<PAGE>










                                LICENSE AGREEMENT

                                     BETWEEN

                         MITSUBISHI CHEMICAL CORPORATION

                                       AND

                         TRIANGLE PHARMACEUTICALS, INC.
















 *** Certain confidential portions of this Exhibit were omitted by means of 
blackout of the text (the "Mark"). This Exhibit has been filed separately 
with the Secretary of the Commission without the Mark pursuant to the 
Company's Application Requesting Confidential Treatment under Rule 24b-2 under 
the 1934 Act.
<PAGE>


                                TABLE OF CONTENTS



ARTICLE 1.  DEFINITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . .  1

ARTICLE 2.  LICENSES AND MANUFACTURING . . . . . . . . . . . . . . . . . . .  8

ARTICLE 3.  ROYALTIES AND MILESTONE PAYMENTS . . . . . . . . . . . . . . . . 11

ARTICLE 4.  REPORTS AND ACCOUNTING . . . . . . . . . . . . . . . . . . . . . 18

ARTICLE 5.  PAYMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

ARTICLE 6.  DEVELOPMENT PROGRAM. . . . . . . . . . . . . . . . . . . . . . . 21

ARTICLE 7.  PATENT PROSECUTION . . . . . . . . . . . . . . . . . . . . . . . 27

ARTICLE 8.  INFRINGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 31

ARTICLE 9.  WARRANTIES AND INDEMNIFICATION . . . . . . . . . . . . . . . . . 32

ARTICLE 10.  CONFIDENTIALITY . . . . . . . . . . . . . . . . . . . . . . . . 34

ARTICLE 11.  TERM AND TERMINATION. . . . . . . . . . . . . . . . . . . . . . 37

ARTICLE 12.  ASSIGNMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . 39

ARTICLE 13.  TRANSFER OF KNOW-HOW; TECHNICAL ASSISTANCE. . . . . . . . . . . 40

ARTICLE 14.  REGISTRATION OF LICENSE . . . . . . . . . . . . . . . . . . . . 43

ARTICLE 15.  NOTIFICATION AND AUTHORIZATION UNDER DRUG PRICE
              COMPETITION AND PATENT TERM RESTORATION ACT. . . . . . . . . . 43

ARTICLE 16.  DISPUTE RESOLUTION AND ARBITRATION. . . . . . . . . . . . . . . 44

ARTICLE 17.  GENERAL PROVISIONS. . . . . . . . . . . . . . . . . . . . . . . 46

<PAGE>


     THIS LICENSE AGREEMENT is made and entered into as of this 17th day of June
1997, by and between MITSUBISHI CHEMICAL CORPORATION, with its principal offices
at 5-2 Marunouchi 2-chome, Chiyoda-ku, Tokyo, Japan (hereinafter referred to as
"Mitsubishi"), and TRIANGLE PHARMACEUTICALS, INC., with principal offices
located at 4 University Place, 4611 University Drive, Durham, NC 27707
(hereinafter referred to as "Triangle").

                                   WITNESSETH:

     WHEREAS, Mitsubishi and Triangle have entered into an Option Agreement,
dated as of December 20, 1995 (the "Option Agreement"), pursuant to which
Triangle was granted an option to obtain an exclusive license under certain of
Mitsubishi's intellectual property rights relating to the Compound (as
hereinafter defined); and

     WHEREAS, Triangle has exercised the option in accordance with the terms and
conditions specified in the Option Agreement;

     NOW, THEREFORE, in consideration of the premises and the covenants herein
contained, the parties agree as follows:

                             ARTICLE 1.  DEFINITIONS

     The following terms as used herein, when written with an initial capital
letter, shall have the meaning ascribed to them below:

     1.1  "Affiliate" shall mean any corporation or non-corporate business
entity which controls, is controlled by, or is under common control with a party
to this Agreement.  A corporation or non-corporate business entity shall be
regarded as in control of another corporation if it owns, or directly or
indirectly controls, at least fifty (50%) percent of the voting stock of the
other corporation, or

          (a) in the absence of the ownership of at least fifty


                                        1
<PAGE>


(50%) percent of the voting stock of a corporation or (b) in the case of a
non-corporate business entity, or non-profit corporation, if it possesses,
directly or indirectly, the power to direct or cause the direction of the
management and policies of such corporation or non-corporate business entity, as
applicable.

     1.2  "Agreement" or "License Agreement" shall mean this Agreement,
including all Appendices attached to this Agreement.

     1.3  "Bulk Drug Substance" shall mean the Compound in bulk form which, if
appropriately formulated and finished, would constitute Finished Drug Product .

     1.4  "Compound" shall mean the compound known as MKC-442, with the chemical
name 6-Benzyl-(ethoxy methyl)-5-isopropyl uracil including any salts and 
esters thereof.

     1.5  "Development Program" shall mean the research and development program
described in Article 6 of this Agreement.

     1.6  "Direct Manufacturing Cost" shall mean Triangle's or its Affiliate's
or sublicensee's, as applicable, direct costs of manufacturing Bulk Drug
Substance including labor, materials, utilities, depreciation, allocated
manufacturing overhead and other manufacturing expenses applied by Triangle ,
its Affiliate or sublicensee and conforming to generally accepted accounting
principles in the country of manufacture, the details of which shall be as
determined in good faith by Triangle.  In the event Triangle, its Affiliates or
sublicensees purchase Bulk Drug Substance from an independent third party, the
Direct Manufacturing Cost for any quantities so purchased shall be the
acquisition cost on an F.O.B. formulating site basis (including custom duties)
from such third party plus, in the case of any quantities so purchased from any
of Mitsubishi's subcontractors identified in Section 13.3, any brokers' fees
paid, directly or indirectly, by Triangle in connection with such purchase.


                                        2






<PAGE>


     1.7  "Dollars" shall mean United States dollars.

     1.8  "Effective Date" shall mean the date first written above.

     1.9  "FDA" shall mean the United States Food and Drug Administration or
successor entity.

     1.10 "Finished Drug Product" shall mean Bulk Drug Substance formulated into
a final dosage form appropriate for human use.

     1.11 "IND" shall mean an Investigational New Drug Application or its
domestic or foreign equivalent.

     1.12 "Indemnitees" shall mean (a) in the case of the indemnity set forth in
Subsection 9.4(a), Mitsubishi, and its Affiliates and their directors, officers
and employees; (b) in the case of the indemnity set forth in Subsection 9.4(b),
Triangle, its Affiliates and sublicensees, and their directors, officers and
employees; and (c) in the case of the Indemnitees referenced in Section 9.5, the
parties identified in Subsections 1.12(a) and 1.12(b) above.

     1.13 "Joint Inventions" shall mean any inventions related to the 
Compounds or the Licensed Products whether patented or not, which are jointly 
made during the period beginning on the Effective Date and ending *** after 
termination or expiration of this Agreement pursuant to Article 11 by at 
least one (1) Mitsubishi employee or person contractually required to assign 
or license patent rights covering such inventions to Mitsubishi and at least 
one (1) Triangle employee or person contractually required to assign or 
license patent rights covering such inventions to Triangle.

     1.14 "Joint Know-How" shall mean all inventions, discoveries, trade
secrets, information, data, formulas, procedures and results which are useful
for development, registration, manufacturing, using or selling of the Compounds
or the Licensed Products


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<PAGE>


which are developed jointly by at least one (1) Mitsubishi employee or person 
contractually required to assign or license such data and know-how to 
Mitsubishi and at least one (1) Triangle employee or person contractually 
required to assign or license such data or know-how to Triangle, during the 
period beginning on the Effective Date and ending *** after termination or 
expiration of this Agreement pursuant to Article 11.  All Joint Know-How 
shall be owned jointly by the parties hereto. Triangle shall have the 
exclusive right to use such Joint Know-How in the Territory, unless the 
license granted pursuant to Section 2.1 is terminated in a given country or 
countries of the Territory by Mitsubishi pursuant to Section 6.3 or 11.2 or 
by Triangle pursuant to Section 11.3, in which case, Mitsubishi shall have a 
non-exclusive right to use the Joint Know-How in such country or countries. 
Mitsubishi shall have the exclusive right to use such Joint Know-How outside 
the Territory.

     1.15 "Licensed Product(s)" shall mean any Compound or any pharmaceutical
product containing the Compound as an active ingredient, alone or in combination
with other active ingredients.

     1.16 "Major Market Country" shall mean Germany, France, the United Kingdom
or the United States of America.

     1.17 "Mitsubishi Know-How" shall mean all inventions, discoveries, trade
secrets, information (including all information relating to subcontractors),
experience, data, formulas, procedures and results which are useful for
development and registration of the Compounds or the Licensed Products and the
development, registration, manufacturing, using or selling of the Licensed
Products which are rightfully held by Mitsubishi as of the Effective Date, or
which are not Joint Know-How or Joint Inventions and are developed or acquired
by Mitsubishi during the period beginning on the Effective Date and ending upon
termination or


                                        4





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<PAGE>


expiration of this Agreement pursuant to Article 11 including, but not limited
to, all manufacturing know-how of (a) Mitsubishi and (b) to the extent
Mitsubishi has the right to disclose to and license third parties, its
subcontractors which supply Bulk Drug Substance pursuant to Section 2.5.

     1.18 "Mitsubishi Patents" shall mean all patents and patent applications in
the Territory owned or controlled by Mitsubishi or under which Mitsubishi has a
right to practice with the right to extend such right to practice to Triangle
(including, but not limited to, all patents and patent applications of
Mitsubishi's subcontractors which supply Bulk Drug Substance pursuant to Section
2.5 to the extent Mitsubishi has the right so to extend such right to practice),
which contain claims the rights to which are useful for the development,
registration, manufacturing, using or selling of the Compounds and Licensed
Products which are filed prior to or during the term of this Agreement in the
United States or any foreign jurisdiction, including any addition, continuation,
continuation-in-part or division thereof or any substitute application therefor;
any patent issued with respect to such patent application, any reissue,
extension or patent term extension of any such patent, and any confirmation
patent or registration patent or patent of addition based on any such patent;
and any other United States and foreign patent or inventor's certificate with
regard thereto.  Mitsubishi Patents shall include but not be limited to those
listed in Appendix A attached hereto.

     1.19 "NDA" shall mean a New Drug Application or its domestic or foreign
equivalent.

     1.20 "Net Sales" of Licensed Products which contain as their active
ingredients only the Compound shall mean the gross sales price of such Licensed
Products billed by Triangle, its Affiliates or sublicensees to independent
customers less (a) normal and customary trade,


                                        5
<PAGE>


quantity and cash discounts, all rebates, sales, use, or other similar taxes,
and all transportation, insurance and handling charges; and (b) all credits and
allowances to such independent customers on account of returns or retroactive
price reductions in lieu of returns, whether during the specific royalty period
or not.

     1.21 "Net Sales" of Licensed Products which contain as their active
ingredients both the Compound and other compounds (a "Combination Product")
shall mean the gross sales price of such Combination Product billed by Triangle,
its Affiliates or sublicensees to independent customers, less all the
allowances, adjustments, reductions, discounts, taxes, duties, rebates or other
items referred to in Section 1.20 multiplied by a fraction, the numerator of
which shall be the average invoice price per gram of Compound contained in the
most comparable stock keeping unit of any product having the Compound as the
sole active ingredient during the applicable royalty period in the applicable
country of the Territory, when such comparable product is sold for the same
indication as such Combination Product and the denominator of which shall be the
average invoice price per gram of the Compound sold alone as described
immediately above plus the average invoice price(s) per gram of the other active
ingredient(s) contained in such Combination Product in such country during the
applicable royalty period when such active ingredients are sold alone for the
same indication as such Combination Product.  If there is no average invoice
price per gram in a given country for one or more of the active ingredients
comprising a Combination Product, the parties shall discuss in good faith and
agree separately on the Net Sales with respect to such Combination Product,
taking into account the medical effects and general prices of all of the active
ingredients contained therein.


                                        6
<PAGE>


     1.22 "Registration" shall mean, in relation to any Licensed Product, such
approvals by the regulatory authorities in a given country (including pricing
approvals) as may be legally required before such Licensed Product may be
commercialized or sold in such country.

     1.23 "Territory" shall mean the entire world, excluding Japan.

     1.24 "Triangle Know-How" shall mean all inventions, discoveries, trade
secrets, information, experience, data, formulas, procedures and results arising
solely out of the Development Program or the manufacture, use or sale of the
Licensed Product which are useful for development, registration, manufacturing,
using or selling of the Compounds or the Licensed Products which are rightfully
held by Triangle as of the Effective Date, or which are not Joint Know-How or
Joint Inventions and are developed or acquired by Triangle during the period
beginning on the Effective Date and ending upon termination or expiration of
this Agreement pursuant to Article 11.

     1.25 "Triangle Patents" shall mean all patents and patent applications
owned or controlled by Triangle or under which Triangle has a right to practice
with the right to extend such right to practice to Mitsubishi  which contain
claims the rights to which are necessary for the development, registration,
manufacturing, using or selling of the Compounds or the Licensed Products,
including any addition, continuation, continuation-in-part or division thereof
or any substitute application therefor; any patent issued with respect to such
patent application, any reissue, extension or patent term extension of any such
patent, and any confirmation patent or registration patent or patent of addition
based on any such patent; and any other United States and foreign patent or
inventor's certificate with regard thereto.

     1.26 "Valid Claim" shall mean (a) an issued claim of any unexpired patent
included among the Mitsubishi Patents, or (b) a pending claim of any pending
patent application


                                        7
<PAGE>


included among the Mitsubishi Patents, which has not been held unenforceable,
unpatentable or invalid by a decision of a court or governmental body of
competent jurisdiction, unappealable or unappealed within the time allowed for
appeal, which has not been rendered unenforceable through disclaimer or
otherwise or which has not been lost through an interference proceeding.

                      ARTICLE 2. LICENSES AND MANUFACTURING

     2.1  LICENSE UNDER MITSUBISHI PATENTS AND KNOW-HOW.

          Mitsubishi hereby grants Triangle the exclusive right and license to
practice the Mitsubishi Patents and the Mitsubishi Know-How to make, have made,
use, import, offer for sale, sell and have sold Licensed Products (including,
but not limited to, Bulk Drug Substance to be used in the formulation of
Finished Drug Product) in the Territory during the term of this Agreement.

     2.2  EXTENSION TO AFFILIATES.  Triangle shall have the right to extend its
rights under the license granted in Section 2.1 to one or more of its
Affiliates, provided, that Triangle (a) gives Mitsubishi advance notice of such
extension, (b) retains control over that portion of the Development Program
which such Affiliate is performing and (c) remains responsible for such
Affiliate's compliance with all obligations under this Agreement which apply to
such Affiliate.

     2.3  SUBLICENSES.  Triangle may grant sublicenses to non-Affiliate third 
parties upon Mitsubishi's prior written approval (which approval shall not be 
unreasonably withheld or delayed).  In the event Mitsubishi does not respond 
to a request for approval to sublicense within *** after receiving such 
request from Triangle, which request must contain information regarding the 
prospective sublicensee, its business activities, the scope and outline of 
the sublicense and the portion of the Territory to which the sublicense will 
apply, such

                                        8





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request shall be deemed to be approved.  Triangle shall provide Mitsubishi 
with complete copies of all sublicense agreements within *** of their 
execution.  Triangle shall remain responsible to Mitsubishi for the 
performance of any Triangle sublicensee under this Agreement.

     2.4  LICENSE UNDER TRIANGLE PATENTS AND KNOW-HOW.  Triangle hereby grants
Mitsubishi a non-exclusive right and license to practice the Triangle Patents
and Triangle Know-How to make, have made, use, import, offer for sale, sell and
have sold Licensed Products, with a right to sublicense, outside the Territory
and, in the event Triangle's license granted under Section 2.1 is terminated in
a given country of the Territory (other than by expiration or by Triangle
pursuant to Section 11.2 of this Agreement), in such country from and after the
date of termination.  The license granted pursuant to this Section 2.4 shall be
royalty free in countries outside the Territory and subject to Section 11.4.  In
the event the license granted pursuant to this Section 2.4 becomes effective in
any country of the Territory because Triangle's license is terminated in such
country, Mitsubishi shall be obligated to pay Triangle reasonable royalties and
other compensation for the license to Triangle Patents in such country.
Triangle and Mitsubishi shall negotiate in good faith in an effort to reach an
agreement on such royalties or other compensation.  If they fail to reach
agreement, the matter shall be resolved in accordance with Article 16.

     2.5  SUPPLY OF BULK DRUG SUBSTANCE.

          (a) Mitsubishi agrees to supply Triangle with those quantities of 
Bulk Drug Substance necessary for Triangle to perform the Development Program 
free of charge, not to exceed ***.  Such obligation shall include all 
preclinical studies and Phase I, II and III clinical trials under the 
Development Program.  In the event

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Triangle requires quantities of Bulk Drug Substance in excess of the quantity
specified above in order to perform the Development Program and demonstrates the
need for such additional quantities to the reasonable satisfaction of
Mitsubishi, Mitsubishi agrees to give due consideration to Triangle's request
for such additional quantities; provided, however, that the cost of such
additional quantities shall be divided equally between Mitsubishi and Triangle.

          (b)  The delivery schedule for all Bulk Drug Substance shall be
determined from time to time by mutual agreement of the parties.  All Bulk Drug
Substance supplied pursuant to this Section 2.6 shall (i)  be manufactured in
accordance with Current Good Manufacturing Practices as promulgated by the FDA,
(ii) be suitable for use in formulating Finished Drug Product, and (iii) meet
specifications, determined in accordance with applicable analytical methodology,
to be mutually agreed upon in good faith by the parties hereto as promptly as
practicable after the Effective Date.  In the event of any failure by Mitsubishi
in supplying the Bulk Drug Substance conforming to such requirements,
Mitsubishi's sole obligation to Triangle shall be promptly to replace the
defective quantities with conforming Bulk Drug Substance.  In no event will
Mitsubishi be liable to Triangle for any damage or losses on account of such
failure.

          (c)  During the Development Program, Mitsubishi shall also provide
Triangle, free of charge, with those quantities of (i)  analytical reference
materials and (ii) all impurities and degradation products to the extent they
are available to Mitsubishi which are measured when performing the analytical
methodology for the Bulk Drug Substance and the Licensed Product and which are
required by Triangle to conduct the analytical work necessary to obtain
Registration of the Licensed Product in each country of the Territory.


                                       10
<PAGE>


          (d)  Mitsubishi shall allow, and shall cause its subcontractors to
allow, Triangle employees and/or consultants and FDA and other regulatory
personnel to perform any quality assurance audits of Mitsubishi's and its
subcontractors' manufacturing facilities that may be required of Triangle by any
governmental authority or reasonably requested by Triangle.

          (e)  Mitsubishi hereby certifies that it has not been debarred under
the provisions of the Generic Drug Enforcement Act of 1992, 21 U.S.C. Section
335a (a) and (b).  In the event that during the term of this Agreement,
Mitsubishi becomes debarred or receives notice of an action or threat of an
action with respect to its debarment, Mitsubishi shall notify Triangle
immediately.  Mitsubishi hereby certifies that it has not and will not use in
any capacity the services of any individual, corporation, partnership or
association which has been debarred under 21 U.S.C. Section 335a (a) or (b) in
connection with the performance of services hereunder.  In the event that
Mitsubishi becomes aware of the debarment or threatened debarment of any
individual, corporation, partnership or association (the "Debarred Entity")
providing services to Mitsubishi which directly or indirectly relate to
activities under this Agreement, Mitsubishi shall notify Triangle immediately.
Upon Triangle's request, Mitsubishi agrees to cease using the services of the
Debarred Entity.

                  ARTICLE 3.  ROYALTIES AND MILESTONE PAYMENTS

     3.1  LICENSE FEE.  As partial consideration for entering into this
Agreement, Triangle agrees to pay Mitsubishi a license fee of Five Hundred
Thousand Dollars ($500,000), payable within thirty (30) days after the Effective
Date; provided, however, that Triangle shall


                                       11
<PAGE>


be entitled to offset (a) *** percent (***%) of the out-of-pocket costs 
incurred by it in engaging the Authorized CRO (as defined in the Option 
Agreement) to perform Development Work (as defined in the Option Agreement) 
in excess of the *** reimbursed to Triangle by Mitsubishi pursuant to the 
Option Agreement and (b) all of the out-of-pocket costs incurred by Triangle 
in engaging contract toxicology laboratories to perform toxicology studies 
relating to the Licensed Product required by relevant governmental agencies; 
provided, further that the offset described in Subsection 3.1(a) shall not 
exceed *** and the sum of the offsets described in Subsections 3.1(a) and 
3.1(b) shall not exceed ***.  Triangle shall submit an invoice to Mitsubishi 
within thirty (30) days after payment of the license fee which sets forth the 
offsets to which Triangle is entitled. Mitsubishi agrees to pay Triangle the 
amount of such offsets within thirty (30) days after Triangle submits its 
invoice.

     3.2  MILESTONE PAYMENTS.

          (a)  Triangle shall pay Mitsubishi a milestone payment ("Milestone
Payment") in the amount specified below no later than thirty (30) days after the
occurrence of the corresponding event designated below (except as otherwise
specified in Subsection 3.2(b)) in the event Mitsubishi exercises the option set
forth therein):

               Event                                        Milestone Payment
               -----                                        -----------------

 (i) ***
     ***                                                       $ ***
(ii) ***
                                                               $ ***
                                                               -----------
                              TOTAL MILESTONE PAYMENTS         $ ***



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          (b)  Mitsubishi may, at its discretion and subject to the 
provisions of this Subsection 3.2(b), elect to replace the Milestone Payment 
payable under clause (i) of Subsection 3.2(a) with the following two 
Milestone Payments, payable within *** after the occurrence of the 
corresponding events designated below:

               Event                                      Milestone Payment
               -----                                      -----------------

 (i) ***                                                    $ ***
     ***                                                      ***

(ii) ***                                                    $ ***
     ***                                                      ***
                                                              ***
                                                              ***
                                                              ***
                                                              ***


Triangle shall notify Mitsubishi upon NDA filing in the first Major Market 
Country for the first Licensed Product.  Thereafter, Mitsubishi shall have 
*** to elect to exercise the option set forth in this Subsection 3.2(b).  In 
the event Mitsubishi elects not to exercise such option or fails to notify 
Triangle of its election within such *** period, the option shall expire and 
the provisions of Subsection 3.2(a) shall apply.

          (c)  As used in Subsection 3.2(b), Triangle "Common Stock" shall mean
the common stock, $0.001 par value, of Triangle.  All Triangle Common Stock
which is issued pursuant to Subsection 3.2(b) shall be issued directly to
Mitsubishi by Triangle as restricted securities pursuant to an investment intent
letter in form and substance acceptable to Triangle.  The fair market value of
the Triangle Common Stock shall be deemed to equal the closing selling price per
share for Triangle Common Stock on the Nasdaq National Market on the date
Mitsubishi exercises its option in the case of clause (i) of Subsection 3.2(b)
and such closing selling price per share on the date of Registration in the case
of clause (ii) of


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Subsection 3.2(b).  If there is no closing selling price on the date in
question, then the closing selling price shall be the closing selling price on
the last preceding date for which such quotation exists.

     3.3  EARNED ROYALTIES; DURATION AND REDUCTION.

          (a)  Triangle shall pay Mitsubishi a royalty equal to *** percent 
(***%) (the "Initial Royalty Rate") of the Net Sales of Licensed Products 
sold in the Territory by Triangle and its Affiliates and sublicensees for the 
periods and subject to the reductions set forth in this Agreement.

          (b)  Royalties shall be paid in respect of Licensed Products in a
given country for a period of *** after commercial introduction of
Licensed Products in such country. On the later of the expiration of (i) ***
after commercial introduction of a Licensed Product in a given
country and (ii) the last to expire of any Valid Claim covering such Licensed
Product in such country, the Initial Royalty Rate applicable to Net Sales of
such Licensed Product in such country shall be reduced by *** percent
(***%).  In addition, if at any time during such *** period, a third
party or third parties commence selling a therapeutic product in a country of
the Territory and (i) such product contains any Compound ("unlicensed unit
sales") and is sold and/or used for the same indication as that of the Licensed
Product and (ii) such unlicensed unit sales for any royalty period amount to
*** percent (***%) or more of Triangle's unit sales of such Licensed Product
in such country in such royalty period, determined in accordance with Subsection
3.3(c) below, then Triangle's royalty obligation in such country with respect to
such Licensed Product shall be reduced by *** percent (***%) of the royalty
otherwise payable commencing with the royalty period next succeeding the royalty
period in which such *** percent (***%)


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<PAGE>


threshold was initially exceeded and shall resume with the royalty period 
next succeeding the first royalty period in which such *** percent (***%) 
threshold is no longer exceeded.  In no event shall the cumulative effect of 
the two reductions set forth in this Subsection 3.3(b) result in a royalty 
rate of less than *** percent (***%) of the Initial Royalty Rate for any 
Licensed Product.

          (c)  For purposes of this Section 3.3, (i) "unlicensed unit sales" 
and "Triangle unit sales" shall be deemed to mean the grams of Compound 
contained in the third party product (irrespective of dosage form) or the 
Licensed Product (irrespective of dosage form), respectively, as reflected on 
the label of each such unit; and (ii) unlicensed unit sales shall be 
determined by the sales reports of *** or any successor to *** or any other 
independent marketing auditing firm selected by Triangle or its sublicensees 
and reasonably acceptable to Mitsubishi.  If Triangle is entitled to a 
royalty reduction based on unlicensed unit sales pursuant to Subsection 3.3 
(b) for any royalty period, it or its sublicensees shall submit the sales 
report of *** or such other independent firm, as applicable, for the relevant 
royalty period to Mitsubishi, together with Triangle's or its sublicensees' 
sales report for the relevant royalty period. Such sales reports for each 
royalty period in which Triangle is entitled to such royalty reduction shall 
be submitted with the royalty report for such royalty period submitted 
pursuant to Section 4.1.

     3.4  ANNUAL MINIMUM ROYALTIES.

          (a)  During the term of this Agreement for as long as royalty
obligations exist in the United States, Triangle shall use its reasonable
efforts to market and sell the Licensed Product in the Territory consistent with
those efforts used by it in marketing and


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<PAGE>


selling other comparable HIV products, giving due consideration to relevant
market factors in each country.  In the event that, during the second full
calendar year following the year during which the first FDA Registration is
granted for a Licensed Product and each calendar year thereafter for so long as
royalty obligations exist in the U.S., Triangle's total annual royalty payments
to Mitsubishi pursuant to Section 3.3 above are less than the annual minimum
payment set forth opposite such year below (the "Annual Minimum"), Triangle
shall make a payment to Mitsubishi together with the report for the fourth
quarter of such year required in Section 4.1 of this Agreement equal to the
difference between such Annual Minimum and the royalties paid to Mitsubishi for
the preceding year pursuant to Section 3.3 above:

               Calendar Year                       Annual Minimum
               -------------                       --------------

               *** . . . . . . . . . . . . . . . . . . $ ***
               *** . . . . . . . . . . . . . . . . . . $ ***
               *** . . . . . . . . . . . . . . . . . . $ ***
               *** . . . . . . . . . . . . . . . . . . $ ***

     3.5  ACCRUAL OF ROYALTIES.  No royalty shall be payable on a Licensed
Product made, sold, or used for tests or development purposes, including those
described in Subsection 2.5 (a), or distributed as samples.  No royalties shall
be payable on sales among Triangle, its Affiliates and sublicensees, but
royalties shall be payable on subsequent sales by Triangle, its Affiliates or
sublicensees to a third party.  No multiple royalty shall be payable because the
manufacture, use, offer for sale, sale or import of a Licensed Product is
covered by more than one Valid Claim or at least one Valid Claim and Mitsubishi
Know-How.

     3.6  THIRD PARTY ROYALTIES.  If Triangle, its Affiliates or sublicensees
determine after consultation with Mitsubishi, but at Triangle's sole discretion,
that it or they are required to pay royalties and other amounts to any third
party because the manufacture, use, offer for sale,


                                       16





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<PAGE>


importation, or sale of a Licensed Product infringes any patent or other
intellectual property rights of such third party in a given country ("Third
Party Royalties"), Triangle, its Affiliates or sublicensees may deduct the Third
Party Royalties from earned royalties thereafter due to Mitsubishi on the Net
Sales of such Licensed Product in such country and any Milestone Payments
thereafter due to Mitsubishi.  In no event shall the royalties due on such Net
Sales of such Licensed Product in such country or any Milestone Payment on
account of any reduction pursuant to this Section 3.6 be thereby reduced by more
than *** percent (***%) of the amount which would have been otherwise payable.

     3.7  COMPULSORY LICENSES.  Should a compulsory license be granted to any
third party in any country of the Territory to make, have made, use, import,
offer for sale or sell Licensed Products, the royalty rate payable hereunder for
sales of the Licensed Products by Triangle in such country shall be adjusted to
match any lower royalty rate granted to the third party for such country.

     3.8  REDUCTION IN ROYALTY DUE TO COST OF BULK DRUG SUBSTANCE.  In the 
event that, for any Triangle fiscal quarter, the Direct Manufacturing Cost 
exceeds *** percent (***%) of Net Sales of Licensed Products, the Initial 
Royalty Rate shall be reduced by *** percent (***%) of the amount by which 
the Direct Manufacturing Cost exceeds *** percent (***%) but does not exceed 
*** percent (***%) of Net Sales of Licensed Products.  The Direct 
Manufacturing Cost shall be determined within *** after the close of each 
Triangle fiscal quarter with respect to such Triangle fiscal quarter.  In the 
event that a deduction is computed to be due Triangle for such Triangle 
fiscal quarter, Triangle shall be entitled to deduct such amount from the 
royalties shown as due Mitsubishi in the quarterly report due Mitsubishi with 
respect to such Triangle fiscal quarter.  Any provision of this Agreement to

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the contrary notwithstanding, all reductions in royalties prescribed in other
sections of this Article 3 and any limitations applicable to such reductions
shall be calculated after taking into effect the reduction prescribed in this
Section 3.8.

                       ARTICLE 4.  REPORTS AND ACCOUNTING

     4.1  ROYALTY REPORTS AND RECORDS.

          (a)  During the term of this Agreement commencing with commercial
introduction of the first Licensed Product, Triangle shall furnish, or cause to
be furnished to Mitsubishi, written reports governing each of Triangle's,
Triangle's Affiliates' and Triangle's sublicensees' fiscal quarters showing:

          (i)    the gross sales of all Licensed Products sold by Triangle, its
Affiliates and sublicensees, during the reporting period, together with the
calculations of Net Sales in accordance with Sections 1.20 and 1.21; and

          (ii)   the royalties payable in Dollars, which shall have accrued
hereunder in respect to such Sales; and

          (iii)  the exchange rates used, if any, in determining the amount of
Dollars; and

          (iv)   any withholding taxes required to be made from such royalties.

          (b)    With respect to sales of the Licensed Product invoiced in
Dollars, the gross sales, Net Sales, and royalties payable shall be expressed in
Dollars.  With respect to sales of the Licensed Product invoiced in a currency
other than Dollars, the gross sales, Net Sales, and royalties payable shall be
expressed in the domestic currency of the party making the sale together with
the Dollar equivalent of the royalty payable, calculated using the simple
average of the exchange rates published in the WALL STREET JOURNAL on the last
day of each


                                       18
<PAGE>


month during the reporting period.  If any Triangle Affiliate or sublicensee
makes any sales invoiced in a currency other than its domestic currency, the
gross sales and Net Sales shall be converted to its domestic currency in
accordance with the Affiliate's or sublicensee's normal accounting practices.
Triangle or its Affiliate or sublicensee making any royalty payment shall
furnish to Mitsubishi appropriate evidence of payment of any tax or other amount
deducted from any royalty payment.

          (c)    Reports shall be made on a quarterly basis. Quarterly reports
shall be due within sixty (60) days of the close of every Triangle fiscal
quarter.  Triangle shall keep accurate records in sufficient detail to enable
royalties and other payments payable hereunder to be determined. Triangle shall
be responsible for all royalties and late payments that are due to Mitsubishi
that have not been paid by Triangle's Affiliates and sublicensees.  Triangle's
Affiliates and sublicensees shall have, and shall be notified by Triangle that
they have, the option of making any royalty payment directly to Mitsubishi.

     4.2  RIGHT TO AUDIT.  Mitsubishi shall have the right, upon prior notice to
Triangle, not more than once in each Triangle fiscal year nor more than once in
respect of any fiscal year, through an independent certified public accountant
selected by Mitsubishi and acceptable to Triangle, which acceptance shall not be
unreasonably refused, to have access during normal business hours to those
records of Triangle as may be reasonably necessary to verify the accuracy of the
royalty reports required to be furnished by Triangle pursuant to Section 4.1 of
the Agreement.  Such records shall include those relating to the Direct
Manufacturing Cost for any Triangle fiscal quarter in which Triangle makes a
deduction pursuant to Section 3.8.  Triangle shall include in any sublicenses
granted pursuant to this Agreement a provision requiring the sublicensee to keep
and maintain records of sales made pursuant to such


                                       19
<PAGE>


sublicense and to grant access to such records by Mitsubishi's independent
certified public accountant.  If such independent certified public accountant's
report shows any underpayment of royalties by Triangle its Affiliates or
sublicensees, within thirty (30) days after Triangle's receipt of such report,
Triangle shall remit or shall cause its sublicensees to remit to Mitsubishi:

          (a)    the amount of such underpayment; and

          (b)    if such underpayment exceeds *** (***%) percent of the total 
royalties owed for the fiscal year then being reviewed, the reasonably 
necessary fees and expenses of such independent certified public accountant 
performing the audit.  Otherwise, Mitsubishi's accountant's fees and expenses 
shall be borne by Mitsubishi.  Any overpayment of royalties shall be fully 
creditable against future royalties payable in any subsequent royalty 
periods.  Upon the expiration of *** following the end of any fiscal year, 
the calculation of royalties payable with respect to such fiscal year shall 
be binding and conclusive on Mitsubishi and Triangle, unless an audit for 
such fiscal year is initiated before expiration of such ***.

    4.3   CONFIDENTIALITY OF RECORDS.  All information subject to review under
this Article 4 shall be confidential.  Except where provided by law, Mitsubishi
and its accountant shall retain all such information in confidence.

                              ARTICLE 5.  PAYMENTS

    5.1   PAYMENTS AND DUE DATES.  Except as otherwise provided herein,
royalties and sublicense and other fees payable to Mitsubishi as a result of
activities occurring during the period covered by each royalty report provided
for under Article 4 of this Agreement shall be due and payable on the date such
royalty report is due.  Payments of royalties in whole or in


                                       20





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<PAGE>


part may be made in advance of such due date.  All payments shall be made by 
wire transfer to an account of Mitsubishi designated by Mitsubishi from time 
to time; provided, however, that in the event that Mitsubishi fails to 
designate such account, Triangle or its Affiliates and sublicensees may remit 
payment to Mitsubishi to the address applicable for the receipt of notices 
hereunder; provided, further, that any notice by Mitsubishi of such account 
or change in such account, shall not be effective until *** after receipt 
thereof by Triangle.

    5.2   CURRENCY RESTRICTIONS.  Except as hereinafter provided in this Section
5.2, all royalties shall be paid in Dollars.  If, at any time, legal
restrictions prevent the prompt remittance of part of or all royalties with
respect to any country in the Territory where Licensed Products are sold,
Triangle or its sublicensee shall have the right and option to make such
payments by depositing the amount thereof in local currency to Mitsubishi's
accounts in a bank or depository in such country.

     5.3  OVERDUE PAYMENTS.  In the event any payment due hereunder is not made
when due, the payment shall accrue interest (beginning on the date such payment
is due) calculated at the rate of *** percent (***%) per month and such payment
when made shall be accompanied by all interest so accrued.

                        ARTICLE 6.  DEVELOPMENT PROGRAM

     6.1  DEVELOPMENT PROGRAM.  Subject to Mitsubishi's timely performance of
its obligations hereunder, and in complete fulfillment of Triangle's development
obligations hereunder and any such obligations implied by law, Triangle will
undertake, or will cause its Affiliates and sublicensees to undertake, the
development activities described in this Article 6.  Triangle shall, at its
expense, use its best efforts to conduct a development program (the "Development
Program") in the Major Market Countries relating to the use of the Licensed


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Product and to seek Registration for the Licensed Product in the Major Market
Countries.  A description of the studies expected to be conducted as part of the
Development Program is set forth on Appendix B, attached hereto and made a part
hereof.  It is understood that such description represents the types of studies
presently anticipated and that Appendix B shall be subject to modification by
mutual agreement of the parties based on Triangle's reasonable proposal or as
otherwise necessary or useful for purposes of obtaining Registration for a
Licensed Product in a given country; provided, however, that Mitsubishi shall
not unreasonably withhold or delay its agreement to such modifications. The
Development Program shall be mutually discussed by the parties hereto and shall
take into consideration studies and experiments carried out, or to be carried
out by, Mitsubishi and its other licensees outside the Territory, but the
activities comprising the Development Program shall be determined at Triangle's
sole discretion.  Anything in this Agreement to the contrary notwithstanding,
Triangle shall be entitled to exercise prudent and justifiable business judgment
in meeting its best efforts obligations hereunder.  For purposes of this Article
6, "best efforts" shall mean that Triangle shall use reasonable efforts
consistent with those used by it in its development projects with other
compounds in its development portfolio deemed to have comparable commercial
potential.

     6.2  FULFILLMENT.  Subject to the foregoing provisions of this Article 6,
Triangle's best efforts obligations set forth in this Article 6 shall be deemed
to have been satisfied if Triangle:

          (a)  files in at least one Major Market Country what it reasonably
believes to be a complete NDA for a Licensed Product with the appropriate
regulatory agency within such *** after the Effective Date;
provided, however, said ***


                                       22






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<PAGE>


period shall be subject to up to *** extensions of *** each at Triangle's 
election by payment to Mitsubishi of a sum of *** for each such *** extension;

          (b)  files in the remaining Major Market Countries what it 
reasonably believes to be a complete NDA for a Licensed Product with the 
appropriate regulatory agency within *** after the Effective Date; provided, 
however, that said *** period shall be subject to up to *** extensions of *** 
each at Triangle's election by payment to Mitsubishi of a sum of *** for each 
such *** extension;

          (c)  receives Registration for such Licensed Product in each Major 
Market Country within *** after filing an NDA in such country; and

          (d)  commercially introduces, or causes its Affiliates or 
sublicensees to commercially introduce, such Licensed Product in each Major 
Market Country of the Territory within *** after Registration of such 
Licensed Product in such Major Market Country, if otherwise commercially 
feasible. Extension payments under Subsections 6.2(a) and 6.2(b) shall be 
made within the first *** of each such extension period.

     6.3  MITSUBISHI REMEDIES.

          (a)  In the event Triangle fails to meet any diligence requirements
set forth  in Subsection 6.2(a), 6.2(b) or 6.2(c) in respect of all Major Market
Countries, and does not demonstrate to Mitsubishi's reasonable satisfaction
that, despite Triangle's efforts, the failure to meet the diligence requirement
was delayed due to reasons beyond Triangle's reasonable control, Mitsubishi
shall have the option, as its sole and exclusive remedy, to terminate the


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<PAGE>


Agreement in the entire Territory, except that, to the extent Triangle has met
the diligence requirements in a given Major Market Country, Mitsubishi shall not
be entitled to terminate this Agreement in such Major Market Country.  The
remedy set forth in this Section 6.3 shall be Mitsubishi's sole and exclusive
remedy.

          (b)  Prior to exercising any rights under this Section 6.3, 
Mitsubishi shall give Triangle *** notice and shall meet with Triangle, at 
Triangle's request and expense, during such *** period, to discuss any 
disagreements about whether Triangle has complied with the applicable 
diligence requirements of this Article 6.  Upon expiration of such *** 
period, Mitsubishi shall have the right in its sole discretion to proceed 
with the exercise of all rights and remedies provided for herein unless the 
applicable diligence requirement is fulfilled during such *** period.

          (c)  Upon termination by Mitsubishi of this Agreement in a country of
the Territory pursuant to this Section 6.3, the provisions of Section 11.4 shall
apply in respect of such country

     6.4  DEVELOPMENT NON-MAJOR MARKET COUNTRIES.  No later than Triangle's
filing of an NDA for a Licensed Product in the last Major Market Country,
Triangle shall directly, or through or in collaboration with Affiliates and
sublicensees, commence its best efforts:

          (a)  to obtain Registration for a Licensed Product in such other
countries of the Territory as Triangle deems appropriate; and

          (b)  upon Registration of a Licensed Product in a particular country
proceed with due diligence to market such Licensed Product in such country.


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In the event Triangle has not filed an NDA in any Non-Major Market Country 
within *** of the Effective Date or, having done so, has not obtained a 
Registration for a Licensed Product in such country within *** from the 
Effective Date, upon Mitsubishi's request, the parties shall meet and attempt 
to agree on appropriate Registration activities which should occur in such 
country.  The remedy set forth in this Section 6.4 shall be Mitsubishi's sole 
and exclusive remedy.

     6.5  PUBLICATIONS.  Each party reserves the right to publish or publicly
present the results of its own development activities in respect of the Licensed
Products (the "Results").  The party proposing to publish or publicly present
the Results (the "publishing party") will, however, submit a draft of any
proposed manuscript, abstract or speech to the other party (the "non-publishing
party") for comments at least fifteen (15) days prior to submission for
publication or oral presentation.  The non-publishing party shall notify the
publishing party in writing within fifteen (15) days of receipt of such draft
whether such draft contains Information (as hereinafter defined) of the non-
publishing party which it considers to be confidential under the provisions of
Article 10 hereof, or information that if published would have an adverse effect
on a patent application for which the non-publishing party has primary patent
prosecution responsibility pursuant to Article 7 of this Agreement.  In the
latter case, the non-publishing party shall have the right to request a delay
and the publishing party shall delay such publication for a period not exceeding
***.  In any such notification,


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the non-publishing party shall indicate with specificity its suggestions
regarding the manner and degree to which the publishing party may disclose such
information.  The publishing party shall have the final authority to determine
the scope and content of any publication, provided that such authority shall be
exercised with reasonable regard for the interests of the non-publishing party,
except that no publication will contain any Information disclosed by the non-
publishing party to the publishing party without the non-publishing party's
prior written permission.  Each party shall cause its Affiliates, licensees or
sublicensees, as the case may be, to comply with the requirements of this
Section 6.5 with respect to any of their proposed publications.

     6.6  PROGRESS REPORTS.  Each party (the "reporting party") shall, no 
less frequently than once every *** until a Licensed Product has been 
Registered, provide the other party (the "reviewing party") with a written 
report summarizing all activities of the reporting party, its Affiliates and 
licensees or sublicensees, as the case may be, related to the development of 
Licensed Products.  The reviewing party may comment on the progress of the 
reporting party's development activities when reviewing such progress reports 
and the reporting party shall give due consideration to such comments, it 
being understood that Triangle shall make ultimate decisions in respect of 
the Development Program and Mitsubishi shall make ultimate decisions in 
respect of the development of the Licensed Products outside the Territory.

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                         ARTICLE 7.  PATENT PROSECUTION

     7.1  TITLE TO INVENTIONS. Each party shall have and retain sole title in
inventions, whether or not patentable, made by it or on its behalf (as by its
employees or agents) in the course of work performed under this Agreement.

     7.2  MITSUBISHI INVENTIONS. Mitsubishi shall, in consultation with
Triangle, file such patent applications regarding any of Mitsubishi's sole
inventions which are useful for the development, registration, manufacture, use
or sale of the Compounds or Licensed Products in the Territory, and thereafter
shall diligently and in the exercise of its discretion in a manner reasonably
consistent with the goals and expectations of the parties, giving due and
reasonable consideration to Triangle's position, prosecute and maintain in force
the resulting Mitsubishi Patents all at the expense of  Mitsubishi.  Mitsubishi
shall enable Triangle to directly contact and confer with Mitsubishi's patent
attorney, at Triangle's expense, with respect to the prosecution of any patent
applications constituting part of the Mitsubishi Patents and shall use its
reasonable efforts to amend, correct or refile any patent or patent application
included in the Mitsubishi Patents to include claims reasonably requested by
Triangle.  The territorial scope of such filings shall be the subject of
specific discussion between the parties, but shall include all Major Market
Countries and all other countries reasonably requested by Triangle to the extent
not already applied for as of the Effective Date.  If for any reason Mitsubishi
declines to file a patent application or, having filed, declines to prosecute or
maintain any of the Mitsubishi Patents within the Territory, Triangle may so
file, prosecute or maintain in Mitsubishi's name and at Triangle's expense in
such country, in which event, Mitsubishi shall at Triangle's request and
expense, provide all reasonable assistance; provided, however, that Triangle
shall be entitled to credit the out-of-pocket expenses so incurred against
earned royalties due hereunder with respect


                                       27
<PAGE>


to Licensed Products sold in such country.

     7.3  TRIANGLE INVENTIONS.   Triangle shall, in consultation with
Mitsubishi, file such patent applications regarding any of Triangle's sole
inventions which are useful for the development, registration, manufacture, use
or sale of the Compounds or Licensed Products, and thereafter shall diligently
and in the exercise of its discretion in a manner reasonably consistent with the
goals and expectations of the parties hereunder, giving due and reasonable
consideration to Mitsubishi's position, prosecute and maintain in force the
resulting Triangle Patents all at Triangle's expense.  Triangle shall enable
Mitsubishi to directly contact and confer with Triangle's patent counsel, at
Mitsubishi's expense, with respect to the prosecution of any patent applications
constituting part of the Triangle Patents and shall use its reasonable efforts
to amend, correct or refile any patent or patent application included in the
Triangle Patents to include claims reasonably requested by Mitsubishi.  The
territorial scope of such filings shall be the subject of specific discussion
between the parties but shall include all Major Market Countries and all other
countries reasonably requested by Mitsubishi.  If for any reason Triangle
declines to file a patent application or, having filed, declines to prosecute or
maintain any of the Triangle Patents in any country, Mitsubishi may so file,
prosecute or maintain in Triangle's name and at Mitsubishi's expense in such
country, in which event, Triangle shall at Mitsubishi's request and expense,
provide all reasonable assistance.

     7.4  JOINT INVENTIONS. With respect to Joint Inventions (a)  all patent
applications and patents with respect thereto shall be jointly owned by
Mitsubishi; (b) Triangle and its sublicensees and assigns shall be free to use
such patents including the Territory and Mitsubishi and its licensees shall be
free to use such patents outside the Territory, without payment of royalty or
accounting therefor; (c) each party agrees to consult with the other party and
to give


                                       28
<PAGE>


due and reasonable consideration to the other party's position in determining 
the territorial scope of patent filings within the Territory  (in the case of 
Triangle) and outside the Territory (in the case of Mitsubishi), and the 
prosecution and maintenance in force, of resulting patent rights based on 
Joint Inventions; and (d) Triangle shall have the initial responsibility to 
file any patent application and prosecute and maintain any resulting patent 
rights on Joint Inventions, in which event Mitsubishi shall, at Triangle's 
request, provide all reasonable assistance and shall promptly reimburse 
Triangle *** percent (***%) of the out-of-pocket expenses so incurred to 
Triangle.

     7.5  FURTHER OBLIGATIONS.

          (a)  Except as otherwise provided in Articles 8 and 15, each party's
responsibilities for patent prosecution activities pursuant to this Article 7
shall also include all other EX PARTE and INTER PARTES  activities relating to
the relevant patent applications and patents, including all interference,
opposition and observation proceedings before any patent offices and litigation
pertaining to the validity, enforceability, allowability or subsistence of such
patent applications and patents.  Each party agrees to give due consideration to
the other party's position with respect to any such patent prosecution
activities (which term, as used herein, shall include without limitation, any
INTER PARTES activities of the type described in the first sentence of this
subsection 7.5 (a)).  In the event a party fails to initiate or pursue any
patent prosecution activities for which it is responsible, or having commenced
such patent prosecution activities, declines to pursue such patent prosecution
activities, the other party may initiate, pursue or assume such patent
prosecution activities, at its expense; provided, however, that in the case of
Triangle's initiation, pursuit or assumption of patent prosecution activities in
respect of Mitsubishi Patents in a given country, Triangle shall be able to
credit the out-of-pocket expenses so incurred against earned royalties due
hereunder with respect to Licensed Products sold in such


                                       29





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country.

          (b)  In conducting its patent prosecution activities under this 
Agreement, each party may use patent attorneys selected by it in its own 
discretion.  In addition to the other obligations set forth in this Article 
7, each party undertakes to keep the other party throughout the term of this 
Agreement regularly informed of the status and progress of the patent 
prosecution activities it undertakes under this Agreement including, but not 
limited to, supplying the other, upon reasonable request, with all 
correspondence with the United States, Japan or European patent office 
counterparts with respect to the United States, Japan and European patents 
and patent applications.  To the extent that a party has not previously done 
so, or promptly upon request by the other party in order to assist such other 
party in connection with any of its activities or the exercise of any of its 
rights pursuant to Articles 7 and 8, such party shall provide the other party 
with such additional relevant documentation which such other party may 
reasonably request relating to such patent applications and patents in the 
Mitsubishi Patents or Triangle Patents, as applicable, including but not 
limited to, copies thereof and access to laboratory notebooks, other 
supporting data and relevant employees. If a party decides to abandon or 
allow to lapse any patent application or patent or not to initiate or any 
other patent prosecution activity for which it has patent prosecution 
responsibility pursuant to this Article 7, it shall give the other party 
notice thereof in a sufficiently timely manner so as to enable such other 
party to determine whether to assume patent prosecution activity in 
connection therewith.  Each party shall use its best efforts to give such 
notice at least *** before any abandonment, lapse or any other relevant 
deadline.

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                            ARTICLE 8.  INFRINGEMENT

     8.1   THIRD PARTY INFRINGEMENT.  If Triangle or Mitsubishi becomes aware of
any activity that it believes represents a substantial infringement of a Valid
Claim, the party obtaining such knowledge shall promptly advise the other of all
relevant facts and circumstances pertaining to the potential infringement.
Mitsubishi shall have the right to enforce any rights within the Mitsubishi
Patents against such infringement, at its own expense.  Triangle shall have the
right to enforce any rights within the Triangle Patents and patents relating to
Joint Inventions, at its expense.

     8.2   TRIANGLE'S RIGHT TO PURSUE THIRD PARTY INFRINGERS.  If Mitsubishi
shall fail, within *** after receiving notice from Triangle of a
potential infringement of the Mitsubishi Patents or after providing Triangle
with notice of such infringement, either (a) to terminate such infringement or
(b) to institute an action to prevent continuation thereof and, thereafter, to
prosecute such action diligently, or if Mitsubishi notifies Triangle that it
does not plan to terminate the infringement of the of the Mitsubishi Patents or
institute such action, then Triangle shall have the right to do so.  Mitsubishi
shall cooperate with Triangle in such effort, including being joined as a party
to such action if necessary.  Any damage award or settlement payments made to
Mitsubishi in connection with any action filed by it relating to infringement of
the Mitsubishi Patents, after first reimbursing Mitsubishi for its expenses,
shall be equally divided by the parties.  In the event Triangle institutes any
action relating to infringement of the Mitsubishi Patents, Triangle may deposit
up to *** percent (***%) of any royalties and Milestone Payments which are
otherwise payable to Mitsubishi during the pendency of any such infringement
action in an interest-bearing escrow account (bearing interest at rates
comparable to other Triangle deposits of immediately available funds).  Triangle
shall, upon



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the final resolution or settlement of such infringement action, provide 
Mitsubishi with an accounting of the total royalty payments and Milestone 
Payments escrowed (and interest thereon) and Triangle's expenses incurred in 
such infringement action.  Triangle shall be entitled to offset any expenses 
which Triangle fails to recoup from any damage award or settlement payments 
arising from such infringement action against such escrowed royalties and 
Milestone Payments.  Any escrowed payments (and interest thereon) in excess 
of Triangle's unrecouped expenses shall be immediately paid to Mitsubishi.  
Any damage award or settlement payments made to Triangle in excess of 
Triangle's expenses in connection with any infringement action it initiates 
relating to the Mitsubishi Patents shall be divided as follows:  *** percent 
(***%) to Mitsubishi and *** percent (***%) to Triangle. Any damage award or 
settlement payments made to Triangle in connection with any action relating 
to infringement of the patents relating to Joint Inventions, after first 
reimbursing Triangle for its expenses, shall be equally divided by the 
parties.  Any damage award or settlement payments made to Triangle in 
connection with any action relating to infringement of the Triangle Patents 
shall be retained by Triangle.

                    ARTICLE 9. WARRANTIES AND INDEMNIFICATION

     9.1   WARRANTIES OF MITSUBISHI.

           (a) Mitsubishi represents and warrants that:  (i) Mitsubishi has
disclosed to Triangle all potential patent rights in the control of third
parties known to Mitsubishi which may be needed to commercialize any Licensed
Products ; and (ii) Appendix A is a complete and accurate list of all patents
and patent applications included in the Mitsubishi Patents as of the date
hereof.  Mitsubishi will, from time to time during the term of this Agreement,


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promptly provide Triangle, upon request, with an updated version of Appendix A.

           (b) Mitsubishi further represents and warrants that it is the
exclusive owner of all right, title and interest in the patents and patent
applications identified in Appendix A.

     9.2   WARRANTIES OF EACH PARTY.  Each party hereto represents to the other
that it is free to enter into this Agreement and to carry out all of the
provisions hereof, including, in the case of Mitsubishi, its grant to Triangle
of the license described in Section 2.1.

     9.3   NO LIABILITY FOR CONSEQUENTIAL DAMAGES AND LIMITATION OF LIABILITY.
NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR SPECIAL, INCIDENTAL,
CONSEQUENTIAL DAMAGES ARISING OUT OF OR RELATED TO THE SUBJECT MATTER OF THIS
AGREEMENT.

     9.4   INDEMNIFICATION.

           (a) Subject to compliance by the Indemnitees with their obligations
set forth in Section 9.5, Triangle shall defend, indemnify, and hold harmless
the Indemnitees, from and against any and all claims, demands, losses,
liabilities, expenses, and damages including investigative costs, court costs
and reasonable attorneys' fees (collectively, the "Liabilities") which
Indemnitees may suffer, pay, or incur as a result of or in connection with, (i)
any and all personal injury (including death) and property damage caused or
contributed to, in whole or in part, by manufacture, testing, design, use, sale,
or labeling of any Licensed Products by Triangle or Triangle's Affiliates or
sublicensees, excluding any Liabilities arising as a result of Mitsubishi's or
its subcontractor's negligence, intentional misconduct or breach of contract in
supplying Bulk Drug Substance and (ii) any material breach by Triangle of its
representations, warranties and covenants contained in this Agreement.
Triangle's obligations under this Article shall survive the expiration or
termination of this Agreement for any reason.


                                       33

<PAGE>

           (b) Subject to compliance by the Indemnitees with their obligations
set forth in Section 9.5, Mitsubishi shall indemnify and hold the Indemnitees
harmless from and against any and all Liabilities which Indemnitees may suffer,
pay or incur as a result of or in connection with any material breach by
Mitsubishi of any of its representations, warranties and covenants set forth in
this Agreement.  Mitsubishi's obligations under this Article shall survive
expiration or termination of this Agreement for any reason.

     9.5   INDEMNIFICATION PROCEDURES.  Any Indemnitee which intends to claim
indemnification under this Article shall promptly notify the other party (the
"Indemnitor") in writing of any matter in respect of which the Indemnitee or any
of its employees intend to claim such indemnification.  The Indemnitee shall
permit, and shall cause its employees to permit, the Indemnitor, at its
discretion, to settle any such matter and agrees to the complete control of such
defense or settlement by the Indemnitor; provided, however, that such settlement
does not adversely affect the Indemnitee's rights hereunder or impose any
material obligations on the Indemnitee in addition to those set forth herein in
order for it to exercise such rights.  No such matter shall be settled without
the prior written consent of the Indemnitor and the Indemnitor shall not be
responsible for any legal fees or other costs incurred other than as provided
herein.  The Indemnitee and its employees shall cooperate fully with the
Indemnitor and its legal representatives in the investigation and defense of any
matter covered by the applicable indemnification.  The Indemnitee shall have the
right, but not the obligation, to be represented by counsel of its own selection
and expense.

                          ARTICLE 10.  CONFIDENTIALITY

     10.1  TREATMENT OF CONFIDENTIAL INFORMATION.  Except as otherwise provided
hereunder, during the term of this Agreement and for a period of five (5) years
thereafter:


                                       34

<PAGE>

           (a) Triangle and its Affiliates and sublicensees shall retain in
confidence and use only for purposes of this Agreement, any written information
and data supplied by or on behalf of Mitsubishi under this Agreement and the
Option Agreement; and

           (b) Mitsubishi shall retain in confidence and use only for purposes
of this Agreement any written information and data supplied by or on behalf of
Triangle to Mitsubishi under this Agreement and the Option Agreement.

     For purposes of this Agreement, all such information and data which a party
is obligated to retain in confidence shall be called "Information."

     10.2  RIGHT TO DISCLOSE.  To the extent that it is reasonably necessary to
fulfill its obligations or exercise its rights under this Agreement, or any
rights which survive termination or expiration hereof, each party may disclose
Information to its Affiliates, sublicensees, consultants, outside contractors,
actual or prospective investors, and clinical investigators on condition that
such entities or persons agree:

           (a) to keep the Information confidential for at least a period of
five (5) years from the date of disclosure and to the same extent as each party
is required to keep the Information confidential; and

           (b) to use the Information only for those purposes for which the
disclosing party is authorized to use the Information.

     Each party or its Affiliates or sublicensees, as applicable, may disclose
Information to the government or other regulatory authorities to the extent that
such disclosure (i) is necessary for the prosecution and enforcement of patents,
or authorizations to conduct preclinical or clinical trials to commercially
market Licensed Products, provided such party is then otherwise entitled to
engage in such activities in accordance with the provisions of this Agreement,
or (ii)


                                       35

<PAGE>

is legally required.

     10.3  RELEASE FROM RESTRICTIONS.  The obligation not to disclose or use
Information shall not apply to any part of such Information that:

           (a) is or becomes patented (but the existence of a patent shall only
permit disclosure and not, unless otherwise provided hereunder, use), published
or otherwise part of the public domain, other than by unauthorized acts of the
party obligated not to disclose such Information (for purposes of this Article
10 the "receiving party") or its Affiliates or sublicensees in contravention of
this Agreement; or

           (b) is disclosed to the receiving party or its Affiliates or
sublicensees by a third party provided that such Information was not obtained by
such third party directly or indirectly from the other party to this Agreement;
or

           (c) prior to disclosure under the Option Agreement or this Agreement,
as the case may be, was already in the possession of the receiving party, its
Affiliates or sublicensees, provided that such Information was not obtained
directly or indirectly from the other party to this Agreement; or

           (d) results from research and development by the receiving party or
its Affiliates or sublicensees, independent of disclosures from the other party
of this Agreement, provided that the persons developing such information have
not had exposure to the information received from the other party to this
Agreement; or

           (e) is required by law to be disclosed by the receiving party,
provided that in the case of disclosure in connection with any litigation, the
receiving party uses reasonable efforts to notify the other party immediately
upon learning of such requirement in order to give the other party reasonable
opportunity to oppose such requirement; or


                                       36

<PAGE>

           (f) Triangle and Mitsubishi agree in writing may be disclosed.

                        ARTICLE 11.  TERM AND TERMINATION

     11.1  TERM.  Unless sooner terminated as otherwise provided in this
Agreement, the term of this Agreement shall commence on the Effective Date and
shall continue in full force and effect until the expiration of Triangle's
obligations to pay royalties hereunder.

     11.2  TERMINATION BY DEFAULT.  If either party defaults in the 
performance of, or fails to be in compliance with, any material agreement, 
condition or covenant of this Agreement, the non-defaulting party may 
terminate this Agreement with respect to the defaulting party if such default 
or noncompliance shall not have been remedied, or reasonable steps shall not 
have been initiated to remedy the same, within *** after receipt by the 
defaulting party of a written notice thereof from the non- defaulting party.

     11.3  TERMINATION BY TRIANGLE.  Triangle shall have the right to 
terminate this Agreement in the entire Territory or one or more countries of 
the Territory (without affecting this Agreement in the remaining countries of 
the Territory), by giving Mitsubishi *** prior written notice thereof.  
Triangle shall base any decision to terminate pursuant to this Section 11.3 
on  the determination that the scientific, regulatory and/or commercial 
profile of the Licensed Product in the country or countries in question does 
not justify continued development or marketing of the Licensed Product using 
the same standard Triangle would use in assessing whether to continue the 
development or marketing of its other HIV products having a comparable 
scientific, regulatory and commercial profiles.

     11.4  OBLIGATIONS UPON TERMINATION.  If this Agreement is terminated as a
result of Triangle's breach pursuant to Section 11.2, or is terminated in whole
or in part by Mitsubishi in accordance with Section 6.3 or by Triangle in
accordance with Section 11.3, then:  (a) in


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<PAGE>

the case of termination in the entire Territory, Triangle shall use its best
efforts to return, or at Mitsubishi's direction, destroy, all data, writings and
other documents and tangible materials supplied to Triangle by Mitsubishi; and
(b) with respect to those countries with respect to which termination occurs,
Triangle shall provide Mitsubishi with full and complete copies of all toxicity,
efficacy, and other data generated by Triangle or Triangle's Affiliates, and
sublicensees, in the course of Triangle's efforts to develop Licensed Products
or to obtain governmental approval for the sale of Licensed Products, including
but not limited to any IND, NDA or other documents filed with any government
agency in such countries.  Mitsubishi shall be authorized to cross-reference any
such IND, NDA or other regulatory filings made by Triangle, its Affiliates and
sublicensees in the countries in which termination occurs were permitted by law.
Mitsubishi shall be entitled to provide information pertaining to the Triangle
Patents, Triangle Know-How and Joint Know-How to any third party with a bona
fide interest in licensing such technology in the countries in which termination
occurs.  Such data shall be provided on a confidential basis; provided, however,
that if such third party concludes a license with Mitsubishi, such third party
shall be free to use such data for all purposes, including to obtain government
approvals to sell any product containing any Compound in such countries.

     11.5  EFFECT OF TERMINATION.  In the event of any expiration or termination
pursuant to this Article 11, neither party shall have any remaining rights or
obligations under this Agreement other than as provided below:

           (a)  Mitsubishi will have the right to receive all payments accrued
prior to the effective date of termination;


                                       38

<PAGE>

           (b)  termination or expiration of this Agreement for any reason shall
have no effect on the parties' obligations under Articles 8, 9 and 10 or their
respective rights in Joint Know-How set forth in Section 1.14;

           (c)  termination of this Agreement pursuant to Section 11.2 shall
have no effect on the non-defaulting party's rights under Sections 2.1, 2.2,
2.3, 2.4 and 7.4;

           (d)  upon expiration of Triangle's royalty obligations under this
Agreement in a given country, Triangle shall have a perpetual, fully paid-up
license to use Mitsubishi's Know-How in such country;

           (e)  termination of this Agreement by Mitsubishi pursuant to Section
6.3 or 11.2 or by Triangle pursuant to Section 11.3, shall have no effect on the
rights and obligations of the parties under Section 11.4; and

           (f)  the parties' shall retain any other remedies for breach of this
Agreement they may otherwise have.

                             ARTICLE 12.  ASSIGNMENT

     Neither party shall assign this Agreement or any part thereof without the
prior written consent of the other party, which consent shall not be
unreasonably withheld or delayed.  Each party may, however, without consent,
assign or sell its rights under this Agreement to an Affiliate subject, in the
case of Triangle, to the provisions of Section 2.2 of this Agreement.  Any
permitted assignee shall assume all obligations of its assignor under this
Agreement.  No assignment shall relieve any party of responsibility for the
performance of any accrued obligation which such party has under this Agreement.


                                       39

<PAGE>

            ARTICLE 13.  TRANSFER OF KNOW-HOW; TECHNICAL ASSISTANCE

     13.1  TRANSFER BY MITSUBISHI.  Within sixty (60) days following the
Effective Date and as far as it has not previously done so, Mitsubishi shall
supply Triangle with all Mitsubishi Know-How to the extent it is available to
Mitsubishi.  With respect to any Mitsubishi Know-How developed by Mitsubishi
during the term of this Agreement, such disclosure will be made at least on a
quarterly basis or sooner, if practicable.

     13.2  TECHNICAL ASSISTANCE.

           (a)  In addition to the specific obligations of Mitsubishi set forth
in Article 2, Mitsubishi shall, upon request by Triangle, provide Triangle with
reasonable cooperation and assistance, consistent with the other provisions
hereof, in connection with the development, use or manufacture of the Licensed
Products.  Such assistance may include, but is not limited to, development of
the formulations of the Licensed Products; procurement of supplies and raw
materials; initial developmental and production batch manufacturing runs;
process, specification and analytical methodology design and improvement; and,
in general, such other assistance as may contribute to the efficient application
by Triangle of the Mitsubishi Know-How.  In this regard, Mitsubishi agrees to
make appropriate employees of Mitsubishi reasonably available to assist
Triangle, and Mitsubishi agrees to provide appropriate Triangle personnel with
access during normal business hours to the appropriate personnel and operations
of Mitsubishi for such periods of time as may be reasonable in order to
familiarize Triangle personnel with the Mitsubishi Know-How as applied by
Mitsubishi.  At Triangle's request, such assistance shall be furnished at
Triangle's or its subcontractors' or sublicensees' facilities in the Territory,
subject to a mutually agreed upon schedule.  Such technical assistance shall
include but not be limited to the follow:


                                       40

<PAGE>

           (i) Mitsubishi shall:  (A) provide Triangle with access to any and
all Drug Master File(s) or counterparts thereof in other countries of the
Territory ("DMF") of Mitsubishi relating to the manufacture of Bulk Drug
Substance existing as of the Effective Date; (B) provide Triangle with letters
of authorization to the FDA and other applicable government authorities in other
countries of the Territory to refer to Mitsubishi's DMF's; and (C) reasonably
cooperate with Triangle in obtaining access to and letters of authorization to
refer to the DMF's of Mitsubishi's subcontractors which are, or will be,
supplying any Bulk Drug Substance during the Development Program; and

           (ii) Within thirty (30) days after the Effective Date, Mitsubishi 
shall provide Triangle promptly after the Effective Date with copies of all 
documentation in Mitsubishi's possession, including all correspondence 
between Mitsubishi and its subcontractors, regarding the manufacture of the 
Bulk Drug Substance which would be necessary or useful to assist Triangle in 
the commercial production of Bulk Drug Substance or to support Registration 
of the Licensed Products.

     (b)  During the period prior to the first anniversary of the Effective 
Date, (i) Mitsubishi shall provide up to *** of such technical assistance at 
Mitsubishi's sole expense and (ii) subsequent to such *** of technical 
assistance, Mitsubishi shall provide such additional technical assistance as 
may be reasonably requested by Triangle, provided, that all reasonable 
out-of-pocket travel costs and expenses incurred by Mitsubishi in rendering 
technical assistance pursuant to this Section 13.2 in excess of such *** 
shall be reimbursed to Mitsubishi by Triangle and, in addition, Triangle will 
pay Mitsubishi a consultancy fee in an amount to be negotiated by the parties 
hereto in good faith (but not to exceed the consultancy fee, if any, then 
being charged by

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<PAGE>

Mitsubishi to third parties) for each consultancy day in excess of *** spent 
by personnel of Mitsubishi in rendering technical assistance to Triangle.  
Technical assistance furnished pursuant to this Section 13.2 shall continue 
only until the first anniversary of the Effective Date of this Agreement.

     13.3  MITSUBISHI SUBCONTRACTORS.  Triangle agrees to give due 
consideration to those Mitsubishi subcontractors which are or will be 
supplying Bulk Drug Substance during the Development Program when making the 
determination of the subcontractors which will supply Bulk Drug Substance to 
Triangle for commercial purposes.  As of the Effective Date, Mitsubishi 
subcontractors are ***, a *** corporation, ***, a *** corporation and ***, a 
*** corporation.  In the event Triangle selects subcontractors other than a 
Mitsubishi subcontractors, it will provide Mitsubishi with notice thereof and 
specify the reasons therefor.

     13.4  REASONABLE EFFORTS RELATING TO MANUFACTURING COST.  The parties
hereto recognize their mutual interest in keeping the manufacturing cost of the
Bulk Drug Substance as low as reasonably possible.  Accordingly, Mitsubishi
shall provide Triangle with technical assistance pursuant to Section 13.2 in a
timely manner and Triangle shall use its reasonable efforts to reduce such
manufacturing cost to the extent reasonably practicable, giving due
consideration to pharmaceutical industry quality standards relating to human
drug products.

     13.5  TRANSFER BY TRIANGLE.  With respect to any Triangle Know-How
developed by Triangle during the term of this Agreement, Triangle shall supply
Mitsubishi with such Triangle Know-How on at least a quarterly basis or sooner,
if practicable.

     13.6  LANGUAGE OF DISCLOSURES.  All disclosures pursuant to this Agreement
will be in English.


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<PAGE>

                      ARTICLE 14.  REGISTRATION OF LICENSE

     Triangle, at its expense, may register the license granted under this
Agreement in any country of the Territory where the use, sale or manufacture of
a Licensed Product in such country would be covered by a Valid Claim.  Upon
request by Triangle, Mitsubishi agrees promptly to execute any "short form"
licenses submitted to it by Triangle in order to effect the foregoing
registration in such country.

           ARTICLE 15. NOTIFICATION AND AUTHORIZATION UNDER DRUG PRICE
                   COMPETITION AND PATENT TERM RESTORATION ACT

     15.1  NOTICES RELATING TO THE ACT.  Mitsubishi shall use its best 
efforts to notify Triangle of (a) the issuance of each U.S. patent included 
among the Mitsubishi Patents, giving the date of issue and patent number for 
each such patent; and (b) each notice pertaining to any patent included among 
the Mitsubishi Patents which Mitsubishi receives as patent owner pursuant to 
the Drug Price Competition and Patent Term Restoration Act of 1984 
(hereinafter the "Act"), including but not necessarily limited to notices 
pursuant to Sections 101 and 103 of the Act from persons who have filed an 
abbreviated NDA ("ANDA") or a "paper" NDA.  Such notices shall be given 
promptly, but in any event within *** of Mitsubishi's notice of each such 
patent's date of issue or receipt of each such notice pursuant to the Act, 
whichever is applicable.

     15.2  AUTHORIZATION RELATING TO PATENT TERM EXTENSION.  Mitsubishi hereby
authorizes Triangle (a) to include in any NDA for a Licensed Product, as
Triangle may deem appropriate under the Act, a list of patents included among
the Mitsubishi Patents that relate to such Licensed Product and such other
information as Triangle in its reasonable discretion believes is appropriate to
be filed pursuant to the Act; (b) to commence suit for any infringement of the


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<PAGE>

Mitsubishi Patents under Section 271(e) (2) of Title 35 of the United States
Code occasioned by the submission by a third party of an IND or a paper NDA for
a Licensed Product pursuant to Sections 101 or 103 of the Act; and (c) subject
to Mitsubishi's consent (which consent will not be unreasonably withheld or
delayed), to exercise any rights that may be exercisable by Mitsubishi as patent
owner under the Act to apply for an extension of the term of any patent included
among the Mitsubishi Patents.  In the event that applicable law in any other
country of the Territory hereafter provides for the extension of the term of any
patent included among the Mitsubishi Patents in such country, upon request by
Triangle, Mitsubishi shall use its best efforts to obtain such extension or, in
lieu thereof, shall authorize Triangle or, if requested by Triangle or its
sublicensees to apply for such extension, in consultation with Mitsubishi.
Mitsubishi agrees to cooperate with Triangle or its sublicensees, as applicable,
in the exercise of the authorization granted herein or which may be granted
pursuant to this Section 15.2 and will execute such documents and take such
additional action as Triangle may reasonably request in connection therewith,
including, if necessary, permitting itself to be joined as a proper party in any
suit for infringement brought by Triangle under subsection (b) above.  Triangle
and Mitsubishi shall share equally the costs and expenses, including but not
limited to attorneys' fees of any suit for infringement brought by Triangle
under subsection (b) above.

                 ARTICLE 16.  DISPUTE RESOLUTION AND ARBITRATION

     16.1  INITIAL RESOLUTION.  In the case of any disputes between the parties
arising from this Agreement, and in case this Agreement does not provide a
solution for how to resolve such disputes, the parties shall discuss and
negotiate in good faith a solution acceptable to both parties and in the spirit
of this Agreement.  If after negotiating in good faith pursuant to the foregoing
sentence, the parties fail to reach agreement, then the President of the


                                       44

<PAGE>

Pharmaceuticals and Diagnostics Company of Mitsubishi and the Chief Executive
Officer or Chief Operating Officer of Triangle shall discuss in good faith an
appropriate resolution to the dispute.  If these executives fail, after good
faith discussions, to reach an amicable agreement then the parties shall submit
to binding arbitration pursuant to Section 16.2.

     16.2  ARBITRATION.

           (a)  Any claim, dispute or controversy arising out of or in
connection with or relating to this Agreement, including, without limitation,
disputes with respect to the rights and obligations of the parties following
termination) not settled by the procedures set forth in Section 16.1 above or
the breach or alleged breach of a material provision of this Agreement shall be
adjudicated by arbitration in accordance with the UNCITRAL Arbitration Rules
then in effect.  The appointing authority shall be the London Court of
Arbitration.  In such event, either party may initiate arbitration by notice to
the other party as required the UNCITRAL Arbitration Rules.  There will be three
arbitrators, one selected by Mitsubishi, and one selected by Triangle.  The
third arbitrator will be selected by the first two arbitrators and will be of a
different nationality than the first two arbitrators and the parties.  The third
arbitrator will serve as presiding arbitrator of the tribunal.  Any arbitration
shall be governed by the following rules:

           (b) The forum shall be in ***, the language for proceedings shall 
be in ***, and the applicable substantive law shall be the law prevailing 
in the ***.

           (c) A hearing shall commence no later than ninety (90) days after
initial notice by one party to the other requesting arbitration, and shall
continue from day to day thereafter until completed unless adjourned by mutual
consent.  The arbitration panel shall


                                       45





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<PAGE>

render its decision in writing within thirty (30) days following conclusion of
hearings.

           (d) Any arbitration proceeding may proceed in the absence of any
party if thirty (30) days notice has been given to that party.  A decision
agreed on by at least two of the arbitrators shall be the decision of the
arbitration panel.  Each party shall bear its own costs and attorneys' fees.
Costs of the arbitration panel shall be shared equally by the parties.

                         ARTICLE 17.  GENERAL PROVISIONS

     17.1  EXPORT CONTROLS.  Mitsubishi acknowledges that Triangle is subject to
United States laws and regulations controlling the export of technical data,
biological materials, chemical compositions and other commodities and that
Triangle's obligations under this Agreement are contingent upon compliance with
applicable United States export laws and regulations.  The transfer of technical
data, biological materials, chemical compositions and commodities may require a
license from the cognizant agency of the United States government or written
assurances by Mitsubishi that Mitsubishi shall not export data or commodities to
certain foreign countries without the prior approval of certain United States
agencies, or as otherwise prescribed by applicable law or regulation.  Triangle
neither represents that an export license shall not be required nor that, if
required, such export license shall issue.

     17.2  LEGAL COMPLIANCE.  Each party shall comply with all laws and
regulations relating to the performance of its obligation or the exercise of its
rights hereunder.

     17.3  INDEPENDENT CONTRACTORS.  It is understood and agreed that the
parties hereto are independent contractors and are engaged in the operation of
their own respective businesses, and neither party hereto is to be considered
the agent of the other party for any purpose whatsoever, and neither party shall
have any authority to enter into any contracts or assume any obligations for the
other party nor make any warranties or representations on behalf of that


                                       46

<PAGE>

other party.

     17.4  PATENT MARKING.  Triangle shall mark Licensed Products sold in the
United States with United States patent numbers.  Licensed Products manufactured
or sold in other countries shall be marked in compliance with the intellectual
property laws in force in such countries.  The foregoing obligations shall be
subject to size and space limitations.

     17.5  PUBLICITY. The parties agree to issue mutual press releases
concerning their entry into this Agreement, with the content of such releases to
be approved (which consent shall not be unreasonably withheld or delayed) in
advance by the parties.  In all other respects, except as required by law,
neither party shall use the name of the other party in any publicity release
without the prior written permission of such other party, which shall not be
unreasonably withheld.  The other party shall have a reasonable opportunity to
review and comment on any such proposed publicity release.  Except as required
by law, neither party shall publicly disclose the terms of this Agreement or
issue any publicity release with regard thereto unless expressly authorized to
do so by the other party which authorization shall be agreed upon.

     17.6  GOVERNING LAW.  This Agreement and all amendments, modifications, 
alterations, or supplements hereto, and the rights of the parties hereunder, 
shall be construed under and governed by the laws of the ***, exclusive of 
its conflicts of laws principles.

     17.7  ENTIRE AGREEMENT.  This Agreement constitutes the entire agreement
between Mitsubishi and Triangle with respect to the subject matter hereof and
shall not be modified, amended or terminated, except as herein provided or
except by another agreement in writing executed by the parties hereto.  Upon the
Effective Date, the Option Agreement shall terminate.


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     17.8  SEVERABILITY.  All rights and restrictions contained herein may be
exercised and shall be applicable and binding only to the extent that they do
not violate any applicable laws and are intended to be limited to the extent
necessary so that they will not render this Agreement illegal, invalid or
unenforceable.  If any provision or portion of any provision of this Agreement,
not essential to the commercial purpose of this Agreement, shall be held to be
illegal, invalid or unenforceable by a court of competent jurisdiction, it is
the intention of the parties that the remaining provisions or portions thereof
shall constitute their agreement with respect to the subject matter hereof, and
all such remaining provisions, or portions thereof, shall remain in full force
and effect.  To the extent legally permissible, any illegal, invalid or
unenforceable provision of this Agreement shall be replaced by a valid provision
which shall implement the commercial purpose of the illegal, invalid, or
unenforceable provision.  In the event that any provision essential to the
commercial purpose of this Agreement is held to be illegal, invalid or
unenforceable and cannot be replaced by a valid provision which will implement
the commercial purpose of this Agreement, this Agreement and the rights granted
herein shall terminate.

     17.9  FORCE MAJEURE.

           (a)  Any delays in, or failure of performance of any party to this
Agreement, shall not constitute a default hereunder, or give rise to any claim
for damages, if and to the extent caused by occurrences beyond the control of
the party affected, including, but not limited to, acts of God, strikes or other
concerted acts of workmen, civil disturbances, fires, floods, explosions, riots,
war, rebellion, sabotage, acts of governmental authority or failure of
governmental authority to issue licenses or approvals which may be required
("Force Majeure").


                                       48

<PAGE>

           (b)  The party asserting the Force Majeure shall promptly notify the
other party of the event constituting Force Majeure and of all relevant details
of the occurrence and where appropriate an estimate of how long such Force
Majeure event shall continue.

           (c)  If such Force Majeure event continues thereafter and in any
event, the parties shall consult with each other in order to find a fair
solution and shall use all reasonable endeavors to minimize the consequences of
such Force Majeure.

     17.10 COUNTERPARTS.  This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

     17.11 NOTICES.  All notices, statements, and reports required to be given
under this Agreement shall be in writing and shall be deemed to have been given
upon delivery in person or, when deposited (a) in the mail in the country of
residence of the party giving the notice, registered or certified postage
prepaid or (b) with a professional courier service (e.g. FedEx or UPS), and
addressed as follows:

     To Mitsubishi: Mitsubishi Chemical Corporation
                    2-24, Higashishinagawa 2-chome,
                    Shinagawa-ku, Tokyo 140, Japan
                    Attn:  General Manager, International Operations Department
                    Pharmaceuticals and Diagnostics Company
                    Fax: 3-5463-0705

     To Triangle:   Triangle Pharmaceuticals, Inc.
                    4 University Place, 4611 University Drive
                    Durham, NC 27707, U.S.A.
                    Attn:  Chris A. Rallis, Vice President Business Development,
                    Secretary and General Counsel
                    Fax: (919) 493-5925


                                       49

<PAGE>

Any party hereto may change the address to which notices to such party are to be
sent by giving notice to the other party at the address and in the manner
provided above.  Any notice may be given, in addition to the manner set forth
above, by telex, facsimile or cable, provided that the party giving such notice
obtains acknowledgment by telex, facsimile or cable that such notice has been
received by the party to be notified.  Notices made in this manner shall be
deemed to have been given when such acknowledgment has been transmitted.


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                                       50

<PAGE>

     IN WITNESS WHEREOF, Mitsubishi and Triangle have caused this Agreement to
be signed by their duly authorized representatives, under seal, as of the day
and year indicated above.

                         MITSUBISHI CHEMICAL CORPORATION


                         By: /s/ [ILLEGIBLE]
                            -----------------------------------------
                         Title:  Managing Director
                                -------------------------------------



                         TRIANGLE PHARMACEUTICALS, INC.


                         By: /s/ M. Nixon Ellis
                            -----------------------------------------
                         Title: President and Chief Operating Officer
                                -------------------------------------




                [SIGNATURE PAGE FOR MITSUBISHI LICENSE AGREEMENT]


                                       51

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                                   APPENDIX A


                     MKC-442 Patent Applications and Patents


1)   SUBSTANCE AND USE

                                  United States
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Docket No.     Country        Serial No.     Filed     Patent No.     Grant Date
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                U.S.A.         222,071      3/9/93     5,461,060       24/10/95
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                Continuation of Ser. No. ***, ***


                                     Foreign
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Docket No.     Country        Serial No.     Filed     Patent No.     Grant Date
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               Australia     63262-90       26/9/90    642906          24/2/94
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               S. Africa     90-7701        26/9/90    90-7701         31/7/91
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               Hungary       6019-90        24/9/90    205917          28/7/92
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               Designated States in ***:              ***
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2)   COMBINATION WITH NUCLEOAIDE ANALOGUE

                                  United States
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Docket No.     Country        Serial No.     Filed     Patent No.     Grant Date
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               U.S.A.         253,274       2/6/94     5,604,209       18/2/97
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                                     Foreign
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Docket No.     Country        Serial No.     Filed     Patent No.     Grant Date
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               Designated States in ***:              ***
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                                   APPENDIX B


Description of Studies under the Development Program.

NONCLINICAL
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CLINICAL

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