CERTIFICATE OF DESIGNATION
                                       of

                  SERIES B JUNIOR PARTICIPATING PREFERRED STOCK

                                       of

                         TRIANGLE PHARMACEUTICALS, INC.

                         (Pursuant to Section 151 of the
                        Delaware General Corporation Law)

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

            TRIANGLE PHARMACEUTICALS, Inc., a corporation organized and existing
under the General Corporation Law of the State of Delaware (hereinafter called
the "Corporation"), hereby certifies that the following resolution was adopted
by the Board of Directors of the Corporation as required by Section 151 of the
General Corporation Law at a meeting duly called and held on January 29, 1999;

            RESOLVED, that pursuant to the authority granted to and vested in
the Board of Directors of the Corporation (hereinafter called the "Board of
Directors" or the "Board") in accordance with the provisions of the Certificate
of Incorporation, the Board of Directors hereby creates a series of Preferred
Stock, par value $.001 per share (the "Preferred Stock"), of the Corporation and
hereby states the designation and number of shares, and fixes the relative
rights, preferences, and limitations thereof as follows:

            Series B Junior Participating Preferred Stock:

            Section 1. Designation and Amount. The shares of such series shall
be designated as "Series B Junior Participating Preferred Stock" (the "Series B
Preferred Stock") and the number of shares constituting the Series B Preferred
Stock shall be One Million Two Hundred Thousand (1,200,000). Such number of
shares may be increased or decreased by resolution of the Board of Directors;
provided, that no decrease shall reduce the number of shares of Series B
Preferred Stock to a number less than the number of shares then outstanding plus
the number of shares reserved for issuance upon the exercise of outstanding
options, rights or warrants or upon the conversion of any outstanding securities
issued by the Corporation convertible into Series B Preferred Stock.

            Section 2. Dividends and Distributions.

            (A) Subject to the rights of the holders of any shares of any series
      of Preferred Stock (or any similar stock) ranking prior and superior to
      the Series B Preferred Stock with respect to dividends, each holder of a
      share of Series B Preferred Stock, in preference to the holders of shares
      of Common Stock, par value $.001 per share (the "Common Stock"), of the
      Corporation, and of any other junior stock, shall be entitled to receive,
      when, as and if declared by the Board of Directors out of funds legally
      available 


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      for the purpose, quarterly dividends payable in cash on the last day of
      March, June, September and December in each year (each such date being
      referred to herein as a "Quarterly Dividend Payment Date"), commencing on
      the first Quarterly Dividend Payment Date after the first issuance of a
      share or fraction of a share Series B Preferred Stock, in an amount per
      share (rounded to the nearest cent) equal to, subject to the provision for
      adjustment hereinafter set forth, One Thousand (1,000) times the aggregate
      per share amount of all cash dividends, and One Thousand (1,000) times the
      aggregate per share amount (payable in kind) of all non-cash dividends or
      other distributions, other than a dividend payable in shares of Common
      Stock or a subdivision of the outstanding shares of Common Stock (by
      reclassification or otherwise), declared on the Common Stock since the
      immediately preceding Quarterly Dividend Payment Date or, with respect to
      the first Quarterly Dividend Payment Date, since the first issuance of a
      share or fraction of Series B Preferred Stock. In the event the
      Corporation shall at any time declare or pay any dividend on the Common
      Stock payable in shares of Common Stock, or effect a subdivision or
      combination or consolidation of the outstanding shares of Common Stock (by
      reclassification or otherwise than by payment of a dividend in shares of
      Common Stock) into a greater or lesser number of shares of Common Stock,
      then in each such case the amount to which holders of shares of Series B
      Preferred Stock were entitled immediately prior to such event under clause
      (b) of the preceding sentence shall be adjusted by multiplying such amount
      by a fraction, the numerator of which is the number of shares of Common
      Stock outstanding immediately after such event and the denominator of
      which is the number of shares of Common Stock that were outstanding
      immediately prior to such event.

            (B) The Corporation shall declare a dividend or distribution on the
      shares of Series B Preferred Stock as provided in paragraph (A) of this
      Section immediately after it declares a dividend or distribution on the
      Common Stock (other than a dividend payable in shares of Common Stock);
      provided, however, that, in the event no dividend or distribution shall
      have been declared on the Common Stock during the period between any
      Quarterly Dividend Payment Date and the next subsequent Quarterly Dividend
      Payment Date, a dividend of $1.00 per share of Series B Preferred Stock
      shall nevertheless be payable on such subsequent Quarterly Dividend
      Payment Date.

            (C) Dividends shall begin to accrue and be cumulative on each
      outstanding share of Series B Participating Preferred Stock from the
      Quarterly Dividend Payment Date next preceding the date of issue of such
      share of Series B Participating Preferred Stock, unless the date of issue
      of such share is prior to the record date for the first Quarterly Dividend
      Payment Date, in which case dividends on such share shall begin to accrue
      from the date of issue of such share, or unless the date of issue is a
      Quarterly Dividend Payment Date or is a date after the record date for the
      determination of holders of shares of Series B Preferred Stock entitled to
      receive a quarterly dividend and before such Quarterly Dividend Payment
      Date, in either of which events such dividends shall begin to accrue and
      be cumulative from such Quarterly Dividend Payment Date. Accrued but
      unpaid dividends shall not bear interest. Dividends paid on the shares of
      Series B Preferred Stock in an amount less than the total amount of such
      dividends at the time accrued and payable on such shares shall be
      allocated pro rata on a share-by-share basis among all 


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      such shares at the time outstanding. The Board of Directors may fix a
      record date for the determination of holders of shares of Series B
      Preferred Stock entitled to receive payment of a dividend or distribution
      declared thereon, which record date shall be not more than 60 days prior
      to the date fixed for the payment thereof.

            Section 3. Voting Rights. The holders of shares of Series B
Preferred Stock shall have the following voting rights:

            (A) Subject to the provision for adjustment hereinafter set forth,
      each share of Series B Preferred Stock shall entitle the holder thereof to
      One Thousand (1,000) votes on all matters submitted to a vote of the
      stockholders of the Corporation. In the event the Corporation shall at any
      time declare or pay any dividend on the Common Stock payable in shares of
      Common Stock, or effect a subdivision or combination or consolidation of
      the outstanding shares of Common Stock (by reclassification or otherwise
      than by payment of a dividend in shares of Common Stock) into a greater or
      lesser number of shares of Common Stock, then in each such case the number
      of votes per share to which holders of shares of Series B Preferred Stock
      were entitled immediately prior to such event shall be adjusted by
      multiplying such number by a fraction, the numerator of which is the
      number of shares of Common Stock outstanding immediately after such event
      and the denominator of which is the number of shares of Common Stock that
      were outstanding immediately prior to such event.

            (B) Except as otherwise provided herein, in any other Certificate of
      Designation creating a series of Preferred Stock or any similar stock, or
      by law, the holders of shares of Series B Preferred Stock and the holders
      of shares of Common Stock and any other capital stock of the Corporation
      having general voting rights shall vote together as one class on all
      matters submitted to a vote of stockholders of the Corporation.

            (C) Except as set forth herein, or as otherwise provided by law,
      holders of Series B Preferred Stock shall have no special voting rights
      and their consent shall not be required (except to the extent they are
      entitled to vote with holders of Common Stock as set forth herein) for
      taking any corporate action.

            Section 4. Certain Restrictions.

            (A) Whenever quarterly dividends or other dividends or distributions
      payable on the Series B Preferred Stock as provided in Section 2 are in
      arrears, thereafter and until all accrued and unpaid dividends and
      distributions, whether or not declared, on shares of Series B Preferred
      Stock outstanding shall have been paid in full, the Corporation shall not:

                  (i) declare or pay dividends, or make any other distributions,
            on any shares of stock ranking junior (either as to dividends or
            upon liquidation, dissolution or winding up) to the Series B
            Preferred Stock;

                  (ii) declare or pay dividends, or make any other
            distributions, on any shares of stock ranking on a parity (either as
            to dividends or upon liquidation, dissolution 


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            or winding up) with the Series B Preferred Stock, except dividends
            paid ratably on the shares of Series B Preferred Stock and all such
            parity stock on which dividends are payable or in arrears in
            proportion to the total amounts to which the holders of all such
            shares are then entitled;

                  (iii) redeem or purchase or otherwise acquire for
            consideration shares of any stock ranking junior (either as to
            dividends or upon liquidation, dissolution or winding up) to the
            Series B Preferred Stock, provided that the Corporation may at any
            time redeem, purchase or otherwise acquire shares of any such junior
            stock in exchange for shares of any stock of the Corporation ranking
            junior (either as to dividends or upon dissolution, liquidation or
            winding up) to the Series B Preferred Stock; or

                  (iv) redeem or purchase or otherwise acquire for consideration
            any shares of Series B Preferred Stock, or any shares of stock
            ranking on a parity with the Series B Preferred Stock, except in
            accordance with a purchase offer made in writing or by publication
            (as determined by the Board of Directors) to all holders of such
            shares upon such terms as the Board of Directors, after
            consideration of the respective annual dividend rates and other
            relative rights and preferences of the respective series Bnd
            classes, shall determine in good faith will result in fair and
            equitable treatment among the respective series or classes.

            (B) The Corporation shall not permit any subsidiary of the
      Corporation to purchase or otherwise acquire for consideration any shares
      of stock of the Corporation unless the Corporation could, under paragraph
      (A) of this Section 4, purchase or otherwise acquire such shares at such
      time and in such manner.

            Section 5. Reacquired Shares. Any shares of Series B Preferred Stock
purchased or otherwise acquired by the Corporation in any manner whatsoever
shall be retired and cancelled promptly after the acquisition thereof. All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock and may be reissued as part of a new series of Preferred Stock
subject to the conditions and restrictions on issuance set forth herein, in the
Certificate of Incorporation, or in any other Certificate of Designation
creating a series of Preferred Stock or any similar stock or as otherwise
required by law.

            Section 6. Liquidation, Dissolution or Winding Up.

            (A) Upon any liquidation, dissolution or winding up of the
      Corporation, no distribution shall be made (1) to the holders of shares of
      stock ranking junior (either as to dividends or upon liquidation,
      dissolution or winding up) to the Series B Preferred Stock unless, prior
      thereto, the holders of shares of Series B Preferred Stock shall have
      received One Thousand Dollars ($1,000) per share, plus an amount equal to
      accrued and unpaid dividends and distributions thereon, whether or not
      declared, to the date of such payment, provided that the holders of shares
      of Series B Preferred Stock shall be entitled to receive an aggregate
      amount per share, subject to the provision for adjustment hereinafter set
      forth, equal to 1,000 times the aggregate amount to be distributed per
      share to holders of shares of Common Stock (the "Common Adjustment"), or
      (2) to the holders of shares of 


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      stock ranking on a parity (either as to dividends or upon liquidation,
      dissolution or winding up) with the Series B Preferred Stock, except
      distributions made ratably on the Series B Preferred Stock and all such
      parity stock in proportion to the total amounts to which the holders of
      all such shares are entitled upon such liquidation, dissolution or winding
      up. In the event the Corporation shall at any time declare or pay any
      dividend on the Common Stock payable in shares of Common Stock, or effect
      a subdivision or combination or consolidation of the outstanding shares of
      Common Stock (by reclassification or otherwise than by payment of a
      dividend in shares of Common Stock) into a greater or lesser number of
      shares of Common Stock, then in each such case the aggregate amount to
      which holders of shares of Series B Preferred Stock were entitled
      immediately prior to such event under the proviso in clause (1) of the
      preceding sentence shall be adjusted by multiplying such amount by a
      fraction the numerator of which is the number of shares of Common Stock
      outstanding immediately after such event and the denominator of which is
      the number of shares of Common Stock that were outstanding immediately
      prior to such event (the "Adjustment Number").

            (B) In the event, however, that there are not sufficient assets
      available to permit payment in full to the Series B Liquidation Preference
      and the liquidation preferences of all other series of Preferred Stock, if
      any, which rank on a parity with the Series B Participating Preferred
      Stock, then such remaining assets shall be distributed ratably to the
      holders of such parity shares in proportion to their respective
      liquidation preferences. In the event, however, that there are not
      sufficient assets available to permit payment in full of the Common
      Adjustment, then such remaining assets shall be distributed ratably to the
      holders of Common Stock.

            (C) In the event the Corporation shall at any time after January 29,
      1999 (i) declare any dividend on Common Stock payable in shares of Common
      Stock, (ii) subdivide the outstanding Common Stock, or (iii) combine the
      outstanding Common Stock into a smaller number of shares, then in each
      such case the Adjustment Number in effect immediately prior to such event
      shall be adjusted by multiplying such Adjustment Number by a fraction the
      numerator of which is the number of shares of Common Stock outstanding
      immediately after such event and the denominator of which is the number of
      shares of Common Stock that were outstanding immediately prior to such
      event.

            Section 7. Consolidation, Merger, etc. In case the Corporation shall
enter into any consolidation, merger, combination or other transaction in which
the shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Series B Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to One Thousand (1,000) times the aggregate amount
of stock, securities, cash and/or any other property (payable in kind), as the
case may be, into which or for which each share of Common Stock is changed or
exchanged. In the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the amount set forth in the preceding sentence with respect to
the exchange or change of 


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shares of Series B Preferred Stock shall be adjusted by multiplying such amount
by a fraction, the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to such
event.

            Section 8. No Redemption. The shares of Series B Preferred Stock
shall not be redeemable.

            Section 9. Rank. The Series B Preferred Stock shall rank, with
respect to the payment of dividends and the distribution of assets, junior to
all series of any other class of the Corporation's Preferred Stock.

            Section 10. Amendment. The Certificate of Incorporation of the
Corporation shall not be amended in any manner which would materially alter or
change the powers, preferences or special rights of the Series B Preferred Stock
so as to affect them adversely without the affirmative vote of the holders of at
least a majority of the outstanding shares of Series B Preferred Stock, voting
together as a single class.

            IN WITNESS WHEREOF, this Certificate of Designation is executed on
behalf of the Corporation by its Chief Financial Officer and Treasurer this 5th
day of February, 1999.

                                    /s/ James A. Klein, Jr.
                                    --------------------------------------------
                                    Name: James A. Klein, Jr.
                                    Title: Chief Financial Officer and Treasurer


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