. SECURITIES ACT OF 1933, AS AMENDED (THE
"SECURITIES ACT"), AND MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE
TRANSFERRED EXCEPT PURSUANT TO AN AVAILABLE EXEMPTION FROM REGISTRATION UNDER
THE SECURITIES ACT AND IN ACCORDANCE WITH ALL APPLICABLE SECURITIES LAWS OF THE
STATES OF THE UNITED STATES AND OTHER JURISDICTIONS.

                         SciClone Pharmaceuticals, Inc.

                      ZERO COUPON CONVERTIBLE NOTE DUE 2006

No. R-1                                                               $2,365,217

        SciClone Pharmaceuticals, Inc., a corporation duly organized and
existing under the laws of California (the "Company"), for value received,
hereby promises to pay to UBS AG, London Branch, or registered assigns, the
principal sum of Two Million Three Hundred Sixty Five Thousand Two Hundred
Seventeen Dollars ($2,365,217) on March 21, 2006 (the "Maturity Date"). The
principal of this Security shall not bear interest except in the case of a
default in payment of principal upon acceleration, upon repurchase or at stated
maturity and in such case the overdue principal and any overdue premium shall
bear interest at the rate of 20.0% per annum (to the extent that the payment of
such interest shall be legally enforceable), from the dates such amounts are due
until they are paid or made available for payment. Interest on any overdue
principal or premium shall be payable on demand. Any such interest on overdue
principal or premium which is not paid on demand shall bear interest at the rate
of 20.0% per annum (to the extent that payment of such interest on interest
shall be legally enforceable), from the date of such demand until the amount so
demanded is paid or made available for payment. Interest on any overdue interest
shall be payable on demand. Payment of the principal of (and premium, if any,
on) this Security shall be made upon the surrender of this Security to the
Company, at its office at 901 Mariner's Island Boulevard, Suite 205, San Mateo,
California 94404, (or such other office within the United States as shall be
notified by the Company to the holder hereof) (the "Designated Office"), in such
coin or currency of the United States of America as at the time of payment shall
be legal tender for the payment of public and private debts, by transfer to a
U.S. dollar account maintained by the payee with a bank in the United States of
America. Payment of any interest on this Security shall be made by wire transfer
to a U.S. dollar account maintained by the payee with a bank in the United
States of America, provided that if the holder shall not have furnished wire
instructions in writing to the Company no later than two business days
immediately prior to the date on which the Company makes such payment, such
payment may be made by U.S. dollar check mailed to the address of the person
entitled thereto as such address shall appear in the Company security register.

        1.     Redemption; Payment at Maturity.

               (a) Subject to Section 3, this Security is not subject to
redemption prior to its stated maturity.


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CONFIDENTIAL TREATMENT--EDITED COPY

               (b) At the option of the Company, the principal of this Security
may be paid at stated maturity in cash or, subject to fulfillment by the Company
of the conditions set forth in Section 1(c), by delivery of shares of Common
Stock having a fair market value equal to the principal amount hereof as
described in Section 1(c). The Company agrees to give the holder of this
Security notice of its intention to make payment in shares, by facsimile
transmission confirmed in writing by overnight courier service, not less than
ten Trading Days prior to the date such payment is due.

               (c) The Company may elect to pay the principal of this Security
at maturity by delivery of shares of Common Stock pursuant to Section 1(b) if
and only if the following conditions have been satisfied:

                      (1) The shares of Common Stock deliverable in payment of
such principal amount shall have a fair market value as of the Maturity Date of
not less than such principal amount. For purposes of this Section 1(c), the fair
market value of shares of Common Stock shall be equal to the average of the
Closing Prices for the five consecutive Trading Days ending on and including the
third Trading Day immediately preceding the Maturity Date;

                      (2) The shares of Common Stock to be issued in payment of
this Security shall have been registered for resale by the holder upon issuance
pursuant to an effective registration statement under the Securities Act of
1933, all in accordance with the Registration Rights Agreement, dated as of
February 16, 2001, between the Company and the Purchaser named therein (the
"Registration Rights Agreement");

                      (3) If any shares of Common Stock to be issued in payment
of this Security require registration with or approval of any governmental
authority under any State law or any other Federal law before such shares may be
validly issued or delivered in payment, such registration shall have been
completed, have become effective and such approval shall have been obtained, in
each case, prior to the Maturity Date;

                      (4) The shares of Common Stock deliverable in payment of
the principal hereof shall have been approved for quotation in the Nasdaq
National Market or listed on a national securities exchange immediately prior to
the Maturity Date;

                      (5) All shares of Common Stock deliverable in payment of
the principal hereof shall be issued out of the Company's authorized but
unissued Common Stock and will, upon issue, be duly and validly issued and fully
paid and non-assessable and free of any preemptive rights; and

                      (6) The Company shall have delivered to the holder, prior
to the Maturity Date, an undertaking of the Company in the form attached as
Annex A hereto.

        If all of the conditions set forth in this Section 1(c) are not
satisfied in accordance with the terms thereof, the principal hereof shall be
paid by the Company only in cash.

               (d) If the Company elects payment in shares pursuant to Section 1
and this Security is surrendered for payment in shares and is not so paid on the
Maturity Date, the principal amount of this Security shall, until paid, bear
interest to the extent permitted by


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CONFIDENTIAL TREATMENT--EDITED COPY

applicable law from the Maturity Date at the rate of 20.0% per annum, payable in
cash, and shall remain convertible into Common Stock until the principal of this
Security shall have been paid or duly provided for.

               (e) Any issuance of shares of Common Stock in payment hereof
shall be deemed to have been effected immediately prior to the close of business
on the Maturity Date and the person or persons in whose name or names any
certificate or certificates for shares of Common Stock shall be issuable upon
such payment shall be deemed to have become on the Maturity Date the holder or
holders of record of the shares represented thereby; provided, however, that if
the stock transfer books of the Company shall be closed on the Maturity Date
then the person or persons in whose name or names the certificate or
certificates for such shares are to be issued shall be deemed to be the record
holder or holders thereof for all purposes at the opening of business on the
next succeeding day on which such stock transfer books are open. Subject to
Section 2(b), no payment or adjustment shall be made for dividends or
distributions on any Common Stock issued upon payment of this Security declared
prior to the Maturity Date.

               (f) No fractions of shares shall be issued upon payment of this
Security. Instead of any fractional share of Common Stock which would otherwise
be issuable on the payment of this Security, the Company will deliver to the
holder its check for the current market value of such fractional share. The
current market value of a fraction of a share shall be determined by multiplying
the current market price of a full share by the fraction, and rounding the
result to the nearest cent. For purposes of this Section 1(f) the current market
price of a share of Common Stock shall be the Closing Price of the Common Stock
on the Trading Day immediately preceding the Maturity Date.

               (g) Any issuance and delivery of certificates for shares of
Common Stock in payment of this Security shall be made without charge to the
holder of this Security for such certificates or for any tax or duty in respect
of the issuance or delivery of such certificates or the securities represented
thereby; provided, however, that the Company shall not be required to pay any
tax or duty which may be payable in respect of any transfer involved in the
issuance or delivery of certificates for shares of Common Stock in a name other
than that of the holder of this Security, and no such issuance or delivery shall
be made unless and until the person requesting such issuance or delivery has
paid to the Company the amount of any such tax or duty or has established, to
the satisfaction of the Company, that such tax or duty has been paid.

               (h) Notwithstanding any other provision of this Security, the
Company shall, if the holder so elects, deliver the shares of Common Stock
issuable pursuant to this Section 1 to any third party designated in writing by
the holder.

        2.     Conversion.

               (a) The holder of this Security is entitled at any time on or
after March 21, 2002 and before the close of business on March 21, 2006 (or, in
case the holder hereof has exercised his right to require the Company to
repurchase this Security or a portion hereof pursuant to Section 3 hereof, then
in respect of this Security or such portion hereof, as the case may be, until
and including, but (unless the Company defaults in making the payment due upon
repurchase) not after, the close of business on the Repurchase Date) to convert
this Security (or


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CONFIDENTIAL TREATMENT--EDITED COPY

any portion of the principal amount hereof that is an integral multiple of
$1,000), into fully paid and nonassessable shares (calculated as to each
conversion to the nearest 1/100 of a share) of Common Stock of the Company at
the rate of 116.9152 shares of Common Stock for each $1,000 principal amount of
Security (or at the current adjusted rate if an adjustment has been made as
provided below) (the "Conversion Rate") by surrender of this Security, duly
endorsed or assigned to the Company or in blank to the Company at the Designated
Office, accompanied by written notice to the Company that the holder hereof
elects to convert this Security (or if less than the entire principal amount
hereof is to be converted, specifying the portion hereof to be converted).
Notwithstanding the foregoing, unless the holder of this Security notifies the
Company to the contrary, such holder shall be deemed for all purposes to have
converted this Security, subject only to surrender of this Security against
delivery of the Shares and cash issuable upon such conversion (which surrender
may take place before or after the date of such deemed conversion, without
affecting the availability thereof), immediately prior to the close of business
on March 21, 2006, if the Closing Price of the Common Stock on the immediately
preceding Trading Day exceeds 115% of the Conversion Price. Subject to Section
2(b) below, no payment or adjustment is to be made on conversion for dividends
on the Common Stock issued on conversion hereof. No fractions of shares or scrip
representing fractions of shares will be issued on conversion, but instead of
any fractional interest, the Company shall pay a cash adjustment, computed on
the basis of the Closing Price of the Common Stock on the date of conversion,
or, at its option, the Company shall round up to the next higher whole share.

        Notwithstanding any other provision of this Security, the Company shall,
if the holder so elects, deliver the shares of Common Stock issuable upon
conversion of this Security to any third party designated in writing by the
holder.

        Notwithstanding the foregoing, no holder of this Security that is
subject to the restrictions of Section 4 of the Bank Holding Company Act of
1956, as amended (the "BHCA") (a "BHCA Person") shall have the right to convert
this Security if, after giving effect to such conversion, the BHCA Person and
its affiliates and transferees would own or be deemed to own shares of Common
Stock in excess of either the maximum number of shares of Common Stock which the
BHCA Person is permitted to own under the BHCA and the regulations of the Board
of Governors of the Federal Reserve System thereunder or such lower number as
the relevant BHCA Person may have requested in writing to the Company. Any
Security held by an assignee or transferee of a holder subject to the
restriction on conversion in this paragraph shall continue to be subject to the
same restriction on conversion unless such Security was assigned or transferred
(i) to the public in an offering registered under the Securities Act, (ii) in a
transaction pursuant to Rule 144 or 144A under the Securities Act in which no
person acquires Securities convertible into more than 2% of the outstanding
Common Stock, (iii) in a single transaction to a third party who acquires a
majority of the Common Stock without regard to the conversion of any Security so
transferred or, (iv) in any other manner permitted under the BHCA. The Company
may rely on the representation of the relevant BHCA Person that a transfer has
been made in a manner which permits conversion of such Security.

        The holder of this Security, by acceptance thereof, shall be deemed to
have agreed to the foregoing restriction on transfers.


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CONFIDENTIAL TREATMENT--EDITED COPY

               (b) The Conversion Rate shall be subject to adjustments from time
to time as follows:

                      (1) In case the Company shall pay or make a dividend or
other distribution on any class of capital stock of the Company payable in
shares of Common Stock, the Conversion Rate in effect at the opening of business
on the day following the Determination Date for such dividend or other
distribution shall be increased by dividing such Conversion Rate by a fraction
of which the numerator shall be the number of shares of Common Stock outstanding
at the close of business on such Determination Date and the denominator shall be
the sum of such number of shares and the total number of shares constituting
such dividend or other distribution, such increase to become effective
immediately after the opening of business on the day following such
Determination Date. For the purposes of this paragraph (1), the number of shares
of Common Stock at any time outstanding shall not include shares held in the
treasury of the Company or issuable upon the exercise or conversion of
outstanding options, warrants or other securities but shall include shares
issuable in respect of scrip certificates issued in lieu of fractions of shares
of Common Stock. The Company will not pay any dividend or make any distribution
on shares of Common Stock held in the treasury of the Company.

                      (2) Subject to the last sentence of paragraph (7) of this
Section 2(b), in case the Company shall issue rights, options or warrants to all
holders of its Common Stock entitling them to subscribe for or purchase shares
of Common Stock at a price per share less than the current market price per
share (determined as provided in paragraph (8) of this Section 2(b)) of the
Common Stock on the Determination Date for such distribution, the Conversion
Rate in effect at the opening of business on the day following such
Determination Date shall be increased by dividing such Conversion Rate by a
fraction of which the numerator shall be the number of shares of Common Stock
outstanding at the close of business on such Determination Date plus the number
of shares of Common Stock which the aggregate of the offering price of the total
number of shares of Common Stock so offered for subscription or purchase would
purchase at such current market price and the denominator shall be the number of
shares of Common Stock outstanding at the close of business on such
Determination Date plus the number of shares of Common Stock so offered for
subscription or purchase, such increase to become effective immediately after
the opening of business on the day following such Determination Date. For the
purposes of this paragraph (2), the number of shares of Common Stock at any time
outstanding shall not include shares held in the treasury of the Company or
issuable upon the exercise or conversion of outstanding options, warrants or
other securities but shall include shares issuable in respect of scrip
certificates issued in lieu of fractions of shares of Common Stock. The Company
will not issue any rights, options or warrants in respect of shares of Common
Stock held in the treasury of the Company.

                      (3) In case outstanding shares of Common Stock shall be
subdivided into a greater number of shares of Common Stock, the Conversion Rate
in effect at the opening of business on the day following the day upon which
such subdivision becomes effective shall be proportionately increased, and,
conversely, in case outstanding shares of Common Stock shall each be combined
into a smaller number of shares of Common Stock, the Conversion Rate in effect
at the opening of business on the day following the day upon which such
combination becomes effective shall be proportionately reduced, such increase or
reduction, as the case may


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CONFIDENTIAL TREATMENT--EDITED COPY

be, to become effective immediately after the opening of business on the day
following the day upon which such sub-division or combination becomes effective.

                      (4) Subject to the last sentence of paragraph (7) of this
Section 2(b), in case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock evidences of its indebtedness, shares of any
class of capital stock, or other property (including securities, but excluding
(i) any rights, options or warrants referred to in paragraph (2) of this Section
2(b), (ii) any dividend or distribution paid exclusively in cash, (iii) any
dividend or distribution referred to in paragraph (1) of this Section 2(b) and
(iv) any merger or consolidation to which Section 2(h) applies), the Conversion
Rate shall be adjusted so that the same shall equal the rate determined by
dividing the Conversion Rate in effect immediately prior to the close of
business on the Determination Date for such distribution by a fraction of which
the numerator shall be the current market price per share (determined as
provided in paragraph (8) of this Section 2(b)) of the Common Stock on such
Determination Date less the then fair market value (as determined in good faith
by the Board of Directors of the Company) of the portion of the assets, shares
or evidences of indebtedness so distributed applicable to one share of Common
Stock and the denominator shall be such current market price per share of the
Common Stock, such adjustment to become effective immediately prior to the
opening of business on the day following such Determination Date. If the Board
of Directors determines the fair market value of any distribution for purposes
of this paragraph (4) by reference to the actual or when issued trading market
for any securities constituting such distribution, it must in doing so consider
the prices in such market over the same period used in computing the current
market price per share pursuant to paragraph (8) of this Section 2(b).

                      (5) In case the Company shall, by dividend or otherwise,
make a Cash Distribution, then, and in each such case, immediately after the
close of business on the Determination Date for such Cash Distribution, the
Conversion Rate shall be adjusted so that the same shall equal the rate
determined by dividing the Conversion Rate in effect immediately prior to the
close of business on such Determination Date by a fraction (a) the numerator of
which shall be equal to the current market price per share (determined as
provided in paragraph (8) of this Section 2(b)) of the Common Stock on such
Determination Date less an amount equal to the quotient of (1) the amount of
such Cash Distribution divided by (2) the number of shares of Common Stock
outstanding on such Determination Date and (b) the denominator of which shall be
equal to the current market price per share (determined as provided in paragraph
(8) of this Section 2(b)) of the Common Stock on such Determination Date.

                      (6) In case the Company or any Subsidiary shall make an
Excess Purchase Payment, then, and in each such case, immediately prior to the
opening of business on the day after the tender offer in respect of which such
Excess Purchase Payment is to be made expires, the Conversion Rate shall be
adjusted so that the same shall equal the rate determined by dividing the
Conversion Rate in effect immediately prior to the close of business on the
Determination Date for such tender offer by a fraction (a) the numerator of
which shall be equal to the current market price per share (determined as
provided in paragraph (8) of this Section 2(b)) of the Common Stock on such
Determination Date less an amount equal to the quotient of (A) the Excess
Purchase Payment divided by (B) the number of shares of Common Stock outstanding
(including any tendered shares) as of the Determination Date less the number of
all shares validly tendered and not withdrawn as of the Determination Date and
(b) the denominator


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CONFIDENTIAL TREATMENT--EDITED COPY

of which shall be equal to the current market price per share (determined as
provided in paragraph (8) of this Section 2(b)) of the Common Stock as of such
Determination Date.

                      (7) The reclassification of Common Stock into securities
other than Common Stock (other than any reclassification upon a consolidation or
merger to which Section 2(h) applies) shall be deemed to involve (a) a
distribution of such securities other than Common Stock to all holders of Common
Stock (and the effective date of such reclassification shall be deemed to be the
Determination Date), and (b) a subdivision or combination, as the case may be,
of the number of shares of Common Stock outstanding immediately prior to such
reclassification into the number of shares of Common Stock outstanding
immediately thereafter (and the effective date of such reclassification shall be
deemed to be "the day upon which such subdivision becomes effective" or "the day
upon which such combination becomes effective", as the case may be, and "the day
upon which such subdivision or combination becomes effective" within the meaning
of paragraph (3) of this Section 2(b)). Rights or warrants issued by the Company
to all holders of its Common Stock entitling the holders thereof to subscribe
for or purchase shares of Common Stock, which rights or warrants (i) are deemed
to be transferred with such shares of Common Stock, (ii) are not exercisable and
(iii) are also issued in respect of future issuances of Common Stock, in each
case in clauses (i) through (iii) until the occurrence of a specified event or
events ("Trigger Event"), shall for purposes of this Section 2(b) not be deemed
issued until the occurrence of the earliest Trigger Event.

                      (8) For the purpose of any computation under paragraphs
(2), (4), (5) or (6) of this Section 2(b), the current market price per share of
Common Stock on any date shall be calculated by the Company and be deemed to be
the average of the daily Closing Prices for the five consecutive Trading Days
commencing seven Trading Days before the earlier of (i) the day in question and
(ii) the day before the "ex" date with respect to the issuance or distribution
requiring such computation. For purposes of this paragraph, the term "ex date",
when used with respect to any issuance or distribution, means the first date on
which the Common Stock trades regular way in the applicable securities market or
on the applicable securities exchange without the right to receive such issuance
or distribution.

                      (9) No adjustment in the Conversion Rate shall be required
unless such adjustment (plus any adjustments not previously made by reason of
this paragraph (9)) would require an increase or decrease of at least one-half
of one percent in such rate; provided, however, that any adjustments which by
reason of this paragraph (9) are not required to be made shall be carried
forward and taken into account in any subsequent adjustment. All calculations
under this Section 2 shall be made to the nearest cent or to the nearest
one-hundredth of a share, as the case may be.

                      (10) The Company may make such increases in the Conversion
Rate, for the remaining term of the Securities or any shorter term, in addition
to those required by paragraphs (1), (2), (3), (4), (5) and (6) of this Section
2(b), as it considers to be advisable in order to avoid or diminish any income
tax to any holders of shares of Common Stock resulting from any dividend or
distribution of stock or issuance of rights or warrants to purchase or subscribe
for stock or from any event treated as such for income tax purposes.


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CONFIDENTIAL TREATMENT--EDITED COPY

               (c) Whenever the Conversion Rate is adjusted as provided in
Section 2(b), the Company shall compute the adjusted Conversion Rate in
accordance with Section 2(b) and shall prepare a certificate signed by the chief
financial officer of the Company setting forth the adjusted Conversion Rate and
showing in reasonable detail the facts upon which such adjustment is based, and
shall promptly deliver such certificate to the holder of this Security.

               (d) In case:

                      (1) the Company shall declare a dividend or other
distribution on its Common Stock payable (i) otherwise than exclusively in cash
or (ii) exclusively in cash in an amount that would require any adjustment
pursuant to Section 2(b); or

                      (2) the Company shall authorize the granting to the
holders of its Common Stock of rights, options or warrants to subscribe for or
purchase any shares of capital stock of any class or of any other rights; or

                      (3) of any reclassification of the Common Stock of the
Company, or of any consolidation, merger or share exchange to which the Company
is a party and for which approval of any shareholders of the Company is
required, or of the conveyance, sale, transfer or lease of all or substantially
all of the assets of the Company; or

                      (4) of the voluntary or involuntary dissolution,
liquidation or winding up of the Company; or

                      (5) the Company or any Subsidiary shall commence a tender
offer for all or a portion of the Company's outstanding shares of Common Stock
(or shall amend any such tender offer);

then the Company shall cause to be delivered to the holder of this Security, at
least 20 days (or 10 days in any case specified in clause (1) or (2) above)
prior to the applicable record, expiration or effective date hereinafter
specified, a notice stating (x) the date on which a record is to be taken for
the purpose of such dividend, distribution, rights, options or warrants, or, if
a record is not to be taken, the date as of which the holders of Common Stock of
record to be entitled to such dividend, distribution, rights, options or
warrants are to be determined, (y) the date on which the right to make tenders
under such tender offer expires or (z) the date on which such reclassification,
consolidation, merger, conveyance, transfer, sale, lease, 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, cash or other property
deliverable upon such reclassification, consolidation, merger, conveyance,
transfer, sale, lease, dissolution, liquidation or winding up. Neither the
failure to give such notice nor any defect therein shall affect the legality or
validity of the proceedings described in clauses (1) through (5) of this Section
2(d).

               (e) The Company shall at all times reserve and keep available,
free from preemptive rights, out of its authorized but unissued Common Stock,
for the purpose of effecting the conversion of the Security, the full number of
shares of Common Stock then issuable upon the conversion of this Security.


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CONFIDENTIAL TREATMENT--EDITED COPY

               (f) Except as provided in the next sentence, the Company will pay
any and all taxes and duties that may be payable in respect of the issue or
delivery of shares of Common Stock on conversion of the Security. The Company
shall not, however, be required to pay any tax or duty which may be payable in
respect of any transfer involved in the issue and delivery of shares of Common
Stock in a name other than that of the holder of this Security, and no such
issue or delivery shall be made unless and until the person requesting such
issue has paid to the Company the amount of any such tax or duty, or has
established to the satisfaction of the Company that such tax or duty has been
paid.

               (g) The Company agrees that all shares of Common Stock which may
be delivered upon conversion of the Security, upon such delivery, will have been
duly authorized and validly issued and will be fully paid and nonassessable (and
shall be issued out of the Company's authorized but unissued Common Stock) and,
except as provided in Section 2(f), the Company will pay all taxes, liens and
charges with respect to the issue thereof.

               (h) In case of any consolidation of the Company with any other
person, any merger of the Company into another person or of another person into
the Company (other than a merger which does not result in any reclassification,
conversion, exchange or cancellation of outstanding shares of Common Stock of
the Company) or any conveyance, sale, transfer or lease of all or substantially
all of the properties and assets of the Company, the person formed by such
consolidation or resulting from such merger or which acquires such properties
and assets, as the case may be, shall execute and deliver to the holder of this
Security a supplemental agreement providing that such holder have the right
thereafter, during the period this Security shall be convertible as specified
in Section 2(a), to convert this Security only into the kind and amount of
securities, cash and other property receivable upon such consolidation, merger,
conveyance, sale, transfer or lease (including any Common Stock retainable) by a
holder of the number of shares of Common Stock of the Company into which this
Security might have been converted immediately prior to such consolidation,
merger, conveyance, sale, transfer or lease, assuming such holder of Common
Stock of the Company (i) is not a person with which the Company consolidated,
into which the Company merged or which merged into the Company or to which such
conveyance, sale, transfer or lease was made, as the case may be (a "Constituent
Person"), or an Affiliate of a Constituent Person and (ii) failed to exercise
his rights of election, if any, as to the kind or amount of securities, cash and
other property receivable upon such consolidation, merger, conveyance, sale,
transfer or lease (provided that if the kind or amount of securities, cash and
other property receivable upon such consolidation, merger, conveyance, sale,
transfer, or lease is not the same for each share of Common Stock of the Company
held immediately prior to such consolidation, merger, conveyance, sale, transfer
or lease by others than a Constituent Person or an Affiliate thereof and in
respect of which such rights of election shall not have been exercised
("Non-electing Share"), then for the purpose of this Section 2(h) the kind and
amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, sale, transfer or lease by the holders of
each Non-electing Share shall be deemed to be the kind and amount so receivable
per share by a plurality of the Non-electing Shares). Such supplemental
agreement shall provide for adjustments which, for events subsequent to the
effective date of such supplemental agreement, shall be as nearly equivalent as
may be practicable to the adjustments provided for in this Section 2. The above
provisions of this Section 2(h) shall similarly apply to successive
consolidations, mergers, conveyances, sales, transfers or leases. In this
paragraph, "securities of the kind receivable" upon such consolidation, merger,


                                       11
<PAGE>   12

CONFIDENTIAL TREATMENT--EDITED COPY

conveyance, transfer, sale or lease by a holder of Common Stock means securities
that, among other things, are registered and transferable under the Securities
Act, and listed and approved for quotation in all securities markets, in each
case to the same extent as such securities so receivable by a holder of Common
Stock.

               (i) The Company (i) will effect all registrations with, and
obtain all approvals by, all governmental authorities that may be necessary
under any United States Federal or state law (including the Securities Act of
1933, the Securities Exchange Act of 1934 and state securities and Blue Sky
laws) for the shares of Common Stock issuable upon conversion of this Security
to be lawfully issued and delivered as provided herein, and thereafter publicly
traded (if permissible under such Securities Act) and qualified or listed as
contemplated by clause (ii) (it being understood that the Company shall not be
required to register the Common Stock issuable on conversion hereof under the
Securities Act, except pursuant to the Registration Rights Agreement between the
Company and the initial holder of this Security); and (ii) will list the shares
of Common Stock required to be issued and delivered upon conversion of
Securities, prior to such issuance or delivery, on each national securities
exchange on which outstanding Common Stock is listed or quoted at the time of
such delivery, or if the Common Stock is not then listed on any securities
exchange, to qualify the Common Stock for quotation on the Nasdaq National
Market or such other interdealer quotation system, if any, on which the Common
Stock is then quoted.

               (j) For purposes hereof:

        "Affiliate" of any specified person means any other person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified person. For the purposes of this definition,
"control", when used with respect to any specified person, means the power to
direct the management and policies of such person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

        "Cash Distribution" means the distribution by the Company to all holders
of its Common Stock of cash, other than any cash that is distributed upon a
merger or consolidation to which Section 2(h) applies or as part of a
distribution referred to in paragraph (4) of Section 2(b).

        "Closing Price" means, with respect to the Common Stock of the Company,
for any day, the reported last sale price per share on the Nasdaq National
Market, or, if the Common Stock is not admitted to trading on the Nasdaq
National Market, on the principal national securities exchange or interdealer
quotation system on which the Common Stock is listed or admitted to trading, or
if not admitted to trading on the Nasdaq National Market, or listed or admitted
to trading on any national securities exchange or interdealer quotation system,
the closing bid price per share in the over-the-counter market as furnished by
any New York Stock Exchange member firm selected from time to time by the
Company for that purpose.

        "Common Stock" means the Common Stock, no par value, of the Company
authorized at the date of this instrument as originally executed. Subject to the
provisions of Section 2(h), shares issuable on conversion or repurchase of this
Security, or in payment of the principal hereof at maturity, shall include only
shares of Common Stock or shares of any class or classes


                                       12
<PAGE>   13
CONFIDENTIAL TREATMENT--EDITED COPY

of common stock resulting from any reclassification or reclassifications
thereof; provided, however, that if at any time there shall be more than one
such resulting class, the shares so issuable on conversion of this Security
shall include shares of all such classes, and the shares of each such class then
so issuable shall be substantially in the proportion which the total number of
shares of such class resulting from all such reclassifications bears to the
total number of shares of all such classes resulting from all such
reclassifications.

        "Determination Date" means, in the case of a dividend or other
distribution, including the issuance of rights, options or warrants, to all
shareholders, the date fixed for the determination of shareholders entitled to
receive such dividend or other distribution and, in the case of a tender offer,
the last time that tenders could have been made pursuant to such tender offer.

        "Excess Purchase Payment" means the product of (A) the excess, if any,
of (i) the amount of cash plus the fair market value (as determined in good
faith by the Company's Board of Directors) of any non-cash consideration
required to be paid with respect to one share of Common Stock acquired or to be
acquired in a tender offer made by the Company or any subsidiary of the Company
for all or any portion of the Common Stock over (ii) the current market price
per share as of the last time that tenders could have been made pursuant to such
tender offer and (B) the number of shares validly tendered and not withdrawn as
of the Determination Date in respect of such tender offer.

        "Trading Day" means (i) if the Common Stock is admitted to trading on
the Nasdaq National Market or any other system of automated dissemination of
quotations of securities prices, a day on which trades may be effected through
such system; (ii) if the Common Stock is listed or admitted for trading on the
New York Stock Exchange or any other national securities exchange, a day on
which such exchange is open for business; or (iii) if the Common Stock is not
admitted to trading on the Nasdaq National Market or listed or admitted for
trading on any national securities exchange or any other system of automated
dissemination of quotation of securities prices, a day on which the Common Stock
is traded regular way in the over-the-counter market and for which a closing bid
and a closing asked price for the Common Stock are available.

        3.     Right to Require Repurchase.

               (a) In the event that a Change in Control (as hereinafter
defined) shall occur, then the holder of this Security shall have the right, at
such holder's option, to require the Company to repurchase, and upon the
exercise of such right the Company shall repurchase, this Security, or any
portion of the principal amount hereof that is equal to $1,000 or any integral
multiple thereof, on the date (the "Repurchase Date") that is 15 Trading Days
after the date on which the Company gives notice of such Change of Control to
the holder of this Security, at a purchase price equal to the Repurchase Price.
At the option of the Company, the Repurchase Price may be paid in cash or,
subject to the fulfillment by the Company of the conditions set forth in Section
3(b), by delivery of shares of Common Stock having a fair market value equal to
the Repurchase Price as described in Section 3(b). The Company agrees to give
the holder of this Security notice of any Change in Control, by facsimile
transmission confirmed in writing by overnight courier service, promptly and in
any event within two Trading Days of the occurrence thereof.


                                       13
<PAGE>   14
CONFIDENTIAL TREATMENT--EDITED COPY

               (b) The Company may elect to pay the Repurchase Price by delivery
of shares of Common Stock pursuant to Section 3(a), if and only if the following
conditions have been satisfied:

                      (1) The shares of Common Stock deliverable in payment of
the Repurchase Price shall have a fair market value as of the Repurchase Date of
not less than the Repurchase Price. For purposes of this Section 3(b), the fair
market value of shares of Common Stock shall be equal to the average of the
Closing Prices for the five consecutive Trading Days ending on and including the
third Trading Day immediately preceding the Repurchase Date;

                      (2) The shares of Common Stock to be issued upon
repurchase of this Security shall have been registered for resale by the holder
upon issuance pursuant to an effective registration statement under the
Securities Act of 1933, all in accordance with the Registration Rights
Agreement;

                      (3) If any shares of Common Stock to be issued upon
repurchase of this Security require registration with or approval of any
governmental authority under any State law or any other Federal law before such
shares may be validly issued or delivered upon repurchase, such registration
shall have been completed, have become effective and such approval shall have
been obtained, in each case, prior to the Repurchase Date;

                      (4) The shares of Common Stock deliverable in payment of
the Repurchase Price shall have been approved for quotation in the Nasdaq
National Market or listed on a national securities exchange immediately prior to
the Repurchase Date;

                      (5) All shares of Common Stock deliverable in payment of
the Repurchase Price shall be issued out of the Company's authorized but
unissued Common Stock and will, upon issue, be duly and validly issued and fully
paid and non-assessable and free of any preemptive rights; and

                      (6) The Company shall have delivered to the holder, prior
to the Repurchase Date, an undertaking of the Company in the form attached as
Annex A hereto.

        Notwithstanding any other provision of this Security, the Company shall,
if the holder so elects, deliver the shares of Common Stock issuable pursuant to
this Section 3 to any third party designated by the holder.

        If all of the conditions set forth in this Section 3(b) are not
satisfied in accordance with the terms thereof, the Repurchase Price shall be
paid by the Company only in cash.

               (c) To exercise a repurchase right, the holder shall deliver to
the Company on or before the 10th day prior to the Repurchase Date, together
with this Security, written notice of the holder's exercise of such right, which
notice shall set forth the name of the holder, the principal amount of this
Security to be repurchased (and, if this Security is to be repurchased in part,
the portion of the principal amount thereof to be repurchased and the name of
the person in which the portion thereof to remain outstanding after such
repurchase is to be registered) and a statement that an election to exercise the
repurchase right is being made thereby, and, in the event that the Repurchase
Price shall be paid in shares of Common Stock, the name or names


                                       14
<PAGE>   15
CONFIDENTIAL TREATMENT--EDITED COPY

(with addresses) in which the certificate or certificates for shares of Common
Stock shall be issued. Such written notice shall be irrevocable, except that the
right of the holder to convert this Security (or the portion hereof with respect
to which the repurchase right is being exercised) shall continue until the close
of business on the Repurchase Date (or if the Company elects to pay the
Repurchase Price by delivery of shares of Common Stock, until the close of
business on the Trading Day immediately preceding the first delivery of Common
Stock in respect thereof).

               (d) In the event a repurchase right shall be exercised in
accordance with the terms hereof, the Company shall pay or cause to be paid to
the holder the Repurchase Price in cash or shares of Common Stock, as provided
above, on or prior to the Repurchase Date.

               (e) If this Security (or portion thereof) is surrendered for
repurchase and is not so paid on the Repurchase Date, the principal amount of
this Security (or such portion hereof, as the case may be) shall, until paid,
bear interest to the extent permitted by applicable law from the Repurchase Date
at the rate of 20.0% per annum, payable in cash, and shall remain convertible
into Common Stock until the principal of this Security (or portion thereof, as
the case may be) shall have been paid or duly provided for.

               (f) If this Security is to be repurchased only in part, it shall
be surrendered to the Company at the Designated Office (with, if the Company so
requires, due endorsement by, or a written instrument of transfer in form
satisfactory to the Company duly executed by, the holder hereof or his attorney
duly authorized in writing), and the Company shall execute and make available
for delivery to the holder without service charge, a new Security or Securities,
containing identical terms and conditions, each in an authorized denomination in
aggregate principal amount equal to and in exchange for the unrepurchased
portion of the principal of the Security so surrendered.

               (g) Any issuance of shares of Common Stock in respect of the
Repurchase Price shall be deemed to have been effected immediately prior to the
close of business on the Repurchase Date and the person or persons in whose name
or names any certificate or certificates for shares of Common Stock shall be
issuable upon such repurchase shall be deemed to have become on the Repurchase
Date the holder or holders of record of the shares represented thereby;
provided, however, that any surrender for repurchase on a date when the stock
transfer books of the Company shall be closed shall constitute the person or
persons in whose name or names the certificate or certificates for such shares
are to be issued as the record holder or holders thereof for all purposes at the
opening of business on the next succeeding day on which such stock transfer
books are open. Subject to Section 2(b), no payment or adjustment shall be made
for dividends or distributions on any Common Stock issued upon repurchase of
this Security declared prior to the Repurchase Date.

               (h) No fractions of shares shall be issued upon repurchase of
this Security. Instead of any fractional share of Common Stock which would
otherwise be issuable on the repurchase of this Security, the Company will
deliver to the holder its check for the current market value of such fractional
share. The current market value of a fraction of a share shall be determined by
multiplying the current market price of a full share by the fraction, and
rounding the result to the nearest cent.


                                       15
<PAGE>   16
CONFIDENTIAL TREATMENT--EDITED COPY

               (i) Any issuance and delivery of certificates for shares of
Common Stock on repurchase of this Security shall be made without charge to the
holder of this Security for such certificates or for any tax or duty in respect
of the issuance or delivery of such certificates or the securities represented
thereby; provided, however, that the Company shall not be required to pay any
tax or duty which may be payable in respect of any transfer involved in the
issuance or delivery of certificates for shares of Common Stock in a name other
than that of the holder of this Security, and no such issuance or delivery shall
be made unless and until the person requesting such issuance or delivery has
paid to the Company the amount of any such tax or duty or has established, to
the satisfaction of the Company, that such tax or duty has been paid.

               (j) For purposes of this Section 3:

                      (1) the term "beneficial owner" shall be determined in
accordance with Rule 13d-3 promulgated by the Securities and Exchange Commission
pursuant to the Securities Exchange Act of 1934;

                      (2) a "Change in Control" shall be deemed to have occurred
at the time, after the original issuance of this Security, of:

                             (i) the acquisition by any person of beneficial
ownership, directly or indirectly, through a purchase, merger or other
acquisition transaction or series of transactions, of shares of capital stock of
the Company entitling such person to exercise 33 1/3% or more of the total
voting power of all shares of capital stock of the Company entitled to vote
generally in the elections of directors (any shares of voting stock of which
such person is the beneficial owner that are not then outstanding being deemed
outstanding for purposes of calculating such percentage) other than any such
acquisition by the Company or any employee benefit plan of the Company; or

                             (ii) any consolidation or merger of the Company
with or into, any other person, any merger of another person with or into the
Company, or any conveyance, transfer, sale, lease or other disposition of all or
substantially all of the assets of the Company to another person (other than (a)
any such transaction (x) which does not result in any reclassification,
conversion, exchange or cancellation of outstanding shares of Common Stock and
(y) pursuant to which holders of Common Stock immediately prior to such
transaction have the entitlement to exercise, directly or indirectly, [****] or
more of the total voting power of all shares of capital stock entitled to vote
generally in the election of directors of the continuing or surviving person
immediately after such transaction and (b) any merger which is effected solely
to change the jurisdiction of incorporation of the Company and results in a
reclassification, conversion or exchange of outstanding shares of Common Stock
into solely shares of common stock);

                      (3) the "current market" price of a share of Common Stock
shall be the Closing Price of the Common Stock on the Trading Day immediately
preceding the Repurchase Date.

                      (4) "Repurchase Price" means, (a) in connection with any
Change of Control involving a Stock Merger, 105% of the principal amount of this
Security to be


                                       16
<PAGE>   17
CONFIDENTIAL TREATMENT--EDITED COPY

repurchased pursuant to this Section 3, and (b) in connection with any other
Change of Control, the greater of (x)120% of the principal amount of this
Security to be repurchased pursuant to this Section and (y) the amount
determined pursuant to the following formula:

                 [****]   = [****]

                 where R  = the Repurchase Price;

                 P        = the principal amount of this Security to be
                            repurchased;

                 CR       = the Conversion Rate in respect of this Security; and

                 M        = the current market price of the Common Stock; plus

                      (5) "Stock Merger" means any merger or consolidation of
the Company with or into another entity in which holders of Common Stock
immediately prior to such transaction receive, in respect of such Common Stock,
consideration not less than 80% of which by value consists of common equity
securities listed on a U.S. national securities exchange or traded on the NASDAQ
National Market System.

        4. Events of Default. (a) "Event of Default", wherever used herein,
means any one of the following events (whatever the reason for such Event of
Default and whether it shall be voluntary or involuntary or be effected by
operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

                      (1) default by the Company in the performance of its
obligations in respect of any conversion of this Security (or any portion
hereof) in accordance with Section 2; or

                      (2) failure by the Company to give any notice of a Change
of Control required to be delivered in accordance with Section 3(a); or

                      (3) default in the performance, or breach, of any material
covenant or warranty of the Company herein (other than a covenant or warranty a
default in the performance or breach of which is specifically dealt with
elsewhere in this Section 4(a)) and continuance of such default or breach for a
period of 30 days after there has been given, by registered or certified mail,
to the Company by the holder of this Security a written notice specifying such
default or breach and requiring it to be remedied and stating that such notice
is a "Notice of Default" hereunder; or

                      (4) a default under any bond, debenture, note or other
evidence of indebtedness for money borrowed by the Company, or under any
agreement, mortgage, indenture or instrument under which there may be issued or
by which there may be secured or evidenced any indebtedness for money borrowed
by the Company, with a principal amount then outstanding in excess of
$1,000,000, whether such indebtedness now exists or shall hereafter be created,
which default shall constitute a failure to pay the principal of such
indebtedness (in whole or in any part greater than $1,000,000) when due and
payable or shall have resulted in


                                       17
<PAGE>   18
CONFIDENTIAL TREATMENT--EDITED COPY

such indebtedness (in whole or in any part greater than $1,000,000) becoming or
being declared due and payable prior to the date on which it would otherwise
have become due and payable, without such indebtedness having been discharged,
or such acceleration having been rescinded or annulled, within a period of 15
days after there shall have been given, by registered or certified mail, to the
Company by the holder of this Security a written notice specifying such default
and requiring the Company to cause such indebtedness to be discharged or cause
such acceleration to be rescinded or annulled and stating that such notice is a
"Notice of Default" hereunder; or

                      (5) the entry by a court having jurisdiction in the
premises of (A) a decree or order for relief in respect of the Company in an
involuntary case or proceeding under any applicable Federal or State bankruptcy,
insolvency, reorganization or other similar law or (B) a decree or order
adjudging the Company a bankrupt or insolvent, or approving as properly filed a
petition seeking reorganization, arrangement, adjustment or composition of or in
respect of the Company under any applicable Federal or State law, or appointing
a custodian, receiver, liquidator, assignee, trustee, sequestrator or other
similar official of the Company or of any substantial part of its property, or
ordering the winding up or liquidation of its affairs, and the continuance of
any such decree or order for relief or any such other decree or order unstayed
and in effect for a period of 60 consecutive days; or

                      (6) the commencement by the Company of a voluntary case or
proceeding under any applicable Federal or State bankruptcy, insolvency,
reorganization or other similar law or of any other case or proceeding to be
adjudicated a bankrupt or insolvent, or the consent by it to the entry of a
decree or order for relief in respect of the Company in an involuntary case or
proceeding under any applicable Federal or State bankruptcy, insolvency,
reorganization or other similar law or to the commencement of any bankruptcy or
insolvency case or proceeding against it, or the filing by it of a petition or
answer or consent seeking reorganization or similar relief under any applicable
Federal or State law, or the consent by it to the filing of such petition or to
the appointment of or taking possession by a custodian, receiver, liquidator,
assignee, trustee, sequestrator or other similar official of the Company or of
any substantial part of its property, or the making by it of an assignment for
the benefit of creditors, or the admission by it in writing of its inability to
pay its debts generally as they become due, or the taking of corporate action by
the Company in furtherance of any such action.

               (b) If an Event of Default (other than an Event of Default
specified in Section 4(a)(5) or 4(a)(6)) occurs and is continuing, then in every
such case the holder of this Security may declare the principal hereof to be due
and payable immediately, by a notice in writing to the Company, and upon any
such declaration such principal become immediately due and payable. If an Event
of Default specified in Section 4(a)(5) or 4(a)(6) occurs and is continuing, the
principal of, and accrued interest on, this Security shall ipso facto become
immediately due and payable without any declaration or other act of the holders.

               (c) The Company will give the holder of this Security notice,
within two Trading Days of the occurrence thereof, of any Event of Default or
any event that, with the giving of notice or passage of time or both, would
become an Event of Default. Such notice shall be given by facsimile transmission
confirmed in writing by overnight courier service.


                                       18
<PAGE>   19
CONFIDENTIAL TREATMENT--EDITED COPY

        5. Consolidation, Merger, Etc. (a) The Company shall not consummate a
consolidation with or merger into any other person or, directly or indirectly,
the conveyance, transfer, sale or lease of all or substantially all of its
properties and assets to any person, and the Company shall not permit any person
to consummate a consolidation with or merger into the Company or, directly or
indirectly, the conveyance, transfer, sale or lease all or substantially all of
its properties and assets to the Company, unless:

                      (1) in case the Company shall consolidate with or merge
into another person or convey, transfer, sell or lease all or substantially all
of its properties and assets to any person, the person formed by such
consolidation or into which the Company is merged or the person which acquires
by conveyance, transfer or sale, or which leases, all or substantially all the
properties and assets of the Company shall be a corporation, limited liability
company, partnership or trust, shall be organized and validly existing under the
laws of the United States of America, any State thereof or the District of
Columbia and shall expressly assume, by an agreement supplemental hereto,
executed and delivered to the holder of this Security in form reasonably
satisfactory to the holder, the due and punctual payment of the principal of
(and premium, if any) and any interest on this Security and the performance or
observance of every covenant of this Security on the part of the Company to be
performed or observed, including the conversion rights provided herein (which
shall thereafter relate to common stock of such successor, on a basis reasonably
designed to preserve the economic value to the holder of this Security of such
conversion rights);

                      (2) immediately after giving effect to such transaction
and treating any indebtedness which becomes an obligation of the Company or a
subsidiary of the Company as a result of such transaction as having been
incurred by the Company or such subsidiary of the Company at the time of such
transaction, no Event of Default, and no event which, after notice or lapse of
time or both, would become an Event of Default, shall have happened and be
continuing; and

                      (3) the Company has delivered to the holder of this
Security an officers' certificate and an opinion of counsel, each stating that
such consolidation, merger, conveyance, transfer, sale or lease and, if a
supplemental agreement is required in connection with such transaction, such
supplemental agreement, comply with this Section in all material respects and
that all conditions precedent herein provided for relating to such transaction
have been complied with in all material respects.

               (b) Upon any consolidation of the Company with, or merger of the
Company into, any other person or any conveyance, transfer, sale or lease of all
or substantially all of the properties and assets of the Company in accordance
with Section 5(a), the successor person formed by such consolidation or into
which the Company is merged or to which such conveyance, transfer, sale or lease
is made shall succeed to, and be substituted for, and may exercise every right
and power of, the Company under this Security with the same effect as if such
successor person had been named as the Company herein, and thereafter, except in
the case of a lease, the predecessor person shall be relieved of all obligations
and covenants under this Security.

        6.     Other.


                                       19
<PAGE>   20
CONFIDENTIAL TREATMENT--EDITED COPY

               (a) No provision of this Security shall alter or impair the
obligation of the Company, which is absolute and unconditional, to pay the
principal of, premium, if any, and interest, if any, on this Security at the
times, places and rate, and in the coin or currency, herein prescribed or to
convert this Security as herein provided.

               (b) The Company will give prompt written notice to the holder of
Security of any change in the location of the Designated Office. Any notice to
the Company or to the holder of this Security shall be given in the manner set
forth in the Option Agreement, dated as of February 16, 2001, between the
Company and the Purchaser named therein (the "Option Agreement"), provided that
the holder of this Security, if not a party to the Option Agreement, may specify
alternative notice instructions to the Company.

               (c) The transfer of this Security is registrable on the Security
Register of the Company upon surrender of this Security for registration of
transfer at the Designated Office, duly endorsed by, or accompanied by a written
instrument of transfer in form satisfactory to the Company duly executed by, the
holder hereof or his attorney duly authorized in writing, and thereupon one or
more new Securities, of authorized denominations and for the same aggregate
principal amount, will be issued to the designated transferee or transferees.
Such Securities are issuable only in registered form without coupons in
denominations of $1,000 and any integral multiple thereof. No service charge
shall be made for any such registration of transfer, but the Company may require
payment of a sum sufficient to recover any tax or other governmental charge
payable in connection therewith. Prior to due presentation of this Security for
registration of transfer, the Company and any agent of the Company may treat the
person in whose name this Security is registered as the owner thereof for all
purposes, whether or not this Security be overdue, and neither the Company nor
any such agent shall be affected by notice to the contrary.

               (d) This Security shall be governed by and construed in
accordance with the laws of the State of New York, United States of America.

        IN WITNESS WHEREOF, the Company has caused this Security to be duly
executed under its corporate seal.

                                    SciClone Pharmaceuticals, Inc.


                                    By:
                                        ----------------------------------------
                                        Name:  Donald R. Sellers
                                        Title: President and
                                               Chief Executive Officer


                                       20
<PAGE>   21
CONFIDENTIAL TREATMENT--EDITED COPY

                    ELECTION OF HOLDER TO REQUIRE REPURCHASE


        1. Pursuant to Section 3(a) of this Security, the undersigned hereby
elects to have all or a portion of this Security repurchased by the Company.

        2. The undersigned hereby directs the Company to pay [choose one] (a) it
or (b) Name: __________________; address: __________________; Social Security or
Other Taxpayer Identification Number, if any: ____________, an amount in cash
or, at the Company's election, Common Stock valued as set forth in the Security,
equal to the Repurchase Price, as provided herein.

                                           Dated:
                                                  ------------------------------

                                           -------------------------------------
                                                        Signature

Number of shares of Common Stock owned
by the holder and its affiliates:
                                                           ---------------------
Principal amount to be repurchased
(an integral multiple of ($1,000):
                                                           ---------------------

Remaining principal amount following
such repurchase (not less than $1,000):
                                                           ---------------------

NOTICE: The signature to the foregoing Election must correspond to the name as
written upon the face of this Security in every particular, without alteration
or any change whatsoever.

                                CONVERSION NOTICE

        The undersigned holder of this Security hereby irrevocably exercises the
option to convert this Security, or any portion of the principal amount hereof
(which is an integral multiple of $1,000) below designated, into shares of
Common Stock in accordance with the terms of this Security, and directs that
such shares, together with a check in payment for any fractional share and any
Security representing any unconverted principal amount hereof, be delivered to
and be registered in the name of the undersigned unless a different name has
been indicated below. If shares of Common Stock or Securities are to be
registered in the name of a person other than the undersigned, the undersigned
will pay all transfer taxes payable with respect thereto.

Dated:
       --------------------                -------------------------------------
                                                          Signature


                                       21
<PAGE>   22
CONFIDENTIAL TREATMENT--EDITED COPY

If shares or Securities are to be registered in the name of a person other than
the holder, please print such person's name and address:


--------------------------------------------------------------------------------
                                      Name


--------------------------------------------------------------------------------
                                     Address


--------------------------------------------------------------------------------
                       Social Security or other Taxpayer
                         Identification Number, if any


If only a portion of the Securities is to be converted, please indicate:

1.  Principal amount to be converted:                     $
                                                           ---------------------

2.  Principal amount and denomination of
    Security representing unconverted
    principal amount to be issued:

Amount:  $
          -----------------------------
Denominations: $
                 ----------------------
(any integral multiple of $1,000)


                                       22
<PAGE>   23
CONFIDENTIAL TREATMENT--EDITED COPY

Annex A

To: [name and address of holder]

SciClone Pharmaceuticals, Inc. (the "Company") is issuing this undertaking
pursuant to Section [1(c)] [3(b)] of its 6% Coupon Convertible Note Due 2006
("Note"). The Company is delivering herewith _____________ shares of its Common
Stock in payment of the [principal amount and accrued and unpaid interest
thereon][Repurchase Price] in respect of $___________ principal amount of the
Note [, which Repurchase Price equals $___________]. In consideration of your
purchase of the Note and acceptance of such shares, the Company undertakes to
pay to you, promptly on demand, an amount in cash equal to the difference
between such [principal amount and accrued and unpaid interest
thereon][Repurchase Price] and the aggregate proceeds realized by you upon
resale of such shares of Common Stock in the open market during the sixty days
following the [Maturity Date of the Note][the Repurchase Date]. Such payment
should be made promptly upon demand, against surrender of any shares of Common
Stock previously delivered to you pursuant to Section [1(c)][3(b)] and then
remaining unsold. The Company acknowledges that the manner of such resale shall
be in your absolute discretion, and that your determination of the amount of
such proceeds should be controlling.

                                       SciClone Pharmaceuticals, Inc.

                                       By:
                                          --------------------------------------
                                          Name:
                                          Title: