Document:

Exhibit 10.21

                 THE SECURITIES REPRESENTED BY THIS CERTIFICATE
                  HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
                 ACT OF 1933 AS AMENDED (THE "SECURITIES ACT"),
                    AND HAVE BEEN SOLD IN RELIANCE ON CERTAIN
                    EXEMPTIONS FROM REGISTRATION PROVIDED BY
                     REGULATION D UNDER THE SECURITIES ACT.

                   REDEEMABLE CONVERTIBLE 10% PROMISSORY NOTE

                             Due September 30, 2002

April 10, 2001                                                  Denver, Colorado

     EMB Corporation, a Hawaii corporation (hereinafter called the "Issuer"),
for value received, hereby promises to pay to the Holder, as defined below, on
September 30, 2002 (the "Maturity Date") in immediately available funds in the
initial principal amount of Five Hundred Thousand Dollars ($500,000), and to pay
interest on the principal sum outstanding at the rate of ten percent (10%) per
annum (the "Note Interest Rate"), payable upon maturity or any earlier
conversion of this Note.

     Accrual of interest shall commence on the date hereof and shall continue
until payment in full of the outstanding principal sum has been made or duly
provided for. The interest so payable will be paid to the person in whose name
this Note is registered on the records of the Issuer regarding registration and
transfers of Notes (the "Note Register").

     The principal of, and interest on, this Note are payable in legal tender of
the United States of America.

     Unless this Note is earlier redeemed or converted in accordance with its
terms, the Issuer will pay the outstanding principal of and all accrued and
unpaid interest due upon this Note on the Maturity Date, less any amounts
required by law to be deducted or withheld, to the Holder of record of this Note
as of the tenth (10th) day prior to the Maturity Date and addressed to such
Holder at the last address appearing on the Note Register.

                                    ARTICLE I
                                   DEFINITIONS

     The capitalized terms used in this Note, if not defined herein, shall have
the respective meanings specified in the Annex I, Annex of Defined Terms.

                                      -1-

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                                   ARTICLE II
                             EXCHANGES AND TRANSFER

     Section 2.1 Exchange and Registration of Transfer of Note. The Holder may,
at its option, surrender this Note at the office of the Issuer and receive in
exchange therefor a Note or Notes, each in the denomination of Ten Thousand
Dollars ($10,000.00) or an integral multiple of $10,000.00 or any amount in
excess thereof, but not more than one Note in any lesser amount, each dated of
the date of this Note, and payable to the Holder, or subject to Section 4.2
hereof, payable to such other Person, as may be designated by such Holder. The
aggregate principal amount of such Note or Notes exchanged in accordance with
Section 2.1 shall equal the aggregate unpaid principal amount of this Note as of
the date of such surrender; provided, however, that upon such exchange there
shall be filed with the Issuer the name and address for all purposes hereof of
the Holder of the Note or Notes delivered in such exchange. This Note, when
presented for registration of transfer or for exchange or conversion, shall (if
so required by the Issuer) be duly endorsed by, or be accompanied by a written
instrument of transfer in form reasonably satisfactory to the Issuer duly
executed by the Holder.

     Section 2.2 Loss, Theft; Destruction of Note. Upon receipt of evidence
satisfactory to the Issuer of the loss, theft, destruction or mutilation of this
Note and, in the case of any such loss, theft or destruction, upon receipt of
indemnity or security reasonably satisfactory to the Issuer, or, in the case of
any such mutilation, upon surrender and cancellation of this Note, the Issuer
will make and deliver, in lieu of such lost, stolen, destroyed or mutilated
Note, a new Note of like tenor and unpaid principal amount dated as of the date
hereof. This Note shall be held and owned upon the express condition that the
provisions of this Section 2.2 are exclusive with respect to the replacement of
a mutilated, destroyed, lost or stolen Note and the Issuer shall have no further
responsibility whatsoever with respect to the mutilated , destroyed, lost or
stolen Note, notwithstanding any law or statute existing or hereafter enacted to
the contrary with respect to the replacement of a negotiable instrument or other
securities without their surrender.

     Section 2.3 Absolute Owner. The Issuer may deem the person in whose name
this Note shall be registered upon the registry books of the issuer to be, and
may treat it as, the absolute owner of this Note (whether or not this Note shall
be overdue) for the purpose of receiving payment of or on account of the
principal of this Note, for the Conversion of this Note and for all other
purposes, and the Issuer shall not be affected by any notice to the contrary,
unless such notice is accompanied by surrender of this Note. All such payments
and such conversion shall be valid and effective to satisfy and discharge the
liability upon this Note to the extent of the sum or sums so paid or the
conversion so made.

                                   ARTICLE III
                               CONVERSION OF NOTE

     Section 3.1 Optional Conversion; Conversion Price. At the option of the
Holder, at any time, from time to time, after seventeen (17) months from
issuance of this Note until this Note is paid in full, including accrued
interest, this Note may be converted, either in whole or in part up to the
principal amount hereof (or in case some portion of this Note shall be converted

                                      -2-

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prior to such date, then that portion that is not so converted), together with
interest accrued thereon to the relevant Conversion Date, into Common Stock of
the Issuer (calculated as to each conversion to the nearest 1/100th of a share),
at the conversion price the ("Conversion Price"), equal to the volume-weighted
trading average Closing Bid Price during the ten (10) consecutive Trading Days
immediately preceding the Conversion Date (the "Valuation Period"); provided,
however, that, in lieu of issuing either or both of the Conversion Shares or
Interest Shares, the Issuer may redeem such portion of the principal or interest
of this Note in respect of which Conversion has been requested.

     Section 3.2 Exercise of Conversion Privilege.

     (a) In order to exercise the conversion privilege, either in whole or in
part, the Holder shall surrender this Note to the Issuer during usual business
hours at its principal office and shall give written notice to the Issuer in the
form attached hereto in Annex II (the "Conversion Notice") at said office that
the Holder elects to convert this Note.

     (b) The Conversion Notice shall specify whether the Holder desires to
receive its interest accumulated to date in cash or Interest Shares. If the
holder elects to receive Interest Shares, the number of Shares issuable shall be
calculated at the same Conversion Price applicable to any conversion of
principal of this Note.

     (c) As promptly as practicable upon the receipt of any Conversion Notice,
and surrender of this Note, the Issuer shall convert the Note and issue the
Common Stock. The Issuer shall (i) issue the Common Stock issuable upon such
conversion in accordance with the provisions of this Article 3, and (ii) deliver
or direct its transfer agent to deliver by overnight delivery to the Holder a
certificate or certificates representing the number of shares of Common Stock to
which the Holder is entitled by virtue of such conversion.

     (d) The Conversion Notice shall also state the name (with address) of the
person who is to become the holder of the Common Stock issued at conversion in
connection with such conversion. Upon surrender for conversion, this Note shall
be accompanied by a proper assignment hereof to the Issuer or in blank.

     (e) Such conversion shall be deemed to have been effected at the time at
which the Conversion Notice indicates, so long as this Note shall have been
surrendered as aforesaid at such time and at such time the rights of the Holder
as holder of this Note shall cease and the person or persons in whose name or
names the Common Stock issued at conversion shall be issuable upon such
conversion shall be deemed to have become the holder or holders of record of the
Common Stock represented thereby.

     (f) The Conversion Notice shall constitute a contract between the Holder
and the Issuer, whereby the Holder shall be deemed to subscribe for the number
of shares of Common Stock that it will be entitled to receive upon such
conversion and in payment and satisfaction of such subscription (and for any
cash adjustment to which it is entitled pursuant to Section 3.3), to surrender
this Note and to release the Issuer from all liabilities thereon.

                                      -3-

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     Section 3.3 Fractional Shares. No fractional share of Common Stock of the
Issuer or scrip representing fractional Common Stock shall be issued upon
conversion of this Note. Instead of any fractional Common Stock which would
otherwise be issuable upon conversion of this Note, the Issuer shall pay a cash
adjustment in respect of such fraction in an amount equal to the same fraction.
No cash payment of less than $1.00 shall be required.

                                   ARTICLE IV
                                   REDEMPTION

     Section 4.1 Redemption. The Notes being issued hereunder are subject to
redemption by the Issuer in whole or in part at any time or from time to time,
but not later than the Maturity Date, unless earlier converted or redeemed
pursuant to Section 3.1, above. The redemption price payable, in cash, shall be
the principal amount of this Note, or such pro rata amount as is then being
redeemed, and all interest accrued thereon to the date of redemption, less a
discount as follows:

Up to three (3) months after issuance - 40% discount from principal amount;

More than three (3) months, and up to six (6) months after issuance - 30%
discount from princpal amount;

More than six (6) months, and up to twelve (12) months after issuance - 20%
discount from principal amount;

More than nine (9) months, and up to twelve (12) months after issuance - 10%
discount from principal amount.

More than twleve (12) months, and up to eighteen (18) months after issuance -
there shall be no discount.

The Notes shall not be thereafter redeemable, without the consent of the holder
thereof.

     Section 4.2. Notices, etc. Subject to the provisions of Section 4.1 hereof,
the Issuer may, at its option, redeem any or all of the Notes held by any Holder
or groups of holders at any time on thirty (30) days notice of redemption. The
discount from the principal amount due shall be determined by the date of the
written notice of redemption.

                                    ARTICLE V
                        STATUS; RESTRICTIONS ON TRANSFER

     Section 5.1 Status of Note. This Note is a direct, general and
unconditional obligation of the Issuer ranking pari passu with all other
unsecured indebtedness of the Issuer, enforceable in accordance with its terms
subject, as to enforcement, to bankruptcy, insolvency, reorganization and other
similar laws of general applicability relating to or affecting creditors' rights
and to general principles of equity.

                                      -4-

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         Section 5.2 Restrictions on Transfer. This Note, and any Common Stock
of the Issuer issued according to the terms hereof, have not been and will not
be registered under the Securities Act. This Note may not be offered or sold,
directly or indirectly, assigned, transferred, hypothecated or pledged in the
absence of an effected registration statement under the Securities Act, or the
opinion of counsel to the Issuer that such transaction is exempt from
registration under the Securities Act.

                                   ARTICLE VI
                                    COVENANTS

     The Issuer covenants and agrees that so long as this Note shall be
outstanding:

     Section 6.1 Conversion. The Issuer will punctually issue shares of Common
Stock at conversion, according to the terms hereof and of the Purchase
Agreement.

     Section 6.2 Notice of Default. If any one or more events occur which
constitute or with the giving of notice or the lapse of time or both, would
constitute an Event of Default or if the Holder shall demand the issuance of
Common Stock or take any other action permitted upon the occurrence of any such
Event of Default, the Issuer will forthwith give notice to the Holder,
specifying the nature and status of the Event of Default or other event or of
such demand or action, as the case may be.

     Section 6.3 Preservation of Existence. The Issuer will preserve and
maintain its existence, rights, franchises and privileges that are material to
both (i) the performance of its obligations under this Note and (ii) the conduct
of its business as presently or proposed to be conducted.

     Section 6.4 Compliance with Laws. The Issuer will comply in all material
respects with all applicable laws, ordinances, rules, regulations and
requirements of governmental authorities, including, but not limited to,
maintianing compliance with any applicable reporting requirements of the
Securities Exchange Act of 1934. In no event, however, shall the provisions of
this Seciton 6.4 apply to any failure of the Issuer to comply, where the
necessity of compliance therewith is contested in good faith by appropriate
proceedings.

     Section 6.7 Inspection of Property, Books and Records. The Issuer will keep
proper books of record and account in which full, true and correct entries shall
be made of all dealings and transactions in relation to its business and
activities and will permit representatives of the Holder at the Holder's expense
to visit and inspect any of its respective properties, to examine and make
abstracts from any of its respective books and records and to discuss its
respective affairs, finances and accounts with its respective officers,
employees and independent public accountants, all at such reasonable times and
as often as may reasonably be desired.

                                      -5-

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     Section 6.8 Reservation of Conversion Shares. The Issuer shall, at all
times, reserve and keep available out of its authorized but unissued shares of
Common Stock, solely for the purpose of effecting the conversion of this Note,
such number of shares of its Common Stock as shall from time to time be
sufficient to effect the conversion of this Note; and if at any time the number
of authorized but unissued shares of Common Stock shall not be sufficient to
effect the conversion of the entire outstanding principal of this Note, in
addition to such other remedies as shall be available to the holder of this
Note, the Issuer shall use its best efforts to take such corporate action as
may, in the opinion of its counsel, be necessary to increase its authorized but
unissued shares of Common Stock to such number of shares as shall be sufficient
for such purposes.

                                   ARTICLE VII
                           EVENTS OF DEFAULT; REMEDIES

     Section 7.1 Events of Default. "Event of Default" wherever used herein
means any of the following events:

     (a) default in the due and punctual payment of the principal of, or
interest on, this Note when and as the same shall become due and payable, and
continuance of such default for a period of thirty (30) calendar days; or

     (b) the Issuer shall fail to perform, or observe any covenant, agreement or
obligation of the Issuer in this Note and the continuance of such default for a
period of forty-five (45) calendar days after there has been given to the Issuer
by a Holder a written notice specifying such default and requiring it to be
remedied; or

     (c) the entry of a decree or order by a court having jurisdiction in the
premises adjudging the Issuer a bankrupt or insolvent, or approving as properly
filed a petition seeking reorganization, arrangement, adjustment or composition
of or in respect of the Issuer under the Bankruptcy Code or any other Federal or
State law, or appointing a receiver, liquidator, assignee, trustee or
sequestrator (or other similar official) of the Issuer 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 unstated and in effect for a
period of 90 calendar days; or

     (d) the institution by the Issuer of proceedings to be adjudicated a
bankrupt or insolvent, or the consent by it to the institution of bankruptcy or
insolvency proceedings against it, or the filing by it of a petition or answer
or consent seeking reorganization or relief under the Federal Bankruptcy Code or
any other applicable Federal or State law, or the consent by it to the filing of
any such petition or to the appointment of a receiver, liquidator, assignee,
trustee or sequestrator (or other similar official) of the Issuer 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
Issuer in furtherance of any such action; or

     (e) (i) with respect to those debts other than those which exist at the
time of the issuance of this Note, the Issuer is unable to pay its debts, as
they fall due, stops, or suspends or threatens in writing to stop or suspend

                                      -6-

<PAGE>

payment of all or any material part of its debts (other than debts contested in
good faith by appropriate proceedings), begins negotiations or takes any
proceeding or other step with a view to readjustment, rescheduling or deferral
of all of its Indebtedness (or any material thereof) that it will or might
otherwise be unable to pay when due or seeks the appointment of a statutory
manager or proposes in writing or makes a general assignment or an arrangement
or composition with or for the benefit of its creditors or any group or class
thereof or files a petition for suspension of payments or other relief of
debtors of for bankruptcy or is declared bankrupt or a moratorium or statutory
management is agreed or declared with respect of or affecting all or any
material part of the Indebtedness of the Issuer, or (ii) the Issuer ceases or
threatens in writing to cease to carry all or any material part of the business
carried on, or proposed to be carried on, by the Issuer taken as a whole and as
a result of such cessation or threat of cessation, the Issuer will not be able
to perform or comply with its payment obligations under this Notes.

     Section 7.2 Acceleration of Maturity, Rescission and Annulment. If an Event
of Default occurs and is continuing following the period in which the Issuer may
cure the default, then and in every such case any Holder may either (a)
accelerate the holding period requirement of seventeen (17) months and
immediately elect to convert all or a portion of the outstanding principal
amount of the Note into Conversion Shares, or (b) rescind any Conversion Notice
given to the Issuer (but only if the Conversion Shares or the Interest Shares so
requested have not then been issued) and obtain payment in immediately available
funds for the entire outstanding principal amount of the Note that remains
unconverted and unredeemed and all interest accrued thereon, by a notice in
writing to the Issuer, and upon any such declaration the principal amount of
this Note shall become immediately due and payable by virtue of such rescission.

     Section 7.3 Remedies Not Waived. No course of dealing between the Issuer
and the Holder or any delay in exercising any rights hereunder shall operate as
a waiver by the Holder.

                                  ARTICLE VIII
                                  MISCELLANEOUS

     Section 8.1 Register.

     (a) The Issuer shall keep at its principal office a register in which the
Issuer shall provide for the registration of this Note. Upon any transfer of
this Note in accordance with the terms of this Note, the Issuer shall register
such transfer in the Note Register.

     (b) The Issuer, may deem the person in whose name this Note shall be
registered upon the registry books of the Issuer to be, and may treat it as, the
absolute power if this Note (whether or not this Note shall be overdue) for the
purpose of receiving payment of interest on or principal of this Note, for the
conversion of this Note and for all other purposes, and the Issuer shall not be
affected by any notice to the contrary. All such payments and such conversions
shall be valid and effective to satisfy and discharge the liability upon this
Note to the extent of the sum or sums so paid or the conversion or conversions
so made.

                                      -7-

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     Section 8.2 Withholding. To the extent required by applicable law, the
Issuer may withhold amounts for or on account of any taxes imposed or levied by
or on behalf of any taxing authority in the United States having jurisdiction
over the Issuer from any payments made pursuant to this Note.

     Section 8.3 Governing Law. This Note shall be governed by, and construed in
accordance with, the laws of the State of Colorado.

     Section 8.4 Headings. The headings of the Articles and Sections of this
Note are solely for convenience only and do not constitute a part of this Note.

IN WITNESS WHEREOF, the Issuer has caused this Note to be signed by its duly
authorized officer and attested by its duly authorized officer, on the date of
this Note.

                                            EMB CORPORATION

                                            By:      /s/ Ben Campbell
                                                     ---------------------------
                                            Name:    Ben Campbell
                                                     ---------------------------
                                            Title:   President
                                                     ---------------------------
                                      -8-
<PAGE>

                                     ANNEX I
                                 EMB CORPORATION
                         REDEEMABLE CONVERTIBLE 10% NOTE
                             ANNEX OF DEFINED TERMS

     "Business Day" shall mean a day other than Saturday, Sunday or any day on
which banks in the State of Colorado are obligated to close.

     "Closing Bid Price" means, for the Common Stock as of any date, the last
closing bid price for the Common Stock on the principal securities exchange or
trading market on which the Common Stock is listed or traded as reported by
Bloomberg Financial Markets ("Bloomberg"), or, if the Common Stock is not listed
or traded on a securities exchange or trading market, the last closing bid price
of the Common Stock on the OTC Bulletin Board for the Common Stock as reported
by Bloomberg, or, if no closing bid price is reported for the Common Stock by
Bloomberg, the last closing trade price of the Common Stock as reported by
Bloomberg, or, if no last closing trade price is reported for the Common Stock
by Bloomberg, the average of the bid prices of any market makers for such
security as reported by Pink Sheets, LLC. If the Closing Bid Price cannot be
calculated for the Common Stock on such date on any of the foregoing bases, the
Closing Bid Price of such security on such date shall be the fair market value
as mutually determined by the Company and the Holder(s) of the Note. (All such
determinations to be appropriately adjusted for any stock dividend, stock split
or other similar transaction during such period).

     "Closing Date" shall mean April __, 2001, or any mutually agreed upon other
date.

     "Common Shares" or "Common Stock" shall mean shares of the Common Stock, no
par value of the Issuer.

     "Conversion Date" shall mean any day on which all or some part of the
principal amount of this Note is converted into Conversion Shares in accordance
with the terms of this Note.

     "Conversion Notice" shall have the meaning set forth in Section 3.2.

     "Conversion Price" shall have the meaning set forth in Section 3.1.

     "Conversion Shares" shall mean all Common Shares issued or issuable upon
conversion of this Note, including the Interest Shares, if any.

     "Event of Default" shall have the meaning set forth in Section 7.1.

     "Holder" means James Saunders and any subsequent holder hereof or of any
Notes for which this Note is exchanged pursuant to Article 2.

                                      -1-

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     "Indebtedness" shall mean the (i) all indebtedness of the Issuer or other
obligations for borrowed money or other claims which would, in accordance with
generally accepted accounting principles, be classified as a liability on the
balance sheet of the Issuer.

     "Interest Shares" shall mean any Conversion Shares issued or issuable, at
the election of any Note holder, in lieu of interest accrued on any Note at the
time of conversion.

     "Issuer" shall mean EMB Corporation and any successor corporation by
merger, consolidation, sale or exchange of all or substantially all of the
Issuer's assets, or otherwise.

     "Note" shall mean this Redeemable Convertible 10% Note or such other Note
or Notes exchanged therefor as provided in Section 2.1.

     "Person" shall mean an individual , a corporation, a partnership, an
association, a trust or other entity or organization, including a government or
political subdivision or an agency or instrumentality thereof.

     "SEC" shall mean the United States Securities and Exchange Commission.

     "Securities Act" shall mean the United States Securities Act of 1933, as
amended, and the rules and regulations of the SEC thereunder, all as in effect
at the time.

     "Subsidiary" shall mean any entity over which the Issuer has directly or
indirectly voting power or other interests sufficient to elect a majority of the
board of directors or other persons performing similar functions.

     "Trading Day" shall mean any day on which the principal securities exchange
or market or OTC Bulletion Board, as the case may be, shall be open for
business.

     "Valuation Period" shall have the meaning set forth in Section 3.1.

                                      -2-

<PAGE>

                                    ANNEX II
                                 EMB CORPORATION
                         REDEEMABLE CONVERTIBLE 10% NOTE

                              NOTICE OF CONVERSION

     (To be Executed by the Registered Holder in order to Convert any Note)

     The undersigned hereby irrevocably elects to convert $_________ of the
above Note No._______ into Shares of Common Stock of EMB Corporation (the
"Company") according to the conditions set forth in such Note, as of the date
written below.

     If Shares are to be issued in the name of a person other than the
undersigned, the undersigned will pay all transfer taxes payable with respect
thereto.

Date of Conversion:
                    -----------------------------------------------------

Conversion Price:
                    -----------------------------------------------------

Name of Holder:
                    -----------------------------------------------------

Address:
           --------------------------------------------------------------

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

Signature:
           --------------------------------------------------------------
           (Print Name and Title of Signatory)EXHIBIT 4.1

                          AMENDMENT TO RIGHTS AGREEMENT

      THIS AMENDMENT (this "AMENDMENT"), is entered into as of August 24, 2001,
by and between TRIANGLE PHARMACEUTICALS, INC., a Delaware corporation (the
"COMPANY"), and AMERICAN STOCK TRANSFER & TRUST COMPANY, as Rights Agent (the
"RIGHTS AGENT").

                                    RECITALS

      A. The Company and the Rights Agent are parties to a Rights Agreement
dated as of February 1, 1999, as amended by the Amendment to Rights Agreement
dated as of June 2, 1999 (as so amended, the "RIGHTS AGREEMENT").

      B. Warburg Pincus Private Equity VIII, L.P. ("WARBURG") and the Company
have entered into a Purchase Agreement dated as of August 24, 2001 (the "WARBURG
STOCK PURCHASE AGREEMENT"), pursuant to which Warburg is to purchase shares of
Company Common Stock.

      C. The Board of Directors of the Company has determined that an amendment
to the Rights Agreement as set forth herein is necessary and desirable to
reflect the foregoing and certain other matters and the Company and the Rights
Agent desire to evidence such amendment in writing.

            Accordingly, the parties agree that:

      1. AMENDMENT TO DEFINITION OF "ACQUIRING PERSON" SET FORTH IN SECTION
1(A). The definition of "Acquiring Person" set forth in Section 1(a) of the
Rights Agreement is amended to read in its entirety as follows:

      (a) "ACQUIRING PERSON" shall mean any Person (as such term is hereinafter
      defined) who or which, together with all Affiliates and Associates (as
      such terms are hereinafter defined) of such Person, shall be the
      Beneficial Owner (as such term is hereinafter defined) of 15% or more of
      the shares of Common Stock of the Company then outstanding but shall not
      include (1) the Company, any Subsidiary (as such term is hereinafter
      defined) of the Company, any employee benefit plan of the Company or any
      Subsidiary of the Company, or any entity holding shares of Common Stock
      for or pursuant to the terms of any such plan, (2) during the Interim
      Period (as defined below), Abbott Laboratories, an Illinois corporation
      (the "PERMITTED INVESTOR"), or any U.S. wholly-owned subsidiaries of the
      Permitted Investor (collectively with the Permitted Investor, the
      "INVESTOR GROUP") but only to the extent that the Permitted Investor may
      be deemed a Beneficial Owner of the Shares (as defined below) as a result
      of the Permitted Investor entering into the Abbott Stock Purchase
      Agreement (as defined below), unless the Permitted Investor becomes the
      Beneficial Owner (as defined in the Abbott Rights Agreement (as defined
      below)) of any additional securities of the Company other than the Shares
      during the Interim Period, (3) during the Threshold Period (as hereinafter
      defined), the Investor Group, or (4) Warburg Pincus Private Equity VIII,
      L.P., together with all its Affiliates ("WARBURG"), unless and until
      Warburg becomes the Beneficial Owner of more than the Permitted Percentage
      (as hereinafter defined); provided, however, that if Warburg files a
      Schedule 13D (or comparable or successor form or report) under the
      Exchange Act disclosing that Warburg holds the Common Stock for any
      purpose of, or with the effect of, causing the Company to enter into a
      merger, consolidation, business combination, acquisition, restructuring,
      recapitalization, tender or

<Page>

      exchange offer, or similar transaction involving the Company, or its
      securities or a material portion of its assets (other than such a
      transaction approved by the Board of Directors of the Company), or in
      connection with or as a participant in any transaction under Rule 13d-3(b)
      under the Exchange Act and Warburg's Beneficial Ownership of Common Stock
      equals fifteen percent (15%) or more, then Warburg shall become an
      Acquiring Person. For purposes of this Agreement, the "INTERIM PERIOD"
      shall mean such period commencing as of the date of the Abbott Stock
      Purchase Agreement and ending on the earlier of (x) the "EFFECTIVE DATE"
      as such term is defined in the Collaboration Agreement (as defined below)
      and (y) termination of the Abbott Stock Purchase Agreement. For purposes
      of this Agreement, the "THRESHOLD PERIOD" shall mean such period
      commencing as of the Effective Date under the Collaboration Agreement and
      ending on the earlier of (xx) such time as the Permitted Investor holds
      less than the Minimum Purchaser Interest in the Company (as defined in
      Section 1.11 of the Abbott Rights Agreement), (yy) such time as the
      Investor Group's Beneficial Ownership (as the term Beneficial Ownership is
      defined in the Abbott Rights Agreement) exceeds the Beneficial Ownership
      Limitation (as defined in Section 5.2(a) of the Abbott Rights Agreement),
      and (zz) such time as the Permitted Investor's rights under Section 7.1 of
      the Abbott Rights Agreement have terminated pursuant to the terms of the
      Abbott Rights Agreement. Notwithstanding the foregoing:

                (i) no Person shall become an "Acquiring Person" as the result
      of an acquisition of shares of Common Stock by the Company which, by
      reducing the number of shares outstanding, (a) increases the proportionate
      number of shares beneficially owned by such Person to 15% or more (or in
      the case of Warburg, more than the Permitted Percentage) of the shares of
      Common Stock of the Company then outstanding, or, (b) in the case of the
      Investor Group during the Interim Period, increases the proportionate
      number of shares which may be deemed beneficially owned by the Investor
      Group, unless the Permitted Investor becomes the Beneficial Owner (as
      defined in the Abbott Rights Agreement) of any additional securities of
      the Company other than the Shares during the Interim Period, or, (c) in
      the case of the Investor Group during the Threshold Period, increases the
      proportionate number of shares Beneficially Owned (as defined in the
      Abbott Rights Agreement) by the Investor Group to more than the Beneficial
      Ownership Limitation; provided, however, that if by reason of share
      purchases by the Company, (1) a Person shall become the Beneficial Owner
      of 15% or more (or in the case of Warburg, more than the Permitted
      Percentage) of the shares of Common Stock of the Company then outstanding
      or, (2) in the case of the Investor Group, the Investor Group's ownership
      increases the Investor Group's Beneficial Ownership (as defined in the
      Abbott Rights Agreement) by any amount during the Interim Period or
      results in the Investor Group's Beneficial Ownership (as defined in the
      Abbott Rights Agreement) to exceed the Beneficial Ownership Limitation at
      any time during the Threshold Period, and, in the case of (1) or (2)
      above, such Person or Investor Group shall, after such share purchases by
      the Company, become the Beneficial Owner of any additional shares of
      Common Stock of the Company, then such Person, including the Investor
      Group, shall be deemed to be an "Acquiring Person" hereunder; and

                (ii) if the Board of Directors of the Company determines in good
      faith that a Person who would otherwise be an "Acquiring Person" as
      defined pursuant to the foregoing provisions of this paragraph (a), has
      become such inadvertently, and such Person divests as promptly as
      practicable a sufficient number of shares of Common Stock so that such
      Person would no longer be an "Acquiring Person" (as defined

                                       2
<Page>

      pursuant to the foregoing provisions of this paragraph (a)), then such
      Person shall not be deemed to be an "Acquiring Person" for any purpose of
      this Agreement."

      2. AMENDMENT TO DEFINITION OF "TRIGGERING EVENT" SET FORTH IN SECTION
1(oo). The definition of "Triggering Event" set forth in Section 1 (oo) of the
Rights Agreement is amended to add the following sentence to the end thereof:

      "Notwithstanding anything in this Rights Agreement to the contrary, a
      Triggering Event shall not be deemed to have occurred by virtue of (i) the
      Warburg Stock Purchase Agreement or by virtue of any of the transactions
      contemplated thereby, or (ii) the Abbott Stock Purchase Agreement and the
      Related Agreements (as such term is defined in the Abbott Stock Purchase
      Agreement) or by virtue of any of the transactions contemplated thereby
      (excluding during the Interim Period, any purchases which result in the
      Permitted Investor becoming the Beneficial Owner (as defined in the Abbott
      Rights Agreement) of any securities of the Company in addition to the
      Shares and excluding, during the Threshold Period, any purchases permitted
      by Section 5.3 of the Abbott Rights Agreement or otherwise which cause the
      Permitted Investor's Beneficial Ownership (as defined in Section 5.4 of
      the Abbott Rights Agreement) of shares of Common Stock to exceed 21% of
      the then total outstanding shares of Common Stock of the Company)."

      3. AMENDMENT TO SECTION 1. The following definitions are hereby added to
the end of Section 1 as Sections 1(tt) and 1(uu):

      "(tt) "WARBURG STOCK PURCHASE AGREEMENT" shall mean that certain Purchase
      Agreement dated as of August 24, 2001, by and between the Company and
      Warburg Pincus Private Equity VIII, L.P.

      (uu) "PERMITTED PERCENTAGE" shall mean the lesser of (a) forty percent
      (40%) of the capital stock of the Company then outstanding having the
      right to vote or (b) (i) for the period effective immediately prior to the
      Initial Closing (as such term is defined in the Warburg Stock Purchase
      Agreement) and continuing until immediately prior to the Second Closing
      (as such term is defined in the Warburg Stock Purchase Agreement), or if
      no Second Closing occurs, then indefinitely, the percentage determined by
      dividing 9,628,002 by the number of shares of Common Stock of the Company
      outstanding (giving effect to the shares issued or to be issued in the
      Initial Closing) and (ii) for the period effective immediately prior to
      the Second Closing and continuing indefinitely, the sum of (x) the
      percentage determined by dividing the number of shares of Common Stock of
      which Warburg is then the Beneficial Owner, after giving effect to the
      purchases of shares of Common Stock of the Company by Warburg at such
      Second Closing, by the number of shares of Common Stock of the Company
      outstanding (giving effect to the shares issued or to be issued in the
      Second Closing), plus (y) five percent (5%); provided, however, that the
      Permitted Percentage shall be reestablished on such date (the "Initial
      Reset Date") as, through sales or other transfers (other than transfers to
      Affiliates of Warburg) by Warburg, Warburg becomes the Beneficial Owner of
      less than seventy-five percent (75%) of the number of shares of Common
      Stock of the Company purchased by Warburg pursuant to the Warburg Stock
      Purchase Agreement, and thereafter reestablished on each date (each such
      date along with the Initial Reset Date being referred to herein as a
      "Reset Date") on which, through sales or other transfers (other than
      transfers to Affiliates of Warburg) by Warburg, the number of shares of
      Common Stock of the Company Beneficially Owned by Warburg decreases from
      any

                                       3
<Page>

      previously established Permitted Percentage by more than two percent (2%)
      of the then outstanding shares of Common Stock of the Company, to that
      percentage of Common Stock of the Company Beneficially Owned by Warburg on
      such Reset Date, plus five percent (5%). For purposes of clause (b) of
      this Section 1(uu), determinations at any given point in time of the
      Permitted Percentage or of the ownership of shares of Common Stock of the
      Company by Warburg in relation to the then applicable Permitted Percentage
      shall be calculated in accordance with Section 1(d)(iv) hereof.
      Notwithstanding the foregoing, the Permitted Percentage shall be adjusted
      at any time so as to permit Warburg to exercise its subscription rights
      under Section 8.5 of the Warburg Stock Purchase Agreement."

      4. AMENDMENT OF SECTION 3(a). The first sentence of Section 3(a) of the
Rights Agreement is amended to read in its entirety as follows:

      "Until the earlier of (i) the Close of Business on the Shares Acquisition
      Date and (ii) the Close of Business on the tenth Business Day (or such
      later date as may be determined by action of the Company's Board of
      Directors prior to such time as any Person becomes an Acquiring Person and
      of which the Company will give the Rights Agent prompt written notice)
      after the date that a tender or exchange offer by any Person (other than
      the Company, any Subsidiary of the Company, any employee benefit plan of
      the Company or of any Subsidiary of the Company or any entity holding
      shares of Common Stock for or pursuant to the terms of any such plan) is
      first published or sent or given within the meaning of Rule 14d-4(a) of
      the Exchange Act Regulations or any successor rule or of the first public
      announcement of the intention of any Person (other than the Company, any
      Subsidiary of the Company, any employee benefit plan of the Company or of
      any Subsidiary of the Company or any entity holding shares of Common Stock
      for or pursuant to the terms of any such plan) to commence, a tender or
      exchange offer, if upon consummation thereof such Person would be the
      Beneficial Owner of 15% or more (or in the case of Warburg, more than the
      PERMITTED PERCENTAGE) of the shares of Company Common Stock then
      outstanding, or, in the case of the Investor Group during the Interim
      Period, the Investor Group purchases any securities of the Company which
      result in the Permitted Investor becoming the Beneficial Owner (as defined
      in the Abbott Rights Agreement) of any securities of the Company in
      addition to the Shares, or in the case of the Investor Group during the
      Threshold Period, the Permitted Investor's Beneficial Ownership (as
      defined in the Abbott Rights Agreement) would exceed the Beneficial
      Ownership Limitation (as defined in the Abbott Rights Agreement), (the
      earlier of (i) and (ii) above being the "DISTRIBUTION DATE"), (x) the
      Rights will be evidenced (subject to the provisions of Section 3(b)
      hereof) by the certificates for shares of Common Stock registered in the
      names of the holders thereof (which certificates shall also be deemed to
      be Rights Certificates) and not by separate Rights Certificates, and (y)
      the right to receive Rights Certificates will be transferable only in
      connection with the transfer of shares of Common Stock."

      5. MISCELLANEOUS. This Amendment shall be deemed to be a contract made
under the laws of the State of Delaware and for all purposes shall be governed
by and construed in accordance with the laws of such State applicable to
contracts to be made and performed entirely within such State. This Amendment
may be executed in any number of counterparts, each of such counterparts shall
for all purposes be deemed to be an original, and all such counterparts shall
together constitute but one and the same instrument. If any term, provision,
covenant or restriction of this Amendment is held by a court of competent
jurisdiction or other authority to be invalid, void or unenforceable, the
remainder of the terms, provisions, covenants

                                       4
<Page>

and restrictions of this Amendment shall remain in full force and effect and
shall in no way be affected, impaired or invalidated.

                          (SIGNATURE ON FOLLOWING PAGE)

                                       5
<Page>

              (SIGNATURE PAGE TO THE AMENDMENT TO RIGHTS AGREEMENT)

      IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
Rights Agreement to be duly executed and attested, all as of the day and year
first above written.

ATTEST:                                 TRIANGLE PHARMACEUTICALS, INC.

By:         /s/ Andrew Finkle           By:         /s/ Chris A. Rallis
     --------------------------------        -----------------------------------
     Name:  Andrew Finkle                    Name:  Chris A. Rallis
     Title: Executive Vice President,        Title: President and
            General Counsel and                     Chief Operating Officer
            Secretary

ATTEST:                                 AMERICAN STOCK TRANSFER & TRUST
                                        COMPANY

By:         /s/ Barry S. Rosenthal      By:         /s/ Herbert J. Lemmer
     --------------------------------        -----------------------------------
     Name:  Barry S. Rosenthal               Name:  Herbert J. Lemmer
     Title: Vice President                   Title: Vice President

                                       6

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