<PAGE>

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                            TRIANGLE PHARMACEUTICALS, INC.

                           COMMON STOCK PURCHASE AGREEMENT

                                     June 6, 1997

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<PAGE>

                                  TABLE OF CONTENTS

                                                                            PAGE

Section 1 Authorization and Sale of Common Stock............................  1
    1.1   Authorization.....................................................  1
    1.2   Sale of Common....................................................  1

Section 2 Closing Date; Delivery............................................  1
    2.1   Closing Date......................................................  1
    2.2   Delivery..........................................................  1

Section 3 Representations and Warranties of the Company.....................  2
    3.1   Organization and Standing.........................................  2
    3.2   Corporate Power; Authorization....................................  2
    3.3   Issuance and Delivery of the Shares...............................  2
    3.4   SEC Documents; Financial Statements...............................  2
    3.5   Governmental Consents.............................................  3
    3.6   No Material Adverse Change........................................  3
    3.7   Authorized Capital Stock..........................................  3
    3.8   No Dividends......................................................  3
    3.9   Litigation........................................................  4
    3.10  Real Property Holding Corporation.................................  4
    3.11  Regulation S Representations......................................  4
    3.12  Amendment to Rights Agreement.....................................  4

Section 4 Representations, Warranties and Covenants of the Purchasers.......  5
    4.1   Authorization.....................................................  5
    4.2   Independent Investment Decision...................................  5
    4.3   Investment Intent.................................................  5
    4.4   Registration or Exemption Requirements............................  5
    4.5   Regulation S Representations......................................  6
    4.6   No Legal, Tax or Investment Advice................................  7
    4.7   Legends...........................................................  7
    4.8   HSR Filings.......................................................  8

Section 5 Conditions to Closing of Purchasers...............................  8
    5.1   Representations and Warranties....................................  8
    5.2   Covenants.........................................................  8
    5.3   Qualifications....................................................  8
    5.4   Amendment to Rights Agreement.....................................  8

Section 6 Conditions to Closing of Company..................................  8
    6.1   Representations and Warranties....................................  9


                                         -i-

<PAGE>

                                  TABLE OF CONTENTS
                                     (CONTINUED)

                                                                            PAGE

    6.2   Covenants.........................................................  9
    6.3   Qualifications....................................................  9
    6.4   Amendment to Rights Agreement.....................................  9

Section 7 Affirmative Covenants of the Company..............................  9
    7.1   Financial Information.............................................  9
    7.2   Registration Requirements.........................................  9
    7.3   Indemnification and Contribution.................................. 12
    7.4   Nomination for Election to Company Board of Directors............. 14
    7.5   Public Statements................................................. 14

Section 8 Miscellaneous..................................................... 15
    8.1   Waivers and Amendments............................................ 15
    8.2   Placement Agent's Fee............................................. 15
    8.3   Governing Law..................................................... 15
    8.4   Survival.......................................................... 15
    8.5   Successors and Assigns............................................ 15
    8.6   Entire Agreement.................................................. 15
    8.7   Notices, etc...................................................... 15
    8.8   Severability of this Agreement.................................... 16
    8.9   Counterparts...................................................... 16
    8.10  Further Assurances................................................ 16
    8.11  Expenses.......................................................... 16
    8.12  Currency.......................................................... 16
    8.13  Attorneys' Fees................................................... 17

Exhibit A -- Schedule of Purchasers
Exhibit B -- Form of First Amendment to Restated Investors' Rights Agreement
Exhibit C -- Form of Registration Statement Questionnaire


                                         -ii-

<PAGE>

                            TRIANGLE PHARMACEUTICALS, INC.

                           COMMON STOCK PURCHASE AGREEMENT



         This Common Stock Purchase Agreement (the "Agreement") is made as of
June 6, 1997, by and among Triangle Pharmaceuticals, Inc., a Delaware
corporation (the "Company") with its principal office at 4 University Place,
4611 University Drive, Durham, North Carolina, 27707, (919) 493-5925 (fax), and
the entities listed on the Schedule of Investors attached hereto as EXHIBIT A
(the "Purchasers").  Unless otherwise defined herein, capitalized terms used
herein and not defined herein shall have the meanings given to them in
Regulation S ("Regulation S") under the Securities Act of 1933, as amended (the
"Securities Act").

                                      Section 1

                        AUTHORIZATION AND SALE OF COMMON STOCK

         1.1  AUTHORIZATION.  The Company has authorized the sale and issuance
of 2,000,000 shares of its Common Stock pursuant to this Agreement (the
"Shares").

         1.2  SALE OF COMMON.  Subject to the terms and conditions of this
Agreement, the Company agrees to issue and sell to each Purchaser and each
Purchaser severally agrees to purchase from the Company the number of Shares set
forth opposite each Purchaser's name on EXHIBIT A for $15.00 per share.  The
Company shall be responsible for any transfer or stamp taxes in respect of
issuing the Shares.

                                      Section 2

                                CLOSING DATE; DELIVERY

         2.1  CLOSING DATE.  The closing of the purchase and sale of the Shares
hereunder (the "Closing") shall be held at the offices of Brobeck, Phleger &
Harrison LLP, 1633 Broadway, 47th Floor, New York, New York 10019 at 2:00 p.m.
Eastern Daylight Savings Time on June 6, 1997, or at such other time and place
upon which the Company and the Purchasers purchasing the majority of the Shares
shall agree.  The date of the Closing is hereinafter referred to as the "Closing
Date."

         2.2  DELIVERY.  At the Closing, the Company will deliver to each
Purchaser a certificate, registered in the Purchaser's name as shown on
EXHIBIT A, representing the number of Shares to be purchased by the Purchaser.
Such delivery shall be against payment of the purchase price therefor by check
or wire transfer to the Company in the amount set forth on EXHIBIT A.  It is
agreed among all parties that the issuance and sale of the Shares to the
Purchasers shall occur as one simultaneous transaction at the Closing.

<PAGE>

                                      Section 3

                    REPRESENTATIONS AND WARRANTIES OF THE COMPANY

         The Company represents and warrants to the Purchasers as of the
Closing as follows:

         3.1  ORGANIZATION AND STANDING.  The Company is a corporation duly
organized and validly existing under, and by virtue of, the laws of the State of
Delaware and is in good standing as a domestic corporation under the laws of
said state.

         3.2  CORPORATE POWER; AUTHORIZATION.  The Company has all requisite
legal and corporate power and has taken all requisite corporate action to
execute and deliver this Agreement, to sell and issue the Shares and to carry
out and perform all of its obligations under this Agreement.  This Agreement
constitutes the legal, valid and binding obligation of the Company, enforceable
in accordance with its terms, except (i) as limited by applicable bankruptcy,
insolvency, reorganization or similar laws relating to or affecting the
enforcement of creditors' rights generally and (ii) as limited by equitable
principles generally.  The execution and delivery of this Agreement does not,
and the performance of this Agreement and the compliance with the provisions
hereof and the issuance, sale and delivery of the Shares by the Company will
not, materially conflict with, or result in a material breach or violation of
the terms, conditions or provisions of, or constitute a material default under,
or result in the creation or imposition of any material lien pursuant to the
terms of, the Certificate of Incorporation or Bylaws of the Company or any
statute, law, rule or regulation or any state or federal order, judgment or
decree or any indenture, mortgage, lease or other material agreement or
instrument to which the Company or any of its properties is subject.

         3.3  ISSUANCE AND DELIVERY OF THE SHARES.  The Shares, when issued and
paid for in accordance with the provisions of this Agreement, will be validly
issued and outstanding, fully paid and nonassessable.  The issuance and delivery
of the Shares is not subject to preemptive or any other similar rights of the
stockholders of the Company or any liens or encumbrances.

         3.4  SEC DOCUMENTS; FINANCIAL STATEMENTS.  Each report or proxy
statement delivered to the Purchasers is a true and complete copy of such
document as filed by the Company with the Securities and Exchange Commission
(the "SEC").  The Company has delivered to each Purchaser its Annual Report on
Form 10-K for the year ended December 31, 1996 (the "1996 10-K") and its
Quarterly Report on Form 10-Q for the quarter ended March 31, 1997 (the "March
10-Q").  The Company has filed in a timely manner all documents that the Company
was required to file with the SEC under Sections 13, 14(a) and 15(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), since its
initial public offering.  As of their respective filing dates, all documents
filed by the Company with the SEC (the "SEC Documents") complied in all material
respects with the requirements of the Exchange Act or the Securities Act, as


                                          2.
<PAGE>

applicable.  None of the SEC Documents as of their respective dates contained
any untrue statement of material fact or omitted to state a material fact
required to be stated therein or necessary to make the statements made therein,
in light of the circumstances under which they were made, not misleading.  The
financial statements of the Company included in the SEC Documents (the
"Financial Statements") comply as to form in all material respects with
applicable accounting requirements and with the published rules and regulations
of the SEC with respect thereto.  The Financial Statements have been prepared in
accordance with generally accepted accounting principles consistently applied
and fairly present the consolidated financial position of the Company and any
subsidiaries at the dates thereof and the consolidated results of their
operations and consolidated cash flows for the periods then ended (subject, in
the case of unaudited statements, to normal, recurring adjustments).

         3.5  GOVERNMENTAL CONSENTS.  No consent, approval, order or
authorization of, or registration, qualification, designation, declaration or
filing with, any federal, state, or local governmental authority on the part of
the Company is required in connection with the consummation of the transactions
contemplated by this Agreement except for (a) such filings as have been made
prior to the Closing, except that any notices of sale required to be filed with
the SEC under Regulation D of the Securities Act, or such post-closing filings
as may be required under applicable state securities laws, which will be timely
filed within the applicable periods therefor, and (b) the filing of the Nasdaq
National Market Notification Form with the Nasdaq National Market.

         3.6  NO MATERIAL ADVERSE CHANGE.  Except as otherwise disclosed herein
or as disclosed to the Purchasers in writing prior to the Closing, since
March 31, 1997, there have not been any changes in the assets, liabilities,
financial condition, business prospects or operations of the Company from that
reflected in the March 10-Q and the Financial Statements except changes in the
ordinary course of business which have not been, either individually or in the
aggregate, materially adverse.

         3.7  AUTHORIZED CAPITAL STOCK.  The authorized capital stock of the
Company consists of (i) 75,000,000 shares of Common Stock, of which 17,585,108
shares are outstanding, and (ii) 5,000,000 shares of Preferred Stock, none of
which is outstanding.  Except as set forth in the March 10-Q or the 1996 10-K or
as disclosed to the Purchasers in writing prior to the Closing, and except for
the grant of options to purchase a total of 15,500 shares of Common Stock
granted on May 1, 1997, there are no outstanding options, warrants or other
securities exercisable for, or convertible into, or commitments to issue
securities exercisable for or convertible into, capital stock of the Company, or
other commitments to issue any capital stock of the Company.

         3.8  NO DIVIDENDS.  The Company has not declared or paid any
dividends, or authorized or made any distribution or established any record date
for the issuance of any dividend or other distribution upon or with respect to
any class or series of its capital stock and will not do any of the foregoing
until after Purchasers have been listed as record holders of the Shares
purchased at the Closing.


                                          3.
<PAGE>

         3.9  LITIGATION.  Except as disclosed in the SEC Documents, there are
no actions, suits, proceedings or investigations pending or, to the best of the
Company's knowledge, threatened against the Company or any of its properties
before or by any court or arbitrator or any governmental body, agency or
official in which there is a reasonable likelihood (in the judgment of the
Company) of an adverse decision that (a) could have a material adverse effect on
the Company's properties or assets or the business of the Company as presently
conducted or proposed to be conducted or (b) could impair the ability of the
Company to perform in any material respect its obligations under this Agreement.

         3.10 REAL PROPERTY HOLDING CORPORATION.  The Company is not and will
not voluntarily become a real property holding corporation within the meaning of
Internal Revenue Code Section 897(c)(2) and any regulations promulgated
thereunder.

         3.11 REGULATION S REPRESENTATIONS.

         (a)  Neither the Company nor any of its affiliates (within the meaning
of Rule 144 under the Securities Act) nor any person acting on its or their
behalf has engaged or will engage in any Directed Selling Efforts in connection
with the offer and sale of the Shares.

         (b)  The Company is a Reporting Issuer within the meaning of
Regulation S.

         (c)  The Company has not offered the Shares to any persons other than
the Purchasers.

         (d)  The offer and sale of the Shares to the Purchasers are not part
of a plan or scheme on the part of the Company, any of its affiliates (within
the meaning of Rule 144 under the Securities Act) or any person acting on its or
their behalf to evade the registration provisions of the Securities Act.

         3.12 AMENDMENT TO RIGHTS AGREEMENT.  The First Amendment to Restated
Investors' Rights Agreement (the "Rights Amendment") in the form attached hereto
as EXHIBIT B. has been executed by the persons and entities that are required to
effectively amend the Restated Investors' Rights Agreement dated June 11, 1996
among the Company and the persons listed in SCHEDULE A attached thereto (the
"Rights Agreement"), and the Rights Amendment constitutes a legal, valid and
binding obligation of the Company.


                                          4.
<PAGE>

                                      Section 4

             REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE PURCHASERS

         Each Purchaser hereby severally represents and warrants to the Company
as of the Closing Date, and agrees in favor of the Company, as follows, except
that Duquesne Fund, L.P. ("Duquesne") does not make any of the representations
or warranties contained in Section 4.5(a), (b) or (f):

         4.1  AUTHORIZATION.  Purchaser represents and warrants to the Company
that:  (i) Purchaser has been duly formed and is validly existing in good
standing under the laws of the jurisdiction of its formation; (ii) Purchaser has
all requisite legal and corporate or other power and capacity and has taken all
requisite corporate or other action to execute and deliver this Agreement, to
purchase the Shares to be purchased by it and to carry out and perform all of
its obligations under this Agreement; and (iii) this Agreement constitutes the
legal, valid and binding obligation of the Purchaser, enforceable in accordance
with its terms, except (a) as limited by applicable bankruptcy, insolvency,
reorganization, or similar laws relating to or affecting the enforcement of
creditors' rights generally and (b) as limited by equitable principles
generally.

         4.2  INDEPENDENT INVESTMENT DECISION.  Purchaser understands that no
United States federal or state agency has passed on, reviewed or made any
recommendation or endorsement of the Shares.  In making the decision to purchase
the Shares in accordance with this Agreement, Purchaser has relied solely upon
independent investigations made by it and not upon any representations made by
the Company other than those made pursuant to this Agreement.

         4.3  INVESTMENT INTENT.  Purchaser is purchasing the Shares for its
own account, for investment purposes only, and not with a view to a distribution
thereof.  Purchaser further understands that its acquisition of the Shares has
not been registered under the Securities Act or registered or qualified under
any state securities law in reliance on specific exemptions therefrom, which
exemptions may depend upon, among other things, the bona fide nature of
Purchaser's investment intent as expressed herein.  Duquesne is an "accredited
investor" as such term is defined in Rule 501(a) of Regulation D under the
Securities Act, and has such knowledge and experience in financial and business
matters that it is capable of evaluating the merits and risks of the investment
in the Shares to be made by it hereunder.

         4.4  REGISTRATION OR EXEMPTION REQUIREMENTS.  Purchaser further
acknowledges and understands that the Shares have not been registered under the
Securities Act and may not be resold or otherwise transferred except in a
transaction registered under the Securities Act or unless an exemption from such
registration is available.


                                          5.
<PAGE>

         4.5  REGULATION S REPRESENTATIONS.

         (a)  Purchaser is not a U.S. Person and is not acquiring the Shares
for the account or benefit of any U.S. Person, and Purchaser is not an affiliate
(within the meaning of Rule 144 under the Securities Act) of the Company.

         (b)  At the time the buy orders for the Shares were originated,
Purchaser was located outside the United States.

         (c)  Neither Purchaser nor any of its affiliates nor anyone acting on
its or their behalf has engaged or will engage in any Directed Selling Efforts
in connection with the offer and sale of the Shares.

         (d)  Purchaser:

              (i)  will not, prior to the later of the end of the Restricted
Period and November 1, 1997, offer or sell any of the Shares (or create or
maintain any derivative position equivalent thereto) in reliance on Regulation S
and will only offer or sell any of the Shares (or create or maintain any
derivative position equivalent thereto) during such period pursuant to
registration under the Securities Act or pursuant to an available exemption from
registration other than Regulation S and, in any case, in accordance with
applicable state securities laws and the provisions of this Agreement; and

              (ii) will, after November 1, 1997, offer or sell the Shares (or
create or maintain any derivative position equivalent thereto) only in
accordance with the provisions of Regulation S, pursuant to registration under
the Securities Act, or pursuant to an available exemption from registration and,
in any case, in accordance with applicable state securities laws and the
provisions of this Agreement.  Purchaser further agrees that unless the transfer
is pursuant to a registration under the Securities Act, prior to the transfer
(A) Purchaser will notify the Company of the proposed transfer and will furnish
the Company with a detailed statement of the circumstances surrounding the
proposed transfer, and (B) if reasonably requested by the Company, Purchaser
will furnish the Company with an opinion of counsel, reasonably satisfactory to
the Company and its counsel, that such transfer will not require registration of
the Shares under the Securities Act.  Purchaser agrees to provide an opinion of
counsel for all transfers pursuant to Regulation S.

         (e)  Neither Purchaser's offer to buy the Shares nor Purchaser's
acquisition of the Shares is part of a plan or scheme on the part of Purchaser,
any of its affiliates or any person acting on its or their behalf to evade the
registration requirements of the Securities Act.

         (f)  Purchaser's offer to buy the Shares constituted, and Purchaser's
acquisition of the Shares will constitute, an Offshore Transaction.


                                          6.
<PAGE>

         (g)  In addition to, and without in any way limiting, the other
restrictions contained in this Agreement, during any Restricted Period
applicable to the Shares, neither Purchaser nor any of its affiliates nor any
person acting on its or their behalf will engage in any Directed Selling Efforts
with respect to such Shares.

         4.6  NO LEGAL, TAX OR INVESTMENT ADVICE.  Purchaser understands that
nothing in this Agreement or any other materials presented to Purchaser in
connection with the purchase and sale of the Shares constitutes legal, tax or
investment advice.  Purchaser has consulted such legal, tax and investment
advisors as it, in its sole discretion, has deemed necessary or appropriate in
connection with its purchase of the Shares.

         4.7  LEGENDS.  To the extent applicable, each certificate or other
document evidencing any of the Shares shall be endorsed with the legends set
forth in Sections 4.7(a) and (b) below (other than the Shares purchased by
Duquesne, which shall be endorsed with the legends set forth in Sections 4.7(b)
and (c) below), and the Purchaser covenants that, except to the extent such
restrictions are waived by the Company, the Purchaser shall not transfer the
shares represented by any such certificate without complying with the
restrictions on transfer described in the legends endorsed on such certificate:

         (a)  "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 THE EXEMPTION FROM REGISTRATION PROVIDED BY
REGULATION S UNDER THE SECURITIES ACT ("REGULATION S").  PRIOR TO NOVEMBER 1,
1997, THE SECURITIES REPRESENTED BY THIS CERTIFICATE MAY NOT BE OFFERED OR SOLD,
DIRECTLY OR INDIRECTLY, EXCEPT PURSUANT TO REGISTRATION UNDER THE SECURITIES ACT
OR PURSUANT TO AN AVAILABLE EXEMPTION FROM REGISTRATION OTHER THAN REGULATION S.
AFTER NOVEMBER 1, 1997, THE SECURITIES REPRESENTED BY THIS CERTIFICATE MAY NOT
BE OFFERED OR SOLD, DIRECTLY OR INDIRECTLY, EXCEPT IN ACCORDANCE WITH THE
PROVISIONS OF REGULATION S, PURSUANT TO REGISTRATION UNDER THE SECURITIES ACT,
OR PURSUANT TO AN AVAILABLE EXEMPTION FROM REGISTRATION."

         (b)  "THE SHARES REPRESENTED HEREBY ARE SUBJECT TO THE RESTRICTIONS ON
TRANSFER CONTAINED IN A CERTAIN COMMON STOCK PURCHASE AGREEMENT, AS AMENDED FROM
TIME TO TIME.  THE COMPANY WILL UPON WRITTEN REQUEST FURNISH A COPY OF SUCH
AGREEMENT TO THE HOLDER HEREOF WITHOUT CHARGE."

         (c)  "THE SHARES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND MAY NOT BE
OFFERED OR SOLD ABSENT AN EFFECTIVE REGISTRATION THEREOF UNDER THE SECURITIES
ACT OR COMPLIANCE WITH RULE 144 PROMULGATED UNDER THE SECURITIES ACT


                                          7.
<PAGE>

OR ANOTHER AVAILABLE EXEMPTION THEREFROM, OR UNLESS THE COMPANY HAS RECEIVED AN
OPINION OF COUNSEL, REASONABLY SATISFACTORY TO THE COMPANY AND ITS COUNSEL, THAT
SUCH REGISTRATION IS NOT REQUIRED."

         (d)  Any other legend required by law.

         4.8  HSR FILINGS.  No filing under the Hart-Scott-Rodino Antitrust
Improvements Act of 1976, as amended, is or will be required by any of the
Purchasers in connection with the acquisition of the Shares by the Purchasers.

                                      Section 5

                         CONDITIONS TO CLOSING OF PURCHASERS

         Each Purchaser's obligation to purchase the Shares at the Closing is,
at the option of such Purchaser, subject to the fulfillment or waiver (in its
sole discretion) on or before the Closing Date of the following conditions:

         5.1  REPRESENTATIONS AND WARRANTIES.  The representations and
warranties of the Company contained in Section 3 shall be true on and as of the
Closing with the same effect as though such representations and warranties had
been made on and as of the date of such Closing.

         5.2  COVENANTS.  The Company shall have performed and complied with
all agreements, obligations and conditions contained in this Agreement that are
required to be performed or complied with by it on or before the Closing.

         5.3  QUALIFICATIONS.  All authorizations, approvals, or permits, if
any, of any governmental authority or regulatory body of the United States or of
any state that are required as of the Closing in connection with the lawful
issuance and sale of the Shares pursuant to this Agreement shall have been duly
obtained and shall be effective as of the Closing.

         5.4  AMENDMENT TO RIGHTS AGREEMENT.  The Company and the persons whose
signatures are required to effectively amend the Rights Agreement shall have
executed the First Amendment to Restated Investors' Rights Agreement in the form
attached hereto as EXHIBIT B.

                                      Section 6

                           CONDITIONS TO CLOSING OF COMPANY

         The Company's obligation to sell and issue the Shares at the Closing
is, at the option of the Company, subject to the fulfillment or waiver of the
following conditions:


                                          8.
<PAGE>

         6.1  REPRESENTATIONS AND WARRANTIES.  The representations and
warranties of the Purchasers contained in Section 4 shall be true on and as of
the Closing with the same effect as though such representations and warranties
had been made on and as of the date of such Closing.

         6.2  COVENANTS.  The Purchasers shall have performed and complied with
all agreements, obligations and conditions contained in this Agreement that are
required to be performed or complied with by the Purchasers on or before the
Closing.

         6.3  QUALIFICATIONS.  All authorizations, approvals, or permits, if
any, of any governmental authority or regulatory body of the United States or of
any state that are required as of the Closing in connection with the lawful
issuance and sale of the Shares pursuant to this Agreement shall have been duly
obtained and shall be effective as of the Closing.

         6.4  AMENDMENT TO RIGHTS AGREEMENT.  The Purchasers and the persons
whose signatures are required to effectively amend the Rights Agreement shall
have executed the First Amendment to Restated Investors' Rights Agreement in the
form attached hereto as EXHIBIT B.

                                      Section 7

                         AFFIRMATIVE COVENANTS OF THE COMPANY

         The Company hereby covenants and agrees as follows:

         7.1  FINANCIAL INFORMATION.  The Company will mail the following
reports to each Purchaser until such Purchaser transfers, assigns or sells the
Shares purchased by such Purchaser pursuant to this Agreement:

         (a)  Within one hundred (100) days after the end of each fiscal year,
a copy of its Annual Report on Form 10-K.

         (b)  Within fifty-five (55) days after the end of the first, second
and third quarterly accounting periods of each fiscal year of the Company, a
copy of its Quarterly Report on Form 10-Q.

         (c)  Within ten (10) days after the Company files any Current Report
on Form 8-K with the SEC, such Current Report on Form 8-K.

         7.2  REGISTRATION REQUIREMENTS.

         (a)  As soon as practicable after the Company becomes eligible to file
a registration statement on Form S-3 registering the resale of the Shares, or,
in the event that the Company is not eligible to file a registration statement
on Form S-3 registering the


                                          9.
<PAGE>

resale of the Shares by November 1, 1997, then on a subsequent date as soon as
practicable after the Purchasers holding more than fifty percent (50%) of the
Shares then outstanding may request in writing, the Company shall prepare and
file a registration statement with the SEC under the Securities Act to register
the resale of the Shares (and the additional 789,500 shares of the Company's
Common Stock held by the Purchasers as of the date hereof) by the Purchasers
(the "Registration Statement") and use its best efforts to cause such
registration statement to be declared effective.  All Purchasers shall deliver
to the Company an executed copy of the Registration Statement Questionnaire in
the form attached hereto as EXHIBIT C as a condition precedent to the Company's
obligation to file the Registration Statement with the SEC and in any event
within ten (10) days of the Company's request therefor.  Each Purchaser will
promptly notify the Company of any changes in the information set forth in the
Registration Statement regarding such Purchaser or such Purchaser's "Plan of
Distribution."

         (b)  The Company shall pay all Registration Expenses (as defined
below) in connection with any registration, qualification or compliance
hereunder, and each Purchaser shall pay all Selling Expenses (as defined below)
and other expenses that are not Registration Expenses relating to the Shares
resold by such Purchaser.  "Registration Expenses" shall mean all expenses,
except for Selling Expenses, incurred by the Company in complying with the
registration provisions herein described, including, without limitation, all
registration, qualification and filing fees, printing expenses, escrow fees,
fees and disbursements of counsel for the Company, blue sky fees and expenses
and the expense of any special audits incident to or required by any such
registration.  "Selling Expenses" shall mean all selling commissions,
underwriting discounts and stock transfer taxes applicable to the Shares and all
fees and disbursements of counsel for any Purchaser.

         (c)  In the case of the registration effected by the Company pursuant
to these registration provisions, the Company will use its best efforts to:
(i) keep such registration effective until the earliest of (A) nineteen (19)
months after the initial effective date of the Registration Statement, which
date shall be extended by the period (not to exceed five (5) months) equal to
the period, if any, that the Purchasers are unable to sell any Shares as a
result of any withdrawal of the Registration Statement by the Company pursuant
to Section 7.2(f) below (other than a withdrawal in response to any Notice of
Sale (as defined in Section 7.2(f) below) that indicates any Purchaser desires
to sell no more than 50,000 Shares)(the "Effective Period"), and (B) such date
as all of the Shares have been resold in transactions in which the Purchasers
have not assigned their benefits and obligations under Section 7 in accordance
with the provisions of Section 8.5 below; (ii) prepare and file with the SEC
such amendments and supplements to the Registration Statement and the prospectus
used in connection with the Registration Statement as may be necessary to comply
with the provisions of the Securities Act with respect to the disposition of all
securities covered by the Registration Statement; (iii) furnish such number of
prospectuses and other documents incident thereto, including any amendment of or
supplement to the prospectus, as a Purchaser from time to time may reasonably
request; (iv) cause all Shares registered as described herein to be listed on
each securities exchange and quoted on each quotation service on which similar
securities issued by the Company are


                                         10.
<PAGE>

then listed or quoted; (v) provide a transfer agent and registrar for all Shares
registered pursuant to the Registration Statement and a CUSIP number for all
such Shares; and (vi) file the documents required of the Company and otherwise
use its best efforts to maintain requisite blue sky clearance in (A) all
jurisdictions in which any of the Shares are originally sold and (B) all other
states specified in writing by a Purchaser, provided as to clause (B), however,
that the Company shall not be required to qualify to do business or to file a
general consent to service of process in any state in which it is not now so
qualified or has not so consented.

         (d)  The Company shall furnish to each Purchaser upon request a
reasonable number of copies of a supplement to or an amendment of such
prospectus as may be necessary in order to facilitate the public sale or other
disposition of all or any of the Shares held by the Purchaser.

         (e)  With a view to making available to the Purchasers the benefits of
Rule 144 promulgated under the Securities Act ("Rule 144") and any other rule or
regulation of the SEC that may at any time permit a Purchaser to sell Shares to
the public without registration or pursuant to the Registration Statement, the
Company covenants and agrees to:  (i) make and keep public information
available, as those terms are understood and defined in Rule 144, until the
earlier of (A) the end of the Effective Period or (B) such date as all of the
Shares have been resold in transactions in which the Purchasers have not
assigned their benefits and obligations under Section 7 in accordance with the
provisions of Section 8.5 below; (ii) file with the SEC in a timely manner all
reports and other documents required of the Company under the Securities Act and
Exchange Act; and (iii) furnish to any Purchaser upon request, as long as the
Purchaser owns any Shares, (A) a written statement by the Company that it has
complied with the reporting requirements of the Securities Act and the Exchange
Act, (B) a copy of the most recent annual or quarterly report of the Company,
and (C) such other information as may be reasonably requested in order to avail
any Purchaser of any rule or regulation of the SEC that permits the selling of
any such Shares without registration or pursuant to the Registration Statement.

         (f)  In the event any Purchaser desires to sell the Purchaser's Shares
pursuant to the Registration Statement, the Purchaser shall give the Company
three (3) business days' notice (which notice, if given orally, will be
confirmed in writing within 24 hours) of its desire to sell in reliance on such
Registration Statement including an estimate of whether its desire is to sell
more than 50,000 Shares (the "Notice of Sale").  The Company may refuse to
permit a Purchaser to resell any Shares pursuant to the Registration Statement;
provided, however, that in order to exercise this right, the Company must
deliver a certificate in writing to the Purchaser within three (3) business days
following the Company's receipt of the Notice of Sale to the effect that
withdrawal of such Registration Statement is necessary because a sale pursuant
to the Registration Statement in its then-current form could constitute a
violation of the federal securities laws.  In such an event, the Company shall
use its best efforts to amend the Registration Statement if necessary as soon as
practicable and in any event within sixty (60) days after the Company's receipt
of the Notice of Sale, and shall notify the Purchasers promptly after it has
determined that such


                                         11.
<PAGE>

sale has become permissible under the federal securities laws.  Notwithstanding
the foregoing, the Company shall not under any circumstances be entitled to
exercise its right to refuse to permit the resale of any Shares pursuant to the
Registration Statement more than two (2) times in any twelve (12) month period,
except that the Company's exercise of its right to refuse to permit the resale
of any Shares pursuant to the Registration Statement in response to any Notice
of Sale that indicates the Purchaser desires to sell no more than 50,000 Shares
shall not count toward its limit of two (2) refusals in any twelve (12) month
period.  The period during which such Registration Statement may be withdrawn
shall not exceed sixty (60) days.  Each Purchaser hereby covenants and agrees
that it will not sell any Shares pursuant to the Registration Statement during
the periods the Registration Statement is withdrawn as set forth in this
Section 7.2(f).

         7.3  INDEMNIFICATION AND CONTRIBUTION.

         (a)  The Company agrees to indemnify and hold harmless each Purchaser
and its affiliates (within the meaning of Rule 144 under the Securities Act)
from and against any losses, claims, damages or liabilities (or actions or
proceedings in respect thereof) to which they may become subject (under the
Securities Act or otherwise) insofar as such losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) arise out of, or are
based upon, (x) any untrue statement of a material fact contained in the
Registration Statement, on the effective date thereof, including any preliminary
prospectus or final prospectus contained therein or any amendments or
supplements thereto, (y) the omission or alleged omission to state therein a
material fact required to be stated therein, or necessary to make the statements
therein not misleading, or (z) any violation or alleged violation by the Company
of the Securities Act, the Exchange Act, or any rule or regulation promulgated
under the Securities Act or the Exchange Act, or arise out of any failure by the
Company to fulfill any undertaking included in the Registration Statement, and
the Company will, as incurred, reimburse such Purchaser for any legal or other
expenses reasonably incurred in investigating, defending or preparing to defend
any such loss, claim, damage or liability (or action or proceeding in respect
thereof); provided, however, that the Company shall not be liable in any such
case to the extent that such loss, claim, damage or liability (or action or
proceeding in respect thereof) arises out of, or is based upon (i) an untrue
statement made in such Registration Statement in reliance upon and in conformity
with written information furnished to the Company by or on behalf of such
Purchaser specifically for use in preparation of the Registration Statement,
including any preliminary prospectus or final prospectus contained therein or
any amendments or supplements thereto, (ii) the failure of such Purchaser to
comply with the covenants and agreements contained in Section 7.3 hereof, or
(iii) any untrue statement in any Prospectus that is corrected in any subsequent
Prospectus that was delivered to the Purchaser prior to the pertinent sale or
sales by the Purchaser.

         (b)  Each Purchaser, severally and not jointly, agrees to indemnify
and hold harmless the Company and its affiliates (within the meaning of Rule 144
under the Securities Act) from and against any losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) to which the Company
may become subject (under the Securities Act or otherwise) insofar as such
losses, claims, damages or liabilities (or actions


                                         12.
<PAGE>

or proceedings in respect thereof) arise out of, or are based upon (i) an untrue
statement made in such Registration Statement in reliance upon and in conformity
with written information furnished to the Company by or on behalf of such
Purchaser specifically for use in preparation of the Registration Statement,
including any preliminary prospectus or final prospectus contained therein or
any amendments or supplements thereto, provided, however, that no Purchaser
shall be liable in any such case for any untrue statement included in any
Prospectus which statement has been corrected, in writing, by such Purchaser and
delivered to the Company before the sale from which such loss occurred, (ii) the
failure of such Purchaser to comply with the covenants and agreements contained
in Section 7.3 hereof, or (iii) any untrue statement in any Prospectus that is
corrected in any subsequent Prospectus that was delivered to the Purchaser prior
to the pertinent sale or sales by the Purchaser, and each Purchaser, severally
and not jointly, will, as incurred, reimburse the Company for any legal or other
expenses reasonably incurred in investigating, defending or preparing to defend
any such loss, claim, damage or liability (or action or proceeding in respect
thereof); provided, however, that no Purchaser shall be liable for any amount in
excess of the amount by which the net amount received by the Purchaser from the
sale of the Shares to which such loss relates exceeds the amount of any damages
which such Purchaser has otherwise been required to pay by reason of such untrue
or alleged untrue statement or omission or alleged omission.

         (c)  Promptly after receipt by any indemnified person of a notice of a
claim or the beginning of any action in respect of which indemnity is to be
sought against an indemnifying person pursuant to this Section 7.3, such
indemnified person shall notify the indemnifying person in writing of such claim
or of the commencement of such action, and, subject to the provisions
hereinafter stated, in case any such action shall be brought against an
indemnified person and the indemnifying person shall have been notified thereof,
the indemnifying person shall be entitled to participate therein, and, to the
extent that it shall wish, to assume the defense thereof, with counsel
reasonably satisfactory to the indemnified person.  After notice from the
indemnifying person to such indemnified person of the indemnifying person's
election to assume the defense thereof, the indemnifying person shall not be
liable to such indemnified person for any legal expenses subsequently incurred
by such indemnified person in connection with the defense thereof; provided,
however, that if there exists or shall exist a conflict of interest that would
make it inappropriate in the reasonable judgment of the indemnified person for
the same counsel to represent both the indemnified person and such indemnifying
person or any affiliate or associate thereof, the indemnified person shall be
entitled to retain its own counsel at the expense of such indemnifying person.

         (d)  If the indemnification provided for in this Section 7.3 is
unavailable to or insufficient to hold harmless an indemnified party under
subsection (a) or (b) above in respect of any losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) referred to therein,
then each indemnifying party shall contribute to the amount paid or payable by
such indemnified party as a result of such losses, claims, damages or
liabilities (or actions in respect thereof) in such proportion as is appropriate
to reflect the relative fault of the Company on the one hand and the Purchasers
on the other in connection with the statements or omissions which resulted in
such losses, claims, damages


                                         13.
<PAGE>

or liabilities (or actions in respect thereof), as well as any other relevant
equitable considerations.  The relative fault shall be determined by reference
to, among other things, whether the untrue or alleged untrue statement of a
material fact or the omission or alleged omission to state a material fact
relates to information supplied by the Company on the one hand or a Purchaser on
the other and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission.  The Company and
the Purchasers agree that it would not be just and equitable if contribution
pursuant to this subsection (d) were determined by pro rata allocation (even if
the Purchasers were treated as one entity for such purpose) or by any other
method of allocation which does not take account of the equitable considerations
referred to above in this subsection (d).  The amount paid or payable by an
indemnified party as a result of the losses, claims, damages, or liabilities (or
actions in respect thereof) referred to above in this subsection (d) shall be
deemed to include any legal or other expenses reasonably incurred by such
indemnified party in connection with investigating or defending any such action
or claim.  Notwithstanding the provisions of this subsection (d), no Purchaser
shall be required to contribute any amount in excess of the amount by which the
net amount received by the Purchaser from the sale of the Shares to which such
loss relates exceeds the amount of any damages which such Purchaser has
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission.  No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
shall be entitled to contribution from any person who was not guilty of such
fraudulent misrepresentation.  The Purchasers' obligations in this subsection
(d) to contribute are several in proportion to their respective sales of Shares
to which such loss relates and not joint.

         (e)  The obligations of the Company and the Purchasers under this
Section 7.3 shall be in addition to any liability which the Company and the
respective Purchasers may otherwise have and shall extend, upon the same terms
and conditions, to each person, if any, who controls the Company or any
Purchaser within the meaning of the Act.

         7.4  NOMINATION FOR ELECTION TO COMPANY BOARD OF DIRECTORS.  Upon the
request of the record holders of more than fifty percent (50%) of the Shares
then outstanding and held by Purchasers (the "Majority Holders"), the Company
shall use its best efforts to cause its Board of Directors to nominate and elect
or have elected after June 24, 1997, an individual designated in writing by the
Majority Holders, which individual must also be acceptable to the Chairman of
the Company's Board of Directors, to serve on the Company's Board of Directors;
provided, however, that the Company's obligation pursuant to this Section 7.4
shall terminate on the earlier of (i) the second anniversary of the Closing Date
and (ii) the date when the aggregate number of shares of the Company's Common
Stock held by the Purchasers is less than ten percent (10%) of the total number
of outstanding shares of the Company's Common Stock.

         7.5  PUBLIC STATEMENTS.  Neither the Company nor the Purchasers shall
use the name of the other in any press release or filing with the SEC (excluding
Schedule 13Ds and Forms 3, 4 and 5) without the prior approval of the other
party, which approval may not be unreasonably withheld or delayed; PROVIDED,
HOWEVER, that to the extent such prior


                                         14.
<PAGE>

approval is impracticable, the party issuing the press release or making the
filing with the SEC shall provide a copy of such press release or SEC filing to
the other party as promptly as practicable thereafter; and PROVIDED, FURTHER,
that if the other party does not approve such press release or SEC filing, the
party issuing the press release or making the filing with the SEC may still use
the name of the other party in any press release or SEC filing without the prior
written approval of the other party, if the party issuing the press release or
making the filing with the SEC is advised by counsel that such disclosure is
required to comply with applicable law.

                                      Section 8

                                    MISCELLANEOUS

         8.1  WAIVERS AND AMENDMENTS.  With the exception of Section 7 hereof,
the terms of this Agreement may be waived or amended with the written consent of
the Company and each Purchaser.  With respect to Section 7 hereof, with the
written consent of the Company and the record holders of more than fifty percent
(50%) of the Shares then outstanding and held by Purchasers, the terms of
Section 7 of this Agreement may be waived or amended and any such amendment or
waiver shall be binding upon the Company and all holders of Shares.

         8.2  PLACEMENT AGENT'S FEE.  Each Purchaser acknowledges that the
Company intends to pay to George McFadden or an entity designated by him a fee
of $500,000 in respect of the sale of the Shares.  Each of the parties hereto
hereby represents that, on the basis of any actions and agreements by it, there
are no other brokers or finders entitled to compensation in connection with the
sale of the Shares to the Purchasers.

         8.3  GOVERNING LAW.  This Agreement shall be governed in all respects
by and construed in accordance with the laws of the State of Delaware without
any regard to conflicts of laws principles.

         8.4  SURVIVAL.  The representations, warranties, covenants and
agreements made in this Agreement shall survive any investigation made by the
Company or the Purchasers and the Closing.

         8.5  SUCCESSORS AND ASSIGNS.  The provisions hereof shall inure to the
benefit of, and be binding upon, the successors, assigns, heirs, executors and
administrators of the parties to this Agreement.  Notwithstanding the foregoing,
no Purchaser shall assign this Agreement without the prior written consent of
the Company, which consent may be withheld by the Company in its sole discretion
for any or no reason; provided, that the benefits and obligations of any
Purchaser under Section 7 may be transferred by a Purchaser without the prior
written consent of the Company to any person that acquires at least 51% of the
Shares acquired by such Purchaser at the Closing, so long as the transferee
agrees in writing to be bound by the provisions of Section 7 to the same extent
as the Purchaser from whom it acquired the Shares.


                                         15.
<PAGE>

         8.6  ENTIRE AGREEMENT.  This Agreement constitutes the full and entire
understanding and agreement between the parties with regard to the subjects
hereof.

         8.7  NOTICES, ETC.  All notices and other communications required or
permitted under this Agreement shall be in writing and may be delivered in
person, by facsimile, overnight delivery service or registered or certified
United States mail, addressed to the Company or the Purchasers, as the case may
be, at their respective addresses set forth at the beginning of this Agreement
or on EXHIBIT A, and in the case of all notices and other communications to the
Purchasers, a copy will be delivered to Soros Fund Management LLC, 888 Seventh
Avenue, Suite 3300, New York, New York 10106, Attn:  Sean Warren, (212) 541-7751
(fax), or at such other address as the Company or the Purchasers shall have
furnished to the other party in writing.  All notices and other communications
shall be effective upon the earlier of actual receipt thereof by the person to
whom notice is directed or (i) in the case of notices and communications sent by
personal delivery or facsimile, one business day after such notice or
communication arrives at the applicable address or was successfully sent to the
applicable facsimile number, (ii) in the case of notices and communications sent
by overnight delivery service, at noon (local time) on the second business day
following the day such notice or communication was sent, and (iii) in the case
of notices and communications sent by United States mail, seven days after such
notice or communication shall have been deposited in the United States mail.

         8.8  SEVERABILITY OF THIS AGREEMENT.  If any provision of this
Agreement shall be judicially determined to be invalid, illegal or
unenforceable, the validity, legality and enforceability of the remaining
provisions shall not in any way be affected or impaired thereby.

         8.9  COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.

         8.10 FURTHER ASSURANCES.  Each party to this Agreement shall use its
best efforts to cause the Closing to occur and shall do and perform or cause to
be done and performed all such further acts and things and shall execute and
deliver all such other agreements, certificates, instruments and documents as
the other party hereto may reasonably request in order to carry out the intent
and accomplish the purposes of this Agreement and the consummation of the
transactions contemplated hereby.

         8.11 EXPENSES.  The Company shall bear its own expenses incurred on
its behalf with respect to the execution of this Agreement and the Closing of
the transactions contemplated hereby, including fees of its legal counsel, and
will, promptly after receipt of an invoice therefor, reimburse the reasonable
fees and costs of one special counsel for the Purchasers up to a maximum amount
of $15,000.

         8.12 CURRENCY.  All references to "dollars" or "$" in this Agreement
shall be deemed to refer to United States dollars.


                                         16.
<PAGE>

         8.13 ATTORNEYS' FEES.  If any action at law or in equity is necessary
to enforce or interpret the terms of this Agreement, the prevailing party shall
be entitled to reasonable attorneys' fees, costs and necessary disbursements in
addition to any other relief to which such party may be entitled.

         The foregoing agreement is hereby executed as of the date first above
written.

                             "COMPANY"

                             TRIANGLE PHARMACEUTICALS, INC.,
                             a Delaware corporation



                             By:
                                    --------------------------------------

                             Title:
                                    --------------------------------------

                             "PURCHASERS"

                             QUANTUM PARTNERS LDC, a Cayman Islands limited
                             duration company



                             By:
                                    --------------------------------------

                             Title:
                                    --------------------------------------

                             QUANTUM INDUSTRIAL PARTNERS LDC, a Cayman Islands
                             limited duration company


                             By:
                                    --------------------------------------

                             Title:
                                    --------------------------------------

                             DUQUESNE FUND, L.P.

                             By:  Duquesne Capital Management, L.L.C., its
                                  investment advisor



                                  By:
                                       -----------------------------------
                                       Gerald Kerner, Managing Director


                                         17.
<PAGE>

                                                                       Exhibit A



                                SCHEDULE OF PURCHASERS


                                               Aggregate
Purchaser                                   Purchase Price           Shares
---------                                   --------------           ------

Quantum Partners LDC                          $3,000,000            200,000
c/o Curacao Corporation N.V.
Kaya Flamboyan 9, Willemstad, Curacao
Netherlands Antilles

Quantum Industrial Partners LDC              $15,000,000          1,000,000
c/o Curacao Corporation N.V.
Kaya Flamboyan 9, Willemstad, Curacao
Netherlands Antilles

Duquesne Fund, L.P.                          $12,000,000            800,000
c/o Duquesne Capital Management, L.L.C.
888 Seventh Avenue, Suite 3300
New York, New York 10106
Attn:  Gerald Kerner



     TOTALS                                  $30,000,000          2,000,000
                                             -----------          ---------
                                             -----------          ---------

<PAGE>

                                                                       Exhibit B

                              FORM OF FIRST AMENDMENT TO
                         RESTATED INVESTORS' RIGHTS AGREEMENT

<PAGE>

                                                                       Exhibit C

                            TRIANGLE PHARMACEUTICALS, INC.
                         REGISTRATION STATEMENT QUESTIONNAIRE



         In connection with the preparation of the Registration Statement,
please provide us with the following information regarding the Purchaser.

         1.   Please state your organization's name exactly as it should appear
in the Registration Statement:

         2.   Have you or your organization had any position, office or other
material relationship within the past three years with the Company or its
affiliates other than as disclosed in the Prospectus included in the
Registration Statement?

                   Yes                      No

         If yes, please indicate the nature of any such relationships below: