TRIANGLE PHARMACEUTICALS INC, 424B4, 1998-04-09

TRIANGLE PHARMACEUTICALS INC
424B4, 1998-04-09
PHARMACEUTICAL PREPARATIONS

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<PAGE>
Filed Pursuant to Rule 424(b)(4)
Registration No. 333-47627

PROSPECTUS April 9, 1998
- --------------------------------------------------------------------------------

3,500,000 Shares

[LOGO]

Common Stock

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

All of the shares of Common Stock, par value $0.001 per share (the "Common
Stock"), offered hereby (the "Offering") are being issued and sold by Triangle
Pharmaceuticals, Inc. (together with its wholly-owned subsidiaries, "Triangle"
or the "Company").

The Common Stock is traded on the Nasdaq National Market under the symbol
"VIRS." On April 8, 1998, the last sale price of the Common Stock as reported on
the Nasdaq National Market was $15.25 per share. See "Price Range of Common
Stock."

FOR A DISCUSSION OF CERTAIN RISKS OF AN INVESTMENT IN THE SHARES OF COMMON STOCK
OFFERED HEREBY, SEE "RISK FACTORS" ON PAGES 7-20.

THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

<TABLE>
<CAPTION>
Underwriting
Price to Discounts and Proceeds to
Public Commissions(1) Company(2)
<S> <C> <C> <C>
Per Common Share $15.00 $0.93 $14.07
Total(3) $52,500,000 $3,255,000 $49,245,000
</TABLE>

(1) THE COMPANY HAS AGREED TO INDEMNIFY THE UNDERWRITERS AGAINST CERTAIN
LIABILITIES, INCLUDING LIABILITIES UNDER THE SECURITIES ACT OF 1933, AS
AMENDED. SEE "UNDERWRITING."

(2) BEFORE DEDUCTING EXPENSES OF THE OFFERING ESTIMATED AT $800,000.

(3) THE COMPANY HAS GRANTED THE UNDERWRITERS AN OPTION, EXERCISABLE WITHIN 30
DAYS AFTER THE DATE HEREOF, TO PURCHASE UP TO AN AGGREGATE OF 525,000
ADDITIONAL SHARES OF COMMON STOCK TO COVER OVER-ALLOTMENTS, IF ANY. IF SUCH
OPTION IS EXERCISED IN FULL, THE TOTAL PRICE TO PUBLIC, UNDERWRITING
DISCOUNTS AND COMMISSIONS AND PROCEEDS TO COMPANY WILL BE $60,375,000,
$3,743,250 AND $56,631,750, RESPECTIVELY. SEE "UNDERWRITING."

The shares of Common Stock offered hereby are offered by the several
Underwriters, subject to prior sale, when, as and if issued to and accepted by
them, subject to approval of certain legal matters by counsel for the
Underwriters and certain other conditions. The Underwriters reserve the right to
withdraw, cancel or modify such offer and to reject orders in whole or in part.
It is expected that delivery of the shares of Common Stock will be made at the
offices of SBC Warburg Dillon Read Inc., New York, New York on or about April
15, 1998.

SBC WARBURG DILLON READ INC.
BEAR, STEARNS & CO. INC.
VECTOR SECURITIES INTERNATIONAL, INC.
<PAGE>
SUMMARY OF TRIANGLE PHARMACEUTICALS'
DRUG CANDIDATES

The following table summarizes the target indications, current development
status and license territory of each of Triangle's drug candidates:

<TABLE>
<CAPTION>
DRUG CANDIDATE (1) INDICATION STATUS (2) TERRITORY (3)
<S> <C> <C> <C>
MKC-442 HIV Phase II/III Worldwide, except Japan
Alanosine Brain, Lung and other Pilot Phase II Worldwide
Cancers
FTC HIV and HBV Phase I/II (4) Worldwide
2-CdAP Psoriasis Phase I/II Worldwide
DMP-450 HIV Phase I Worldwide
L-FMAU HBV Preclinical Worldwide, except Korea
DAPD HIV and HBV Preclinical Worldwide
CS-92 HIV Pilot Phase I/II (5) Worldwide
Acyclovir Resistant Herpes and Preclinical (5) Worldwide
Monophosphate Herpes Labialis
</TABLE>

(1) The Company has licensed all drug candidates except alanosine, for which it
has acquired an option to obtain a license. See
"Business--License, Option and Other Material Agreements." The Company's
drug candidates have not been approved by the United States Food and Drug
Administration for commercial sale.

(2) "Preclinical" indicates potency, pharmacology and/or toxicology testing of a
drug candidate in animal models or biochemical or cell culture systems.
"Phase I" indicates that a drug candidate is being tested at a very early
stage in humans for preliminary safety and pharmacologic profile in a
limited patient population. "Phase I/II" indicates that a drug candidate is
being tested at an early stage in humans for safety, pharmacologic profile
and preliminary indications of efficacy in a limited patient population.
"Phase II" indicates that a drug candidate is being tested in humans for
safety, efficacy and, in some cases, optimal dosage in a limited patient
population. "Phase II/III" indicates that a drug candidate is being tested
in humans for safety and efficacy in an expanded patient population at
geographically dispersed clinical sites. "Pilot" when used herein to
describe a clinical trial means a clinical trial conducted with a small
number of patients. See "Business--Government Regulation."

(3) Indicates the geographic territory in which the Company has licensed, or has
an option to acquire a license to, the right to commercialize products under
the applicable license or option agreement. The Company's ability to
commercialize products in each country in the licensed territory may be
limited by proprietary rights of third parties other than the Company's
licensors. See "Business--Patents and Proprietary Rights."

(4) The Company is currently conducting clinical trials with FTC only for HIV.
See "Business--Viral Disease Program--HIV-- Development Status--FTC" and
"Business--Viral Disease Program--HBV--Development Status--FTC."

(5) In order to focus financial and human resource support on drug candidates
which it believes have the greatest potential, the Company has elected to
limit the current support of CS-92 to the completion of the ongoing clinical
trial and of Acyclovir Monophosphate to the completion of the current
preclinical tests. Should circumstances warrant, investment in the further
development of these drug candidates may be made in the future. See
"Business--Viral Disease Program--HIV--Development Status--CS-92" and
"Business--Viral Disease Program--Herpes Simplex Virus--Development Status
of Acyclovir Monophosphate."

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

CERTAIN PERSONS PARTICIPATING IN THE OFFERING MAY ENGAGE IN TRANSACTIONS
THAT STABILIZE, MAINTAIN, OR OTHERWISE AFFECT THE PRICE OF THE COMMON STOCK,
INCLUDING OVER-ALLOTMENT, STABILIZING AND SHORT COVERING TRANSACTIONS AND THE
IMPOSITION OF A PENALTY BID. FOR A DESCRIPTION OF THESE ACTIVITIES, SEE
"UNDERWRITING."

IN CONNECTION WITH THIS OFFERING, CERTAIN UNDERWRITERS MAY ENGAGE IN PASSIVE
MARKET MAKING TRANSACTIONS IN THE COMMON STOCK ON THE NASDAQ NATIONAL MARKET IN
ACCORDANCE WITH RULE 103 OF REGULATION M. SEE "UNDERWRITING."

2
<PAGE>
PROSPECTUS SUMMARY

THE FOLLOWING SUMMARY IS QUALIFIED IN ITS ENTIRETY BY THE MORE DETAILED
INFORMATION AND THE CONSOLIDATED FINANCIAL STATEMENTS AND NOTES THERETO
APPEARING ELSEWHERE AND INCORPORATED BY REFERENCE IN THIS PROSPECTUS, INCLUDING
THE INFORMATION UNDER "RISK FACTORS." EXCEPT AS OTHERWISE NOTED, ALL INFORMATION
IN THIS PROSPECTUS ASSUMES NO EXERCISE OF THE UNDERWRITERS' OVER-ALLOTMENT
OPTION. UNLESS THE CONTEXT OTHERWISE REQUIRES, REFERENCES IN THIS PROSPECTUS TO
"TRIANGLE" AND THE "COMPANY" ARE TO TRIANGLE PHARMACEUTICALS, INC. AND ITS
WHOLLY-OWNED DIRECT AND INDIRECT SUBSIDIARIES, AVID CORPORATION, A PENNSYLVANIA
CORPORATION, AND AVID THERAPEUTICS, INC., A PENNSYLVANIA CORPORATION
(COLLECTIVELY, "AVID"). THIS PROSPECTUS CONTAINS, IN ADDITION TO HISTORICAL
INFORMATION, FORWARD-LOOKING STATEMENTS THAT INVOLVE RISKS AND UNCERTAINTIES.
THE COMPANY'S ACTUAL RESULTS AND THE TIMING OF CERTAIN EVENTS COULD DIFFER
MATERIALLY FROM THOSE DISCUSSED IN OR PROJECTED BY THE FORWARD-LOOKING
STATEMENTS. FACTORS THAT COULD CAUSE OR CONTRIBUTE TO SUCH DIFFERENCES INCLUDE
THOSE DISCUSSED UNDER "RISK FACTORS," AS WELL AS THOSE DISCUSSED ELSEWHERE IN
THIS PROSPECTUS. SEE "SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS."

THE COMPANY

Triangle is engaged in the development of new drug candidates primarily in
the antiviral area, with a particular focus on therapies for the human
immunodeficiency virus ("HIV"), including the acquired immunodeficiency syndrome
("AIDS"), and the hepatitis B virus ("HBV"). Triangle has an existing portfolio
consisting of eight licensed drug candidates and one drug candidate for which
the Company has an option to acquire a license. Members of the Company's senior
management, prior to joining Triangle, played instrumental roles in the
development of several leading antiviral therapies. The Company is capitalizing
on its management team's expertise in the identification, clinical development
and commercialization of drug candidates, as well as on advances in virology and
immunology, to develop and commercialize new drug candidates that can be used
alone or in combination ("coactively") to treat serious diseases.

The treatment of HIV infection using coactive therapy has shown significant
clinical benefits, including reducing virus levels and increasing patient
longevity. The Company was founded based in part on its management team's belief
that the prolonged use of coactive therapy will generate demand for new anti-HIV
drugs with favorable resistance, compliance and/or tolerance profiles. The
Company believes the use of anti-HIV drugs will increase because (i) the use of
multiple drugs by individual patients on coactive therapy will continue to
increase, (ii) significant numbers of previously untreated patients will seek
medical care as the benefits of coactive therapy become more widely understood
and (iii) patient longevity will continue to increase and thus lengthen the
duration of drug therapy.

The Company believes that certain other serious diseases, such as hepatitis
and cancer, may also be effectively treated with coactive therapy. Currently,
the most common treatment for HBV infection involves therapy with a single drug,
which is administered by injection, is not always successful in controlling the
virus and is associated with significant side effects. The Company believes that
this virus, like HIV, due to its complexity and demonstrated ability to develop
resistance to therapeutic agents, may be more effectively and safely treated
with coactive therapy. Additionally, the Company believes that there is a
significant need to develop drugs for the treatment of cancer because of the
limited clinical benefits offered by many of the current treatments,
particularly in those patients with advanced (metastatic) disease.

Triangle is actively developing the following drug candidates which it
believes have the potential to become valuable tools in the coactive treatment
of serious diseases:

DRUG CANDIDATES TO TREAT HIV

MKC-442. A nucleoside analogue which functions as a non-nucleoside reverse
transcriptase inhibitor, MKC-442 interferes with the early stages of HIV
replication and readily penetrates the central nervous system in animals, which
is an important reservoir of HIV infection. In ongoing Phase I/II studies,
MKC-442 has produced clinically significant antiviral responses and has
generally been well tolerated. Triangle recently initiated the first in a series
of pivotal Phase II/III studies where MKC-442 will be used in combination with
other anti-HIV therapies.

3
<PAGE>
DMP-450. A protease inhibitor acquired by Triangle in late 1997 through the
acquisition of Avid, DMP-450 has demonstrated potent IN VITRO activity against
HIV and was generally well tolerated in a Phase I study. Triangle re-initiated
Phase I trials with DMP-450 in January 1998.

DRUG CANDIDATE TO TREAT HBV

L-FMAU. A nucleoside analogue, L-FMAU is a recent addition to Triangle's
portfolio and has demonstrated potent activity against a hepatitis virus in
naturally infected woodchucks (a disease state closely resembling that of
hepatitis B in humans), both during the course of treatment and for a period of
up to 36 weeks following treatment. Triangle intends to conduct preclinical
studies with L-FMAU in 1998.

DRUG CANDIDATES TO TREAT HIV AND HBV

FTC. A nucleoside analogue, FTC has been shown to be a potent inhibitor IN
VITRO of both HIV and HBV replication. Against HIV, preclinical studies have
demonstrated that FTC is consistently more potent than 3TC (lamivudine), which
is a member of the same nucleoside series as FTC. Triangle is completing Phase
I/II studies of FTC in the treatment of HIV infection and intends to commence
later stage trials based on coactive therapy by the end of 1998. Against HBV,
FTC has demonstrated activity as potent as 3TC IN VITRO as well as in studies
with the woodchuck hepatitis model. Triangle intends to initiate Phase I
clinical trials with FTC for the treatment of HBV in 1998.

DAPD. A purine dioxolane nucleoside, Triangle believes that DAPD is the only
drug candidate in its nucleoside series that is currently being developed for
the treatment of viral diseases. Against HIV, the Company believes that, because
of its unique structure and pharmacological properties, DAPD may offer
advantages over other currently marketed nucleosides. Against HBV, DAPD has
demonstrated activity as potent as 3TC IN VITRO as well as in studies with the
woodchuck hepatitis model. Triangle intends to initiate Phase I clinical trials
with DAPD in late 1998 or early 1999.

DRUG CANDIDATE TO TREAT CANCER

ALANOSINE. An amino acid analogue, the Company believes that alanosine can
selectively target cancer cells with a particular enzyme deficiency by
inhibiting the synthesis of a molecule necessary for cellular growth. The
deficiency of this particular enzyme (MTAP) occurs in up to 30% of non-small
cell lung cancers and in up to 75% of certain severe primary brain tumors.
Triangle is currently conducting Pilot Phase II efficacy studies with alanosine.

The Company believes that certain of its drug candidates may meet the
criteria established by the United States Food and Drug Administration ("FDA")
for accelerated approval. If so, the Company may be able to commercialize these
drug candidates in a shorter time period than has historically been required for
drugs that do not meet the criteria for accelerated approval. There can be no
assurance, however, that any of the Company's drug candidates will qualify for
accelerated approval or be approved in a time period that is shorter than would
be historically expected. See "Business--Government Regulation."

Triangle intends to maintain a limited corporate infrastructure that is
focused on drug development. The Company does not intend to engage in basic drug
discovery, thereby avoiding much of the significant investment of time and
capital that is generally required before a compound is identified and brought
to clinical trials. The Company intends to use its expertise to perform
internally what it believes are the most critical aspects of the drug
development process, such as the design of clinical trials and the optimization
of drug synthesis. The Company out-sources many aspects of the conduct of
clinical trials and the manufacture of drug substance to carefully selected
third parties. The Company believes that the high concentration of major
prescribers of anti-HIV and cancer therapies in the United States will enable
the Company to promote most drug candidates that are successfully developed to
these prescribers through a small, direct sales force. The Company does not
currently have a sales force.

Triangle is a development stage company, has not received any revenues from
the sale of products, and does not expect any of its drug candidates to be
commercially available until at least the year 2000. As of December 31, 1997,
the Company's accumulated deficit was approximately $49.6 million and the
Company had utilized approximately $40.0 million of cash. There can be no
assurance that the Company will ever achieve profitable operations or generate
positive cash flow.

4
<PAGE>
THE OFFERING

<TABLE>
<S> <C>
Common Stock offered hereby.................... 3,500,000 shares
Common Stock to be outstanding after the
Offering..................................... 23,502,338 shares (1)
Use of proceeds................................ For general corporate purposes, including the
Company's drug development programs such as
preclinical testing and clinical trials, the
payment of license fees, the costs of obtaining
patent protection and other payments to
licensors, the potential acquisition of
additional drug candidates, the development of
computerized systems to support clinical trials
and working capital. See "Use of Proceeds."
Nasdaq National Market symbol.................. VIRS
</TABLE>

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

(1) Excludes as of January 31, 1998, (i) 1,797,768 shares of Common Stock
issuable upon the exercise of outstanding options (at a weighted average
exercise price of $9.57 per share) under the Company's 1996 Stock Incentive
Plan (the "1996 Plan"), (ii) an aggregate of 1,350,451 additional shares of
Common Stock reserved for future option grants or stock issuances under the
1996 Plan and the Company's Employee Stock Purchase Plan (which amount
includes 1,000,000 shares of Common Stock available for issuance as a result
of an amendment to the 1996 Plan that has been approved by the Company's
Board of Directors (the "Board") but is subject to stockholder approval,
(iii) 46,000 shares of Common Stock issuable upon the exercise of
outstanding warrants (at a weighted average exercise price of $2.23 per
share), (iv) up to 2,100,000 shares of Common Stock issuable upon the
achievement of certain development milestones relating to DMP-450 or one of
Avid's other compounds and (v) additional shares of Common Stock available
for issuance in 1999, 2000 and 2001 as a result of an amendment to the 1996
Plan providing for automatic annual increases in the number of shares
available for issuance under the 1996 Plan, which amendment has been
approved by the Board but is subject to stockholder approval. See
"Capitalization," "Description of Capital Stock" and notes 6, 7 and 10 of
notes to consolidated financial statements.

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

The Company was incorporated in Delaware in July 1995. The Company's
principal executive offices are located at 4 University Place, 4611 University
Drive, Durham, North Carolina 27707, and its telephone number is (919) 493-5980.

Triangle Pharmaceuticals and the Triangle logo are trademarks of the
Company. This Prospectus also includes names and trademarks of companies other
than the Company.

5
<PAGE>
SUMMARY CONSOLIDATED FINANCIAL INFORMATION

<TABLE>
<CAPTION>
PERIOD FROM
INCEPTION
(JULY 12,
YEAR ENDED 1995)
DECEMBER 31, THROUGH
-------------------- DECEMBER 31,
1997 1996 1995
--------- --------- -------------
(IN THOUSANDS, EXCEPT PER SHARE
AMOUNTS)
<S> <C> <C> <C>
STATEMENT OF OPERATIONS DATA:
Operating expenses:
License fees.................................................. $ 610 $ 3,267 $ --
Development .................................................. 22,240 4,967 --
Purchased research and development (1)........................ 11,261 -- --
General and administrative.................................... 7,071 3,558 1,004
--------- --------- -------------
Loss from operations............................................ (41,182) (11,792) (1,004)
Interest income, net............................................ 3,514 875 37
--------- --------- -------------
Net loss ....................................................... $ (37,668) $ (10,917) $ (967)
--------- --------- -------------
--------- --------- -------------
Basic and diluted net loss per common share (2)................. $ (2.00) $ (1.89) $ (0.60)
--------- --------- -------------
--------- --------- -------------
Shares used in computing net loss per common share (2).......... 18,871 5,784 1,624
--------- --------- -------------
--------- --------- -------------
</TABLE>
<TABLE>
<CAPTION>
DECEMBER 31, 1997
--------------------------
<S> <C> <C>
AS ADJUSTED
ACTUAL (3)
---------- --------------

<CAPTION>
(IN THOUSANDS)
<S> <C> <C>
BALANCE SHEET DATA:
Cash and cash equivalents................................................................... $ 34,698 $ 83,143
Investments................................................................................. 23,098 23,098
Working capital (4)......................................................................... 50,247 98,692
Total assets................................................................................ 61,878 110,323
Capital lease obligation--noncurrent........................................................ 300 300
Long-term debt.............................................................................. 178 178
Accumulated deficit during development stage ............................................... (49,552) (49,552)
Total stockholders' equity.................................................................. 52,717 101,162
</TABLE>

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(1) See note 10 of notes to consolidated financial statements for information
concerning the Company's acquisition of Avid on August 28, 1997. As a result
of the acquisition, the Company recorded an in-process research and
development charge of $11.3 million in the Company's 1997 consolidated
financial statements. The operating results of Avid have been included in
the Company's consolidated financial statements from the date of the
acquisition.

(2) See note 1 of notes to consolidated financial statements for information
concerning the computation of net loss per common share and shares used in
computing net loss per common share.

(3) As adjusted to reflect the sale of 3,500,000 shares of Common Stock offered
hereby at the public offering price of $15.00 per share and the application
of the estimated net proceeds therefrom. See "Use of Proceeds."

(4) Working capital represents the difference between the Company's current
assets and current liabilities.

6
<PAGE>
RISK FACTORS

AN INVESTMENT IN THE COMMON STOCK OFFERED HEREBY INVOLVES A HIGH DEGREE OF
RISK. IN ADDITION TO THE OTHER INFORMATION CONTAINED IN THIS PROSPECTUS,
PROSPECTIVE INVESTORS SHOULD CAREFULLY CONSIDER THE FOLLOWING RISK FACTORS
BEFORE PURCHASING THE COMMON STOCK OFFERED HEREBY.

DEVELOPMENT STAGE COMPANY; UNCERTAINTY OF PRODUCT DEVELOPMENT

Triangle was incorporated in July 1995 and accordingly has only a limited
operating history upon which an evaluation of the Company's business and
prospects can be based. In addition, many of the Company's drug candidates are
in the early developmental stage and all of the Company's drug candidates will
require significant, time consuming and costly development, testing and
regulatory clearances. The Company does not expect any of its drug candidates to
be commercially available until at least the year 2000. The successful
development of any new drug, including each of the Company's drug candidates, is
highly uncertain and is subject to a number of significant risks. These risks
include, among others, the possibility that any or all of the Company's drug
candidates will be found to be ineffective, toxic or otherwise fail to receive
necessary regulatory clearances; that the drug candidates will be uneconomical
to manufacture or market or will not achieve broad market acceptance; that third
parties will hold proprietary rights that will preclude the Company from
marketing the drug candidates; or that third parties will market equivalent or
superior products. The failure of the Company's drug development programs to
result in commercially viable products would have a material adverse effect on
the Company. See "Management's Discussion and Analysis of Financial Condition
and Results of Operations" and "Business--Product Development Programs."

HISTORY OF OPERATING LOSSES; ACCUMULATED DEFICIT; UNCERTAINTY OF FUTURE
PROFITABILITY

The Company has incurred losses since its inception. As of December 31,
1997, the Company's consolidated accumulated deficit was approximately $49.6
million and the Company had utilized approximately $40.0 million of cash. Losses
have resulted principally from costs incurred in the acquisition and development
of the Company's drug candidates (including an $11.3 million charge related to
the acquisition of Avid) and general and administrative costs. These costs have
exceeded the Company's revenues, which to date have been generated primarily
from interest income. The Company has not generated any revenue to date from the
sale of drugs and does not expect to do so until at least the year 2000. The
Company will incur significant additional operating losses over the next several
years and expects these losses to increase as the Company's drug development
efforts expand. The Company's ability to achieve profitability will depend upon
its ability to develop and obtain regulatory approval for its drug candidates
and to develop the capacity (or establish and maintain relationships with third
parties) to manufacture, market and sell any drug candidates it successfully
develops. There can be no assurance that the Company will ever generate
significant revenues or achieve profitable operations. See "Management's
Discussion and Analysis of Financial Condition and Results of Operations."

FUTURE CAPITAL NEEDS; UNCERTAINTY OF ADDITIONAL FUNDING

7
<PAGE>
commercial potential of the Company's drug candidates, administrative and legal
expenses, the establishment of internal capacity and third party arrangements
for sales and marketing functions, the establishment of third party arrangements
for manufacturing and other factors. The Company expects that its capital
requirements will increase significantly in the future.

The Company has incurred negative cash flow from operations since inception
and does not expect to generate positive cash flow to fund its operations for at
least the next several years. As a result, substantial additional equity or debt
financings will be required in the near future to fund the Company's operations.
There can be no assurance that the Company will be able to consummate any such
financings on favorable terms or at all, or that such financings, if
consummated, will be adequate to meet the Company's capital requirements. Any
additional equity or convertible debt financings could result in substantial
dilution to the Company's stockholders. If adequate funds are not available, the
Company may be required to delay, reduce the scope of or eliminate one or more
of its drug development programs or attempt to continue development by entering
into arrangements with collaborative partners or others that may require the
Company to relinquish some or all of its rights to certain technologies or drug
candidates that the Company would not otherwise desire to relinquish. In
addition, from time to time, the Company considers the acquisition of
technologies and drug candidates that, if completed, could increase the
Company's capital requirements. The Company's inability to fund its capital
requirements would have a material adverse effect on the Company. See
"Management's Discussion and Analysis of Financial Condition and Results of
Operations."

UNCERTAINTIES RELATED TO CLINICAL TRIALS

Before obtaining required regulatory approvals for the commercial sale of
any of its drug candidates under development, the Company must demonstrate
through preclinical testing and clinical trials that each product is safe and
effective for use in each target indication. The results from preclinical
testing and early clinical trials may not be predictive of results that will be
obtained in pivotal clinical trials, and there can be no assurance that the
Company's clinical trials will demonstrate sufficient safety and effectiveness
to obtain required regulatory approvals or will result in marketable products. A
number of companies in the pharmaceutical industry have suffered significant
setbacks in advanced clinical trials, even after promising results in earlier
trials. The administration of any drug candidate developed by the Company may
produce undesirable side effects in humans. The occurrence of side effects could
interrupt, delay or halt clinical trials of such drug candidate and could
ultimately prevent its approval by the FDA or foreign regulatory authorities for
any and all targeted indications. The Company, the FDA or foreign regulatory
authorities may suspend or terminate clinical trials at any time if it is
believed that the trial participants are being exposed to unacceptable health
risks. There can be no assurance that clinical trials will demonstrate that any
drug candidate under development by the Company is safe or effective.

The rate of completion of the Company's clinical trials will depend upon,
among other factors, obtaining adequate supplies of drug substance and the rate
of patient enrollment. Patient enrollment is a function of many factors,
including the size of the patient population, the nature of the protocol, the
proximity of patients to clinical sites and the eligibility criteria for the
clinical trial. Delays in planned patient enrollment can result in increased
costs or longer development times or both, which could have a material adverse
effect on the Company. There can be no assurance that if clinical trials are
successfully completed, the Company will be able to file any required regulatory
submissions in a timely manner or that any such submissions will be approved by
regulatory agencies. Any failure of the Company to complete successfully its
clinical trials and obtain approvals of corresponding regulatory submissions
would have a material adverse effect on the Company. See "Business--Product
Development Programs" and "Business--Government Regulation."

8
<PAGE>
UNCERTAINTY OF PATENTS; DEPENDENCE ON PATENTS, LICENSES AND PROPRIETARY RIGHTS

The Company's success will depend in large part on the ability of the
Company and its licensors to obtain patent protection with respect to its drug
candidates, defend patents once obtained, maintain trade secrets and operate
without infringing upon the patents and proprietary rights of others and to
obtain appropriate licenses to patents or proprietary rights held by third
parties, both in the United States and in foreign countries. The Company has no
patents in its own name and has only one patent application of its own pending,
but has obtained or has an option to obtain licenses to patents, patent
applications and other proprietary rights from third parties with respect to
each of its nine drug candidates.

The patent positions of pharmaceutical companies, including those of the
Company, are uncertain and involve complex legal and factual questions for which
important legal principles are unresolved. There can be no assurance that the
Company or its licensors have or will develop or obtain the rights to products
or processes that are patentable, that patents will issue from patent
applications or that claims allowed will be sufficient to protect the technology
licensed to or owned by the Company. In addition, no assurance can be given that
any patents issued to or licensed by the Company will not be challenged,
invalidated, infringed or circumvented, or that the rights granted thereunder
will provide competitive advantages to the Company. The Company's success will
also depend in large part on the Company not breaching the licenses pursuant to
which the Company obtained its technology and drug candidates.

A number of pharmaceutical and biotechnology companies, universities and
research institutions have filed patent applications or received patents to
technologies that cover or are similar to the technologies licensed to or owned
by the Company. The Company is aware of certain patent applications previously
filed by and patents already issued to others that conflict with patents or
patent applications licensed to the Company either by claiming the same methods
or compounds or by claiming methods or compounds that could dominate those
licensed to the Company. In addition, there can be no assurance that the Company
is aware of all patents or patent applications that may materially affect the
Company's ability to make, use or sell any drug candidates that are successfully
developed. For example, United States patent applications are confidential while
pending in the Patent and Trademark Office ("PTO"), and patent applications
filed in foreign countries are often first published six months or more after
filing. Any conflicts resulting from third party patent applications and patents
could significantly reduce the coverage of the patents licensed to or owned by
the Company and limit the ability of the Company or its licensors to obtain
meaningful patent protection. If patents are issued to other companies that
contain conflicting claims, the Company may be required to obtain licenses to
these patents or to develop or obtain alternative technology. There can be no
assurance that the Company will be able to obtain any such license on acceptable
terms or at all. If such licenses are not obtained, the Company could be delayed
in or prevented from pursuing the development or commercialization of its drug
candidates, which would have a material adverse effect on the Company.

The Company is aware of significant risks regarding the patent rights
licensed by the Company relating to three of the nine compounds comprising the
Company's existing drug candidate portfolio. The Company may not be able to
commercialize FTC, DAPD or CS-92 for HIV and/or HBV due to patent rights held by
third parties other than the Company's licensors. The Company is aware of
numerous patent applications and issued patents in the United States and
numerous foreign countries held by third parties other than the Company's
licensors that relate to these compounds and their use alone or coactively to
treat HIV and HBV. As a result, the positions of the Company and its licensors
with respect to the use of FTC, DAPD and CS-92 to treat HIV and/or HBV are
highly uncertain and involve numerous complex legal and factual questions that
are unknown or unresolved. If any of these questions is resolved in a manner
that is not favorable to the Company's licensors or the Company, the Company
would not have the right to commercialize FTC, DAPD and/or CS-92 in the absence
of a license from one or more third parties, which may not be available on
acceptable terms or at all. In addition, even in the absence of an unfavorable
resolution of any of these questions, the Company may attempt to obtain licenses
from one or more third parties in order to reduce or eliminate the risks
relating to some or all of these matters. There

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can be no assurance that the Company will elect to obtain any such licenses or
that such licenses will be available on acceptable terms or at all. The
Company's inability to commercialize any of these compounds could have a
material adverse effect on the Company.

FTC

FTC belongs to the same general class of nucleosides as 3TC, which has been
approved in the United States by the FDA for use in combination with AZT for the
treatment of HIV and by similar regulatory agencies in many other countries for
use in combination with other nucleoside analogues for the treatment of HIV. 3TC
is currently being sold by Glaxo Wellcome plc ("Glaxo") for the treatment of HIV
under a license agreement with BioChem Pharma Inc. ("BioChem Pharma"). The
Company obtained its rights to purified forms of FTC under a license from Emory
University ("Emory"). In 1990 and 1991, Emory filed in the United States and
thereafter in numerous foreign countries patent applications with claims to
composition of matter and methods to treat HIV and HBV with FTC. Yale University
("Yale") filed patent applications on FTC and its use to treat HBV in 1991 in
the United States, and subsequently licensed all of its rights to FTC and its
uses claimed in these patent applications to Emory. The Company's license
arrangement with Emory includes all rights to FTC and its uses claimed in the
Yale patent applications.

HIV. Emory received a United States patent in 1993 covering a method to
treat HIV infection with FTC. BioChem Pharma filed a patent application in the
United States in 1989 and was issued a patent in 1991 covering a group of
nucleosides in the same general class as FTC, but which did not include FTC.
BioChem Pharma filed foreign patent applications in 1990 based upon its 1989
United States patent application, and in those foreign applications included FTC
among a large class of nucleosides. The foreign patent applications are pending
in many countries and have issued in a number of countries with claims directed
to FTC and its use to treat HIV. In addition, BioChem Pharma filed a United
States patent application in 1991 specifically directed to a purified form of
FTC that exhibits advantageous properties for the treatment of HIV on which two
patents have issued, one directed to the purified form of FTC and another
directed to a method for treating antiviral diseases with the purified form of
FTC. The PTO has declared an interference between the latter BioChem Pharma
patent and a patent application filed by Emory. There can be no assurance that
Emory will prevail in the interference proceeding, or that the interference
proceeding will not delay the decision of the PTO regarding Emory's patent
application. BioChem Pharma has also filed patent applications in many foreign
countries based upon its 1991 United States patent application, and patents have
issued in certain countries. BioChem Pharma may have additional patent
applications pending in the United States.

In the United States, the first to invent a subject matter is entitled to
patent protection on that invention. With respect to patent applications filed
prior to January 1, 1996, United States patent law provides that if a party
invented a technology outside the United States, then for purposes of
determining the first to invent the technology, that party is deemed to have
invented the technology on the earlier of the date it introduced the invention
in the United States or the date it filed its patent application. In a recent
filing with the Securities and Exchange Commission (the "Commission"), BioChem
Pharma stated that since it conducts substantially all of its research
activities outside the United States, it is at a disadvantage as to inventions
made prior to January 1, 1996, with respect to obtaining United States patents
as compared to companies that maintain research facilities in the United States.
The Company does not know whether Emory or BioChem Pharma was the first to
invent the subject matter claimed in their respective United States patent
applications or patents, or whether BioChem Pharma invented the technology
disclosed in its patent applications in the United States or introduced that
technology in the United States before the date of its patent applications. In
foreign countries, the first party to file a patent application on an invention,
not the first to invent the subject matter, is entitled to patent protection on
that invention. While the Company believes that Emory's patent applications that
disclosed FTC as a useful anti-HIV agent were filed in many foreign countries
before BioChem Pharma filed its foreign patent applications on that subject
matter, BioChem Pharma has been issued patents in several foreign countries.
Further,

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BioChem Pharma has filed for patent protection on FTC and its uses in certain
countries in which Emory did not file for patent protection. Emory has opposed
or otherwise challenged patent claims on FTC granted to BioChem Pharma in
Australia, Japan and Norway. There can be no assurance that Emory will initiate
opposition proceedings in any other countries or be successful in any pending or
subsequently filed foreign proceeding attempting to revoke patents issued to
BioChem Pharma or addressing the relative rights of BioChem Pharma and Emory.
BioChem Pharma has opposed patent claims on FTC granted to Emory in Japan and
Australia. There can also be no assurance that BioChem Pharma will not make
additional challenges to any Emory patents or patent applications, or that Emory
will succeed in defending any such challenges. There can be no assurance that
the sale of FTC by the Company for the treatment of HIV would not be held to
infringe United States and foreign patent rights of BioChem Pharma. Under the
patent laws of most countries, a product can be found to infringe a third party
patent either if the third party patent expressly covers the product or method
of treatment using the product, or in certain circumstances, if the third party
patent, while not expressly covering the product or method, covers subject
matter that is substantially equivalent in nature to the product or method. If
it is determined that the sale of FTC for the treatment of HIV infringes a
BioChem Pharma patent, the Company would not have the right to make, use or sell
FTC for the treatment of HIV in one or more countries in the absence of a
license from BioChem Pharma. There can be no assurance that the Company could
obtain such a license from BioChem Pharma on acceptable terms or at all.

HBV. Burroughs Wellcome Co. ("Burroughs Wellcome") filed patent
applications in March 1991 and May 1991 in Great Britain on a method to treat
HBV with FTC. Burroughs Wellcome filed similar patent applications in other
countries, which the Company believes includes the United States. Glaxo
subsequently acquired Burroughs Wellcome's rights under those patent
applications. Those patent applications were filed in many foreign countries
prior to the date Emory filed its patent application on the use of FTC to treat
HBV, and therefore, the foreign patent applications filed by Burroughs Wellcome
have priority over those filed by Emory. In July 1996, Emory instituted
litigation against Glaxo in the United States District Court to obtain ownership
of the patent applications filed by Burroughs Wellcome, alleging that Burroughs
Wellcome converted and misappropriated Emory's invention and property, and that
an Emory employee is the inventor or a co-inventor of the subject matter covered
by the Burroughs Wellcome patent applications. There can be no assurance that
Emory will succeed in its efforts to establish ownership rights. If Emory fails
to establish ownership rights, the Company could not make, use or sell FTC for
the treatment of HBV in countries in which patents are issued to Glaxo without a
license from Glaxo. If Emory establishes only co-ownership rights (and not sole
ownership) to these patents and patent applications, laws in Europe, Korea and
perhaps other countries could prohibit Emory from licensing any co-owned patent
rights without Glaxo's consent. If the Company is required to obtain a license
from Glaxo to sell FTC for the treatment of HBV, there can be no assurance that
the Company would be able to obtain such a license on acceptable terms or at
all.

BioChem Pharma filed a patent application in May 1991 in Great Britain also
directed to a method to treat HBV with FTC. BioChem Pharma filed similar patent
applications in other countries, and in January 1996 was issued a patent in the
United States. The PTO has declared an interference between the BioChem Pharma
patent and a patent application filed by Yale. Yale licensed all of its rights
relating to FTC and its uses claimed in this patent application to Emory, which
subsequently licensed these rights to the Company. There can be no assurance
that Yale will prevail in the interference proceeding, or that the interference
proceeding will not delay the decision of the PTO regarding Yale's patent
application. In addition, interference proceedings may be declared with respect
to other patent applications filed by Emory, Burroughs Wellcome's patent
application and BioChem Pharma's issued United States patent. There can be no
assurance that Emory will pursue or succeed in any such proceedings. The Company
cannot sell FTC for the treatment of HBV in the United States unless the BioChem
Pharma patent is held invalid by a United States court or administrative body or
unless the Company obtains a license from BioChem Pharma. There can be no
assurance that the Company would be able to obtain such a license on acceptable
terms or at all. In July 1991, BioChem Pharma was issued a United States patent
on the use of

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3TC to treat HBV and has corresponding patent applications pending or issued in
foreign countries. If it is determined that the use of FTC to treat HBV is not
substantially different from the use of 3TC to treat HBV, a court could hold
that the use of FTC to treat HBV infringes these BioChem Pharma 3TC patents.

In addition, BioChem Pharma has filed in the United States and foreign
countries several patent applications on manufacturing methods relating to a
class of nucleosides that includes FTC, from which several patents have issued
in the United States and many foreign countries. If the Company uses a
manufacturing method that is covered by patents issued on any of these
applications, the Company would not be able to manufacture FTC without a license
from BioChem Pharma. There can be no assurance that the Company would be able to
obtain such a license on acceptable terms or at all.

DAPD

The Company obtained its rights to DAPD under a license from Emory and the
University of Georgia Research Foundation, Inc. ("UGARF"). The DAPD portfolio
licensed to the Company consists of three issued United States patents and
several United States and foreign patent applications that cover a method for
the synthesis of DAPD and its use to treat HIV and HBV. Emory and UGARF filed
patent applications claiming these inventions in the United States in 1990 and
1992. BioChem Pharma filed a patent application in the United States in 1988 on
a group of nucleosides in the same general class as DAPD and their use to treat
HIV, and has filed corresponding patent applications in foreign countries. The
PTO issued a patent to BioChem Pharma in 1993 covering a class of nucleosides
that includes DAPD and its use to treat HIV. Corresponding patents have been
issued to BioChem Pharma in many foreign countries. Emory has filed an
opposition to BioChem Pharma's granted patent application in the European Patent
Office based, in part, upon Emory's assertion that BioChem Pharma's patent does
not disclose how to make DAPD, and Emory has informed the Company that Emory
intends to challenge BioChem Pharma's patents and patent applications in other
countries. Patent claims granted to Emory on a portion of the DAPD technology by
the Australian Patent Office have been opposed by BioChem Pharma. There can be
no assurance that a court or administrative body would invalidate BioChem
Pharma's patent claims or that a sale of DAPD by the Company would not infringe
BioChem Pharma's patents. If Emory, UGARF and the Company do not challenge, or
are not successful in any challenge to, BioChem Pharma's issued patents or
pending patent applications (or patents that may issue as a result of such
applications), the Company will not be able to manufacture, use or sell DAPD in
the United States and any foreign countries in which BioChem Pharma receives a
patent without a license from BioChem Pharma. There can be no assurance that the
Company would be able to obtain such a license from BioChem Pharma on acceptable
terms or at all.

CS-92

The Company obtained its rights to CS-92 under a license from Emory and
UGARF. Emory and UGARF have obtained two United States patents that cover CS-92
and its use to treat HIV and have filed a European patent application and a
Japanese patent application with claims limited to the use of CS-92 as a method
for administering AZT, which includes the administration of CS-92 as a precursor
form of AZT, to treat HIV infection. Burroughs Wellcome filed an application
with the European Patent Office in September 1986 directed to a broad group of
nucleosides that includes CS-92 and AZT, and their use to treat HIV infection.
Burroughs Wellcome subsequently filed similar applications in other countries,
including the United States. Patents have been issued to Burroughs Wellcome in
certain countries based upon these patent applications. Glaxo now has the rights
to these patents and patent applications. There can be no assurance that, if
challenged, a court would uphold the Emory/UGARF patents in light of the
disclosures contained in the earlier filed Burroughs Wellcome patent
applications. If the use of CS-92 is found to infringe patents owned by Glaxo,
then the Company would not have the right to sell CS-92 in one or more countries
without a license from Glaxo. There can be no assurance that the Company would
be able to obtain such a license from Glaxo on acceptable terms or at all.

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With respect to any of the Company's drug candidates, litigation and
interference proceedings declared by the PTO, including the currently pending
proceedings, could result in substantial cost to the Company. The Company
expects the costs of the currently pending interference proceedings to increase
significantly during the next several years. The Company anticipates that
additional litigation and/or patent interference or opposition proceedings will
be necessary or may be initiated by the Company's licensors or by third parties
to enforce any patents to which the Company has rights or to determine the
scope, validity and enforceability of other parties' proprietary rights and the
priority of an invention, any of which could result in substantial costs and/or
delays to the Company. The outcome of any of these proceedings may affect the
Company's drug candidates and technology. United States patents carry a
presumption of validity and generally can be invalidated only through clear and
convincing evidence. As indicated above, two interferences have already been
declared by the PTO in connection with the FTC technology. There can be no
assurance that the Company's licensed patents would be held valid by a court or
administrative body or that an alleged infringer would be found to be
infringing. Further, with respect to the drug candidates licensed or optioned by
the Company from Emory, UGARF, The Regents of the University of California (the
"Regents"), The DuPont Merck Pharmaceutical Company ("DuPont Merck") and
Mitsubishi Chemical Corporation ("Mitsubishi"), each of these licensors is
primarily responsible for any patent prosecution activities for the technology
licensed to the Company, such as litigation, interference, opposition or other
actions and, except for litigation expenses incurred by DuPont Merck and all
patent prosecution expenses incurred by Mitsubishi, the Company is required to
reimburse these licensors for the costs they incur in performing these
activities. Similarly, Yale and UGARF, the licensors of L-FMAU to Bukwang Pharm.
Ind. Co., Ltd. ("Bukwang"), are primarily responsible for patent prosecution
activities with respect to L-FMAU at the Company's expense. As a result, the
Company generally does not have the ability to institute or determine the
conduct of any such patent proceedings unless Emory, UGARF, the Regents, DuPont
Merck, Mitsubishi and/or Yale do not elect to institute or elect to abandon such
proceedings. In cases where Emory, UGARF, the Regents, DuPont Merck, Mitsubishi
and/or Yale elect to institute and prosecute patent proceedings, the Company's
rights will be dependent in part upon the manner in which these licensors
conduct the proceedings. These licensors could, in any proceedings they elect to
initiate and maintain, decide not to vigorously pursue or defend or to settle
such proceedings on terms that are not favorable to the Company. An adverse
outcome in any patent litigation or interference proceeding could subject the
Company to significant liabilities to third parties, require disputed rights to
be licensed from third parties or require the Company to cease using such
technology, any of which could have a material adverse effect on the Company.
Moreover, the mere uncertainty resulting from the initiation and continuation of
any technology related litigation or interference proceeding could have a
material adverse effect on the Company pending resolution of the disputed
matters.

The Company also relies on unpatented trade secrets and know-how to maintain
its competitive position, which it seeks to protect, in part, by confidentiality
agreements with employees, consultants and others. There can be no assurance
that these agreements will not be breached or terminated, that the Company will
have adequate remedies for any breach, or that the Company's trade secrets will
not otherwise become known or be independently discovered by competitors. The
Company relies on certain technologies to which it does not have exclusive
rights or which may not be patentable or proprietary and thus may be available
to competitors. The Company has filed an application for but has not obtained a
trademark registration with respect to its corporate name and its logo. The
Company is aware that several other companies use trade names that are similar
to the Company's for their businesses. If the Company is not able to obtain any
licenses that may be necessary for the Company to use its corporate name, it may
be required to change its corporate name. The Company's management personnel
were previously employed by other pharmaceutical companies. In many cases, these
individuals are conducting drug development activities for the Company in areas
similar to those in which they were involved prior to joining the Company. As a
result, the Company, as well as these individuals, could be subject to
allegations of violation of trade secrets and other similar claims. See
"Business--Patents and Proprietary Rights."

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EXTENSIVE GOVERNMENT REGULATION; NO ASSURANCE OF REGULATORY APPROVAL

Human pharmaceutical products are subject to rigorous preclinical testing
and clinical trials and other approval procedures mandated by the FDA and
foreign regulatory authorities. Various federal and foreign statutes and
regulations also govern or influence the manufacturing, safety, labeling,
storage, record keeping, reporting and marketing of pharmaceutical products. The
process of obtaining these approvals and the subsequent compliance with
appropriate United States and foreign statutes and regulations are time
consuming and require the expenditure of substantial resources. In addition,
these requirements and processes vary widely from country to country. The time
required for completing preclinical testing and clinical trials and obtaining
regulatory approvals is uncertain. The Company may decide to replace a drug
candidate in preclinical testing and/or clinical trials with a modified drug
candidate, thus extending the development period. In addition, the FDA or
similar foreign regulatory authorities may require additional clinical trials,
which could result in increased costs and significant development delays. Delays
or rejections may also be encountered based upon changes in FDA policy during
the period of product development and FDA review. Similar delays or rejections
may be encountered in other countries. The Company's drug candidates may not
qualify for accelerated development and/or approval under FDA regulations and,
even if some of the Company's drug candidates qualify for accelerated
development and/or approval, they may not be approved for marketing sooner than
would be historically expected or at all. There can be no assurance that even
after substantial time and expenditures, any of the Company's drug candidates
under development will receive marketing approval in any country on a timely
basis or at all. If the Company is unable to demonstrate the safety and
effectiveness of its drug candidates to the satisfaction of the FDA or foreign
regulatory authorities, the Company will be unable to commercialize its drug
candidates and would be materially adversely affected. Further, even if
regulatory approval of a drug candidate is obtained, the approval may entail
limitations on the indicated uses for which the drug candidate may be marketed.
A marketed product, its manufacturer and the manufacturer's facilities are
subject to continual review and periodic inspections, and subsequent discovery
of previously unknown problems with a product, manufacturer or facility may
result in restrictions on such product or manufacturer, including withdrawal of
the product from the market. The failure to comply with applicable regulatory
requirements can, among other things, result in fines, suspension of regulatory
approvals, refusal to approve pending applications, refusal to permit exports
from the United States, product recalls, seizure of products, injunctions,
operating restrictions and criminal prosecutions. Further, the FDA and/or
foreign regulatory authorities may adopt policy changes or additional government
regulations that could prevent or delay regulatory approval of the Company's
drug candidates.

The effect of governmental regulation may be to delay the marketing of new
products for a considerable period of time or to prevent such marketing
altogether, to impose costly requirements on the Company's activities or to
provide a competitive advantage to other companies that compete with the
Company. Adverse clinical results by others could have a negative impact on the
regulatory process and timing with respect to the development and approval of
the Company's drug candidates. A delay in obtaining or failure to obtain
regulatory approvals for any of the Company's drug candidates could have a
material adverse effect on the Company. To the extent that the Company's drug
candidates are intended for use as coactive therapy with one or more other
drugs, adverse safety, effectiveness or regulatory developments in connection
with such other drugs may also have a material adverse effect on the Company.
The extent and character of potentially adverse governmental regulation that may
arise from future legislation or administrative action cannot be predicted.

The Company is also subject to various federal, state and local laws and
regulations relating to safe working conditions, laboratory and manufacturing
practices, the experimental use of animals and the use and disposal of hazardous
or potentially hazardous substances, including radioactive compounds and
infectious disease agents, used in connection with its development work. See
"Business--Government Regulation."

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INTENSE COMPETITION; RISK OF TECHNOLOGICAL CHANGE

The Company is engaged in segments of the pharmaceutical industry that are
highly competitive and rapidly changing. If successfully developed and approved,
the drug candidates that the Company is currently developing will compete with
numerous existing therapies. In addition, a number of companies are pursuing the
development of novel pharmaceuticals that target the same diseases the Company
is targeting. The Company believes that a significant number of drugs are
currently under development and will become available in the future for the
treatment of HIV, HBV and cancer. The Company anticipates that it will face
intense and increasing competition in the future as new products enter the
market and advanced technologies become available. There can be no assurance
that any products that are successfully developed by the Company will be more
effective, or more effectively marketed and sold, than any products that may be
developed by the Company's competitors. Competitive products may render the
Company's licensed technology and products obsolete or noncompetitive prior to
the Company's recovery of development or commercialization expenses incurred
with respect to any such products. The development by others of a cure or new
treatment methods for the indications for which the Company is developing drug
candidates could render the Company's drug candidates noncompetitive, obsolete
or uneconomical. Many of the Company's competitors have significantly greater
financial, technical and human resources than the Company and may be better
equipped to develop, manufacture and market products. Many of these companies
also have extensive experience in preclinical testing and clinical trials,
obtaining FDA and other regulatory approvals and manufacturing and marketing
pharmaceutical products. Many of these competitors also have products that have
been approved or are in late stage development and operate large, well funded
research and development programs. Smaller companies may also prove to be
significant competitors, particularly through collaborative arrangements with
large pharmaceutical and biotechnology companies. Furthermore, academic
institutions, governmental agencies and other public and private research
organizations are becoming increasingly aware of the commercial value of their
inventions and are more actively seeking to commercialize the technology they
have developed.

If the Company's drug candidates are successfully developed and approved,
the Company will face competition based on the safety and effectiveness of its
products, the timing and scope of regulatory approvals, the availability of
supply, marketing and sales capability, reimbursement coverage, price, patent
position and other factors. There can be no assurance that the Company's
competitors will not develop or commercialize more effective or more affordable
technology or products, or obtain more effective patent protection, than the
Company. Accordingly, the Company's competitors may succeed in commercializing
products more rapidly or effectively than the Company, which could have a
material adverse effect on the Company. See "Business--Competition."

RISKS RELATED TO LICENSE AND OPTION AGREEMENTS

The agreements pursuant to which the Company has in-licensed or obtained an
option to in-license its drug candidates permit the Company's licensors to
terminate the agreements under certain circumstances, such as the failure by the
Company to achieve certain development milestones or the occurrence of an
uncured material breach by the Company. The termination of any of these
agreements could have a material adverse effect on the Company. Upon termination
of the license agreements with Emory, UGARF and Bukwang, the Company is required
to grant to Emory, UGARF and Bukwang a non-exclusive, royalty free license to
all of the Company's interest in the licensed technology (including any
improvements to the technology developed by the Company). Upon termination of
the license agreement with DuPont Merck, the Company is required to transfer all
approved and pending New Drug Applications ("NDAs") relating to DMP-450 to
DuPont Merck. In addition, the license and option agreements with Emory, UGARF,
the Regents, DuPont Merck and Mitsubishi provide that each of these licensors is
primarily responsible for any patent prosecution activities for the technology
licensed to the Company, such as litigation, interference, opposition or other
actions and, except for litigation expenses incurred by

15
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DuPont Merck and all patent prosecution expenses incurred by Mitsubishi, the
Company is required to reimburse these licensors for the costs they incur in
performing these activities. Similarly, Yale and UGARF, the licensors of L-FMAU
to Bukwang, are primarily responsible for patent prosecution activities with
respect to L-FMAU at the Company's expense. The Company believes that these
costs as well as other costs under the license and option agreements relating to
the Company's drug candidates will be substantial and may increase significantly
during the next several years, and any inability or failure of the Company to
pay these costs with respect to any drug candidate could result in the
termination of the license or option agreement for such drug candidate, which
could have a material adverse effect on the Company. See "Business--License,
Option and Other Material Agreements."

LACK OF MANUFACTURING CAPABILITIES

The Company does not have any manufacturing capacity and relies on third
party manufacturers for the manufacture of all of its clinical trial material.
The Company currently plans to expand its existing relationships or to seek to
establish relationships with additional third party manufacturers for the
commercial production of any products it may develop. There can be no assurance
that the Company will be able to establish or maintain relationships with third
party manufacturers on commercially acceptable terms or that third party
manufacturers will be able to manufacture products in commercial quantities
under applicable Good Manufacturing Practices ("GMP") regulations of the FDA on
a cost effective basis. The Company's dependence upon third parties for the
manufacture of its products may adversely affect the Company's profit margins
and its ability to develop and commercialize products on a timely and
competitive basis. Further, there can be no assurance that manufacturing or
quality control problems will not arise in connection with the manufacture of
the Company's products or that third party manufacturers will be able to
maintain the necessary governmental licenses and approvals to continue
manufacturing the Company's products. Any failure to establish or maintain
relationships with third parties for its manufacturing requirements on
commercially acceptable terms would have a material adverse effect on the
Company. See "Business--Manufacturing" and "Business--Government Regulation."

LACK OF SALES AND MARKETING CAPABILITIES

The Company currently has only two marketing employees and no sales
personnel. The Company will have to develop a sales force or rely on marketing
partners or other arrangements with third parties for the marketing,
distribution and sale of any products it develops. The Company currently intends
to market in the United States most of the drug candidates that it successfully
develops primarily through a direct sales force and outside the United States
through a combination of a direct sales force and arrangements with third
parties. There can be no assurance that the Company will be able to establish
marketing, distribution or sales capabilities or make arrangements with third
parties to perform those activities on terms satisfactory to the Company or that
any internal capabilities or third party arrangements will be cost effective.

In addition, any third parties with whom the Company establishes marketing,
distribution or sales arrangements may have significant control over important
aspects of the commercialization of the Company's products, including market
identification, marketing methods, pricing, composition of sales force and
promotional activities. There can be no assurance that the Company will be able
to control the amount and timing of resources that any third party may devote to
the Company's products or prevent any third party from pursuing alternative
technologies or products that could result in the development of products that
compete with the Company's products and the withdrawal of support for the
Company's programs. See "Business--Sales and Marketing."

DEPENDENCE ON THIRD PARTIES FOR DEVELOPMENT AND ACQUISITION OF DRUG CANDIDATES

The Company intends to engage third party contract research organizations
("CROs") to perform certain functions in connection with the development of the
Company's drug candidates. The Company

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intends to design clinical trials, but have CROs conduct the clinical trials.
The Company will rely on the CROs to perform many important aspects of clinical
trials. As a result, these aspects of the Company's drug development programs
will be outside the direct control of the Company. In addition, there can be no
assurance that the CROs or other third parties will perform all of their
obligations under arrangements with the Company. In the event that the CROs or
other third parties do not perform clinical trials in a satisfactory manner or
breach their obligations to the Company, the development and commercialization
of any drug candidate may be delayed or precluded, which would have a material
adverse effect on the Company. The Company does not intend to engage in drug
discovery. The Company's strategy for obtaining additional drug candidates is to
utilize the relationships of its management team and Scientific Advisory Board
to identify drug candidates for in-licensing from companies, universities,
research institutions and other organizations. There can be no assurance that
the Company will succeed in acquiring additional drug candidates on acceptable
terms or at all. See "Business--Strategy."

DEPENDENCE ON KEY EMPLOYEES

The Company is highly dependent on its senior management and scientific
staff, including Dr. David Barry, the Company's Chairman and Chief Executive
Officer. Except for Dr. Barry, the Company has not entered into non-competition
agreements with any of its personnel. The loss of the services of any member of
its senior management or scientific staff may significantly delay or prevent the
achievement of product development and other business objectives. Retaining and
attracting qualified personnel, consultants and advisors is critical to the
Company's success. In order to pursue its drug development programs and
marketing plans, the Company will be required to hire additional qualified
scientific and management personnel. Competition for qualified individuals is
intense and the Company faces competition from numerous pharmaceutical and
biotechnology companies, universities and other research institutions. There can
be no assurance that the Company will be able to attract and retain such
individuals on acceptable terms or at all, and the failure to do so would have a
material adverse effect on the Company. In addition, the Company relies on
members of its Scientific Advisory Board to assist the Company in formulating
its drug development strategy. All of the members of the Scientific Advisory
Board are employed by other employers and each such member may have commitments
to, or consulting or advisory contracts with, other entities that may limit his
availability to the Company.

UNCERTAINTY OF HEALTH CARE REFORM MEASURES AND THIRD PARTY REIMBURSEMENT

The business and financial condition of pharmaceutical companies will
continue to be affected by the efforts of governments and third party payors to
contain or reduce the cost of health care through various means. A number of
legislative and regulatory proposals aimed at changing the health care system
have been proposed in recent years. In addition, an increasing emphasis on
managed care in the United States has and will continue to increase pressure on
pharmaceutical pricing. While the Company cannot predict whether legislative or
regulatory proposals will be adopted or what effect those proposals or managed
care efforts may have on its business, the announcement and/or adoption of such
proposals or efforts could have a material adverse effect on the Company. In the
United States and elsewhere, sales of prescription pharmaceuticals are dependent
in whole or in part on the availability of reimbursement to the consumer from
third party payors, such as government and private insurance plans, and these
third party payors frequently mandate predetermined discounts from list prices.
Third party payors are increasingly challenging the prices charged for medical
products and services. If the Company succeeds in bringing one or more products
to the market, there can be no assurance that these products will be considered
cost effective or that reimbursement to the consumer will be available or will
be sufficient to allow the Company to sell its products on a competitive basis.
See "Business--Health Care Reform Measures and Third Party Reimbursement."

17
<PAGE>
NO ASSURANCE OF MARKET ACCEPTANCE

The Company's success will depend in substantial part on the extent to which
any product it develops achieves market acceptance. The degree of market
acceptance will depend upon a number of factors, including the receipt and scope
of regulatory approvals, the establishment and demonstration in the medical
community of the safety and effectiveness of the Company's products and their
potential advantages over existing treatment methods, and reimbursement policies
of government and third party payors. There can be no assurance that physicians,
patients, payors or the medical community in general will accept or utilize any
product that the Company may develop.

RISKS RELATING TO COACTIVE THERAPY

The Company's success will also depend in large part on the extent to which
coactive therapy for the treatment of HIV in the United States and Europe and
for the treatment of HBV in developing areas of the world, particularly Asia,
achieves market acceptance. Present coactive treatment regimens for the
treatment of HIV are expensive (published reports indicate the cost per patient
per year can exceed $13,000), and may increase as new combinations are
developed. These costs have resulted in limitations in the reimbursement
available from third party payors for the treatment of HIV infection, and the
Company expects that reimbursement pressures will continue in the future. If
coactive therapy is accepted as a method to treat HBV, treatment regimens are
also likely to be expensive. The Company expects that even the cost of
monotherapy for HBV will be considered expensive in developing countries where
HBV infection is most prevalent. Any failure of coactive therapy to achieve
significant market acceptance for the treatment of HIV or potentially HBV could
have a material adverse effect on the Company.

LIMITED PRODUCT LIABILITY INSURANCE; INSURANCE RISKS

The Company's business will expose it to potential product liability risks
that are inherent in the testing, manufacturing and marketing of pharmaceutical
products. There can be no assurance that product liability claims will not be
asserted against the Company. The Company currently has only limited product
liability insurance relating to potential claims arising from its clinical
trials. The Company intends to expand its insurance coverage if and when the
Company begins marketing commercial products. There can be no assurance,
however, that the Company will be able to obtain any additional product
liability insurance on commercially acceptable terms or that the Company will be
able to maintain its existing insurance and/or any additional insurance it may
obtain in the future at a reasonable cost or in sufficient amounts to protect
the Company against potential losses. A successful product liability claim or
series of claims brought against the Company could have a material adverse
effect on the Company.

HAZARDOUS MATERIALS

The Company's drug development programs involve the controlled use of
hazardous materials, chemicals, viruses and various radioactive compounds.
Although the Company believes that its handling and disposing of such materials
comply with the standards prescribed by state and federal regulations, the risk
of accidental contamination or injury from these materials cannot be completely
eliminated. In the event of such an accident, the Company could be held liable
for any damages or fines that result and any such liability could exceed the
resources of the Company. See "Business--Government Regulation."

CONCENTRATION OF STOCK OWNERSHIP; CONTROL BY MANAGEMENT AND EXISTING
STOCKHOLDERS

Upon completion of the Offering, the Company's directors, executive officers
and their respective affiliates will beneficially own approximately 37.8% of the
Company's outstanding Common Stock (approximately 37.0% if the Underwriters'
over-allotment option is exercised in full). As a result, these stockholders
will be able to exercise significant influence over all matters requiring
stockholder approval,

18
<PAGE>
including the election of directors and the approval of significant corporate
transactions. Such concentration of ownership may also have the effect of
delaying or preventing a change in control of the Company that may be favored by
other stockholders. See "Management" and "Principal Stockholders."

POTENTIAL ADVERSE MARKET IMPACT OF SHARES ELIGIBLE FOR FUTURE SALE; REGISTRATION
RIGHTS

Sales of a substantial number of shares of Common Stock in the public market
following the Offering could adversely affect the market price of the Common
Stock. In addition, holders of approximately 10,850,000 shares of Common Stock
(including shares issuable upon the exercise of outstanding warrants) are
entitled to certain rights with respect to registration of such shares of Common
Stock for offer or sale to the public, and the Company recently filed a
registration statement to register the resale of 2,789,500 of these shares. The
holders of approximately 10,250,000 of the shares with registration rights, as
well as the holders of approximately 3,700,000 additional shares of Common
Stock, have executed lockup agreements pursuant to which they have agreed not to
sell any of these shares for a period of 90 days after the date of this
Prospectus without the prior written consent of SBC Warburg Dillon Read Inc. See
"Underwriting." Any such sales may have an adverse effect on the Company's
ability to raise needed capital through an offering of its equity or convertible
debt securities and may adversely affect the prevailing market price of the
Common Stock. See "Description of Capital Stock--Registration Rights."

VOLATILITY OF STOCK PRICE

The market price of the Company's Common Stock is likely to be volatile and
could be subject to wide fluctuations in response to factors such as
announcements of the results of clinical trials, developments with respect to
patents or proprietary rights, announcements of technological innovations, new
products or new contracts by the Company or its competitors, actual or
anticipated variations in the Company's operating results due to a number of
factors including, among others, the level of development expenses, changes in
financial estimates by securities analysts, conditions and trends in the
pharmaceutical and other industries, adoption of new accounting standards
affecting the industry, general market conditions and other factors. As a
result, it is possible that the Company's operating results will be below the
expectations of market analysts and investors, which could have a material
adverse effect on the prevailing market price of the Common Stock.

Further, the stock market has experienced extreme price and volume
fluctuations that have particularly affected the market prices of equity
securities of many pharmaceutical and biotechnology companies and that often
have been unrelated or disproportionate to the operating performance of such
companies. These market fluctuations, as well as general economic, political and
market conditions such as recessions or international currency fluctuations, may
adversely affect the market price of the Common Stock. In the past, following
periods of volatility in the market price of the securities of companies in the
pharmaceutical and biotechnology industries, securities class action litigation
has often been instituted against those companies. Such litigation, if
instituted against the Company, could result in substantial costs and a
diversion of management attention and resources, which would have a material
adverse effect on the Company. The realization of any of the risks described in
these "Risk Factors" could have a dramatic and adverse impact on the market
price of the Common Stock.

BROAD DISCRETION IN USE OF PROCEEDS

The net proceeds of the Offering will be added to the Company's working
capital and will be available for general corporate purposes, including product
development programs. As of the date of this Prospectus, the Company cannot
specify with certainty the particular uses for the net proceeds to be added to
its working capital. Accordingly, management will have broad discretion in the
application of such net proceeds. See "Use of Proceeds" and "Management's
Discussion and Analysis of Financial Condition and Results of Operations."

19
<PAGE>
ANTITAKEOVER EFFECTS OF CHARTER, BYLAWS AND DELAWARE LAW

The Company's Second Restated Certificate of Incorporation (the
"Certificate") authorizes the Board to issue shares of undesignated preferred
stock without stockholder approval on such terms as the Board may determine. The
rights of the holders of Common Stock will be subject to, and may be adversely
affected by, the rights of the holders of any such preferred stock that may be
issued in the future. Moreover, the issuance of such preferred stock may make it
more difficult for a third party to acquire, or may discourage a third party
from acquiring, a majority of the voting stock of the Company. The Company's
Restated Bylaws (the "Bylaws") divide the Board into three classes of directors
with each class serving a three year term. These and other provisions of the
Certificate and the Bylaws, as well as certain provisions of Delaware law, could
delay or impede the removal of incumbent directors and could make more difficult
a merger, tender offer or proxy contest involving the Company, even if such
events could be beneficial to the interest of the Company's stockholders. Such
provisions could limit the price that certain investors might be willing to pay
in the future for the Common Stock. See "Description of Capital Stock--
Preferred Stock" and "Description of Capital Stock--Antitakeover Effects of
Charter, Bylaws and Delaware Law."

IMMEDIATE AND SUBSTANTIAL DILUTION

Purchasers of the Common Stock in the Offering will experience immediate and
substantial dilution estimated at $10.69 per share in the net tangible book
value of the Common Stock from the public offering price. To the extent that
outstanding options and warrants to purchase the Company's Common Stock are
exercised, there will be further dilution. See "Dilution."

NO DIVIDENDS

The Company has never declared or paid any cash dividends on its capital
stock. The Company currently does not intend to pay any cash dividends in the
foreseeable future and intends to retain its earnings, if any, for the operation
of its business.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

Statements in this Prospectus regarding the dates on which the Company
anticipates commencing clinical trials with its drug candidates and anticipated
developments in the market for anti-HIV drugs constitute forward-looking
statements within the meaning of Section 27A of the Securities Act of 1933, as
amended (the "Securities Act"), and Section 21E of the Securities Exchange Act
of 1934, as amended (the "Exchange Act"). These statements are subject to
certain risks and uncertainties that could cause the actual timing of such
clinical trials and developments in the market for anti-HIV drugs to differ
materially from those projected. With respect to the dates on which the Company
anticipates commencing clinical trials, management has made certain assumptions
regarding, among other things, the successful and timely completion of
preclinical tests, the approval to conduct clinical trials by the FDA or other
regulatory authorities, the availability of adequate supplies of drug substance,
the pace of patient enrollment and the availability of the capital resources
necessary to complete preclinical tests and conduct clinical trials. With
respect to future developments in the market for anti-HIV drugs, management's
assumptions include, among other things, that the number of individuals infected
with HIV will continue to increase, that current therapies will continue to have
only limited effectiveness in controlling the virus, and that additional drugs
with improved safety or effectiveness will be developed. The Company's ability
to commence clinical trials on the dates anticipated and developments in the
market for anti-HIV drugs are subject to numerous risks, including the risks
discussed under the caption "Risk Factors" contained herein. Undue reliance
should not be placed on the dates on which the Company anticipates commencing
clinical trials with respect to any of its drug candidates or anticipated
increases in the market for anti-HIV drugs. These estimates are based on the
current expectations of the Company's management which may change in the future
due to a large number of potential events, including unanticipated future
developments.

20
<PAGE>
USE OF PROCEEDS

The net proceeds to the Company from the sale of the 3,500,000 shares of
Common Stock offered hereby are estimated to be $48,445,000 ($55,831,750 if the
Underwriters' over-allotment option is exercised in full), after deducting the
underwriting discounts and commissions and estimated expenses of the Offering
payable by the Company.

The Company intends to use the net proceeds from the Offering, including the
interest thereon, for general corporate purposes, including the Company's drug
development programs such as preclinical testing and clinical trials, the
payment of license fees, the costs of obtaining patent protection and other
payments to licensors, the potential acquisition of additional drug candidates,
the development of computerized systems to support clinical trials and working
capital. The amounts actually expended for each purpose may vary significantly
depending upon numerous factors, including the progress of the Company's
development programs, the magnitude of these programs, the scope and results of
preclinical testing and clinical trials, the cost, timing and outcome of
regulatory reviews, costs under the license and/or option agreements relating to
the Company's drug candidates (including the costs of obtaining patent
protection for the Company's drug candidates), the timing and the terms of the
acquisition of any additional drug candidates, the rate of technological
advances, determinations as to the commercial potential of the Company's drug
candidates, administrative and legal expenses, the establishment of internal
capacity and third party arrangements for sales and marketing functions, the
establishment of third party arrangements for manufacturing and other factors.
The Company believes that its existing cash, cash equivalents and short-term
investments, in addition to the net proceeds of the Offering, will be adequate
to satisfy its anticipated capital requirements through June 1999.

Pending application of the net proceeds of the Offering as described above,
the Company intends to invest such net proceeds in interest-bearing, investment
grade debt securities.

PRICE RANGE OF COMMON STOCK

The Company's Common Stock is traded on the Nasdaq National Market under the
symbol "VIRS." The following table sets forth the high and low sale prices for
the Common Stock on the Nasdaq National Market from its initial public offering
on November 1, 1996, through April 8, 1998.

<TABLE>
<CAPTION>
HIGH LOW
--------- ---------
<S> <C> <C>
YEAR ENDED DECEMBER 31, 1996:
4th Quarter (November 1 through December 31) .............................................. $ 24.25 $ 10.00

YEAR ENDED DECEMBER 31, 1997:
1st Quarter................................................................................ $ 24.75 $ 14.75
2nd Quarter ............................................................................... 26.88 14.50
3rd Quarter................................................................................ 24.88 18.13
4th Quarter................................................................................ 19.75 14.50

YEAR ENDED DECEMBER 31, 1998:
1st Quarter................................................................................ $ 21.13 $ 14.63
2nd Quarter (through April 8).............................................................. 17.75 15.13
</TABLE>

On April 8, 1998, the last reported sale price of the Common Stock was
$15.25 per share. As of January 31, 1998, there were approximately 215 holders
of record, and approximately 1,700 beneficial holders, of the Common Stock. The
Company has never declared or paid any cash dividends on its capital stock. The
Company currently does not intend to pay any cash dividends in the foreseeable
future and intends to retain its earnings, if any, for the operation of its
business.

21
<PAGE>
CAPITALIZATION

The following table sets forth the capitalization of the Company at December
31, 1997, and as adjusted to give effect to the sale by the Company of the
3,500,000 shares of Common Stock offered hereby at the public offering price of
$15.00 per share, after deducting the underwriting discounts and commissions and
estimated expenses of the Offering payable by the Company, and the application
of the net proceeds therefrom. See "Use of Proceeds." This table should be read
in conjunction with the Company's consolidated financial statements and the
notes thereto included elsewhere herein.
<TABLE>
<CAPTION>
DECEMBER 31, 1997
----------------------
<S> <C> <C> <C>
AS
ACTUAL ADJUSTED
---------- ----------

<CAPTION>
(IN THOUSANDS)
<S> <C> <C> <C>
Short-term debt:
Capital lease obligation--current.................................................... $ 178 $ 178
Long-term debt--current ............................................................. 181 181
-
---------- ----------
Total short-term debt ............................................................. $ 359 $ 359
-
-
---------- ----------
---------- ----------
Long-term debt, less current portion:
Capital lease obligation--noncurrent................................................. $ 300 $ 300
Long-term debt....................................................................... 178 178
-
---------- ----------
Total long-term debt, less current portion......................................... 478 478
-
---------- ----------
Stockholders' equity:
Common Stock, $0.001 par value; 75,000,000 shares authorized; 19,995,338 shares
issued and outstanding actual; 23,502,338 shares issued and outstanding as adjusted
(1)................................................................................ 20 24
Warrants............................................................................. 114 114
Additional paid-in capital........................................................... 102,260 150,701
Accumulated deficit during development stage......................................... (49,552) (49,552)
Deferred compensation................................................................ (125) (125)
-
---------- ----------
Total stockholders' equity ........................................................ 52,717 101,162
-
---------- ----------
Total capitalization............................................................. $ 53,554 $ 101,999
-
-
---------- ----------
---------- ----------
</TABLE>

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

(1) Excludes as of January 31, 1998, (i) 1,797,768 shares of Common Stock
issuable upon the exercise of outstanding options (at a weighted average
exercise price of $9.57 per share) under the 1996 Plan, (ii) an aggregate of
1,350,451 additional shares of Common Stock reserved for future option
grants or stock issuances under the 1996 Plan and the Company's Employee
Stock Purchase Plan (which amount includes 1,000,000 shares of Common Stock
available for issuance as a result of an amendment to the 1996 Plan that has
been approved by the Board but is subject to stockholder approval), (iii)
46,000 shares of Common Stock issuable upon the exercise of outstanding
warrants (at a weighted average exercise price of $2.23 per share), (iv) up
to 2,100,000 shares of Common Stock issuable upon the achievement of certain
development milestones relating to DMP-450 or one of Avid's other compounds
and (v) additional shares of Common Stock available for issuance in 1999,
2000 and 2001 as a result of an amendment to the 1996 Plan providing for
automatic annual increases in the number of shares available for issuance
under the 1996 Plan, which amendment has been approved by the Board but is
subject to stockholder approval. See "Description of Capital Stock" and
notes 6, 7 and 10 of notes to consolidated financial statements.

22
<PAGE>
DILUTION

The net tangible book value of the Company at December 31, 1997, was
$52,717,000, or $2.64 per share. Net tangible book value per share represents
the amount of total tangible assets of the Company less total liabilities
divided by the number of shares of Common Stock outstanding. After giving effect
to the sale by the Company of the 3,500,000 shares of Common Stock offered
hereby at the public offering price of $15.00 per share and after deducting the
underwriting discounts and commissions and estimated expenses of the Offering
payable by the Company, the Company's net tangible book value as of December 31,
1997, would have been approximately $101,162,000, or approximately $4.31 per
share. This represents an immediate increase in net tangible book value per
share of $1.67 to existing holders of Common Stock and immediate dilution in net
tangible book value per share of $10.69 per share to new investors purchasing
Common Stock in the Offering. The following table illustrates the per share
dilution:

<TABLE>
<S> <C> <C>
Public offering price per share............................. $ 15.00
Net tangible book value per share of Common Stock
as of December 31, 1997................................. $ 2.64
Increase per share attributable to new investors ......... 1.67
---------

Net tangible book value per share of Common Stock
as adjusted as of December 31, 1997....................... 4.31
---------
Dilution per share to new investors......................... $ 10.69
---------
---------
</TABLE>

23
<PAGE>
SELECTED CONSOLIDATED FINANCIAL DATA

The selected consolidated statement of operations data with respect to the
years ended December 31, 1997 and 1996, and with respect to the period from
inception (July 12, 1995) through December 31, 1995, and the consolidated
balance sheet data at December 31, 1997 and 1996, set forth below are derived
from the consolidated financial statements of the Company included elsewhere in
this Prospectus, which have been audited by Price Waterhouse LLP, independent
accountants. The consolidated balance sheet data at December 31, 1995, set forth
below is derived from the consolidated financial statements of the Company which
are included in the Company's Annual Report on Form 10-K for the year ended
December 31, 1996, which has been audited by Price Waterhouse LLP, independent
accountants. The selected consolidated financial data set forth below should be
read in conjunction with "Management's Discussion and Analysis of Financial
Condition and Results of Operations" and the Company's consolidated financial
statements and the notes thereto included elsewhere herein. Historical results
are not necessarily indicative of future results of operations.

<TABLE>
<CAPTION>
PERIOD FROM
INCEPTION
(JULY 12,
YEAR ENDED DECEMBER 1995)
31, THROUGH
---------------------- DECEMBER 31,
1997 1996 1995
---------- ---------- --------------
<S> <C> <C> <C>
(IN THOUSANDS, EXCEPT PER SHARE
AMOUNTS)
STATEMENT OF OPERATIONS DATA:
Operating expenses:
License fees......................................................... $ 610 $ 3,267 $ --
Development ......................................................... 22,240 4,967 --
Purchased research and development (1)............................... 11,261 -- --
General and administrative........................................... 7,071 3,558 1,004
---------- ---------- -------
Loss from operations .................................................. (41,182) (11,792) (1,004)
Interest income, net .................................................. 3,514 875 37
---------- ---------- -------
Net loss .............................................................. $ (37,668) $ (10,917) $ (967)
---------- ---------- -------
---------- ---------- -------
Basic and diluted net loss per common share (2)........................ $ (2.00) $ (1.89) $ (0.60)
---------- ---------- -------
---------- ---------- -------
Shares used in computing net loss per common share (2)................. 18,871 5,784 1,624
---------- ---------- -------
---------- ---------- -------
</TABLE>

<TABLE>
<CAPTION>
DECEMBER 31,
---------------------------------------
1997 1996 1995
---------- ---------- ---------------
<S> <C> <C> <C>
(IN THOUSANDS)
BALANCE SHEET DATA:
Cash and cash equivalents.............................................. $ 34,698 $ 25,255 $ 3,082
Working capital (3).................................................... 50,247 41,349 2,868
Investments............................................................ 23,098 27,946 --
Total assets........................................................... 61,878 55,495 3,102
Capital lease obligation--noncurrent................................... 300 364 --
Long-term debt ........................................................ 178 -- --
Accumulated deficit during development stage........................... (49,552) (11,884) (967)
Total stockholders' equity ............................................ 52,717 52,656 2,888
</TABLE>

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

(2) See note 1 of notes to consolidated financial statements for information
concerning the computation of net loss per common share and shares used in
computing net loss per common share.

(3) Working capital represents the difference between the Company's current
assets and current liabilities.

24
<PAGE>
MANAGEMENT'S DISCUSSION AND ANALYSIS OF
FINANCIAL CONDITION AND RESULTS OF OPERATIONS

THE FOLLOWING DISCUSSION AND ANALYSIS SHOULD BE READ IN CONJUNCTION WITH
"SELECTED CONSOLIDATED FINANCIAL DATA" AND THE COMPANY'S CONSOLIDATED FINANCIAL
STATEMENTS AND NOTES THERETO APPEARING ELSEWHERE IN THIS PROSPECTUS.

OVERVIEW

Triangle is engaged in the development of new drug candidates primarily in
the antiviral area. Since its inception on July 12, 1995, the Company's
operating activities have related primarily to recruiting personnel, negotiating
license and option arrangements for its drug candidates, raising capital and
developing its drug candidates. The Company has not received any revenues from
the sale of products and does not expect any of its drug candidates to be
commercially available until at least the year 2000. As of December 31, 1997,
the Company's accumulated deficit was approximately $49.6 million and the
Company had utilized approximately $40.0 million of cash.

The Company's drug development programs require substantial capital
expenditures, including expenditures for preclinical testing, chemical synthetic
scale-up, manufacture of drug substance for clinical trials and toxicology
studies, clinical trials of drug candidates and payments to the Company's
licensors. The Company has been unprofitable since its inception and expects to
incur substantial and increasing losses for at least the next several years, due
primarily to the expansion of its drug development programs. The Company will
also require substantial capital expenditures relating to activities many of
which may need to occur prior to, and in anticipation of, the potential
regulatory approval of its drug candidates, including expenditures associated
with the establishment of a sales and marketing organization, the manufacture of
drug substance, the development of a distribution system with outside vendors
and other administrative expenditures necessary to support the Company. Many of
these capital expenditures may be incurred irrespective of whether the Company's
drug candidates are approved when anticipated or at all. The Company expects
that losses will fluctuate from period to period and that such fluctuations may
be substantial. See "Risk Factors--History of Operating Losses; Accumulated
Deficit; Uncertainty of Future Profitability."

The Company has only a limited operating history upon which an evaluation of
the Company and its prospects can be based. The risks, expenses and difficulties
encountered by companies at an early stage of development must be considered
when evaluating the Company's prospects. To address these risks, the Company
must, among other things, successfully develop and commercialize its drug
candidates, secure all necessary proprietary rights, respond to competitive
developments and continue to attract, retain and motivate qualified personnel.
There can be no assurance that the Company will be successful in addressing
these risks. See "Risk Factors--Development Stage Company; Uncertainty of
Product Development."

The operating expenses of the Company will depend on several factors,
including the level of development expenses and the potential commercialization
of its drug candidates. Development expenses will depend on the progress and
results of the Company's drug development efforts, which the Company cannot
predict. Management may in some cases be able to control the timing of
development expenses in part by accelerating or decelerating preclinical testing
and clinical trial activities. The level of expenses relating to the
establishment of a sales and marketing organization, the manufacture of drug
substance, the development of a distribution system with outside vendors and
other administrative expenditures will depend on the success of the development
of the Company's drug candidates; however, many of these capital expenditures
may be incurred irrespective of whether the Company's drug candidates are
approved when anticipated or at all. As a result of these factors, the Company
believes that period to period comparisons are not necessarily meaningful and
should not be relied upon as an indication of future performance. Due to all of
the foregoing factors, it is possible that the Company's operating results will
be

25
<PAGE>
below the expectations of market analysts and investors. In such event, the
prevailing market price of the Common Stock could be materially adversely
affected. See "Risk Factors--Volatility of Stock Price."

RESULTS OF OPERATIONS

AVID CORPORATION ACQUISITION

On August 28, 1997 (the "Acquisition Date"), the Company acquired Avid.
Pursuant to the merger agreement, Triangle issued 400,000 shares of Common Stock
in exchange for all outstanding capital stock of Avid. Triangle also agreed to
issue up to 2,100,000 additional shares of Common Stock, the issuance of
1,600,000 shares of which is contingent upon Triangle initiating pivotal Phase
II clinical trials with DMP-450 before February 28, 1999, or electing on or
before that date to continue the development of DMP-450 even if such clinical
trials have not been initiated. The issuance of the remaining 500,000 shares is
contingent upon the attainment of other development milestones with DMP-450 or
one of Avid's other compounds. Issuance of any of these contingent shares will
be recorded as additional purchase price and will be allocated upon resolution
of the underlying contingency. The 400,000 shares issued had an aggregate fair
market value of approximately $8.1 million and direct transaction costs were
approximately $1.1 million, primarily comprised of investment banking and legal
fees. The total purchase price of $9.2 million has been allocated to the assets
purchased and liabilities assumed based on their respective fair market values.
In connection with the acquisition, the Company incurred a charge of $11.3
million in the third quarter of 1997 for acquired in-process research and
development as it assumed operating and other liabilities of Avid totaling
approximately $1.3 million and certain development liabilities totaling
approximately $1.0 million. The merger was accounted for as a purchase and the
operating results of Avid have been included in the Company's consolidated
financial statements from the Acquisition Date.

Avid's principal assets consist of worldwide license rights to DMP-450, a
protease inhibitor, for the treatment of HIV infection, early preclinical stage
compounds for the treatment of HBV infection, proprietary assays to screen
compounds for the treatment of HBV and assay technology for potential use in
screening compounds for the treatment of hepatitis C virus infection.

INTEREST INCOME, NET

The Company had total net interest income of $3.5 million in 1997, compared
to $875,000 in 1996 and $37,000 in the period from inception (July 12, 1995)
through December 31, 1995 (the "Inception Period"). The increase in interest
income in 1997 compared to 1996 and the Inception Period is due primarily to an
increase in investments associated with financing activities. See "--Liquidity
and Capital Resources."

LICENSE FEES

License fees totaled $610,000 in 1997, compared to $3.3 million in 1996. The
decrease relates to the decrease in the number of license agreements executed in
1997 as compared to 1996 and the achievement by the Company of certain financing
milestones in 1996. All license fees incurred to date are related to the
execution of license agreements and the achievement by the Company of certain
financing milestones. The Company recorded no license fees in the Inception
Period. Future license fees may also consist of milestone payments under
licensing arrangements, the amount of which could be substantial and the timing
of which will depend on a number of factors that the Company cannot predict.
These factors include, among others, the success of the Company's drug
development programs and the extent to which the Company in-licenses additional
drug candidates. See "--Liquidity and Capital Resources."

DEVELOPMENT EXPENSES

Development expenses totaled $22.2 million in 1997, compared to $5.0 million
in 1996. Development expenses in 1997 consisted primarily of expenses for drug
synthesis, clinical trials, toxicology studies,

26
<PAGE>
compensation, and preclinical testing and patent related activities of the
Company's drug candidates. The significant increase in development expenses in
1997 compared to 1996 is due primarily to the expansion of the Company's
development activities for its drug candidates. During 1997 and 1996,
development expenses were reduced by approximately $1.2 million and $832,000,
respectively, relating to the reimbursement of certain development expenses
under a license agreement for one of the Company's drug candidates. No
development expenses were incurred in the Inception Period. The Company expects
its development expenses to increase substantially in the future due to
continued expansion of drug development activities, including preclinical
testing, toxicology studies and the manufacture of drug substance for
preclinical tests and clinical trials. In addition, if the Company in-licenses
or otherwise acquires rights to additional drug candidates, development expenses
would increase as a result. For example, the Company's recent acquisition of a
license to L-FMAU will increase the Company's development expenses in future
periods.

PURCHASED RESEARCH AND DEVELOPMENT EXPENSES

Purchased research and development expenses totaled $11.3 million in 1997,
and relate to the Company's acquisition of Avid. This amount represents a charge
for Avid's in-process research and development. If the Company initiates pivotal
Phase II clinical trials with DMP-450 before February 28, 1999, or elects on or
before that date to continue the development of DMP-450 even if such clinical
trials have not been initiated, the Company will be obligated to issue an
additional 1,600,000 shares of Common Stock. The issuance of another 500,000
shares of Common Stock is contingent upon the attainment of other development
milestones with DMP-450 or one of Avid's other compounds. Issuance of any of
these contingent shares will be recorded as additional purchase price and will
be allocated upon resolution of the underlying contingency. The amount recorded
will be the fair market value of the Common Stock issued at the time the
contingency is resolved. No purchased research and development expenses were
incurred in 1996 or in the Inception Period.

GENERAL AND ADMINISTRATIVE EXPENSES

General and administrative expenses totaled $7.1 million in 1997, compared
to $3.6 million and $1.0 million in 1996 and the Inception Period, respectively.
Administrative expenses in 1997 consisted primarily of compensation expenses,
rent expense and amounts paid for outside professional services. The increases
in 1997 compared to 1996 and the Inception Period are due primarily to the
growth of the Company's operations. The Company expects its general and
administrative expenses to increase significantly in future periods.

LIQUIDITY AND CAPITAL RESOURCES

The Company has financed its operations since inception (July 12, 1995)
through December 31, 1997, primarily with the net proceeds received from private
placements of equity securities, which provided aggregate net proceeds of
approximately $51.7 million (net of offering costs), and from the Company's
initial public offering, which was completed in November 1996 and provided
aggregate net proceeds of approximately $41.0 million (net of offering costs).
In addition, the Company received approximately $2.0 million as reimbursement of
certain development expenses under a license agreement for one of its drug
candidates.

At December 31, 1997, the Company had net working capital of $50.2 million,
an increase of $8.9 million over December 31, 1996. The increase in working
capital is principally the result of a private placement of equity securities
completed by the Company in June 1997 and returns on larger cash and investment
balances. The Company's principal source of liquidity at December 31, 1997, was
$34.7 million in cash and cash equivalents and $23.1 million in investments
which are "available for sale," reflecting a $4.6 million increase of cash, cash
equivalent and investment balances over December 31, 1996. The Company utilized
approximately $29.0 million in cash during 1997, primarily for its expanded drug

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<PAGE>
development activities, and has utilized approximately $40.0 million in cash
since its inception on July 12, 1995.

The Company had a note payable and secured equipment lease line obligations
totaling $837,000 at December 31, 1997 ($466,000 at December 31, 1996), of which
$359,000 was classified as a current liability. The note payable was issued to
finance an insurance policy over a two year period. The Company had utilized
$530,000 of the secured equipment lease line facility at December 31, 1997,
which expired on August 9, 1997. The Company utilized $2.3 million in cash in
1997, as compared to $794,000 and $23,000 in 1996 and the Inception Period,
respectively, for the purchase of property, plant and equipment, primarily
associated with the growth of the Company's laboratory operations. The Company
expects its capital expenditures to increase in future periods.

In conjunction with the development of its drug candidates, the Company
out-sources certain aspects of clinical trials and focuses on what it believes
are the most critical aspects of the development process. Accordingly, the
Company has entered into contractual arrangements with selected third parties
for certain aspects of its drug development. Although the commitment under these
contracts is dependent upon results of the underlying clinical and toxicology
studies, the Company's management estimates the commitment to be approximately
$3.6 million at December 31, 1997, and immaterial at December 31, 1996.

The Company expects that its capital requirements will increase
substantially in future periods as the Company funds its drug development
programs, develops a sales and marketing organization, acquires drug substance
from third party manufacturers, develops a distribution system with outside
vendors and incurs other administrative expenditures necessary to support the
Company. The Company's future capital requirements will depend on many factors,
including the progress of the Company's drug development programs, the magnitude
of these programs, the scope and results of preclinical testing and clinical
trials, the cost, timing and outcome of regulatory reviews, costs under the
license and/or option agreements relating to the Company's drug candidates
(including the costs of obtaining patent protection for the Company's drug
candidates), the timing and the terms of the acquisition of any additional drug
candidates, the rate of technological advances, determinations as to the
commercial potential of the Company's drug candidates, administrative and legal
expenses, the establishment of internal capacity and third party arrangements
for sales and marketing functions, the establishment of third party arrangements
for manufacturing and other factors. Amounts payable by the Company in the
future under its existing license agreements are uncertain due to a number of
factors, including the progress of the Company's drug development programs, the
Company's ability to obtain approval to commercialize any drug candidate and the
commercial success of any approved drug. The Company's existing license
agreements and the merger agreement with Avid, as of December 31, 1997, require
future payments of up to $43.3 million in cash and up to 2,100,000 shares of
Common Stock contingent upon the achievement of certain development milestones.
One of the Company's licensors has the option to receive $2.0 million of such
future milestone payments in shares of Common Stock (based on the then current
market price) in lieu of a cash payment. Additionally, the Company will pay
royalties based on a percentage of net sales of each licensed product
incorporating these drug candidates. Most of the Company's license agreements
require minimum royalty payments after regulatory approval. Depending on the
Company's success and timing in obtaining regulatory approval, aggregate annual
minimum royalty payments could range from $500,000 (if only a single drug
candidate is approved for one indication) to $49.5 million (if all drug
candidates are approved for all indications) under the Company's existing
license agreements.

On February 27, 1998, the Company executed a license agreement with Bukwang
for L-FMAU, the Company's eighth licensed drug candidate, for the treatment of
HBV and all other human antiviral applications. The Company paid a license
initiation fee of $6.0 million and will be required to make development
milestone payments of up to $32.5 million and sales milestone payments of up to
$30.0 million. The Company is also required to make annual minimum royalty
payments beginning the third year after FDA registration is granted for the
first licensed product. Payment of the license initiation fee

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<PAGE>
resulted in the Company incurring a $6.0 million charge in the first quarter of
1998. The license agreement grants Triangle exclusive worldwide rights, except
for Korea. The Company will be required to meet certain milestone obligations
and to conduct and fund certain development work with respect to L-FMAU.

The Company believes that its existing cash, cash equivalents and short-term
investments, in addition to the net proceeds of the Offering, will be adequate
to satisfy its anticipated capital requirements through June 1999. The Company
expects that it will be required to raise substantial additional funds through
equity or debt financings, collaborative arrangements with corporate partners or
from other sources. There can be no assurance that additional funding will be
available on favorable terms from any of these sources or at all. See "Risk
Factors--Future Capital Needs; Uncertainty of Additional Funding."

LITIGATION AND OTHER CONTINGENCIES

As discussed in note 11 of the notes to consolidated financial statements,
the Company is indirectly involved in several opposition and interference
proceedings and one lawsuit filed in Australia regarding the patent rights
related to three of its licensed drug candidates, including FTC. Although the
Company is not a named party in any of these proceedings, it is obligated to
reimburse its licensors for certain legal expenses associated with these
proceedings. The Company cannot predict the outcome of these proceedings. The
Company believes that an adverse judgment would not result in a material
financial obligation to the Company, nor would the Company have to recognize an
impairment under Statement of Financial Accounting Standards No. 121 "ACCOUNTING
FOR IMPAIRMENT OF LONG-LIVED ASSETS" as no amounts have been capitalized related
to these drug candidates. However, any development in these proceedings adverse
to the Company's interests, including but not limited to any adverse development
related to the patent rights licensed to the Company for these three drug
candidates or the Company's rights or obligations related thereto, could have a
material adverse effect on the Company's future consolidated financial position,
results of operations and cash flow. See "Risk Factors--Uncertainty of Patents;
Dependence on Patents, Licenses and Proprietary Rights."

RECENT ACCOUNTING PRONOUNCEMENTS

Effective December 31, 1997, the Company adopted Statement of Financial
Accounting Standard No. 128 "EARNINGS PER SHARE" ("SFAS 128") and will adopt
Statement of Financial Accounting Standard No. 130 "REPORTING COMPREHENSIVE
INCOME" ("SFAS 130") in 1998. SFAS 128 establishes and simplifies the standard
for computing earnings per share ("EPS") from previous EPS guidance. Adoption of
SFAS 128 resulted in the restatement of the Company's net loss per share for all
previous periods as this standard requires a historical approach methodology in
calculating EPS rather than the methodology required by superceded guidance
under which EPS was previously presented.

YEAR 2000 COMPLIANCE

The Company recognizes the need to ensure that its operations will not be
adversely impacted by Year 2000 hardware and software issues. The Company
intends to confirm its compliance regarding Year 2000 issues for both internal
and external information systems by the end of 1998. This process will entail
communicating with significant suppliers, financial institutions, insurance
companies and other parties that provide significant services to the Company.
Expenditures required to make the Company Year 2000 compliant will be expensed
as incurred and are not expected to be material to the Company's consolidated
financial position or results of operations.

29
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BUSINESS

OVERVIEW

Triangle is engaged in the development of new drug candidates primarily in
the antiviral area, with a particular focus on therapies for HIV, including
AIDS, and HBV. Triangle has an existing portfolio consisting of eight licensed
drug candidates and one drug candidate for which the Company has an option to
acquire a license. Members of the Company's senior management, prior to joining
Triangle, played instrumental roles in the development of several leading
antiviral therapies. The Company is capitalizing on its management team's
expertise in the identification, clinical development and commercialization of
drug candidates, as well as on advances in virology and immunology, to develop
and commercialize new drug candidates that can be used alone or coactively to
treat serious diseases.

The treatment of HIV infection using coactive therapy (combination therapy)
has shown significant clinical benefits, including reducing virus levels and
increasing patient longevity. The Company was founded based in part on its
management team's belief that the prolonged use of coactive therapy will
generate demand for new anti-HIV drugs with favorable resistance, compliance
and/or tolerance profiles. The Company believes the use of anti-HIV drugs will
increase because (i) the use of multiple drugs by individual patients on
coactive therapy will continue to increase, (ii) significant numbers of
previously untreated patients will seek medical care as the benefits of coactive
therapy become more widely understood and (iii) patient longevity will continue
to increase and thus lengthen the duration of drug therapy.

Triangle is actively developing the following drug candidates which it
believes have the potential to become valuable tools in the coactive treatment
of serious diseases:

DRUG CANDIDATES TO TREAT HIV

DMP-450. A protease inhibitor acquired by Triangle in late 1997 through the
acquisition of Avid, DMP-450 has demonstrated potent IN VITRO activity against
HIV and was generally well tolerated in a Phase I study. Triangle re-initiated
Phase I trials with DMP-450 in January 1998.

DRUG CANDIDATE TO TREAT HBV

L-FMAU. A nucleoside analogue, L-FMAU is a recent addition to Triangle's
portfolio and has demonstrated potent activity against a hepatitis virus in
naturally infected woodchucks (a disease state

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<PAGE>
closely resembling that of hepatitis B in humans), both during the course of
treatment and for a period of up to 36 weeks following treatment. Triangle
intends to conduct preclinical studies with L-FMAU in 1998.

DRUG CANDIDATES TO TREAT HIV AND HBV

DAPD. A purine dioxolane nucleoside, Triangle believes that DAPD is the
only drug candidate in its nucleoside series that is currently being developed
for the treatment of viral diseases. Against HIV, the Company believes that,
because of its unique structure and pharmacological properties, DAPD may offer
advantages over other currently marketed nucleosides. Against HBV, DAPD has
demonstrated activity as potent as 3TC IN VITRO as well as in studies with the
woodchuck hepatitis model. Triangle intends to initiate Phase I clinical trials
with DAPD in late 1998 or early 1999.

DRUG CANDIDATE TO TREAT CANCER

The Company believes that certain of its drug candidates may meet the
criteria established by the FDA for accelerated approval. If so, the Company may
be able to commercialize these drug candidates in a shorter time period than has
historically been required for drugs that do not meet the criteria for
accelerated approval. There can be no assurance, however, that any of the
Company's drug candidates will qualify for accelerated approval or be approved
in a time period that is shorter than would be historically expected. See
"--Government Regulation."

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STRATEGY

Triangle's goal is to create a portfolio of commercialized drugs primarily
for antiviral and anticancer therapies. The Company seeks to achieve its goal
through the following strategies:

FOCUS ON VIRAL DISEASES AND CANCER. The expertise of Triangle's management
team lies in identifying, developing and commercializing drugs for the treatment
of viral diseases and cancer. The Company is targeting the viral disease and
cancer markets because the Company believes the significant unmet medical need
and the rapid pace of scientific advances occurring in the treatment of these
diseases give these significant markets attractive growth potential. The Company
also believes that the relatively high concentration of prescribers that treat
HIV and cancer will enable the Company to promote most drug candidates it
successfully develops to these prescribers through a small, specialized direct
sales force.

APPLY SELECTIVE CRITERIA TO DRUG CANDIDATES. In evaluating drug candidates
for its product development programs, the Company seeks to in-license drug
candidates for which favorable preclinical, and where possible, clinical data
already exist. The Company uses its expertise to identify drug candidates that
it judges to have attractive preclinical profiles. In addition, the Company
prefers, where practical, to in-license drug candidates that have either
undergone some testing in humans (E.G., FTC, DMP-450 and alanosine) or share
characteristics with drugs that are currently approved for use in humans (E.G.,
2-CdAP). The Company intends to apply these selection standards where feasible
in evaluating potential drug candidates for in-licensing.

LEVERAGE RELATIONSHIPS. As a result of their instrumental roles in the
identification, clinical development and commercialization of antiviral and
anticancer therapies, members of the Company's management team and Scientific
Advisory Board have extensive contacts in academia and industry. These contacts
were instrumental to the Company's acquisition of its existing drug candidates,
and the Company believes they will be valuable in its efforts to develop and
commercialize its existing and future drug candidates.

DEVELOP DRUGS FOR USE IN COACTIVE THERAPY. Coactive therapy is currently a
common method to treat certain cancers and the Company believes that it is
becoming an increasingly accepted method to treat viral diseases such as HIV
infection. The Company seeks to identify and develop drug candidates for use in
coactive therapy that have resistance, compliance and/or tolerance profiles that
are complementary to the profiles of existing drugs. In addition, in contrast to
the competitive marketing of single drug regimens, the Company believes that any
drug it develops as part of a coactive regimen will benefit from the promotional
efforts of the marketers of the other drugs in the regimen.

FOCUS ON SMALL MOLECULE DRUGS. Members of the Company's management team are
well known for their successful development of and expertise in small molecule
drugs generally, and nucleosides in particular. Small molecule drugs have
several advantages over large molecule drugs such as proteins, polypeptides and
polynucleotides. For example, they are often simpler to scale-up and manufacture
than large molecule drugs. Furthermore, small molecule drugs are more likely to
be orally bioavailable, a significant advantage in treating long-term chronic
illnesses where patients prefer not to be subjected to injections over extended
periods of time.

STRATEGICALLY OUT-SOURCE ROUTINE ASPECTS OF DRUG DEVELOPMENT. Triangle
intends to maintain a limited corporate infrastructure that is focused on drug
development. Much of the drug development process consists of routine elements
that can be out-sourced to high quality, high capacity contractors. As a result,
the Company intends to focus on the aspects of drug development that require
particular expertise. For example, the Company intends to concentrate on the
design of clinical trials and the optimization of drug synthesis and to
out-source many aspects of the conduct of clinical trials and the manufacture of
drug substance. The Company believes this strategy will enable it to respond
rapidly to certain changing events, such as clinical trial results and the
availability of funds, by increasing or decreasing expenditures on particular
drug development projects or by shifting the Company's emphasis among projects.

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PRODUCT DEVELOPMENT PROGRAMS

The Company is currently focused on the development of drugs for the
treatment of viral diseases to take advantage of the opportunities presented by
the increasing use of coactive therapy. The Company believes that coactive
therapy is now recognized as the most effective available method to treat HIV
and AIDS, and is being used increasingly in the United States and Western
Europe. The Company also believes that HBV, due to its complexity and
demonstrated ability to develop resistance to therapeutic agents, may also be
more effectively treated with coactive therapy. Additionally, the Company
believes that there is a significant opportunity to develop drugs for the
treatment of cancer because of the limited clinical benefits offered by many of
the current treatments.

The Company performs a variety of tests when evaluating a drug candidate
that are designed to evaluate the potential activity, resistance profile and
toxicity of the drug candidate. For example, anti-HIV drug candidates are tested
in the Company's laboratories against both laboratory and clinical strains of
HIV in several cell lines, individually and in combination with other compounds.
In addition, other resistance and toxicity tests are sometimes performed on
behalf of the Company by carefully selected third parties.

The following table summarizes the target indications, current development
status and license territory of each of Triangle's drug candidates:

(1) The Company has licensed all drug candidates except alanosine, for which it
has acquired an option to obtain a license. See
"--License, Option and Other Material Agreements." The Company's drug
candidates have not been approved by the FDA for commercial sale.

(4) The Company is currently conducting clinical trials with FTC only for HIV.
See "--Viral Disease Program--HIV--Development Status--FTC" and "--Viral
Disease Program--HBV--Development Status--FTC."

(5) In order to focus financial and human resource support on drug candidates
which it believes have the greatest potential, the Company has elected to
limit the current support of CS-92 to the completion of the ongoing clinical
trial and of Acyclovir Monophosphate to the completion of the current
preclinical tests. Should circumstances warrant, investment in the further
development of these drug candidates may be made in the future. See "--Viral
Disease Program--HIV--Development Status-- CS-92" and "--Viral Disease
Program--Herpes Simplex Virus--Development Status of Acyclovir
Monophosphate."

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VIRAL DISEASE PROGRAM

HIV

BACKGROUND. The World Health Organization ("WHO") estimates that through
1997, 29.5 million people worldwide were living with HIV or AIDS. It is
generally believed that, in the absence of therapeutic intervention, the vast
majority of individuals infected with HIV will ultimately develop AIDS, which
currently has a fatality rate approaching 100%.

It is currently believed that a key factor in how quickly a person infected
with HIV develops AIDS is the amount of HIV in the body at any one time (the
"viral load" or "viral burden"). The failure of vaccines and other immunotherapy
to control the virus has led current researchers to focus on halting HIV
replication and reducing viral load by blocking one or both of two key enzymes
required for viral replication.

The first enzyme, reverse transcriptase, is active early in the replication
cycle and allows the virus, which is made of RNA, to transform to its DNA form
necessary for continued replication. This enzyme can be inhibited by two general
classes of drugs defined both by their structure as well as their mechanism of
action. The first general class, nucleoside analogue reverse transcriptase
inhibitors such as AZT, ddI, ddC, d4T and 3TC, bears a strong chemical
resemblance to the natural building blocks (nucleotides) of DNA and interferes
with the function of the enzyme by displacing the natural nucleotides used by
the enzyme. The second general class, non-nucleoside reverse transcriptase
inhibitors such as nevirapine and delavirdine, is composed of an extremely
diverse group of chemicals that act by attaching to the reverse transcriptase
enzyme and modifying it so that it functions less efficiently. The second
enzyme, protease, is required to permit full virus maturation. Inhibitors of
this enzyme are represented by such drugs as saquinavir, ritonavir, indinavir
and nelfinavir.

The genetic material responsible for the production of both enzymes is
extremely prone to mutations that can produce resistance to drugs targeted at
these enzymes. If antiviral therapy does not halt all viral replication, natural
selection allows the mutant strains of virus that are resistant to the drug the
patient is receiving to continue to replicate. Depending upon the particular
mutations that occur, these virus strains may be resistant to only one of the
drugs used in therapy or may be resistant to some or all of the drugs in the
same chemical or functional class. This latter phenomenon is known as
cross-resistance.

Initially, HIV was treated only with AZT, a nucleoside analogue reverse
transcriptase inhibitor, which was first introduced in 1987. Three other
nucleoside analogues--ddI, ddC and d4T--were introduced to the market in the
late 1980's. These drugs, when used alone, provided only short-term clinical
benefit, were sometimes toxic and were often considered expensive relative to
their clinical benefits. As a result, the use of anti-HIV therapy was limited
and market penetration was low (less than 25% of the infected population in the
United States).

More recently, clinical research in HIV has been facilitated by the
introduction in the mid-1990's of tests that can reliably determine the viral
load in the blood at any given time. As a result, it is now possible to rapidly
evaluate potential therapeutic agents and combinations of agents and to
determine accurately the potency and resistance profiles of these agents. This
has led to the accelerated development of a number of new therapeutic agents and
their use in coactive therapy. The use of coactive therapy, including
combinations of protease inhibitors with one or two reverse transcriptase
inhibitors, has demonstrated significant therapeutic benefit, sometimes
rendering the virus undetectable in the blood of certain patients for up to two
years to date. Additional combinations may be possible as new therapeutic agents
are developed.

In spite of these significant advances, numerous challenges remain in the
treatment of HIV. In the absence of a cure, the disease is lifelong. Although
coactive therapy has demonstrated the ability to markedly slow resistance
development, resistant mutants are already being identified to several of the
drugs currently used during the course of coactive therapy studies, and
cross-resistance among many

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<PAGE>
agents, including protease inhibitors, is being increasingly recognized. Present
coactive treatments are also often complex and expensive (published reports
indicate the cost per patient per year can exceed $13,000). Adverse reactions to
many of the drugs used in coactive therapy are common and may limit compliance
or even preclude use in some patients. Even brief instances of non-compliance
can reduce or eliminate the ability of the combination therapy to suppress the
virus, and may thus accelerate the development of resistance. The Company
believes that these challenges present an opportunity to develop additional
drugs that have attractive safety, pharmacokinetic and/or resistance profiles.

DEVELOPMENT STATUS. The Company has a portfolio of five drug candidates for
the treatment of HIV: MKC-442, FTC, DMP-450, DAPD and CS-92. Triangle's
portfolio includes at least one drug candidate in each of the three classes of
drugs currently approved for the treatment of HIV. Four are reverse
transcriptase inhibitors, although one of these (MKC-442) functions as a
non-nucleoside reverse transcriptase inhibitor, and one (DMP-450) is a protease
inhibitor.

MKC-442. The Company is currently conducting pivotal Phase II/III clinical
trials in Europe with MKC-442 in coactive regimens in HIV-infected patients to
demonstrate safety and efficacy as measured by viral load. Triangle intends to
use these trials as part of the basis of regulatory filings in the United States
and other countries. Triangle has licensed from Mitsubishi rights to MKC-442
worldwide, except in Japan, for the treatment of HIV.

MKC-442, although a nucleoside analogue, functions as a non-nucleoside
reverse transcriptase inhibitor. Preclinical tests suggest that MKC-442 may
possess characteristics that address several of the therapeutic challenges of
HIV. When tested in cell culture assay systems against wild-type
(drug-sensitive) and several mutant strains of HIV known to be resistant to
established non-nucleoside reverse transcriptase inhibitors, MKC-442 retained
much of its ability to inhibit HIV replication. In these studies, MKC-442
displayed greater potency than nevirapine against wild-type and mutant strains
of HIV. Preclinical studies of MKC-442 in two-drug combinations with AZT and ddI
and in two-drug and three-drug combinations with certain nucleoside analogue
reverse transcriptase inhibitors and protease inhibitors suggest that MKC-442
may work well in coactive therapy.

Studies in animals suggest a favorable safety and pharmacokinetic profile
for MKC-442. Animal pharmacokinetic analyses showed good oral bioavailability
and excellent penetration into the central nervous system, a significant site of
HIV replication that is poorly penetrated by many currently marketed anti-HIV
drugs. In rats, for example, the concentration of MKC-442 in the brain was 100%
of that seen in the plasma.

A Phase I study conducted by the Company evaluated the pharmacokinetics and
tolerance of single escalating doses of MKC-442 in HIV-infected volunteers. The
compound was generally well tolerated, with only a few participants experiencing
minor adverse effects at the higher dose levels. In the groups receiving higher
doses, concentrations of the drug in the plasma reached levels much higher than
the levels required to suppress 90% of the virus in culture.

The Company has also released preliminary data from an ongoing Phase I/II
double-blind, placebo-controlled trial designed to evaluate the safety and
efficacy of repeated multiple oral doses of MKC-442 in HIV-infected patients. To
date, the Company has released interim results from a total of 49 patients
treated with MKC-442 for up to two months. Doses ranging from 100 mg to 1000 mg
twice a day were given to groups of six to eight patients at each dosage level.
At the highest doses tested (750 mg and 1000 mg twice a day), the viral load was
reduced by an average of 96% in all patients after one week. This reduction was
mostly sustained at two weeks whereafter it was followed by a gradual increase
in viral load from the nadir towards baseline levels. A single point mutation at
position 103 of the reverse transcriptase that may be associated with resistance
was found in the virus obtained from some patients. In over 308 patient-weeks of
drug exposure, MKC-442 has been well tolerated and only five patients (one at
100 mg twice a day, one at 750 mg twice a day and three at 1000 mg twice a day)
have experienced a rash.

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<PAGE>
Pharmacokinetic drug interaction studies with protease inhibitors and other
agents are currently ongoing under an IND. The Company is currently conducting
pivotal Phase II/III clinical trials of MKC-442 in coactive regimens at a dose
of 750 mg twice a day in Europe under the United States IND.

FTC. The Company is completing Phase I/II clinical trials with FTC for the
treatment of HIV. Triangle has licensed worldwide rights to FTC for the
treatment of HIV and HBV from Emory.

FTC is a member of the same nucleoside series as 3TC. IN VITRO studies have
demonstrated that FTC is consistently more potent than 3TC against HIV and is a
potent antiviral agent against HIV strains obtained from a geographically
diverse set of HIV-infected patients. IN VITRO studies have also shown that FTC
shares cross-resistance patterns with 3TC. The most common resistance mutation
to these two agents also reverses resistance of the virus to AZT in some cases.

The pharmacokinetics and metabolism of FTC have been investigated in animal
studies that demonstrated that FTC was cleared rapidly from the bloodstream over
all doses studied and had good oral bioavailability. FTC was also well
tolerated. Mild anemia in mice was seen only at extremely high doses (3000
mg/kg/day).

A Phase I single dose study evaluated the pharmacokinetics and tolerance of
FTC in 12 HIV-infected volunteers. The volunteers received six single oral doses
of FTC at six day intervals ranging from 100 mg to 1200 mg. FTC was well
tolerated by all subjects in the dose range studied. FTC was absorbed rapidly
into the blood stream following oral administration and was excreted primarily
through the kidneys. While food intake slightly decreased the rate of
absorption, it did not affect overall oral bioavailability. The absorption,
metabolism and excretion of FTC were generally consistent among the subjects.

Triangle recently released initial data from an ongoing Phase I/II clinical
trial of FTC. The first two dose levels of the Phase I/II trial were
administered to ten HIV-infected volunteers to assess pharmacokinetics, safety
and antiviral efficacy over a 14-day dosing period. This brief duration was
chosen to minimize the risk of resistance development which can occur when
anti-HIV drugs are used as monotherapy. This period, however, allows preliminary
assessment of the tolerance and efficacy of the drug candidate. The preliminary
results indicated that FTC significantly reduced plasma HIV-1 RNA viral load at
the first two dose levels of 25 mg twice a day and 200 mg once a day. At the
dose of 25 mg twice a day, HIV-1 RNA in plasma in all five patients was reduced
from baseline (4.2 log(10)) by an average of 96% (1.4 log(10)) at day 14. At the
higher dose of 200 mg once a day, HIV-1 RNA in plasma from all five patients was
reduced from baseline (4.7 log(10)) by an average of 99% (2.03 log(10)) at day
14. FTC was generally well tolerated in these ten patients. The degree of viral
suppression was very consistent among patients within a given dosage group.

DMP-450. DMP-450 is currently in Phase I pharmacokinetic and tolerance
studies in the United States and Europe. Triangle obtained worldwide license
rights to DMP-450 through its acquisition of Avid in 1997. See "--License,
Option and Other Material Agreements--The DuPont Merck Pharmaceutical Company
and Avid Corporation."

DMP-450 is a potent, selective inhibitor of the HIV-1 protease that belongs
to a novel chemical class, the cyclic ureas. In preclinical laboratory tests,
DMP-450 showed a dose-dependent inhibition of HIV replication in three different
cell types and reduced the yield of virus by more than 99.9% at concentrations
as low as 0.5 mM. Resistance to the compound is conferred by the 82 or 84
mutation, consistent with mutations observed with several other protease
inhibitors. In two-drug IN VITRO combination studies with nucleoside analogue
reverse transcriptase inhibitors, such as AZT and ddI, and with MKC-442, which
functions as a non-nucleoside reverse transcriptase inhibitor, DMP-450 showed a
synergistic antiviral effect. Toxicology studies of three-month duration have
been completed in rats and dogs.

Data from a Phase I study conducted by DuPont Merck showed that DMP-450 was
generally well tolerated following single oral doses that ranged from 60 mg to
1250 mg in normal, healthy male volunteers

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for up to four days. A Phase I/II trial initiated by Avid and ongoing at the
time of the acquisition of Avid by Triangle was put on clinical hold by the FDA
in October 1997 because of the FDA's concerns regarding the toxicity observed in
some animals exposed to extremely high doses of DMP-450. The patients in the
Phase I/II study were administered oral doses that ranged from 500 mg to 750 mg
three times a day and experienced no significant adverse reactions. Following
extensive discussions between Triangle and the FDA, a Phase I pharmacokinetic
study in the United States and a Phase I safety and tolerance study in Europe
were initiated in January 1998.

DAPD. Triangle currently intends to initiate Phase I clinical trials with
DAPD for the treatment of HIV in late 1998 or early 1999. Triangle has licensed
worldwide rights to DAPD for the treatment of HIV and HBV from Emory and UGARF.

DAPD is a member of a different nucleoside series from FTC and CS-92. The
Company believes that DAPD is the only purine dioxolane nucleoside that is
currently being developed for the treatment of viral diseases and that it may
offer advantages over several nucleosides from other series that are already on
the market because of its unique structure and pharmacological properties. IN
VITRO studies indicate that DAPD inhibits the growth of HIV at submicromolar
levels and is synergistic in combination with a number of other anti-HIV drugs.
HIV strains that are resistant to AZT, 3TC or FTC are not cross-resistant to
DAPD. Pharmacokinetic studies have been completed in animals and demonstrated
that DAPD is rapidly converted to dioxolane guanosine ("DXG"), the active
anti-HIV agent. Preliminary analyses of these pharmacokinetic studies indicate
that DXG serum concentrations decline with a terminal half-life ranging from
approximately two to eight hours. The analysis of several urine samples from
this study indicate the presence of DXG with no other metabolites detected.

CS-92. Triangle is currently conducting a Pilot Phase I/II clinical trial
of CS-92 in Europe. The Company has licensed worldwide rights to CS-92 for the
treatment of HIV from Emory and UGARF.

CS-92 is a member of the same nucleoside series as AZT and has been
extensively studied in various preclinical assays. IN VITRO studies have
demonstrated unexpected synergy with AZT by mechanisms which have not yet been
fully characterized. In animal studies, CS-92 demonstrated a lack of systemic
toxicity compared to AZT, reasonable bioavailability and conversion of a
significant portion of the administered dose of CS-92 to AZT. Interim results of
the Company's ongoing Pilot Phase I/II clinical trial with CS-92 administered as
monotherapy have similarly shown little toxicity, but no significant conversion
of CS-92 to AZT nor any substantial lowering of the viral load with doses
administered to date. The current clinical trial is limited to determining
whether combination therapy with AZT will produce a substantial lowering of the
viral load as a result of synergy between the two agents.

In order to focus financial and human resource support on drug candidates
which it believes have the greatest potential, the Company has elected to limit
the current support of CS-92 to the completion of this ongoing clinical trial.
Pending evaluation of the results of this clinical trial, investment in the
further development of this drug candidate may be made in the future.

HBV

BACKGROUND. HBV is the causative agent of both the acute and chronic forms
of hepatitis B, a liver disease that is a major cause of illness and death
throughout the world. HBV can lead to cirrhosis and cancer of the liver. In the
United States approximately 300,000 people become acutely infected each year and
approximately one million people currently are chronic HBV carriers. Of these,
as many as 5,000 die each year as a result of the consequences of this liver
damage. Worldwide, over 300 million people are chronically infected. Presently,
there are over 120 million carriers of HBV in Asia, of whom one-fourth may
develop serious illnesses such as cirrhosis and liver cancer. Of these, between
1.0 million and 2.0 million die each year.

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Vaccines are currently available that can prevent the transmission of HBV;
however, they have no activity in those already infected with the virus.
Interferon, approved for the treatment of HBV, is administered by injection, is
not always successful in controlling the virus and is associated with
significant side-effects, the most common being severe flu-like symptoms. While
a few compounds under development may have some activity in the treatment of HBV
infection, the Company believes it is likely that additional drugs will be
necessary to effectively treat the disease. For example, clinical trials with
3TC to date have shown good tolerance and effective suppression of HBV
replication during the course of treatment. However, virus replication usually
returns after a six to 12 month course of therapy has been completed. Studies of
more prolonged therapy are in progress, but antiviral resistance has already
been observed with certain patients.

The Company believes that HBV, like HIV, may be treated more effectively
with combination therapy. Therefore, even if other drugs are approved for the
treatment of HBV, the Company believes there will still be a need for additional
safe and effective oral therapies for chronic HBV that can be used in coactive
therapies.

DEVELOPMENT STATUS. The Company is developing three compounds for the
treatment of HBV, two of which, FTC and DAPD, are also being developed for the
treatment of HIV.

FTC. The Company currently intends to initiate Phase I clinical trials with
FTC for the treatment of HBV in 1998. Some of the development activities the
Company plans to undertake with FTC for the treatment of HIV will also be used
by the Company in its development of FTC for the treatment of HBV. See
"--HIV--Development Status--FTC."

FTC has been shown to be a potent inhibitor IN VITRO of HBV replication, and
is synergistic IN VITRO in combination with several types of interferons
approved for the treatment of HBV. The anti-hepatitis activity of FTC has been
demonstrated in a chimeric mouse model and against woodchuck hepatitis virus
("WHV") in naturally infected woodchucks. The hepatitis infection of the
woodchuck results in a disease state closely resembling that found in humans
infected with HBV. In the woodchuck model, at doses above 3 mg/kg all treated
animals had significantly reduced levels of WHV DNA in their blood. One week
after treatment was stopped, WHV levels returned to pretreatment levels, as is
seen with 3TC.

L-FMAU. Triangle currently plans to initiate 90-day toxicology studies with
L-FMAU in 1998. The Company has licensed from Bukwang rights to L-FMAU
worldwide, except in Korea, for all human antiviral applications.

L-FMAU is a pyrimidine nucleoside analogue that has been shown to be a
potent inhibitor of HBV replication in vitro, having an EC(50) value ranging
from 0.02 mM to 0.15 mM with a mean of 0.08 mM. Pharmacokinetic studies with
L-FMAU have been performed in adult woodchucks and in rats and showed favorable
oral bioavailability. At a 25 mg/kg dose of L-FMAU given to woodchucks, oral
bioavailability ranged from 19% to 29%. The bioavailability of L-FMAU in rats
was 59% to 64%. The pharmacokinetics of L-FMAU in these animal studies were
independent of dose over a range of 10 mg/kg to 50 mg/kg.

The IN VIVO efficacy of L-FMAU has been demonstrated in woodchucks
chronically infected with WHV who were treated at varying doses for four weeks.
Within seven days of initial treatment, a greater than 1000-fold reduction in
serum WHV DNA was observed, and at all but the lowest dose, the WHV DNA became
undetectable shortly thereafter. In a subsequent study where L-FMAU was given at
a dose of 10 mg/kg for 12 weeks, the virus did not return in the majority of
animals for prolonged periods after the cessation of dosing. Molecular evidence
of viral infection in the liver could no longer be detected between four and 12
weeks after treatment and remained undetectable for the entire 36-week
post-treatment observation period.

The toxicity of L-FMAU has been evaluated in three studies in woodchucks and
in a 30-day study in mice. Liver biopsies taken from woodchucks at the end of
the 12-week exposure to L-FMAU were normal.

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There were no effects on body weight and no overt indications of toxicity
attributable to L-FMAU during or up to one year after treatment. In mice, a
30-day preliminary toxicity study with L-FMAU administered orally at 10 mg/kg
and 50 mg/kg twice a day for one month did not show any apparent toxicity or
decreased body weights.

DAPD. The Company currently intends to initiate Phase I clinical trials
with DAPD for the treatment of HBV in late 1998 or early 1999. Some of the
development activities the Company plans to undertake with DAPD for the
treatment of HIV will also be used by the Company in its development of DAPD for
the treatment of HBV. See "--HIV--Development Status--DAPD."

DAPD has been shown to be a potent inhibitor IN VITRO of HBV replication. In
a woodchuck model, DAPD was found to be as active as 3TC in reducing serum
levels of circulating WHV DNA when administered for 12 weeks.

HERPES SIMPLEX VIRUS

BACKGROUND. Herpes labialis (cold sores) caused by Herpes Simplex Virus
Type I ("HSV-1") is a latent viral infection that is found in approximately 90%
of adults over age 30. Genital herpes, caused by Herpes Simplex Virus Type 2
("HSV-2"), is one of the most common sexually transmitted diseases. There is no
cure for HSV-1 or HSV-2, and, aside from suppressive therapy to prevent frequent
recurrences of HSV-2, treatments for either viral infection are of limited
efficacy.

DEVELOPMENT STATUS OF ACYCLOVIR MONOPHOSPHATE. The Company is developing a
topical formulation of Acyclovir Monophosphate ("ACVMP"), a monophosphate
derivative of the nucleoside acyclovir, for the treatment of labial and genital
herpes. Triangle has licensed the worldwide rights to ACVMP from Dr. Karl
Hostetler, a director of the Company and member of its Scientific Advisory
Board.

The results of early animal model studies had shown that ACVMP has the
potential to overcome the most common form of resistance to acyclovir and to
provide enhanced efficacy on topical application. The Company is currently
attempting to confirm these early animal model studies by conducting preclinical
and formulation studies using a variety of vehicles suitable for topical
application. However, in order to focus financial and human resource support on
drug candidates which it believes have the greatest potential, the Company has
elected to limit the current support of ACVMP to the completion of these
studies. Should circumstances warrant, investment in the further development of
this drug candidate may be made in the future.

CANCER PROGRAM

BACKGROUND. Cancer, which can occur in almost any part of the body, is a
major cause of death in developed countries. In the United States, approximately
1.3 million new cases of cancer are diagnosed annually, and more than 1,500
people die of cancer each day. Colorectal, breast, prostate and lung cancers
account for approximately half of all diagnoses.

Treatments currently approved for cancer vary greatly depending on where the
disease originates in the body and the extent of the disease at the time of
treatment. The three conventional modes of treatment are radiation therapy,
chemotherapy and surgery. Radiation therapy and chemotherapy often have
significant negative side effects that may include nausea, hair loss, liver
toxicity, extreme fatigue and lowered resistance to infection. Both forms of
therapy generally require repeated treatments over extended periods of time. If
the disease recurs in a patient following these therapies, it is frequently
impossible to repeat the treatment because the recurring cancer will have
developed resistance to the form of treatment used (either drug or radiation),
or the patient will have received maximum levels of radiation. Surgery does not
cause the same side effects as radiation therapy or chemotherapy and is
considered the treatment of choice for many cancers; however, many patients are
not eligible for surgery because of the location of the

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cancerous tissue or their physical condition. Even for those patients who are
not subject to these limitations, surgery can be traumatic and can require long
recovery periods. For most advanced stages of cancer, current therapies provide
only short-term benefit and the majority of patients die of their disease within
a few months to a few years.

Non-small cell lung cancer ("NSCLC") is a highly fatal disease caused
predominantly by smoking. Approximately 100,000 people are diagnosed with the
disease in the United States each year and their prognoses are typically very
poor. Surgery and radiation are the treatments of choice for NSCLC, but result
in only about ten percent five-year survival rates. For the 70% of patients
whose tumors are not amenable to surgical removal, median survival rates are
measured in months. Chemotherapeutic agents are marginally effective in
extending survival in the early stages of the disease and are used primarily to
relieve symptoms and sometimes shrink tumors to provide short-term benefit.
Antitumor agents generally do not provide significantly prolonged benefit to
NSCLC patients during their later stages of disease.

The drug options for treating brain cancer are also limited. Approximately
13,500 patients in the United States develop primary brain tumors each year, and
the currently approved chemotherapeutic agents lack specificity, resulting in
dose-limiting toxicities.

DEVELOPMENT STATUS OF ALANOSINE. The Company is funding and conducting
Pilot Phase II efficacy studies with alanosine at several sites in the United
States for the treatment of NSCLC and brain cancers that lack the enzyme
methylthioadenosine phosphorylase ("MTAP").

Alanosine is an amino acid analogue derived from STREPTOMYCES ALANOSINICUS.
Triangle has obtained an option from the Regents that expires in September 1998
(with an option for Triangle to extend the exercise period for one year) for a
worldwide license to use alanosine in treating various cancers lacking MTAP.

Alanosine has antitumor activity based upon its ability to interfere with
the synthesis of adenosine, a molecule necessary for cellular growth and
activity. Cells use two synthetic pathways to make adenosine: by DE NOVO
synthesis and by the "salvage pathway." Alanosine interferes with the DE NOVO
synthesis of adenosine in both malignant and normal cells. In cancer cells that
lack MTAP (a required enzyme in the salvage pathway), alanosine will deprive
such cancer cells, but not normal cells, of all means to make adenosine.

Alanosine was evaluated in Phase I and Phase II clinical trials at the
National Cancer Institute ("NCI") during the early 1980's. The trials were
discontinued because alanosine caused toxicity typically associated with
chemotherapy and did not produce significant response rates in common tumors
such as breast or colon cancers. Since that time, investigators at the
University of California, San Diego discovered that malignant cells from certain
cancer patients lack MTAP. The enzyme deficiency occurs in up to 30% of NSCLCs
and in up to 75% of certain severe primary brain tumors. It is absent in a lower
percentage of patients with leukemias, lymphomas, melanomas, breast cancer and
renal adenocarcinomas. The Company believes that the growth of these
MTAP-deficient tumors should be inhibited by alanosine.

A diagnostic test has been developed to identify in tumor biopsies cancers
that lack MTAP and therefore are most likely to respond to therapy with
alanosine. The Company is working to improve the current diagnostic test so that
it can be used in wide-spread clinical trials. The NCI has already conducted
dose-escalating studies and established dose-limiting toxicities. Triangle
intends to attempt to recharacterize alanosine by using advanced molecular
biological techniques to select the patients most likely to respond to
alanosine: those with malignant cancer cells that lack MTAP.

PSORIASIS PROGRAM

BACKGROUND. Psoriasis is a chronic condition of the skin manifested by
scaly patches, which may cause itching. The disease affects an estimated two
percent of the world's population, including approximately five million people
in the United States. It is characterized by spontaneous remissions, but
relapses are

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common. Although it is not usually a life-threatening condition, psoriasis
causes significant psychological distress to those affected who may feel
ostracized because of their physical appearance. In severe cases, patients
suffer from extensive skin damage and, in some cases, arthritis. There is no
known cure for psoriasis and sufferers are often treated for each recurrent
episode.

Treatments for psoriasis, though varied, are generally of only short-term
benefit. For milder symptoms, treatments range from topical therapy, including
steroids, Vitamin D derivatives, coal tars and emollients, to phototherapy and
for more severe cases, more toxic systemic treatments, such as cyclosporine,
tretinoin and methotrexate, are prescribed.

DEVELOPMENT STATUS OF 2-CDAP. The Company submitted an IND in late 1997 and
currently intends to initiate Phase I clinical trials with a topical formulation
of 2-CdAP for the treatment of psoriasis in early 1998. 2-CdAP is a derivative
of 2-CdA (cladribine), a potent immunosuppressive and anti-proliferative agent
that is currently an approved drug and the treatment of choice for hairy cell
leukemia. Triangle has licensed worldwide rights to the topical administration
of 2-CdAP from Dr. Karl Hostetler and Dr. Dennis Carson.

In a prior clinical trial, seven patients with psoriasis enrolled in a three
month study of orally administered 2-CdA. Of six patients completing therapy,
skin lesions improved in five (two dramatic responses) and joint disease
improved in four. However, immunosuppression occurred in all patients and an
opportunistic infection occurred in one patient.

Prior experiments have shown that complex polynucleotides administered
topically are absorbed by cells such as keratinocytes and macrophages within the
superficial skin. Based on these findings, the Company believes that topical
mononucleotides such as 2-CdAP will also penetrate the skin. If this occurs, the
Company believes that the therapeutic utility of 2-CdAP in psoriasis would
result from its ability to gain direct access to hyperproliferating
keratinocytes in an activated form that would be cytotoxic. The Company believes
that 2-CdAP should also penetrate lymphocytes found in the psoriatic skin,
killing them without producing systemic toxicity. The Company believes that
systemic toxicity is unlikely to occur because of the small amount of drug that
would enter the bloodstream.

LICENSE, OPTION AND OTHER MATERIAL AGREEMENTS

The Company has licensed MKC-442 from Mitsubishi, L-FMAU from Bukwang, FTC
from Emory, DAPD and CS-92 from Emory and UGARF, ACVMP from Dr. Karl Hostetler,
and 2-CdAP from Dr. Karl Hostetler and Dr. Dennis Carson. The Company acquired
its license rights to DMP-450 by virtue of its acquisition of Avid. Avid
licensed DMP-450 from DuPont Merck. The Company has entered into an option
agreement with the Regents with respect to the acquisition of certain license
rights to alanosine. See "Risk Factors--Risks Related to License and Option
Agreements."

MITSUBISHI CHEMICAL CORPORATION

In December 1995, the Company entered into an option agreement with
Mitsubishi pursuant to which Mitsubishi granted the Company an option through
December 1997 to obtain an exclusive license to MKC-442. The Company exercised
this option and, in June 1997, entered into a license agreement with Mitsubishi
pursuant to which the Company received an exclusive license to all of
Mitsubishi's rights to MKC-442 (the "MKC-442 Technology") for use in the HIV
field. The license includes all countries of the world except Japan. As
consideration for the exclusive license, Triangle paid a license initiation fee
and agreed to make certain milestone and royalty payments, including minimum
annual payments, to Mitsubishi. The Company is also required to meet certain
milestone obligations and conduct certain development work with respect to
MKC-442. Under the license agreement, Triangle has agreed to perform preclinical
testing and clinical trials with MKC-442 and, in turn, Mitsubishi has agreed to
supply a certain amount of

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bulk drug substance, at its own expense, for Triangle's development work.
Mitsubishi is primarily responsible for prosecuting all patents related to the
MKC-442 Technology at its own expense. The Company is obligated to indemnify
Mitsubishi against any claims or losses incurred as a result of the Company's
breach of the license agreement or the Company's manufacture, testing, design,
use, sale and labeling of products utilizing the MKC-442 Technology. Mitsubishi
has the right to terminate the license if the Company does not satisfy certain
milestone obligations or does not cure any material breach of the license
agreement. The termination of the license agreement could have a material
adverse effect on the Company.

BUKWANG PHARM. IND. CO., LTD.

In February 1998, the Company entered into a license agreement with Bukwang
pursuant to which the Company received an exclusive license to all of Bukwang's
rights to L-FMAU (the "L-FMAU Technology") for use in the HBV field as well as
all other human antiviral applications. Bukwang obtained its rights to L-FMAU
through an exclusive license from Yale and UGARF. The Company's license includes
all countries of the world except Korea. As consideration for the exclusive
license of the L-FMAU Technology, the Company paid a license initiation fee of
$6.0 million and agreed to pay development milestones of up to $32.5 million and
sales milestones of up to $30.0 million. Triangle also agreed to pay a royalty
of 14% of net sales of any licensed products. Beginning the third year after the
first FDA registration is granted for an FDA-approved product incorporating the
L-FMAU Technology, the Company will be required to pay an annual minimum
royalty. Under the license agreement, Yale and UGARF are primarily responsible
for prosecuting all patents related to the L-FMAU Technology which they licensed
to Bukwang, at the Company's expense. The Company, at its expense, is primarily
responsible for prosecuting all patents related to any L-FMAU Technology that
may be acquired by Bukwang or Triangle. In addition, Yale and UGARF have the
first right to pursue any actions against third parties for infringement of the
L-FMAU Technology, either jointly with the Company (with the expenses shared
equally) or, if not jointly with the Company, at their expense. Upon the
conclusion of any such infringement action brought solely by the Company, the
Company is entitled to offset its unrecovered expenses incurred in connection
with the infringement action against a percentage of the aggregate milestone
payments and royalties that were owing to Bukwang during the time the
infringement action was pending. The Company is obligated to indemnify Bukwang
against any claims or losses incurred as a result of the Company's breach of the
license agreement or the Company's manufacture, testing, design, use, sale and
labeling of products utilizing the L-FMAU Technology. Bukwang has the right to
terminate the license agreement in the event the Company does not achieve
certain milestone obligations. Bukwang may also terminate the license agreement
upon an uncured breach of the agreement by the Company. In the event of such
termination, the Company will grant Bukwang certain nonexclusive, royalty free
license rights in all intellectual property under the Company's control relating
to the L-FMAU Technology necessary for marketing products which contain L-FMAU.
The termination of the license agreement could have a material adverse effect on
the Company.

THE DUPONT MERCK PHARMACEUTICAL COMPANY AND AVID CORPORATION

Triangle completed its acquisition of Avid on August 28, 1997, pursuant to
the terms of a reorganization agreement among Triangle, a wholly-owned
subsidiary of Triangle and Avid (the "Reorganization Agreement"). Avid's
principal assets consist of worldwide license rights to DMP-450 (the "DMP-450
Technology") for use in the HIV field, early preclinical stage compounds for the
treatment of HBV infection, proprietary assays to screen compounds for the
treatment of HBV and assay technology for potential use in screening compounds
for the treatment of hepatitis C virus infection. Avid acquired its rights to
the DMP-450 Technology in December 1996 through an exclusive license from DuPont
Merck. Pursuant to the license agreement, Triangle is required to make certain
milestone and royalty payments and to pay license preservation fees to DuPont
Merck beginning in 1998 in the event other payments do not equal certain annual
amounts. Under the license agreement, DuPont Merck is primarily responsible for
prosecuting all patents related to the DMP-450 Technology. The Company is
required to reimburse

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DuPont Merck for the patent prosecution costs it incurs after the date of the
license agreement, other than any litigation expenses incurred by DuPont Merck.
In certain circumstances, the Company has the right to pursue any actions
against third parties for infringement of the DMP-450 Technology at the
Company's expense. In addition, the Company is obligated to indemnify DuPont
Merck against any claims or losses incurred as a result of the Company's
production, manufacture, use, sale, lease, consumption or advertisement of
products utilizing the DMP-450 Technology. DuPont Merck may terminate the
license agreement upon an uncured breach of the agreement by the Company. The
termination of the license agreement could have a material adverse effect on the
Company.

Pursuant to the terms of the Reorganization Agreement, Triangle issued
400,000 shares of Common Stock in exchange for all outstanding capital stock of
Avid. Triangle also agreed to issue up to 2,100,000 additional shares of Common
Stock, the issuance of 1,600,000 shares of which is contingent upon Triangle
initiating pivotal Phase II clinical trials with DMP-450 before February 28,
1999, or electing on or before that date to continue the development of DMP-450
even if such clinical trials have not been initiated. The issuance of the
remaining 500,000 shares is contingent upon the attainment of other development
milestones with DMP-450 or one of Avid's other compounds. In connection with the
acquisition, Triangle also assumed operating and other liabilities of Avid
totaling approximately $1.3 million and certain development liabilities totaling
approximately $1.0 million.

EMORY UNIVERSITY AND UNIVERSITY OF GEORGIA RESEARCH FOUNDATION, INC.

FTC. In April 1996, the Company entered into a license agreement with Emory
pursuant to which the Company received an exclusive worldwide license to all of
Emory's rights to purified forms of FTC (the "FTC Technology") for use in the
HIV and HBV fields. As consideration for the exclusive license of the FTC
Technology, the Company issued 500,000 shares of Common Stock and agreed to pay
certain license fees, all of which have been paid to Emory. In addition, the
Company agreed to make certain milestone and royalty payments to Emory.
Beginning the third year after the first FDA registration is granted for an
anti-HIV product incorporating the FTC Technology in the United States and after
the first registration is granted for an anti-HBV product incorporating the FTC
Technology in certain major market countries, the Company will be required to
pay Emory minimum annual royalties for the HIV and HBV indications,
respectively. Under the license agreement, Emory is primarily responsible for
prosecuting all patents related to the FTC Technology. The Company agreed to
reimburse Emory for the patent prosecution costs it incurs after December 1996.
The Company has the right to pursue any actions against third parties for
infringement of the FTC Technology at the Company's expense. Upon the conclusion
of any such infringement action, the Company is entitled to offset its
unrecovered expenses incurred in connection with the infringement action against
a percentage of the aggregate milestone payments and royalties that were owing
to Emory during the time the infringement action was pending. In addition, the
Company is obligated to defend, indemnify and hold harmless Emory and certain of
its representatives against any claims or losses incurred as a result of the
Company's manufacturing, testing, design, use and sale of products utilizing the
FTC Technology. Emory has the right to terminate the license agreement or to
convert the exclusive license to a nonexclusive license in the event the Company
does not satisfy certain milestone obligations. Emory may also terminate the
license agreement upon an uncured breach of the agreement by the Company. In the
event of such termination or conversion, the Company will grant Emory certain
nonexclusive, royalty-free license rights in all intellectual property under the
Company's control relating to the FTC Technology necessary for the marketing of
products incorporating the FTC Technology. The termination of the license
agreement or the conversion from an exclusive to a nonexclusive agreement could
have a material adverse effect on the Company.

DAPD. In March 1996, the Company entered into a license agreement with
Emory and UGARF pursuant to which the Company received an exclusive worldwide
license to all of Emory's and UGARF's rights to a series of nucleoside analogues
including DAPD and DXG (the "DAPD Technology") for use in

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the HIV and HBV fields. As consideration for the exclusive license of the DAPD
Technology, the Company issued an aggregate of 150,000 shares of Common Stock to
Emory and UGARF. In addition, the Company agreed to make certain milestone and
royalty payments to Emory and UGARF. The Company is required to pay license
maintenance fees beginning in March 1999 in the event certain development
milestones have not been achieved. Beginning the third year after the first FDA
registration is granted for an FDA-approved product incorporating the DAPD
Technology, the Company will be required to pay Emory and UGARF a minimum annual
royalty. Under the license agreement, Emory and UGARF are primarily responsible
for prosecuting all patents related to the DAPD Technology. The Company agreed
to reimburse Emory and UGARF for the patent prosecution costs they incur after
the date of the license agreement. The Company has the right to pursue any
actions against third parties for infringement of the DAPD Technology at the
Company's expense. Upon the conclusion of any such infringement action, the
Company is entitled to offset its unrecovered expenses incurred in connection
with the infringement action against a percentage of the aggregate milestone
payments and royalties that were owing to Emory and UGARF during the time the
infringement action was pending. In addition, the Company is obligated to
defend, indemnify and hold harmless Emory, UGARF and certain of their
representatives against any claims or losses incurred as a result of the
Company's manufacturing, testing, design, use and sale of products utilizing the
DAPD Technology. Emory and UGARF have the right to terminate the license
agreement or to convert the exclusive license to a nonexclusive license in the
event the Company does not satisfy certain milestone obligations. Emory and
UGARF may also terminate the license agreement upon an uncured breach of the
agreement by the Company. In the event of such termination or conversion, the
Company will grant Emory and UGARF certain nonexclusive, royalty-free license
rights in all intellectual property under the Company's control relating to the
DAPD Technology necessary for the marketing of products incorporating the DAPD
Technology. The termination of the license agreement or the conversion from an
exclusive to a nonexclusive agreement could have a material adverse effect on
the Company.

CS-92. In March 1996, the Company entered into a license agreement with
Emory and UGARF pursuant to which the Company received an exclusive worldwide
license to all of Emory's and UGARF's rights to CS-92 (the "CS-92 Technology")
for use in the HIV field. As consideration for the exclusive license of the
CS-92 Technology, the Company issued an aggregate of 50,000 shares of Common
Stock to Emory, UGARF and Dr. Raymond Schinazi, a co-inventor of the CS-92
Technology and a member of the Company's Scientific Advisory Board. In addition,
the Company agreed to make certain milestone and royalty payments to Emory and
UGARF. The Company is required to pay license maintenance fees beginning in
March 1999 in the event certain development milestones have not been achieved.
Beginning the third year after the first FDA registration is granted for an
FDA-approved product incorporating the CS-92 Technology, the Company will be
required to pay Emory and UGARF a minimum annual royalty. Under the license
agreement, Emory and UGARF are primarily responsible for prosecuting all patents
related to the CS-92 Technology. The Company agreed to reimburse Emory and UGARF
for the patent prosecution costs they incur after the date of the license
agreement. The Company has the right to pursue any actions against third parties
for infringement of the CS-92 Technology at the Company's expense. Upon the
conclusion of any such infringement action, the Company is entitled to offset
its unrecovered expenses incurred in connection with the infringement action
against a percentage of the aggregate milestone payments and royalties that were
owing to Emory and UGARF during the time the infringement action was pending. In
addition, the Company is obligated to defend, indemnify and hold harmless Emory,
UGARF and certain of their representatives against any claims or losses incurred
as a result of the Company's manufacturing, testing, design, use and sale of
products utilizing the CS-92 Technology. Emory and UGARF have the right to
terminate the license agreement or to convert the exclusive license to a
nonexclusive license in the event the Company does not satisfy certain milestone
obligations. Emory and UGARF may also terminate the license agreement upon an
uncured breach of the agreement by the Company. In the event of such termination
or conversion, the Company will grant Emory and UGARF certain nonexclusive,
royalty-free license rights in all intellectual property under the Company's
control relating to the CS-92 Technology necessary for the marketing of products
incorporating the CS-92

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Technology. The termination of the license agreement or the conversion from an
exclusive to a nonexclusive agreement could have a material adverse effect on
the Company.

DRS. HOSTETLER AND CARSON

In November 1995, the Company entered into a license agreement with Dr. Karl
Hostetler and Dr. Dennis Carson pursuant to which Dr. Hostetler granted the
Company an exclusive worldwide license to his rights to ACVMP and Drs. Hostetler
and Carson granted the Company an exclusive worldwide license to their rights to
2-CdAP (the "ACVMP and 2-CdAP Technologies"). As consideration for the exclusive
license of the ACVMP and 2-CdAP Technologies, the Company sold an aggregate of
500,000 shares of Common Stock to Drs. Hostetler and Carson. The interests of
Drs. Hostetler and Carson in such shares of Common Stock vest over time as they
continue to serve as consultants to the Company. The Company also agreed to make
two separate milestone payments of $1.0 million each and to make royalty
payments ranging from 3% to 8% of net sales of products incorporating the ACVMP
and 2-CdAP Technologies to Drs. Hostetler and Carson. The Company is obligated
to hold harmless Drs. Hostetler and Carson against any claims or losses caused
by or arising out of the Company's use of the ACVMP and 2-CdAP Technologies.
Drs. Hostetler and Carson have the right to terminate the license agreement or
convert the exclusive license to a nonexclusive license in the event that the
Company does not satisfy certain development, marketing and milestone
obligations. Additional termination events include the failure of the Company to
pay royalties to Drs. Hostetler and Carson when due. The termination of the
license agreement or the conversion from an exclusive to a nonexclusive
agreement could have a material adverse effect on the Company.

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

In September 1996, the Company entered into an option agreement with the
Regents pursuant to which the Regents granted the Company an option through
September 1, 1998 (with an option to extend the exercise period for one year),
to obtain an exclusive worldwide license to all of the Regents' rights to
alanosine and related technologies (the "Alanosine Technology") for use in the
treatment of various cancers lacking MTAP. As consideration for the grant of the
option, the Company agreed to pay the Regents certain option fees. In the event
the Company exercises the option, the Company will be required to pay a license
initiation fee and annual license maintenance fees. The Company will also be
required to make certain milestone and royalty payments to the Regents,
including minimum annual royalties. The Regents are primarily responsible for
prosecuting all patents and initiating infringement actions related to the
Alanosine Technology (and will remain primarily responsible for patent
prosecution and infringement actions if the Company exercises the option). The
Company has agreed to reimburse the Regents for all patent prosecution costs
they incur. In addition, the Company is obligated to defend, indemnify and hold
harmless the Regents and certain of their representatives against any claims or
losses incurred as a result of the Company's exercise of its rights under the
option agreement.

The Company also entered into a sponsored research agreement (the "Research
Agreement") with the Regents whereby the Company has agreed to provide
approximately $450,000 to fund two clinical trials with alanosine. These Pilot
Phase II clinical trials have been initiated at several sites in the United
States to assess the efficacy of alanosine in the treatment of NSCLC and brain
cancers. Either the Regents or the Company may terminate these trials upon the
uncured breach of the Research Agreement by the other party. In the event both
studies are terminated under the Research Agreement (other than for reasons of
the uncured breach on the part of the Regents), the Company's rights under the
option agreement would be terminated. The termination of the Company's rights
under the option agreement, the failure of the Company to enter into the related
license agreement or the termination of the license agreement could have a
material adverse effect on the Company.

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PATENTS AND PROPRIETARY RIGHTS

A number of pharmaceutical and biotechnology companies, universities and
research institutions have filed patent applications or received patents to
technologies that cover or are similar to the technologies licensed to or owned
by the Company. The Company is aware of certain patent applications previously
filed by and patents already issued to others that conflict with patents or
patent applications licensed to the Company either by claiming the same methods
or compounds or by claiming methods or compounds that could dominate those
licensed to the Company. In addition, there can be no assurance that the Company
is aware of all patents or patent applications that may materially affect the
Company's ability to make, use or sell any drug candidates that are successfully
developed. For example, United States patent applications are confidential while
pending in the PTO, and patent applications filed in foreign countries are often
first published six months or more after filing. Any conflicts resulting from
third party patent applications and patents could significantly reduce the
coverage of the patents licensed to or owned by the Company and limit the
ability of the Company or its licensors to obtain meaningful patent protection.
If patents are issued to other companies that contain competitive or conflicting
claims, the Company may be required to obtain licenses to these patents or to
develop or obtain alternative technology. There can be no assurance that the
Company will be able to obtain any such license on acceptable terms or at all.
If such licenses are not obtained, the Company could be delayed in or prevented
from pursuing the development or commercialization of its drug candidates, which
would have a material adverse effect on the Company.

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FTC

FTC belongs to the same general class of nucleosides as 3TC, which has been
approved in the United States by the FDA for use in combination with AZT for the
treatment of HIV and by similar regulatory agencies in many other countries for
use in combination with other nucleoside analogues for the treatment of HIV. 3TC
is currently being sold by Glaxo for the treatment of HIV under a license
agreement with BioChem Pharma. The Company obtained its rights to purified forms
of FTC under a license from Emory. In 1990 and 1991, Emory filed in the United
States and thereafter in numerous foreign countries patent applications with
claims to composition of matter and methods to treat HIV and HBV with FTC. Yale
filed patent applications on FTC and its use to treat HBV in 1991 in the United
States, and subsequently licensed all of its rights to FTC and its uses claimed
in these patent applications to Emory. The Company's license arrangement with
Emory includes all rights to FTC and its uses claimed in the Yale patent
applications.

In the United States, the first to invent a subject matter is entitled to
patent protection on that invention. With respect to patent applications filed
prior to January 1, 1996, United States patent law provides that if a party
invented a technology outside the United States, then for purposes of
determining the first to invent the technology, that party is deemed to have
invented the technology on the earlier of the date it introduced the invention
in the United States or the date it filed its patent application. In a recent
filing with the Commission, BioChem Pharma stated that since it conducts
substantially all of its research activities outside the United States, it is at
a disadvantage as to inventions made prior to January 1, 1996, with respect to
obtaining United States patents as compared to companies that maintain research
facilities in the United States. The Company does not know whether Emory or
BioChem Pharma was the first to invent the subject matter claimed in their
respective United States patent applications or patents, or whether BioChem
Pharma invented the technology disclosed in its patent applications in the
United States or introduced that technology in the United States before the date
of its patent applications. In foreign countries, the first party to file a
patent application on an invention, not the first to invent the subject matter,
is entitled to patent protection on that invention. While the Company believes
that Emory's patent applications that disclosed FTC as a useful anti-HIV agent
were filed in many foreign countries before BioChem Pharma filed its foreign
patent applications on that subject matter, BioChem Pharma has been issued
patents in several foreign countries. Further, BioChem Pharma has filed for
patent protection on FTC and its uses in certain countries in which Emory did
not file for patent protection. Emory has opposed or otherwise challenged patent
claims on FTC granted to BioChem Pharma in Australia, Japan and Norway. There
can be no assurance that Emory will initiate opposition proceedings in any other
countries or be successful in any pending or subsequently filed foreign
proceeding attempting to revoke patents

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issued to BioChem Pharma or addressing the relative rights of BioChem Pharma and
Emory. BioChem Pharma has opposed patent claims on FTC granted to Emory in Japan
and Australia. There can also be no assurance that BioChem Pharma will not make
additional challenges to any Emory patents or patent applications, or that Emory
will succeed in defending any such challenges. There can be no assurance that
the sale of FTC by the Company for the treatment of HIV would not be held to
infringe United States and foreign patent rights of BioChem Pharma. Under the
patent laws of most countries, a product can be found to infringe a third party
patent either if the third party patent expressly covers the product or method
of treatment using the product, or in certain circumstances, if the third party
patent, while not expressly covering the product or method, covers subject
matter that is substantially equivalent in nature to the product or method. If
it is determined that the sale of FTC for the treatment of HIV infringes a
BioChem Pharma patent, the Company would not have the right to make, use or sell
FTC for the treatment of HIV in one or more countries in the absence of a
license from BioChem Pharma. There can be no assurance that the Company could
obtain such a license from BioChem Pharma on acceptable terms or at all.

HBV. Burroughs Wellcome filed patent applications in March 1991 and May
1991 in Great Britain on a method to treat HBV with FTC. Burroughs Wellcome
filed similar patent applications in other countries, which the Company believes
includes the United States. Glaxo subsequently acquired Burroughs Wellcome's
rights under those patent applications. Those patent applications were filed in
many foreign countries prior to the date Emory filed its patent application on
the use of FTC to treat HBV, and therefore, the foreign patent applications
filed by Burroughs Wellcome have priority over those filed by Emory. In July
1996, Emory instituted litigation against Glaxo in the United States District
Court to obtain ownership of the patent applications filed by Burroughs
Wellcome, alleging that Burroughs Wellcome converted and misappropriated Emory's
invention and property, and that an Emory employee is the inventor or a
co-inventor of the subject matter covered by the Burroughs Wellcome patent
applications. There can be no assurance that Emory will succeed in its efforts
to establish ownership rights. If Emory fails to establish ownership rights, the
Company could not make, use or sell FTC for the treatment of HBV in countries in
which patents are issued to Glaxo without a license from Glaxo. If Emory
establishes only co-ownership rights (and not sole ownership) to these patents
and patent applications, laws in Europe, Korea and perhaps other countries could
prohibit Emory from licensing any co-owned patent rights without Glaxo's
consent. If the Company is required to obtain a license from Glaxo to sell FTC
for the treatment of HBV, there can be no assurance that the Company would be
able to obtain such a license on acceptable terms or at all.

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In addition, BioChem Pharma has filed in the United States and foreign
countries several patent applications on manufacturing methods relating to a
class of nucleosides that includes FTC, from which several patents have issued
in the United States and many foreign countries. If the Company uses a
manufacturing method that is covered by patents issued on any of these
applications, the Company would not be able to manufacture FTC without a license
from BioChem Pharma. There can be no assurance that the Company would be able to
obtain such a license on acceptable terms or at all.

DAPD

The Company obtained its rights to DAPD under a license from Emory and
UGARF. The DAPD portfolio licensed to the Company consists of three issued
United States patents and several United States and foreign patent applications
that cover a method for the synthesis of DAPD and its use to treat HIV and HBV.
Emory and UGARF filed patent applications claiming these inventions in the
United States in 1990 and 1992. BioChem Pharma filed a patent application in the
United States in 1988 on a group of nucleosides in the same general class as
DAPD and their use to treat HIV, and has filed corresponding patent applications
in foreign countries. The PTO issued a patent to BioChem Pharma in 1993 covering
a class of nucleosides that includes DAPD and its use to treat HIV.
Corresponding patents have been issued to BioChem Pharma in many foreign
countries. Emory has filed an opposition to BioChem Pharma's granted patent
application in the European Patent Office based, in part, upon Emory's assertion
that BioChem Pharma's patent does not disclose how to make DAPD, and Emory has
informed the Company that Emory intends to challenge BioChem Pharma's patents
and patent applications in other countries. Patent claims granted to Emory on a
portion of the DAPD technology by the Australian Patent Office have been opposed
by BioChem Pharma. There can be no assurance that a court or administrative body
would invalidate BioChem Pharma's patent claims or that a sale of DAPD by the
Company would not infringe BioChem Pharma's patents. If Emory, UGARF and the
Company do not challenge, or are not successful in any challenge to, BioChem
Pharma's issued patents or pending patent applications (or patents that may
issue as a result of such applications), the Company will not be able to
manufacture, use or sell DAPD in the United States and any foreign countries in
which BioChem Pharma receives a patent without a license from BioChem Pharma.
There can be no assurance that the Company would be able to obtain a license
from BioChem Pharma on acceptable terms or at all.

CS-92

The Company obtained its rights to CS-92 under a license from Emory and
UGARF. Emory and UGARF have obtained two United States patents that cover CS-92
and its use to treat HIV and have filed a European patent application and a
Japanese patent application with claims limited to the use of CS-92 as a method
for administering AZT, which includes the administration of CS-92 as a precursor
form of AZT, to treat HIV infection. Burroughs Wellcome filed an application
with the European Patent Office in September 1986 directed to a broad group of
nucleosides that includes CS-92 and AZT, and their use to treat HIV infection.
Burroughs Wellcome subsequently filed similar applications in other countries,
including the United States. Patents have been issued to Burroughs Wellcome in
certain countries based upon these patent applications. Glaxo now has the rights
to these patents and patent applications. There can be no assurance that, if
challenged, a court would uphold the Emory/UGARF patents in light of the
disclosures contained in the earlier filed Burroughs Wellcome patent
applications. If the use of CS-92 is found to infringe patents owned by Glaxo,
then the Company would not have the right to sell CS-92 in one or more countries
without a license from Glaxo. There can be no assurance that the Company would
be able to obtain a license from Glaxo on acceptable terms or at all.

With respect to any of the Company's drug candidates, litigation and
interference proceedings declared by the PTO, including the currently pending
proceedings, could result in substantial cost to the Company. The Company
expects the costs of the currently pending interference proceedings to increase
significantly during the next several years. The Company anticipates that
additional litigation and/or patent

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interference or opposition proceedings will be necessary or may be initiated by
the Company's licensors or by third parties to enforce any patents to which the
Company has rights or to determine the scope, validity and enforceability of
other parties' proprietary rights and the priority of an invention, any of which
could result in substantial costs and/or delays to the Company. The outcome of
any of these proceedings may affect the Company's drug candidates and
technology. United States patents carry a presumption of validity and generally
can be invalidated only through clear and convincing evidence. As indicated
above, two interferences have already been declared by the PTO in connection
with the FTC technology. There can be no assurance that the Company's licensed
patents would be held valid by a court or administrative body or that an alleged
infringer would be found to be infringing. Further, with respect to the drug
candidates licensed or optioned by the Company from Emory, UGARF, the Regents,
DuPont Merck and Mitsubishi, each of these licensors is primarily responsible
for any patent prosecution activities for the technology licensed to the
Company, such as litigation, interference, opposition or other actions and,
except for litigation expenses incurred by DuPont Merck and all patent
prosecution expenses incurred by Mitsubishi, the Company is required to
reimburse these licensors for the costs they incur in performing these
activities. Similarly, Yale and UGARF, the licensors of L-FMAU to Bukwang, are
primarily responsible for patent prosecution activities with respect to L-FMAU
at the Company's expense. As a result, the Company generally does not have the
ability to institute or determine the conduct of any such patent proceedings
unless Emory, UGARF, the Regents, DuPont Merck, Mitsubishi and/or Yale do not
elect to institute or elect to abandon such proceedings. In cases where Emory,
UGARF, the Regents, DuPont Merck, Mitsubishi and/or Yale elect to institute and
prosecute patent proceedings, the Company's rights will be dependent in part
upon the manner in which these licensors conduct the proceedings. These
licensors could, in any proceedings they elect to initiate and maintain, decide
not to vigorously pursue or defend or to settle such proceedings on terms that
are not favorable to the Company. An adverse outcome in any patent litigation or
interference proceeding could subject the Company to significant liabilities to
third parties, require disputed rights to be licensed from third parties or
require the Company to cease using such technology, any of which could have a
material adverse effect on the Company. Moreover, the mere uncertainty resulting
from the initiation and continuation of any technology related litigation or
interference proceeding could have a material adverse effect on the Company
pending resolution of the disputed matters.

GOVERNMENT REGULATION

The development of Triangle's drug candidates and the manufacturing and
marketing of any drug candidates that are successfully developed are subject to
extensive regulation by numerous governmental

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authorities in the United States and other countries. See "Risk
Factors--Extensive Government Regulation; No Assurance of Regulatory Approval."

FDA APPROVAL

In the United States, pharmaceuticals are subject to rigorous FDA
regulation. The Federal Food, Drug, and Cosmetic Act ("FDCA") governs the
testing, manufacture, approval, labeling, storage, record keeping, reporting,
advertising and promotion of Triangle's drug candidates and any products that
Triangle may successfully develop. Product development and approval within this
regulatory framework takes a number of years and involves the expenditure of
substantial resources.

The steps required before a new prescription drug may be marketed in the
United States include (i) preclinical laboratory and animal tests, (ii) the
submission to the FDA of an IND, which must be evaluated and found acceptable by
the FDA before human clinical trials may commence, (iii) adequate and
well-controlled human clinical trials to establish the safety and effectiveness
of the drug, (iv) the submission of an NDA to the FDA and (v) FDA approval of
the NDA. Prior to obtaining FDA approval of an NDA, the facilities that will be
used to manufacture the drug must undergo a preapproval inspection to ensure
compliance with GMP regulations. A company must also pay a one-time user fee for
each NDA submission and pay annual user fees for each approved product and
manufacturing establishment.

Preclinical tests include laboratory evaluation of the drug candidate and
animal studies to assess the safety and effectiveness of the drug candidate and
its formulation. The results of such preclinical tests are submitted to the FDA
as part of an IND, and unless the FDA objects, the IND will become effective 30
days following its receipt by the FDA. If the FDA has concerns about the
proposed clinical trial, it may delay the trial and require modifications to the
trial protocol prior to permitting the trial to begin. As a result, there can be
no assurance that the FDA will permit a proposed IND to become effective.

Clinical trials involve the administration of the drug candidate to normal,
healthy volunteers or to patients identified as having the condition for which
the drug candidate is being tested. The drug candidate is administered under the
supervision of a qualified principal investigator. Clinical trials are conducted
in accordance with protocols previously submitted to the FDA as part of the IND
that detail the objectives of the trial, the parameters used to monitor safety
and the efficacy criteria that are being evaluated. Each clinical trial is
conducted under the auspices of an Institutional Review Board ("IRB") at the
institution at which the trial is conducted. The IRB considers, among other
things, ethical factors, the safety of the human subjects and the possible
liability risk for the institution.

Clinical trials are typically conducted in three sequential phases that may
overlap. In Phase I, the initial introduction of the drug candidate in normal,
healthy volunteers, the emphasis is on testing for safety (adverse effects),
dosage tolerance, metabolism, distribution, excretion, clinical pharmacology and
early evidence of effectiveness. In serious diseases such as AIDS or cancer,
patients suffering from the disease rather than normal, healthy volunteers are
used in Phase I trials. Phase II involves trials in a limited patient population
to determine the effectiveness of the drug candidate for specific targeted
indications, to determine dosage tolerance and optimal dosage and to identify
possible short-term side effects and safety risks. After a drug candidate has
been shown in Phase II trials to have an acceptable safety profile and probable
effectiveness, Phase III trials are undertaken to further evaluate clinical
effectiveness and to further test for safety within an expanded patient
population at multiple clinical study sites. Pilot trials are clinical trials
involving a small number of patients. The FDA reviews both the clinical trial
plans and the results of the trials at each phase and may discontinue the trials
at any time if there are significant safety issues.

The results of the preclinical tests and clinical trials are submitted to
the FDA in the form of an NDA for marketing approval. The testing and approval
process is likely to require substantial time and effort and there can be no
assurance that any approval will be granted on a timely basis or at all. The
approval process is affected by a number of factors, including the severity of
the disease, the availability of

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alternative treatments and the risks and benefits demonstrated in clinical
trials. Additional animal studies or clinical trials may be requested during the
FDA review process and may delay marketing approval. Upon approval, a drug may
be marketed only for the approved indications in the approved dosage forms.
Further clinical trials would be necessary to gain approval for the use of the
product for any additional indications or dosage forms. The FDA may also require
post-marketing testing, such as monitoring for adverse effects, which can
involve significant expense.

A company may conduct clinical trials outside of the United States, using a
product manufactured outside the country, and in some circumstances manufactured
within the United States, without an IND. The FDA will accept data from foreign
clinical trials to support clinical investigations in the United States and/or
approval of an NDA only if the agency determines that the trials are
well-designed, well-conducted, performed by qualified investigators, and
conducted in accordance with internationally recognized ethical principles and
any applicable foreign requirements. Triangle initiated Phase I/II clinical
trials in Europe for MKC-442 prior to submitting an IND and is conducting a
Pilot Phase I/II clinical trial in Europe for CS-92 without an IND. Triangle may
in the future conduct clinical trials with other drug candidates in various
foreign countries without an IND. There can be no assurance that clinical trials
conducted in either the United States or foreign countries will demonstrate that
any drug candidates under development by the Company are safe and effective, or
that the FDA will not require additional clinical trials to support approval of
an NDA.

As part of its IND regulations, the FDA has developed several regulatory
procedures to accelerate the clinical testing and approval of drugs intended to
treat life-threatening or seriously debilitating illnesses under certain
circumstances. For example, in 1988, the FDA issued regulations to expedite the
development, evaluation and marketing of drugs for life-threatening and severely
debilitating illnesses, especially where no alternative therapy exists (the
"1988 Regulations"). These procedures encourage early consultation between the
IND sponsors and the FDA in the preclinical testing and clinical trial phases to
determine what evidence will be necessary for marketing approval and to assist
the sponsors in designing clinical trials. Under this program, the FDA works
closely with the IND sponsors to accelerate and condense Phase II clinical
trials, which may, in some cases, eliminate the need to conduct Phase III trials
or limit the scope of Phase III trials. Under the 1988 Regulations, the FDA may
require post-marketing (Phase IV) clinical trials to obtain additional
information on the drug's risks, benefits and optimal use.

The FDA has issued regulations establishing an accelerated NDA approval
procedure for certain drugs under Subpart H of the agency's NDA approval
regulations ("Subpart H Regulations"). The Subpart H Regulations provide for
accelerated NDA approval for new drugs intended to treat serious or life-
threatening diseases where the drugs provide a meaningful therapeutic advantage
over existing treatment. Under this accelerated approval procedure, the FDA may
approve a drug based on evidence from adequate and well-controlled studies of
the drug's effect on a surrogate endpoint that is reasonably likely to predict
clinical benefits, or on evidence of the drug's effect on a clinical endpoint
other than survival or irreversible morbidity. This approval is conditional on
the favorable completion of post-marketing trials to establish and define the
degree of clinical benefits to the patient. These clinical trials would usually
be underway when the product obtains this accelerated approval. The FDA may also
impose distribution restrictions where necessary to assure safe use of the drug.
If, after approval, such a post-marketing clinical study establishes that the
drug does not perform as expected, or if post-marketing restrictions are not
adhered to or are not adequate to ensure the safe use of the drug, or other
evidence demonstrates that the product is not safe and/or effective under its
conditions of use, the FDA may withdraw approval through expedited
administrative procedures. The Subpart H accelerated approval regulation can
complement the 1988 Regulations for expediting the development, evaluation and
marketing of drugs. These two procedures for expediting the clinical evaluation
and approval of certain drugs may shorten the drug development process by as
much as two to three years.

The Food and Drug Administration Modernization Act of 1997 ("FDAMA")
essentially codifies, in new section 506 of the FDCA, the standards and
conditions in the Subpart H Regulations. Section 506

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provides for the designation of a "fast track" product, and establishes
procedures to facilitate development and expedite FDA review of a drug intended
for treatment of a serious or life-threatening condition that demonstrates the
potential to address unmet medical needs. Approval of a fast track product may
be subject to conditions, including requirements to conduct post approval
clinical trials and to presubmit promotional materials. Approval of a fast track
product can be withdrawn, using expedited procedures, for reasons similar to
those specified in the Subpart H Regulations.

The Company believes that some of its drug candidates may be candidates for
accelerated development and/or approval under the 1988 Regulations and/or the
Subpart H Regulations and/or section 506 of the FDCA. However, there can be no
assurance that any of these drug candidates or any future drug candidates the
Company may develop will be eligible for development and/or approval under these
regulations. In addition, there can be no assurance that these drug candidates
or any future drug candidates (if eligible for development and/or approval under
these regulations) will be approved by the FDA for marketing at all or, if
approved for marketing, will be approved for marketing sooner than would be
traditionally expected.

Once the sale of a product is approved, the FDA regulates the manufacturing,
marketing, safety reporting and other activities under the FDCA and the FDA's
implementing regulations. The FDA periodically inspects both domestic and
foreign drug manufacturing facilities to ensure compliance with applicable GMP
regulations, NDA conditions and other requirements. In addition, manufacturers
must register with the FDA and submit a list of every drug in commercial
distribution. The Company does not have or currently intend to develop the
facilities to manufacture its drug candidates in commercial quantities, and
intends to establish relationships with contract manufacturers for the
commercial manufacture of any products that are successfully developed. Some of
these contract manufacturers may be located outside the United States. There can
be no assurance that the Company's contract manufacturers will be able to attain
or maintain compliance with GMP regulations and NDA conditions. Changes in
contract manufactures may result in the need for new NDA submissions or delays
in the availability of product. Post-marketing reports are also required, for
purposes such as monitoring the product's usage and any adverse effects. Product
approvals may be withdrawn, or other actions may be ordered, or criminal or
other sanctions imposed if compliance with regulatory requirements is not
maintained.

Under the Orphan Drug Act, the FDA may grant orphan drug designation to
drugs intended to treat a "rare disease or condition," which generally is a
disease or condition that affects populations of fewer than 200,000 individuals
in the United States. Orphan drug designation must be requested before
submitting an NDA, and after the FDA grants orphan drug designation, the generic
identity of the therapeutic agent and its potential orphan use are publicly
disclosed by the FDA. Under current law, approval of the first NDA for a drug
with orphan drug designation confers United States marketing exclusivity to
market such designated drug for the designated indication for a period of seven
years following approval of the NDA, subject to certain limitations. Orphan drug
designation does not convey any advantage in, or shorten the duration of, the
regulatory approval process.

The Company believes that alanosine, if successfully developed for the
treatment of NSCLC and/or brain cancers, may qualify for orphan drug
designation. There can be no assurance, however, that alanosine or any future
products the Company may develop will be designated as an orphan drug or that
the current statutory provisions for marketing exclusivity will not change. In
addition, there can be no assurance that alanosine or any future products will
be approved for marketing.

FOREIGN REGULATORY APPROVAL AND SALE

Many foreign countries also regulate the clinical testing, manufacturing,
reporting, marketing and use of pharmaceutical products. The requirements
relating to the conduct of clinical trials, product approval, manufacturing,
marketing, pricing and reimbursement vary widely from country to country and
there can

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be no assurance that the Company or any third parties with whom the Company may
establish collaborative relationships will be able to attain or maintain
compliance with such requirements.

In addition to the import requirements of foreign countries, a company must
also comply with United States laws governing the export of FDA regulated
products. Pursuant to the FDA Export Reform and Enhancement Act of 1996, a drug
that has not obtained FDA approval may be exported to any country in the world
without FDA authorization if the product both complies with the laws of the
importing country and has obtained valid marketing authorization in one of the
following countries: Australia, Canada, Israel, Japan, New Zealand, Switzerland,
South Africa, the European Union, or a country in the European Economic Area.
The FDA is authorized to add countries to this list in the future. Among other
restrictions, a drug that has not obtained FDA approval may be exported under
the new law only if it is not adulterated, accords to the specifications of the
foreign purchaser, complies with the laws of the importing country, is labeled
for export, is manufactured in substantial compliance with GMP regulations and
is not sold in the United States.

OTHER REGULATIONS

In addition to regulations enforced by the FDA, the Company also is subject
to regulation under the Occupational Safety and Health Act, the Controlled
Substances Act, the Toxic Substances Control Act, the Resource Conservation and
Recovery Act and other similar federal, state and local regulations governing
permissible laboratory activities, waste disposal, handling of toxic, dangerous
or radioactive materials and other matters. The Company believes that it is in
substantial compliance, in all material respects, with applicable regulations.
These regulations are subject to change, however, and may, in the future,
require substantial effort and cost to the Company to comply with each of the
regulations, and may possibly restrict the Company's business activities. See
"Risk Factors--Hazardous Materials."

COMPETITION

54
<PAGE>
value of their inventions and are more actively seeking to commercialize the
technology they have developed.

MANUFACTURING

The Company does not have any manufacturing capacity and relies on third
party manufacturers for the manufacture of all of its clinical trial material.
The Company currently plans to expand its existing relationships or to seek to
establish relationships with additional third party manufacturers for the
commercial production of any products it may develop. There can be no assurance
that the Company will be able to establish or maintain relationships with third
party manufacturers on commercially acceptable terms or that third party
manufacturers will be able to manufacture products in commercial quantities
under applicable GMP regulations on a cost effective basis. The Company's
dependence upon third parties for the manufacture of its products may adversely
affect the Company's profit margins and its ability to develop and commercialize
products on a timely and competitive basis. Further, there can be no assurance
that manufacturing or quality control problems will not arise in connection with
the manufacture of the Company's products or that third party manufacturers will
be able to maintain the necessary governmental licenses and approvals to
continue manufacturing the Company's products. Any failure to establish or
maintain relationships with third parties for its manufacturing requirements on
commercially acceptable terms would have a material adverse effect on the
Company. See "Risk Factors--Lack of Manufacturing Capabilities" and
"--Government Regulation."

SALES AND MARKETING

55
<PAGE>
HEALTH CARE REFORM MEASURES AND THIRD PARTY REIMBURSEMENT

The business and financial condition of pharmaceutical companies will
continue to be affected by the efforts of governments and third party payors to
contain or reduce the cost of health care through various means. A number of
legislative and regulatory proposals aimed at changing the health care system
have been proposed in recent years. In addition, an increasing emphasis on
managed care in the United States has and will continue to increase pressure on
pharmaceutical pricing. While the Company cannot predict whether legislative or
regulatory proposals will be adopted or what effect those proposals or managed
care efforts may have on its business, the announcement and/or adoption of such
proposals or efforts could have a material adverse effect on the Company. In the
United States and elsewhere, sales of prescription pharmaceuticals are dependent
in whole or in part on the availability of reimbursement to the consumer
from third party payors, such as government and private insurance plans, and
these third party payors frequently mandate predetermined discounts from list
prices. Third party payors are increasingly challenging the prices charged for
medical products and services. If the Company succeeds in bringing one or more
products to the market, there can be no assurance that these products will be
considered cost effective or that reimbursement to the consumer will be
available or will be sufficient to allow the Company to sell its products on a
competitive basis. See "Risk Factors--Uncertainty of Health Care Reform Measures
and Third Party Reimbursement."

HUMAN RESOURCES

As of January 31, 1998, Triangle had 70 employees, including 49 in
development and 21 in finance and administration. Of these employees, 30 hold
advanced degrees, of which 17 are M.D.s or Ph.D.s. The Company's future success
will depend in large part upon its ability to attract and retain highly
qualified personnel. The Company's employees are not represented by any
collective bargaining agreements, and the Company has never experienced a work
stoppage. The Company believes that its employee relations are good. The Company
has entered into confidentiality agreements with all of its employees. See "Risk
Factors--Dependence on Key Employees."

FACILITIES

As of January 31, 1998, the Company occupied an approximately 35,000 square
foot administrative office, laboratory and pilot manufacturing facility in
Durham, North Carolina pursuant to a lease that continues through September
2003. Under the terms of the lease, the Company will occupy approximately 17,000
square feet of additional space beginning in August 1998. The Company believes
its facilities will be adequate to meet its needs through the end of 1998.

LEGAL PROCEEDINGS

From time to time, Triangle may be involved in litigation relating to claims
arising out of its operations in the normal course of business. As of the date
of this Prospectus, the Company is not a party to any legal proceedings. Emory,
from which the Company has licensed several of its drug candidates, including
FTC, is a party to several interference and opposition proceedings and one
lawsuit in Australia regarding certain of the patents and patent applications
related to these drug candidates. There can be no assurance that Emory will
prevail in any of these proceedings and any significant adverse development with
respect to Emory's claims could have a material adverse effect on the Company
and its ability to commercialize these drug candidates. In addition, the Company
is obligated to reimburse Emory for certain expenses related to these
proceedings and these expenses could be substantial. See "Risk
Factors--Uncertainty of Patents; Dependence on Patents, Licenses and Proprietary
Rights" and "Management's Discussion and Analysis of Financial Condition and
Results of Operations."

56
<PAGE>
MANAGEMENT

EXECUTIVE OFFICERS AND DIRECTORS

The executive officers and directors of the Company as of January 31, 1998,
were as follows:

<TABLE>
<CAPTION>
NAME AGE POSITION
- ---------------------------------------- --------- ----------------------------------------------------------------
<S> <C> <C>

David W. Barry, M.D..................... 54 Chairman of the Board and Chief Executive Officer
M. Nixon Ellis, Ph.D.................... 48 Director, President and Chief Operating Officer
Phillip A. Furman, Ph.D................. 53 Chief Scientific Officer
James A. Klein, Jr...................... 35 Chief Financial Officer and Treasurer
Bruce J. McCreedy, Jr., Ph.D............ 38 Vice President, Clinical Virology and Diagnostics
Anne F. McKay........................... 43 Vice President, Drug Regulatory Affairs
George R. Painter, III, Ph.D............ 47 Vice President, Research and Development
Chris A. Rallis, J.D.................... 44 Vice President, Business Development, General Counsel and
Secretary
Franck S. Rousseau, M.D................. 40 Vice President, Medical Affairs and Chief Medical Officer
Carolyn S. Underwood.................... 41 Vice President, Commercial Operations
Anthony B. Evnin, Ph.D. (1)............. 56 Director
Standish M. Fleming (2)................. 50 Director
Karl Y. Hostetler, M.D. (3)............. 58 Director and Member of the Scientific Advisory Board
George McFadden (1)..................... 57 Director
Peter McPartland (2).................... 44 Director
</TABLE>

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

(1) Member of the Compensation Committee.

(2) Member of the Audit Committee.

(3) Dr. Hostetler has decided not to stand for reelection at the Company's 1998
Annual Meeting of Stockholders. Dennis B. Gillings, the Chairman of the
Board and Chief Executive Officer of Quintiles Transnational Corp., a
provider of contract research, sales and marketing services to the
pharmaceutical, biotechnology and medical device industries, has agreed to
serve on the Company's Board if elected by the Company's stockholders at the
1998 Annual Meeting of Stockholders.

DAVID W. BARRY, M.D. has served as Chairman of the Board and Chief
Executive Officer since July 1995 and served as the Company's President from
July 1995 through September 1995. Prior to joining the Company, Dr. Barry served
as a member of the Board of Directors and as the Director of Research,
Development and Medical Affairs of Wellcome plc ("Wellcome"), a pharmaceutical
company, from May 1994 through May 1995. From May 1989 through May 1994, Dr.
Barry served as a member of the Board of Directors and Vice President, Research,
Development and Medical Affairs of Burroughs Wellcome, a pharmaceutical company
and an indirect, wholly-owned subsidiary of Wellcome. Dr. Barry is considered a
leader in the field of antiviral therapy and is one of the co-inventors of the
first anti-HIV drug, AZT. Dr. Barry also directed the clinical development of
the first selective anti-herpes drug, acyclovir. Before joining Burroughs
Wellcome in 1977, Dr. Barry spent five years at the FDA in various capacities,
including Director of the Influenza Task Force of the Bureau of Biologics and
Acting Deputy Director of the Division of Virology at the Bureau of Biologics.
Dr. Barry received a B.A. in French literature from Yale College and an M.D.
from Yale University. Dr. Barry is currently a director of Family Health
International, a not-for-profit company engaged in the business of family
planning, and Molecular Biosystems, Inc., a publicly-held medical diagnostics
company. Dr. Barry is a consultant to Life Science

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<PAGE>
Ventures GmbH, a European venture capital company, and is also Chairman of the
Inter-Company Collaboration on AIDS Drug Development, a pharmaceutical industry
consortium.

M. NIXON ELLIS, PH.D. has served as a director of the Company since July
1995 and as President and Chief Operating Officer since September 1995. Prior to
joining the Company, Dr. Ellis served as Global Brand Director,
HIV/Retrovir-Registered Trademark- of Wellcome from January 1995 through June
1995, where he was responsible for managing a $300 million worldwide business.
From April 1993 through December 1994, Dr. Ellis served as Assistant Director,
Group Licensing of Wellcome. Prior to that, Dr. Ellis served as Assistant
Division Director, Virology of Burroughs Wellcome from March 1991 to March 1993.
Prior to assuming his management responsibilities at Wellcome, Dr. Ellis'
research focused on the disease producing potential of drug resistant viral
mutants. Dr. Ellis received a B.S. in biology from the University of South
Carolina, an M.B.A. from the University of North Carolina, Chapel Hill, and an
M.S. in medical microbiology and a Ph.D. in microbiology from the University of
Georgia.

PHILLIP A. FURMAN, PH.D. has served as Chief Scientific Officer since July
1997, and served as Vice President, Research and Chief Scientific Officer of the
Company from September 1995 through June 1997. Prior to joining the Company, Dr.
Furman served as Director, Virology of Burroughs Wellcome from July 1989 through
June 1995, where he played a significant role in the development of both AZT and
acyclovir. Dr. Furman's research while at Burroughs Wellcome focused on the
structure and function of nucleic acid polymerizing enzymes. He is a co-inventor
of the use of AZT for HIV therapy as well as a co-inventor of the use of FTC to
treat HBV infections. Dr. Furman received a B.S. in biology from Piedmont
College, an M.A. in microbiology from the University of Southern Florida and a
Ph.D. in microbiology from Tulane University.

JAMES A. KLEIN, JR. has served as Chief Financial Officer and Treasurer
since November 1995, and served as Secretary and Treasurer from July 1995
through November 1995. Prior to joining the Company, Mr. Klein served as
International Research, Development and Medical Financial Controller of Wellcome
from May 1994 through June 1995. From June 1992 through May 1994, Mr. Klein
served as Senior Financial Analyst of Burroughs Wellcome. Prior to that, Mr.
Klein held various management positions in finance at Burroughs Wellcome. Mr.
Klein received a B.A. in accounting from the University of Mississippi and is a
certified public accountant.

BRUCE J. MCCREEDY, JR., PH.D. has served as Vice President, Clinical
Virology and Diagnostics since August 1997 and served as Vice President,
Clinical Diagnostics of the Company from March 1997 through July 1997. Prior to
joining the Company, Dr. McCreedy served in the following positions at
Laboratory Corporation of America (formerly Roche Biomedical Laboratories):
Associate Vice President of Infectious Diseases and Clinical Trials from July
1995 to February 1997, Director of Infectious Diseases and Clinical Trials from
1993 to 1995, and Associate Director of Infectious Diseases from 1990 to 1993.
While at Laboratory Corporation of America, Dr. McCreedy was involved in the
development of diagnostic test systems for the detection and quantitation of
human retroviruses and hepatitis B and C viruses. Dr. McCreedy received his B.S.
degree from Wake Forest University in medical microbiology and a Ph.D. in
microbiology from the Bowman Gray School of Medicine.

ANNE F. MCKAY has served as Vice President, Drug Regulatory Affairs since
October 1996. Prior to joining the Company, Ms. McKay served as Director of
Regulatory Affairs with Medco Research, Inc. ("Medco") from July 1995 to
September 1996. Prior to joining Medco, Ms. McKay served as Director of
Regulatory Affairs, North America, with Burroughs Wellcome, and held various
other regulatory positions during a 15-year tenure at Burroughs Wellcome. While
at Burroughs Wellcome, Ms. McKay's department was responsible for providing
support for various FDA submissions, including the NDA submissions for AZT and
acyclovir. Ms. McKay received her B.S. in animal science from Michigan State
University.

GEORGE R. PAINTER, III, PH.D. has served as Vice President, Research and
Development since July 1997, and served as Vice President, Chemistry and
Technical Development of the Company from

58
<PAGE>
January 1996 through June 1997. From July 1995 through January 1996, Dr. Painter
served as Director of Research Process for Glaxo and from June 1993 through July
1995, he served as Assistant Director of Virology for Burroughs Wellcome. While
at Burroughs Wellcome, Dr. Painter led the international development of both an
HIV protease inhibitor and FTC. He is also a co-inventor of the use of FTC to
treat HBV infections. Dr. Painter received a B.S. in chemistry, an M.S. in
physical chemistry and a Ph.D. in organic chemistry from Emory University.

CHRIS A. RALLIS, J.D. has served as Vice President, Business Development,
General Counsel and Secretary since November 1995. Prior to joining the Company,
Mr. Rallis served in the following positions with Burroughs Wellcome: Vice
President, Planning and Business Development from February 1994 to June 1995;
Director, Planning and Business Development from June 1993 through February
1994; and Assistant General Counsel from June 1991 through June 1993. During Mr.
Rallis' tenure at Burroughs Wellcome, his department was responsible for
finalizing licensing agreements with Emory University and Vertex Pharmaceuticals
Incorporated and a consumer healthcare joint venture with Warner-Lambert
Company. Mr. Rallis received an A.B. degree in economics from Harvard College
and a J.D. from Duke University.

FRANCK S. ROUSSEAU, M.D. has served as Vice President, Medical Affairs and
Chief Medical Officer since March 1997. From 1995 through March 1997, Dr.
Rousseau served as Associate Director, International Antiviral Clinical Research
for Glaxo. Prior to joining Glaxo, Dr. Rousseau was Director of Infectious
Diseases and HIV Clinical Research at Wellcome France from 1993 through 1995.
From 1990 through 1993, Dr. Rousseau was a Clinical Research Physician with the
French National Agency for Research Against AIDS. Dr. Rousseau has been involved
with the clinical development of several anti-HIV drugs. Dr. Rousseau received
the equivalent of a B.A. from the University of Paris and his M.D. from the
University of Paris, College of Medicine.

CAROLYN S. UNDERWOOD has served as Vice President, Commercial Operations
since January 1998. Ms. Underwood served as Vice President, Marketing and
Investor Relations of the Company from November 1996 through December 1997 and
served as Vice President, Marketing from January 1996 through November 1996.
Prior to joining the Company, Ms. Underwood served as Director, CNS Marketing of
Glaxo from June 1995 through December 1995. Prior to that, Ms. Underwood served
as Director, Marketing Division of Nippon Wellcome KK, a pharmaceutical company
of which Wellcome was one of the joint venture partners, from February 1994
through June 1995. Ms. Underwood also served as Senior Director of Marketing of
Burroughs Wellcome from July 1991 through January 1994. Ms. Underwood received a
B.S. in nursing from the University of North Carolina, Chapel Hill.

ANTHONY B. EVNIN, PH.D. has served as a director of the Company since
November 1995. Since 1975, Dr. Evnin has been a general partner of Venrock
Associates, a venture capital firm. Dr. Evnin received an A.B. in chemistry from
Princeton University and a Ph.D. in chemistry from Massachusetts Institute of
Technology. Dr. Evnin is currently a director of several privately-held
companies and the following publicly-held companies: AxyS Pharmaceuticals, Inc.,
Centocor, Inc., and Ribozyme Pharmaceuticals, Inc., all of which are
biopharmaceutical companies, and Opta Food Ingredients, Inc., a food ingredients
company.

STANDISH M. FLEMING has served as a director of the Company since July
1995. Since April 1993, Mr. Fleming has been a general partner of Forward
Ventures, a venture capital firm. Mr. Fleming also served in an advisory
position with Forward Ventures from February 1992 through April 1993. Prior to
that, Mr. Fleming joined Ventana, a venture capital firm, in 1986 and served as
a fund manager from January 1990 through January 1992. Mr. Fleming received a
B.A. in English from Amherst College and an M.B.A. from the University of
California, Los Angeles. Mr. Fleming currently serves as a director of four
privately-held companies.

59
<PAGE>
KARL Y. HOSTETLER, M.D. has served as a director of the Company since July
1995. Dr. Hostetler has served as a professor of medicine at the University of
California, San Diego and has practiced medicine at the Veterans Affairs Medical
Center in San Diego since January 1973. From June 1987 through June 1992, Dr.
Hostetler served as a director and as Vice President of Research and Development
of Vical Incorporated, a gene therapy company. Dr. Hostetler received a B.A. in
chemistry from Depaul University and an M.D. from Western Reserve University.

GEORGE MCFADDEN has served as a director of the Company since November
1995. Since 1979, Mr. McFadden has served as a general partner of McFadden
Brothers, an investment company. Mr. McFadden received a B.A. in business from
Vanderbilt University and an M.B.A. from Columbia University. Mr. McFadden is
currently a director of four privately-held companies, Washington, Inc. (where
he serves as Chairman of the Board), Chemical Leaman Corporation, Cryogenics
Holdings, Inc. and Squaw Valley Corp., and of one publicly-held packaging
company, Ball Corporation.

PETER MCPARTLAND has served as a director of the Company since June 1996.
Mr. McPartland has served as a director of Schroder Ventures Life Sciences
Advisers (UK) Ltd., a venture capital firm, since July 1995. He served as a
principal of Schroder Venture Advisers from April 1988 through July 1995. Mr.
McPartland received a B.Sc. in pharmacology from University College, London. Mr.
McPartland currently serves as Deputy Chairman of Cerebrus Limited (a
privately-held, United Kingdom company).

60
<PAGE>
PRINCIPAL STOCKHOLDERS

The following table sets forth certain information regarding the beneficial
ownership of the Common Stock as of January 31, 1998, and as adjusted to reflect
the completion of the Offering, by (i) each person known by the Company to
beneficially own more than five percent of the Company's Common Stock, (ii) each
of the Company's directors, (iii) the Company's Chief Executive Officer and the
four additional most highly compensated executive officers of the Company and
(iv) all directors and executive officers of the Company as a group.

<TABLE>
<CAPTION>
PERCENTAGE OF SHARES
SHARES BENEFICIALLY OWNED (2)
BENEFICIALLY ----------------------------------
NAME AND ADDRESS OF BENEFICIAL OWNER (1) OWNED (1) PRIOR TO OFFERING AFTER OFFERING
- ------------------------------------------------------------------- ----------- ----------------- ---------------
<S> <C> <C> <C>
Funds advised by Soros Fund Management LLC (3)..................... 1,989,500 9.95% 8.5%
888 Seventh Avenue, Suite 3300
New York, NY 10106
Venrock Associates (4)............................................. 1,467,371 7.3 6.2
30 Rockefeller Plaza
New York, NY 10112
Forward Ventures II, L.P. (5)...................................... 1,343,517 6.7 5.7
9255 Towne Centre Drive, Suite 300
San Diego, CA 92121
The Wellcome Trust (6)............................................. 1,300,000 6.5 5.5
183 Euston Road
London, England NN1 2BE
Duquesne Fund, L.P. (7)............................................ 800,000 4.0 3.4
Box N9204
Charlotte House, Charlotte Street
Nassau, Bahamas
David W. Barry, M.D. (8)........................................... 1,303,881 6.5 5.5
M. Nixon Ellis, Ph.D. (9) (10)..................................... 620,934 3.1 2.6
Anthony B. Evnin, Ph.D. (11)....................................... 1,467,371 7.3 6.2
30 Rockefeller Plaza
New York, NY 10112
Standish M. Fleming (12)........................................... 1,343,517 6.7 5.7
9255 Towne Centre Drive, Suite 300
San Diego, CA 92121
Karl Y. Hostetler, M.D. (13)....................................... 409,850 2.0 1.7
14024 Rue St. Raphael
Del Mar, CA 92104
George McFadden (14)............................................... 2,315,000 11.6 9.9
745 Fifth Avenue
New York, NY 10151
Peter McPartland (15).............................................. 642,250 3.2 2.7
20 Southampton Street
London WC2E 7QG
United Kingdom
George R. Painter, III, Ph.D. (10) (16)............................ 143,853 * *
Chris A. Rallis, J.D. (10) (17).................................... 249,836 1.2 1.1
Carolyn S. Underwood (10) (18)..................................... 178,605 * *
All directors and executive officers as a group (15 persons)
(8)-(19)......................................................... 9,149,414 44.2 37.8
</TABLE>

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

* Less than 1%

61
<PAGE>
(1) Except as otherwise indicated, (i) the stockholders listed in the table have
sole voting and investment power with respect to all shares of Common Stock
shown as beneficially owned by them, subject to community property laws,
where applicable, and (ii) the address of all stockholders listed in the
table is: 4 University Place, 4611 University Drive, Durham, North Carolina
27707.

(2) Percentage of ownership is based on 20,002,338 shares of Common Stock
outstanding on January 31, 1998, and is calculated pursuant to Rule
13d-3(d)(1) under the Exchange Act.

(3) Includes shares of Common Stock held by the following entities that are
advised by Soros Fund Management LLC ("SFM LLC"): (i) 1,000,000 shares of
Common Stock held for the account of Quantum Industrial Partners LDC, (ii)
964,500 shares of Common Stock held for the account of Quantum Partners LDC,
and (iii) 25,000 shares of Common Stock held for the account of Quasar
International Partners C.V. Stanley F. Druckenmiller is the Lead Portfolio
Manager and a Member of the Management Committee of SFM LLC, and is also the
sole managing member of Duquesne LLC ("Duquesne"), an investment advisory
firm which serves as a discretionary investment advisor to Duquesne Fund,
L.P.

(4) Includes 478,754 shares of Common Stock beneficially owned by Venrock
Associates II, L.P. and 25,535 shares of Common Stock beneficially owned by
Anthony B. Evnin, Ph.D. Dr. Evnin, a director of the Company, is a general
partner of Venrock Associates and Venrock Associates II, L.P. Dr. Evnin
disclaims beneficial ownership of the shares beneficially owned by Venrock
Associates and Venrock Associates II, L.P. other than to the extent of his
individual partnership interests, but exercises shared voting and investment
power with respect to all such shares.

(5) Includes 233,663 shares of Common Stock beneficially owned by Forward
Ventures III, L.P. and 84,854 shares of Common Stock beneficially owned by
Standish M. Fleming. Mr. Fleming is a general partner of Forward II
Associates, L.P., which is the general partner of Forward Ventures II, L.P.,
and a managing member of Forward III Associates, L.L.C., which is the
general partner of Forward Ventures III, L.P. Mr. Fleming disclaims
beneficial ownership of the shares beneficially owned by Forward Ventures
II, L.P. and Forward Ventures III, L.P. other than to the extent of his
individual partnership and member interests, but exercises shared voting and
investment power with respect to all such shares.

(6) All shares beneficially owned by The Wellcome Trust Limited as trustee of
The Wellcome Trust.

(7) Stanley F. Druckenmiller is the sole managing member of Duquesne and is also
the Lead Portfolio Manager and a Member of the Management Committee of SFM
LLC.

(8) Includes 25,381 shares of Common Stock issuable upon the exercise of options
that are exercisable within 60 days of January 31, 1998, and 30,000 shares
of Common Stock held by the Barry Charitable Foundation, Inc., a charitable
North Carolina corporation of which Dr. Barry serves as President.

(9) Includes 230,867 shares of Common Stock issuable upon the exercise of
options that are exercisable within 60 days of January 31, 1998, and 8,000
shares of Common Stock held by the Ellis Charitable Foundation, Inc., a
charitable North Carolina corporation of which Dr. Ellis serves as
President.

(10) Excludes an aggregate of 6,483 shares of Common Stock purchased by certain
executive officers upon the conclusion of the purchase interval, ending
February 27, 1998, under the Company's Employee Stock Purchase Plan.

(11) Includes 963,082 shares and 478,754 shares of Common Stock beneficially
owned by Venrock Associates and Venrock Associates II, L.P., respectively.
Dr. Evnin is a general partner of Venrock Associates and Venrock Associates
II, L.P. and consequently shares voting and investment power with respect to
all such shares. Dr. Evnin disclaims beneficial ownership of these shares
other than to the extent of his individual partnership interest.

(12) Includes 1,025,000 shares and 233,633 shares of Common Stock beneficially
owned by Forward Ventures II, L.P. and Forward Ventures III, L.P.,
respectively. Mr. Fleming is a general partner of Forward II Associates,
L.P., which is the general partner of Forward Ventures II, L.P., and a
managing member of Forward III Associates, L.L.C., which is the general
partner of Forward Ventures III, L.P., and consequently shares voting and
investment power with respect to all such shares. Mr. Fleming

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<PAGE>
disclaims beneficial ownership of these shares other than to the extent of
his individual partnership and member interests.

(13) All shares of Common Stock are beneficially owned by a family trust.

(14) Includes 100,000 shares, 200,000 shares, 600,000 shares, 240,000 shares,
510,000 shares, 90,000 shares, 75,000 shares and 100,000 shares of Common
Stock beneficially owned by (i) McFadden Brothers, (ii) McFadden Securities,
L.P., (iii) a family trust under the will of Alexander B. McFadden, (iv)
three family trusts for the benefit of Mr. McFadden's children, (v) other
family members, (vi) a former family member, (vii) a former family member as
custodian for one of Mr. McFadden's children and (viii) a retirement plan
for employees of Chemical Leaman Corporation and affiliated corporations,
respectively. Mr. McFadden exercises shared voting and investment power with
respect to all such shares. Mr. McFadden disclaims beneficial ownership of
these shares other than to the extent of his pecuniary interest in the
shares beneficially owned by McFadden Brothers, McFadden Securities, L.P.
and the family trust under the will of Alexander B. McFadden.

(15) All shares beneficially owned by Schroder Venture Managers Limited, as
manager for Schroder Ventures International Life Sciences Fund LP1, Schroder
Ventures International Life Sciences Fund LP2, Schroder Ventures
International Life Sciences Fund Trust and Schroder Venture Managers
Limited, as investment manager for the Schroder Ventures International Life
Sciences Fund Co-investment Scheme. Mr. McPartland is a director of Schroder
Ventures Life Sciences Advisers (UK) Ltd., a wholly-owned subsidiary of
Schroder Ventures Life Sciences Advisors Limited, which acts as an advisor
to Schroder Venture Managers Limited. Mr. McPartland disclaims beneficial
ownership of these shares other than to the extent of his individual
interest arising from his position as a director of Schroder Ventures Life
Science Advisers (UK) Ltd.

(16) Includes 24,057 shares of Common Stock issuable upon the exercise of
options that are exercisable within 60 days of January 31, 1998. Also
includes 40,000 shares of Common Stock held by the George R. Painter III &
Gwendolyn S. Powell Charitable Remainder Trust.

(17) Includes 57,970 shares of Common Stock issuable upon the exercise of
options that are exercisable within 60 days of January 31, 1998. Also
includes 500 shares held separately by Mr. Rallis' wife and 500 shares held
by Mr. Rallis' wife as custodian for their children under the Uniform Gift
to Minors Act.

(18) Includes 168,535 shares of Common Stock issuable upon the exercise of
options that are exercisable within 60 days of January 31, 1998. Also
includes 500 shares held by Ms. Underwood as custodian for her son under the
Uniform Gift to Minors Act.

(19) Includes 679,854 shares of Common Stock issuable upon the exercise of
options that are exercisable within 60 days of January 31, 1998.

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<PAGE>
DESCRIPTION OF CAPITAL STOCK

The authorized capital stock of Triangle consists of 75,000,000 shares of
Common Stock and 5,000,000 shares of Preferred Stock, $0.001 par value per share
("Preferred Stock").

COMMON STOCK

The holders of Common Stock are entitled to one vote for each share held of
record on all matters submitted to a vote of the stockholders. Subject to
preferences that may be applicable to any outstanding Preferred Stock, holders
of Common Stock are entitled to receive ratably such dividends, if any, as may
be declared by the Board out of funds legally available. See "Price Range of
Common Stock." In the event of liquidation, dissolution or winding up of
Triangle, holders of Common Stock are entitled to share ratably in all assets
remaining after payment of liabilities and the liquidation preference of any
outstanding Preferred Stock. Holders of Common Stock have no preemptive rights
or rights to convert their Common Stock into any other securities. There are no
redemption or sinking fund provisions applicable to the Common Stock. All
outstanding shares of Common Stock are fully paid and nonassessable.

At January 31, 1998, there were 20,002,338 shares of Common Stock
outstanding and held of record by approximately 215 stockholders and
beneficially by approximately 1,700 stockholders.

PREFERRED STOCK

The Board has the authority to issue Preferred Stock in one or more series
and to fix or alter the designation, powers, preferences, rights,
qualifications, limitations and restrictions of the shares of each such series,
including the dividend rights, dividend rate, conversion rights, voting rights,
rights and terms of redemption (including sinking fund provisions), liquidation
preferences and the number of shares constituting any such series, without any
further vote or action by the stockholders. The rights and preferences of
Preferred Stock may in all respects be superior and prior to the rights of
Common Stock. The issuance of Preferred Stock could decrease the amount of
earnings and assets available for distribution to holders of Common Stock or
adversely affect the rights and powers, including voting rights, of the holders
of Common Stock and could have the effect of delaying, deferring or preventing a
change in control of Triangle.

There are no shares of Preferred Stock outstanding on the date of this
Prospectus.

WARRANTS TO PURCHASE COMMON STOCK

At January 31, 1998, there were outstanding warrants to purchase 46,000
shares of Common Stock at a weighted average exercise price of $2.23 per share.
Each warrant contains provisions for the adjustment of the exercise price and
the aggregate number of shares issuable upon exercise of the warrant under
certain circumstances, including stock dividends, stock splits, reorganizations,
reclassifications or consolidations. Holders of certain of the warrants are
entitled to certain registration rights with respect to Common Stock issued or
issuable upon exercise thereof. See "--Registration Rights."

REGISTRATION RIGHTS

Pursuant to a certain Restated Investors' Rights Agreement, the holders (the
"Holders") of approximately 9,600,000 shares of Common Stock (the "Registrable
Securities") are entitled to certain rights with respect to the registration of
such shares of Common Stock under the Securities Act.

If the Company proposes to register any of its securities under the
Securities Act, either for its own account or for the account of other
stockholders, such Holders are entitled to notice of such registration and are
entitled to include shares of such Common Stock therein. A majority of such
Holders of the Registrable Securities are also entitled to certain demand
registration rights pursuant to which they may require the Company to file a
registration statement under the Securities Act at the Company's expense

64
<PAGE>
with respect to their shares of Common Stock, and the Company is required to use
its best efforts to effect such registration. Further, the Holders of such
Registrable Securities may require the Company to file additional registration
statements on Form S-3 at the Company's expense. All of these registration
rights are subject to certain conditions and limitations, among them the right
of the underwriters of an offering to limit the number of shares of Registrable
Securities included in such registration and the right of the Company not to
effect a requested registration within 180 days following an offering of the
Company's securities, including the Offering. The Company is required to bear
all expenses, other than underwriting discounts and commissions, in connection
with any registration of the Registrable Securities. The Company is also
required to indemnify the Holders and the underwriters for the Holders, if any,
under certain circumstances.

The Company has also entered into two additional Investors' Rights
Agreements, pursuant to which the holders ("Additional Rights Holders") of
approximately 410,000 shares of Common Stock and the holder of a warrant to
purchase up to 30,000 shares of Common Stock ("Additional Registrable
Securities") are entitled to certain rights with respect to the registration of
such shares of Common Stock under the Securities Act. If the Company proposes to
register any of its securities under the Securities Act, either for its own
account or for the account of other stockholders, such Additional Rights Holders
are entitled to notice of such registration and are entitled to include shares
of such Common Stock therein. These registration rights are subject to certain
conditions and limitations, among them the right of the underwriters of an
offering to limit the number of shares of Additional Registrable Securities
included in such registration. The Company is required to bear all expenses,
other than underwriting discounts and commissions, in connection with any
registration of the Additional Registrable Securities. The Company is also
required to indemnify the Additional Rights Holders and the underwriters for the
Additional Rights Holders, if any, under certain circumstances.

The Company has also filed a registration statement to register the resale
of 2,789,500 shares of Common Stock, 2,000,000 of which were issued in a private
placement in June 1997. The Company is obligated to keep the registration
statement effective for a period of 19 months from January 1998, which period
may be extended (by a maximum of five months) to the extent that the holders of
these shares are not able to resell their shares due to a temporary withdrawal
of the registration statement by the Company. The Company is also required to
indemnify these holders and the underwriters for these holders, if any, under
certain circumstances.

All of the registration rights granted by the Company expire on the earlier
of (i) November 6, 2001, or (ii) the date after which all shares of Common Stock
for which registration rights have been granted may be immediately sold under
Rule 144(k) under the Securities Act.

ANTITAKEOVER EFFECTS OF CHARTER, BYLAWS AND DELAWARE LAW

SECOND RESTATED CERTIFICATE OF INCORPORATION AND RESTATED BYLAWS

The Company's Certificate authorizes the Board to establish one or more
series of Preferred Stock, the terms of which can be determined by the Board at
the time of issuance. The Certificate also provides that all stockholder action
must be effected at a duly called meeting of stockholders and not by a consent
in writing. The Company's Bylaws divide the Company's Board into three classes
of directors with each class serving a three year term. In addition, the Bylaws
do not permit stockholders of the Company to call a special meeting of
stockholders; only the Company's Chief Executive Officer, President, Chairman of
the Board or a majority of the Board are permitted to call a special meeting of
stockholders. The Bylaws also require that stockholders give advance notice to
the Company's secretary of any nominations for director or other business to be
brought by stockholders at any stockholders' meeting and require a supermajority
vote of members of the Board and/or stockholders to amend certain Bylaw
provisions. These provisions of the Certificate and the Bylaws could discourage
potential acquisition proposals and could delay or prevent a change in control
of the Company. Such provisions may also have the effect of preventing changes
in the

65
<PAGE>
management of the Company. See "Risk Factors--Antitakeover Effects of Charter,
Bylaws and Delaware Law."

DELAWARE TAKEOVER STATUTE

The Company is subject to Section 203 of the Delaware General Corporation
Law ("Section 203") which, subject to certain exceptions, prohibits a Delaware
corporation from engaging in any business combination with any interested
stockholder (defined as any person or entity that is the beneficial owner of at
least 15% of a corporation's voting stock) for a period of three years following
the time that such stockholder became an interested stockholder, unless: (i)
prior to such time, the board of directors of the corporation approved either
the business combination or the transaction that resulted in the stockholder's
becoming an interested stockholder; (ii) upon consummation of the transaction
that resulted in the stockholder's becoming an interested stockholder, the
interested stockholder owned at least 85% of the voting stock of the corporation
outstanding at the time the transaction commenced, excluding, for purposes of
determining the number of shares outstanding, those shares owned (x) by persons
who are directors and also officers and (y) by employee stock plans in which
employee participants do not have the right to determine confidentially whether
shares held subject to the plan will be tendered in a tender or exchange offer;
or (iii) at or subsequent to such time, the business combination is approved by
the Board and authorized at an annual or special meeting of stockholders, and
not by written consent, by the affirmative vote of at least two-thirds of the
outstanding voting stock that is not owned by the interested stockholder.

Section 203 defines business combination to include: (i) any merger or
consolidation involving the corporation and the interested stockholder; (ii) any
sale, lease, exchange, mortgage, transfer, pledge or other disposition involving
the interested stockholder and 10% or more of the assets of the corporation;
(iii) subject to certain exceptions, any transaction which results in the
issuance or transfer by the corporation of any stock of the corporation to the
interested stockholder; (iv) any transaction involving the corporation that has
the effect of increasing the proportionate share of the stock of any class or
series of the corporation beneficially owned by the interested stockholder; or
(v) the receipt by the interested stockholder of the benefit of any loans,
advances, guarantees, pledges or other financial benefits provided by or through
the corporation.

TRANSFER AGENT AND REGISTRAR

The transfer agent and registrar for the Common Stock is American Stock
Transfer & Trust Company.

66
<PAGE>
UNDERWRITING

The names of the Underwriters of the shares of Common Stock offered hereby
and the aggregate number of shares of Common Stock which each has severally
agreed to purchase from the Company, subject to the terms and conditions
specified in the Underwriting Agreement, are as follows:

<TABLE>
<CAPTION>
NUMBER
UNDERWRITERS OF SHARES
- --------------------------------------------------------------------------------- ----------
<S> <C>
SBC Warburg Dillon Read Inc...................................................... 1,237,000
Bear, Stearns & Co. Inc.......................................................... 963,000
Vector Securities International, Inc............................................. 550,000
Hambrecht & Quist LLC............................................................ 125,000
Lehman Brothers Inc.............................................................. 125,000
Merrill Lynch, Pierce, Fenner & Smith Incorporated............................... 125,000
Morgan Stanley & Co. Incorporated................................................ 125,000
PaineWebber Incorporated......................................................... 125,000
UBS Securities LLC............................................................... 125,000
----------
Total...................................................................... 3,500,000
----------
----------
</TABLE>

The Managing Underwriters are SBC Warburg Dillon Read Inc., Bear, Stearns &
Co. Inc. and Vector Securities International, Inc.

If any of the shares of Common Stock offered hereby are purchased by the
Underwriters, all such shares of Common Stock offered hereby (other than shares
of Common Stock covered by the over-allotment option described below) must be so
purchased. The Underwriting Agreement contains provisions whereby if any
Underwriter defaults in its obligations to purchase such shares and if the
aggregate obligations of the Underwriters so defaulting do not exceed ten
percent of the shares offered hereby, the remaining Underwriters, or some of
them, must assume such obligations.

The Underwriters propose to offer the shares of Common Stock to the public
initially at the offering price set forth on the cover page of this Prospectus,
and to certain dealers at such price less a concession not to exceed $0.55 per
share. The Underwriters must allow, and such dealers may re-allow, a concession
not to exceed $0.10 per share on sales to certain other dealers. The offering of
the shares of Common Stock is made for delivery when, as and if accepted by the
Underwriters and subject to prior sale and withdrawal, cancellation or
modification of the offer without notice. The Underwriters reserve the right to
reject any order for the purchase of the shares. After the shares are released
for sale to the public, the public offering price, the concession and the
reallowance may be changed by the Managing Underwriters.

The Company has granted to the Underwriters an option exercisable for 30
days from the date of the Underwriting Agreement to purchase up to an additional
525,000 shares of Common Stock at the offering price less the underwriting
discount set forth on the cover page of this Prospectus. The Underwriters may
exercise such option only to cover over-allotments made of the shares in
connection with the Offering. To the extent the Underwriters exercise this
option, each of the Underwriters will be obligated, subject to certain
conditions, to purchase the number of additional shares that is proportionate to
such Underwriter's initial commitment.

The Company, each of its directors and officers and certain of its
stockholders, optionholders and warrantholders have agreed that they will not
offer, sell, contract to sell, grant any option to sell, pledge or otherwise
dispose of, directly or indirectly, any shares of Common Stock or any securities
convertible into or exchangeable or exercisable for Common Stock or warrants or
other rights to purchase or receive Common Stock, for a period of 90 days after
the date of this Prospectus, without the prior written consent of SBC Warburg
Dillon Read Inc.; provided, however, that the Company is permitted to (i) issue
shares of

67
<PAGE>
Common Stock upon the exercise of outstanding stock options and warrants and
(ii) grant stock options under the 1996 Plan.

The Company has agreed to indemnify the Underwriters against certain
liabilities, including any liabilities under the Securities Act, or to
contribute to payments the Underwriters may be required to make in respect
thereof.

In connection with the Offering, the Managing Underwriters, on behalf of the
Underwriters, may engage in transactions that stabilize, maintain or otherwise
affect the price of the Common Stock. Specifically, the Managing Underwriters
may over-allot the Offering, creating a syndicate short position. In addition,
the Managing Underwriters may bid for and purchase shares of Common Stock in the
open market to cover syndicate short positions or to stabilize the price of the
Common Stock. Finally, the Managing Underwriters may reclaim selling concessions
from a syndicate member in the Offering if shares of Common Stock originally
sold by such syndicate member are repurchased in syndicate covering
transactions, in stabilizing transactions or otherwise. Any of these activities
may stabilize or maintain the market price of the Common Stock above independent
market levels. The Managing Underwriters are not required to engage in these
activities, and may end any of these activities at any time.

In connection with the Offering, the Managing Underwriters, on behalf of the
Underwriters, may engage in passive market making on Nasdaq in accordance with
Rule 103 of Regulation M under the Exchange Act during the one day period before
the commencement of the offers or sales of Common Stock. The passive market
making transactions must comply with applicable volume and price limits and be
identified as such. In general, a passive market maker must display its bid at a
price not in excess of the highest independent bid for such security; if all
independent bids are lowered before the passive market maker's bid, however,
such bid must then be lowered when certain purchase limits are exceeded. Passive
market making may stabilize the market price of the Common Stock above
independent market levels and, if commenced, may be discontinued at any time.

SBC Warburg Dillon Read Inc. provided financial advisory services to the
Company in connection with its acquisition of Avid in August 1997. In addition,
certain of the Underwriters may provide investment banking services to the
Company for customary fees in the future.

LEGAL MATTERS

The validity of the Common Stock offered hereby will be passed upon for the
Company by Brobeck, Phleger & Harrison LLP, San Diego, California. Members of
such firm own a total of 15,333 shares of the Company's Common Stock. Certain
legal matters relating to the Offering will be passed upon for the Underwriters
by Palmer & Dodge LLP, Boston, Massachusetts.

EXPERTS

The financial statements included in this Prospectus and incorporated in
this Prospectus by reference to the Annual Report on Form 10-K of Triangle
Pharmaceuticals, Inc. for the year ended December 31, 1997, have been so
included and incorporated by reference in reliance on the report of Price
Waterhouse LLP, independent accountants, given on the authority of said firm as
experts in auditing and accounting.

The financial statements incorporated herein by reference to the audited
historical financial statements of Avid included on pages 5 through 20 of the
Company's Amendment No. 1 to Current Report on Form 8-K/A filed on November 12,
1997, have been so incorporated in reliance on the report of KPMG Peat Marwick
LLP, independent auditors, given upon their authority as experts in auditing and
accounting. The report of KPMG Peat Marwick LLP covering the December 31, 1996,
financial statements of Avid contains an explanatory paragraph that states that
Avid has suffered recurring losses from operations and will require additional
capital to fund future operations, which raises substantial doubt about such
entity's

68
<PAGE>
ability to continue as a going concern. The consolidated financial statements of
Avid do not include any adjustments which might result from the outcome of that
uncertainty.

The statements in this Prospectus under the captions "Risk
Factors--Uncertainty of Patents; Dependence on Patents, Licenses and Proprietary
Rights" and "Business--Patents and Proprietary Rights" (other than the
statements in the last paragraph of each such portion of this Prospectus) have
been reviewed and approved by King & Spalding, Atlanta, Georgia, patent counsel
for the Company, as experts in such matters and are included herein in reliance
upon that review and approval.

AVAILABLE INFORMATION

The Company has filed the Registration Statement with the Commission under
the Securities Act with respect to the Common Stock offered hereby. This
Prospectus does not contain all of the information set forth in the Registration
Statement and the exhibits and schedules filed therewith. For further
information with respect to the Company and the Common Stock offered hereby,
reference is hereby made to such Registration Statement and to the exhibits and
schedules filed therewith. Statements contained in this Prospectus regarding the
contents of any contract or other document are not necessarily complete, and in
each instance reference is made to the copy of such contract or document filed
as an exhibit to the Registration Statement or the documents incorporated into
the Prospectus by reference, each such statement being qualified in all respects
by such reference. The Registration Statement, including the exhibits and
schedules thereto, may be inspected without charge at the principal office of
the Commission, 450 Fifth Street, N.W., Washington, D.C. 20549, and copies of
all or any part thereof may be obtained from such office upon payment of the
prescribed fees.

The Company is subject to the reporting requirements of the Exchange Act,
and in accordance therewith files annual and quarterly reports, proxy statements
and other information with the Commission. Such reports, proxy statements and
other information may be inspected at the Commission's Public Reference Section,
Room 1024, 450 Fifth Street, N.W., Washington, D.C. 20549, as well as at the
Commission's regional offices at 7 World Trade Center, 13th Floor, New York, New
York 10048 and Citicorp Center, 500 West Madison Street, Room 1400, Chicago,
Illinois 60661-2511. Copies of such material can also be obtained at prescribed
rates from the Public Reference Section of the Commission at 450 Fifth Street,
N.W., Washington, D.C. 20549. In addition, the Commission maintains a World Wide
Web site on the Internet at http://www.sec.gov that contains reports, proxy and
information statements and other information regarding registrants that file
electronically with the Commission. The Common Stock is traded on the Nasdaq
National Market, and copies of such materials can also be inspected at the
offices of the National Association of Securities Dealers, Inc., 1735 K Street,
N.W., Washington, D.C. 20006.

INFORMATION INCORPORATED BY REFERENCE

The following documents filed by the Company with the Commission are hereby
incorporated by reference in this Prospectus: (i) the Annual Report of the
Company on Form 10-K for the fiscal year ended December 31, 1997; (ii) the
Current Report of the Company on Form 8-K filed September 11, 1997, as amended
on Form 8-K/A filed November 12, 1997; (iii) the Current Report of the Company
on Form 8-K filed April 2, 1998; and (iv) the description of the Common Stock
contained in its Registration Statement on Form 8-A filed on October 18, 1996.

All reports and other documents subsequently filed by the Company pursuant
to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
Prospectus and prior to the termination of the Offering shall be deemed to be
incorporated by reference herein and to be a part hereof from the date of filing
of such reports and documents. Any statement contained in any document
incorporated or deemed to be incorporated by reference herein shall be deemed to
be modified or superseded for purposes of this Prospectus to the extent that a
statement contained herein or in any other subsequently filed document which
also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement.

69
<PAGE>
Any statement so modified or superseded shall not be deemed, except as so
modified or superseded, to constitute a part of this Prospectus.

The Company will provide without charge to each person to whom this
Prospectus is delivered, upon written or oral request of such person, a copy of
any or all of the foregoing documents incorporated by reference herein (other
than exhibits to such documents, unless such exhibits are specifically
incorporated by reference into any such document). Requests for such documents
should be directed to Chris A. Rallis, Vice President, Business Development,
General Counsel and Secretary, at Triangle Pharmaceuticals, Inc., 4 University
Place, 4611 University Drive, Durham, North Carolina 27707 or by telephone at
(919) 493-5980.

70
<PAGE>
INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

<TABLE>
<CAPTION>
PAGE
-----
<S> <C>
Report of Independent Accountants.......................................................................... F-2

Consolidated Balance Sheets as of December 31, 1997 and 1996............................................... F-3

Consolidated Statements of Operations for the years ended December 31, 1997 and 1996 and for the period
from inception (July 12, 1995) through December 31, 1995................................................. F-4

Consolidated Statements of Cash Flows for the years ended December 31, 1997 and 1996 and for the period
from inception (July 12, 1995) through December 31, 1995 ................................................ F-5

Consolidated Statements of Stockholders' Equity for the years ended December 31, 1997 and 1996 and for the
period from inception (July 12, 1995) through December 31, 1995.......................................... F-6

Notes to Consolidated Financial Statements................................................................. F-7
</TABLE>

F-1
<PAGE>
REPORT OF INDEPENDENT ACCOUNTANTS

To the Board of Directors and Stockholders
of Triangle Pharmaceuticals, Inc.

In our opinion, the accompanying consolidated balance sheets and the related
consolidated statements of operations, of cash flows and of stockholders' equity
present fairly, in all material respects, the financial position of Triangle
Pharmaceuticals, Inc. and its subsidiaries (the "Company") at December 31, 1997
and 1996, and the results of its operations and its cash flows for the years
ended December 31, 1997 and 1996, and the period from inception (July 12, 1995)
through December 31, 1995, in conformity with generally accepted accounting
principles. These financial statements are the responsibility of the Company's
management; our responsibility is to express an opinion on these financial
statements based on our audits. We conducted our audits of these statements in
accordance with generally accepted auditing standards which require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements, assessing the accounting principles used and significant estimates
made by management, and evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for the opinion expressed
above.

PRICE WATERHOUSE LLP
Raleigh, North Carolina
March 3, 1998

F-2
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

CONSOLIDATED BALANCE SHEETS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

<TABLE>
<CAPTION>
DECEMBER 31, DECEMBER 31,
1997 1996
------------ ------------
<S> <C> <C>
ASSETS

Current assets:
Cash and cash equivalents.......................................................... $ 34,698 $ 25,255
Restricted deposits................................................................ 43 56
Investments........................................................................ 23,098 17,226
Interest receivable................................................................ 300 273
Other receivables.................................................................. -- 456
Prepaid expenses................................................................... 791 558
------------ ------------
Total current assets............................................................. 58,930 43,824
------------ ------------
Property, plant and equipment, net................................................... 2,872 832
Investments.......................................................................... -- 10,720
Restricted deposits.................................................................. 76 119
------------ ------------
Total assets..................................................................... $ 61,878 $ 55,495
------------ ------------
------------ ------------

LIABILITIES AND STOCKHOLDERS' EQUITY

Current liabilities:
Accounts payable................................................................... $ 3,152 $ 1,584
Capital lease obligation--current.................................................. 178 102
Long-term debt--current............................................................ 181 --
Accrued expenses................................................................... 5,172 789
------------ ------------
Total current liabilities........................................................ 8,683 2,475
------------ ------------
Capital lease obligation--noncurrent................................................. 300 364
Long-term debt....................................................................... 178 --
------------ ------------
Total liabilities................................................................ 9,161 2,839
------------ ------------
Commitments and contingencies (See notes 3, 4, 8, 10, 11, and 12).................... -- --
Stockholders' equity:
Common Stock, $0.001 par value; 75,000 shares authorized; 19,995 and 17,568 shares,
issued and outstanding, respectively............................................. 20 18
Warrants........................................................................... 114 152
Additional paid-in capital......................................................... 102,260 64,549
Accumulated deficit during development stage....................................... (49,552) (11,884)
Deferred compensation.............................................................. (125) (179)
------------ ------------
Total stockholders' equity....................................................... 52,717 52,656
------------ ------------
Total liabilities and stockholders' equity....................................... $ 61,878 $ 55,495
------------ ------------
------------ ------------
</TABLE>

The accompanying notes are an integral part of these consolidated financial
statements.

F-3
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

CONSOLIDATED STATEMENTS OF OPERATIONS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

Loss from operations................................. (41,182) (11,792) (1,004) (53,978)
Interest income, net................................. 3,514 875 37 4,426
------------ ------------ -------------- --------------
Net loss............................................. $ (37,668) $ (10,917) $ (967) $ (49,552)
------------ ------------ -------------- --------------
------------ ------------ -------------- --------------

Basic and diluted net loss per common share.......... $ (2.00) $ (1.89) $ (0.60)
------------ ------------ --------------
------------ ------------ --------------
Shares used in computing net loss per common share... 18,871 5,784 1,624
------------ ------------ --------------
------------ ------------ --------------
</TABLE>

The accompanying notes are an integral part of these consolidated financial
statements.

F-4
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

CONSOLIDATED STATEMENTS OF CASH FLOWS

(IN THOUSANDS)

<TABLE>
<CAPTION>
PERIOD FROM PERIOD FROM
INCEPTION INCEPTION
(JULY 12, (JULY 12,
YEAR YEAR 1995) 1995)
ENDED ENDED THROUGH THROUGH
DECEMBER 31, DECEMBER 31, DECEMBER 31, DECEMBER 31,
1997 1996 1995 1997
------------ ------------ -------------- --------------
<S> <C> <C> <C> <C>
Cash flows from operating activities:
Net loss......................................................... $ (37,668) $ (10,917) $ (967) $ (49,552)
Adjustments to reconcile net loss to net cash used by operating
activities:
Depreciation and amortization.................................. 313 98 3 414
Purchased research and development............................. 11,261 -- -- 11,261
Stock-based compensation: license fees......................... -- 636 -- 636
Stock-based compensation: development.......................... 43 347 -- 390
Stock-based compensation: general and administrative........... -- 231 -- 231
Change in assets and liabilities:
Receivables.................................................. 429 (729) -- (300)
Prepaid expenses............................................. (233) (558) -- (791)
Accounts payable............................................. 1,568 1,462 122 3,152
Accrued license fees and other expenses...................... 4,358 628 92 5,078
------------ ------------ -------------- --------------
Net cash used by operating activities............................ (19,929) (8,802) (750) (29,481)
------------ ------------ -------------- --------------
Cash flows from investing activities:
Sale (purchase) of restricted deposits......................... 56 (175) -- (119)
Purchase of investments........................................ (29,259) (33,268) -- (62,527)
Proceeds from sale and maturity of investments................. 34,108 5,322 -- 39,430
Purchase of property, plant and equipment...................... (2,295) (794) (23) (3,112)
Acquisition of Avid Corporation, net of
cash acquired................................................ (3,053) -- -- (3,053)
------------ ------------ -------------- --------------
Net cash used by investing activities............................ (443) (28,915) (23) (29,381)
------------ ------------ -------------- --------------
Cash flows from financing activities:
Sale of stock, net of related issuance costs................... 29,523 59,515 3,855 92,893
Sale of stock options under salary investment option grant
program...................................................... 70 -- -- 70
Proceeds from stock options exercised.......................... 1 25 -- 26
Proceeds from notes payable.................................... 374 -- -- 374
Equipment financing............................................ -- 354 -- 354
Principal payments on capital lease obligation and note
payable...................................................... (153) (4) -- (157)
------------ ------------ -------------- --------------
Net cash provided by financing activities........................ 29,815 59,890 3,855 93,560
------------ ------------ -------------- --------------
Net increase in cash and cash equivalents........................ 9,443 22,173 3,082 34,698

Cash and cash equivalents at beginning of period................. 25,255 3,082 -- --
------------ ------------ -------------- --------------
Cash and cash equivalents at end of period....................... $ 34,698 $ 25,255 $ 3,082 $ 34,698
------------ ------------ -------------- --------------
------------ ------------ -------------- --------------
</TABLE>

Supplemental disclosure of noncash investing and financing activities:

Noncash investing activities during 1997 and 1996 totaled $59 and $116,
respectively, and relate to the acquisition of laboratory equipment for the
assumption of a capital lease obligation.

On August 28, 1997, the Company issued 400 shares of Common Stock, valued at
$8,117, in exchange for all outstanding shares of Avid Corporation.

The accompanying notes are an integral part of these consolidated financial
statements.

F-5
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
(IN THOUSANDS)
<TABLE>
<CAPTION>
CONVERTIBLE PREFERRED
STOCK COMMON STOCK ADDITIONAL
------------------------ ---------------------- PAID-IN
SHARES AMOUNT WARRANTS SHARES AMOUNT CAPITAL
----------- ----------- ----------- --------- ----------- ----------
<S> <C> <C> <C> <C> <C> <C>
Initial sale of stock............................... 933 $ 1 $ -- 1,175 $ 1 $ 710
Additional sale of stock............................ 4,249 4 -- 1,495 2 3,137
Stock-based compensation............................ -- -- -- -- -- 12
Net loss, July 12 through December 31, 1995......... -- -- -- -- -- --
----------- --- ----------- --------- ----------- ----------
Balance, December 31, 1995.......................... 5,182 5 -- 2,670 3 3,859

Sale of stock....................................... 3,756 4 -- 4,943 5 59,506
Stock-based compensation............................ -- -- 152 700 1 1,127
Stock options exercised............................. -- -- -- 317 -- 57
Conversion of Preferred to Common Stock............. (8,938) (9) -- 8,938 9 --
Net loss............................................ -- -- -- -- -- --
----------- --- ----------- --------- ----------- ----------
Balance, December 31, 1996.......................... -- -- 152 17,568 18 64,549

Sale of stock....................................... -- -- -- 2,014 2 29,521
Acquisition of Avid Corporation..................... -- -- -- 400 -- 8,117
Sale of stock options............................... -- -- -- -- -- 70
Stock-based compensation............................ -- -- (38) -- -- --
Stock options exercised............................. -- -- -- 13 -- 3
Net loss............................................ -- -- -- -- -- --
----------- --- ----------- --------- ----------- ----------
Balance, December 31, 1997.......................... -- $ -- $ 114 19,995 $ 20 $ 102,260
----------- --- ----------- --------- ----------- ----------
----------- --- ----------- --------- ----------- ----------

ACCUMULATED
DEFICIT COMPENSATION TOTAL
------------ --------------- ---------
<S> <C> <C> <C>
Initial sale of stock............................... $ -- $ -- $ 712
Additional sale of stock............................ -- -- 3,143
Stock-based compensation............................ -- (12) --
Net loss, July 12 through December 31, 1995......... (967) -- (967)
------------ ------ ---------
Balance, December 31, 1995.......................... (967) (12) 2,888
Sale of stock....................................... -- -- 59,515
Stock-based compensation............................ -- (141) 1,139
Stock options exercised............................. -- (26) 31
Conversion of Preferred to Common Stock............. -- -- --
Net loss............................................ (10,917) -- (10,917)
------------ ------ ---------
Balance, December 31, 1996.......................... (11,884) (179) 52,656
Sale of stock....................................... -- -- 29,523
Acquisition of Avid Corporation..................... -- -- 8,117
Sale of stock options............................... -- -- 70
Stock-based compensation............................ -- 48 10
Stock options exercised............................. -- 6 9
Net loss............................................ (37,668) -- (37,668)
------------ ------ ---------
Balance, December 31, 1997.......................... $ (49,552) $ (125) $ 52,717
------------ ------ ---------
------------ ------ ---------
</TABLE>

The accompanying notes are an integral part of these consolidated financial
statements.

F-6
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

ORGANIZATION AND PRINCIPLES OF CONSOLIDATION

Triangle Pharmaceuticals, Inc. and its subsidiaries (the "Company" or
"Triangle"), a development stage company, was formed July 12, 1995 (the
"Inception Date"), as a Delaware corporation. The Company is engaged in the
development of new drug candidates primarily in the antiviral area and has not
yet generated revenues from operations. The consolidated financial statements
include the accounts of the Company and its wholly-owned subsidiaries. All
significant intercompany accounts and transactions have been eliminated in
consolidation.

CASH AND CASH EQUIVALENTS

The Company considers all short-term deposits with an initial maturity at
date of purchase of three months or less to be cash equivalents. The carrying
amount of cash and cash equivalents approximates fair value.

RESTRICTED DEPOSITS

Restricted deposits consist of cash and cash equivalents which collateralize
a letter of credit and have been classified as current or long-term based on the
expected release date of such restriction. The carrying amount of these
restricted deposits approximates fair value.

INVESTMENTS

Investments consist primarily of United States and municipal government
agency obligations, corporate bonds, notes and commercial paper, and other fixed
income investments. Investments with original maturities at date of purchase
beyond three months and less than twelve months are classified as current.
Investments with a maturity beyond twelve months are classified as long-term.
Investments are considered to be available-for-sale and are carried at fair
value. Realized gains and losses are determined using the specific
identification method.

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment are recorded at cost and depreciated using the
straight-line method over the estimated useful lives as follows: laboratory
equipment -- 5 years; office equipment -- 4 to 7 years; and leasehold
improvements -- lease term.

NOTE PAYABLE

The carrying value of the note payable approximates its fair value as the
note bears interest at market rates.

REVENUE RECOGNITION

Revenue recognition for any products that are developed will be based upon
shipment of products.

F-7
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
LICENSE FEES

Upon execution and continuation of license agreements, license initiation
and preservation fees are evaluated as to whether the underlying drug candidate
has alternative use, and if none, have been recorded as an expense at fair
value. License milestone criteria are continuously evaluated. When criterion
achievement is probable, the Company records expense at fair value, or will
capitalize the fair value if marketing approval is obtained for the licensed
compound or if the compound has an alternate future use.

ACCRUED EXPENSES

The carrying value of accrued expenses approximates fair value because of
their short-term maturity.

INCOME TAXES

Income taxes are computed using the asset and liability approach that
requires the recognition of deferred tax assets and liabilities for the expected
future tax consequences of events that have been recognized in the Company's
financial statements or tax returns. In estimating future tax consequences, the
Company generally considers all expected future events other than enactment of
changes in tax law or rates. If it is "more likely than not" that some portion
or all of a deferred tax asset will not be realized, a valuation allowance is
recorded.

NET LOSS PER COMMON SHARE

Basic net loss per share is computed using the weighted average number of
shares of Common Stock outstanding during the period. Diluted net loss per share
is computed using the weighted average number of shares of common and dilutive
potential common shares outstanding during the period. Potential common shares
consist of stock options and warrants using the treasury stock method and are
excluded if their effect is antidilutive. Had such options and warrants not been
antidilutive, their effect would be to increase the shares used in computing
diluted net loss per share to 20,113 shares at December 31, 1997.

Effective December 31, 1997, the Company adopted Statement of Financial
Accounting Standards No. 128 ("SFAS 128"), "EARNINGS PER SHARE" ("EPS"). SFAS
128 establishes and simplifies the standards for computing earnings per share
previously found in Accounting Principles Board Opinion No. 15 "EARNINGS PER
SHARE" ("APB 15") and makes them comparable to international EPS standards.
Pursuant to the adoption of SFAS 128 and Securities and Exchange Commission
Staff Accounting Bulletin No. 98, the Company has restated its net loss per
share for all previously issued periods. Accordingly, all net loss per share
calculations reflect a historical approach methodology rather than the
methodology required by the superceded guidance of APB 15 and Staff Accounting
Bulletin No. 83 under which amounts were previously presented.

USE OF ESTIMATES

The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. Actual results could differ from those estimates.

F-8
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
STOCK-BASED COMPENSATION

During 1996, the Company adopted Statement of Financial Accounting Standards
No. 123, "ACCOUNTING FOR STOCK BASED COMPENSATION" ("SFAS 123"). As provided by
SFAS 123, the Company has elected to continue to account for its stock-based
compensation programs according to the provisions of Accounting Principles Board
Opinion No. 25, "ACCOUNTING FOR STOCK ISSUED TO EMPLOYEES." Accordingly,
compensation expense has been recognized to the extent of employee or director
services rendered based on the intrinsic value of compensatory options or shares
granted under the plans. The Company has adopted the disclosure provisions
required by SFAS 123.

RECENT ACCOUNTING PRONOUNCEMENTS

Statement of Financial Accounting Standards No. 130, "REPORTING
COMPREHENSIVE INCOME" ("SFAS 130"), was issued in June 1997. SFAS 130
establishes standards for reporting and display of comprehensive income and its
components in a full set of general-purpose financial statements. The Company
will adopt SFAS 130 in 1998 and believes the adoption of SFAS 130 will not have
a material impact on the Company's financial position or results of operations.

RECLASSIFICATIONS

Certain prior year amounts have been reclassified to conform with the
current year presentation.

2. INVESTMENTS

The following is a summary of the fair value of "available for sale"
securities by balance sheet classification:

<TABLE>
<CAPTION>
DECEMBER 31,
----------------------
<S> <C> <C>
1997 1996
---------- ----------
United States Government obligations............................... $ 6,136 $ 17,895
Taxable municipals................................................. -- 1,016
Corporate bonds, notes and commercial paper........................ 15,966 9,035
Other fixed income................................................. 996 --
---------- ----------
Total.............................................................. $ 23,098 $ 27,946
---------- ----------
---------- ----------
</TABLE>

Maturities of debt securities at market value are as follows:

<TABLE>
<CAPTION>
DECEMBER 31,
----------------------
<S> <C> <C>
1997 1996
---------- ----------
Mature in one year or less......................................... $ 23,098 $ 17,226
Mature after one year through five years........................... -- 10,720
---------- ----------
Total.............................................................. $ 23,098 $ 27,946
---------- ----------
---------- ----------
</TABLE>

Gross realized and unrealized holding gains and losses for the years ended
December 31, 1997 and 1996 were not significant.

F-9
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

3. PROPERTY, PLANT & EQUIPMENT

<TABLE>
<CAPTION>
DECEMBER 31,
--------------------
<S> <C> <C>
1997 1996
--------- ---------
Laboratory equipment................................................... $ 1,892 $ 643
Office equipment....................................................... 655 237
Leasehold improvements................................................. 169 53
Construction-in-progress (office and laboratory equipment)............. 570 --
--------- ---------
3,286 933
Accumulated depreciation............................................... (414) (101)
--------- ---------
$ 2,872 $ 832
--------- ---------
--------- ---------
</TABLE>

The Company leases office and laboratory facilities and office equipment
under various operating leases. Rent expense totaled $998 and $646 for 1997 and
1996, respectively. The Company has provided a $175 letter of credit,
collateralized by an equivalent amount of cash and cash equivalents, as security
for a lessor.

Minimum lease payments under operating leases at December 31, 1997 are as
follows:

<TABLE>
<CAPTION>
YEAR AMOUNT
- ----------------------------------------------------------------------------------- ---------
<S> <C>
1998............................................................................... $ 1,256
1999............................................................................... 1,350
2000............................................................................... 1,312
2001............................................................................... 1,268
2002............................................................................... 1,300
Thereafter......................................................................... 991
---------
Total.............................................................................. $ 7,477
---------
---------
</TABLE>

The Company leases certain laboratory equipment under capital lease
agreements. Details of the capitalized leased assets are as follows:

<TABLE>
<CAPTION>
DECEMBER 31,
--------------------
<S> <C> <C>
1997 1996
--------- ---------
Laboratory equipment...................................................... $ 567 $ 520
Less: accumulated depreciation............................................ (156) (47)
--------- ---------
Net capitalized leased assets............................................. $ 411 $ 473
--------- ---------
--------- ---------
</TABLE>

F-10
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

3. PROPERTY, PLANT & EQUIPMENT (CONTINUED)
Future minimum lease payments under capital lease obligations at December
31, 1997 are as follows:

<TABLE>
<CAPTION>
YEAR AMOUNT
- ------------------------------------------------------------------------------------- -----------
<S> <C>
1998................................................................................. $ 222
1999................................................................................. 168
2000................................................................................. 153
2001................................................................................. 8
-----------
Total................................................................................ 551
Less: amounts representing interest and executory costs.............................. (73)
-----------
Net present values................................................................... $ 478
-----------
-----------
</TABLE>

Because the interest rates associated with these lease agreements
approximate a market rate, the carrying value of these obligations approximates
fair value. Interest expense under capital lease obligations for 1997 and 1996
was $40 and $2, respectively.

4. ACCRUED EXPENSES

Accrued expenses consist of the following:

<TABLE>
<CAPTION>
DECEMBER 31,
--------------------
<S> <C> <C>
1997 1996
--------- ---------
Accrued drug substance................................................. $ 1,137 $ 24
Accrued clinical studies............................................... 2,394 32
Accrued license fees................................................... 80 150
Accrued compensation and benefits...................................... 279 178
Accrued professional fees.............................................. 497 188
Other.................................................................. 785 217
--------- ---------
$ 5,172 $ 789
--------- ---------
--------- ---------
</TABLE>

The Company enters into contractual arrangements regarding clinical and
toxicology studies in the development of its drug candidates. At December 31,
1997, the Company estimates its commitment to be approximately $3,600 under
these agreements; however, this estimate is dependent upon results of the
underlying studies.

F-11
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

5. LONG-TERM DEBT

Long-term debt consists of the following:

<TABLE>
<CAPTION>
DECEMBER 31,
--------------------
<S> <C> <C>
1997 1996
--------- ---------
Unsecured note payable to a finance company; twenty-four monthly
payments with final payment due November 1999; interest payable at a
variable rate (6.85% at December 31, 1997)............................ $ 359 $ --
Current portion......................................................... (181) --
--------- ---------
$ 178 $ --
--------- ---------
--------- ---------
</TABLE>

Interest expense associated with long-term debt obligations for 1997 was $2.

6. STOCKHOLDERS' EQUITY

During 1996 and 1995, the Company issued 5,232 shares of Series A
convertible Preferred Stock with a par value of $0.001 per share for $3,900, net
of offering costs. During 1996, the Company issued 3,706 shares of Series B
convertible Preferred Stock with a par value of $0.001 per share for $18,400,
net of offering costs. Preferred voting and dividend rights were one vote for
each share, and noncumulative dividends were at an annual rate of $0.05 per
share for Series A and $0.35 for Series B. No preferred dividends were declared
or paid from the date of inception (July 12, 1995) through the date of
conversion of all Preferred Stock into Common Stock on a one-for-one basis in
connection with the closing of the Company's initial public offering (the
"IPO").

In connection with a consulting agreement executed in May 1996, the Company
issued warrants which entitle the holder to purchase 130 shares of Common Stock
at a price of $0.75 per share. The shares represented by the warrants vest over
a five year period commencing March 1, 1996. On November 27, 1997, the Company
terminated the consulting agreement, and pursuant to the terms of the agreement,
canceled 100 of the warrants which were outstanding. In accordance with the
terms of the agreement, 30 warrants were vested and are exercisable at December
31, 1997.

In connection with an equipment lease line obtained in August 1996, the
Company issued warrants which entitle the holder to purchase 16 shares of Common
Stock at a price of $5.00 per share. The Company recognized $16 of interest
expense during 1996 for these warrants.

On November 6, 1996, the Company completed its IPO of 4,533 shares of Common
Stock (including the exercise of the U.S. Underwriters over-allotment option) at
$10.00 per share. The net proceeds of this offering, after underwriting
discounts and costs in connection with the sale and distribution of the
securities, were approximately $41,000. Prior to the closing of the IPO, the
Company's certificate of incorporation was amended to modify the number of
authorized capital stock to 75,000 shares of Common Stock, $0.001 par value per
share, and 5,000 shares of Preferred Stock, $0.001 par value per share. The
Company's certificate of incorporation authorizes the Board of Directors (the
"Board"), without further action by the stockholders, to issue Preferred Stock,
in one or more series and to fix the rights, priorities, preferences,
qualifications, limitations and restrictions, including dividend rights,
conversion rights, voting

F-12
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

6. STOCKHOLDERS' EQUITY (CONTINUED)
rights, terms of redemption, terms of sinking funds and liquidation preferences
of each series of Preferred Stock issued.

On June 6, 1997, the Company issued 2,000 shares of Common Stock for $30,000
in cash, or a price of $15.00 per share (a discount of approximately 15% from
the average closing price of the Common Stock over the 30 trading days prior to
the date of the transaction). Net proceeds to the Company from the sale were
approximately $29,400. The shares were offered and sold to two non-U.S entities
and to one accredited investor under Regulation S and Regulation D,
respectively. Pursuant to the purchase agreement, the resale of the 2,000 shares
was registered on January 23, 1998 on a Registration Statement on Form S-3. The
Company was introduced to the purchaser of these shares by one of the Company's
outside directors. The director received a finders fee of $500 in connection
with the transaction which was recorded as a cost of the offering.

Under the terms of various agreements, the Company has the option to
repurchase shares of Common Stock from certain stockholders who were employed by
or who provided services to the Company at the time they acquired those shares.
The Company may repurchase such shares in the event the stockholder discontinues
employment or provision of services. The repurchase price is limited to the
amount the stockholder originally paid for the shares. During 1996 and 1995, the
Company issued shares subject to vesting totaling 560 and 2,140, respectively.
The number of shares subject to repurchase decreases to zero over periods
ranging from three to four years. The Company exercised its option to repurchase
all 150 shares of Common Stock from an officer upon her departure from the
Company in July 1996. At December 31, 1997, 941 shares were subject to
repurchase rights.

The Company accrued $43 and $347 as of December 31, 1997 and 1996,
respectively, for consulting expense related to the portion of the shares for
which the Company's repurchase option had lapsed based on the differences
between fair value and the selling price per share. During 1997 and 1996, the
Company recognized compensation expense of $43 and $1,214, respectively, related
to equity instruments for which the Company's repurchase option had lapsed based
on the differences between fair value and the selling price per share. Based on
the vesting of all equity instruments, the Company expects to recognize expenses
of $81 in 1998, $81 in 1999, and $19 in 2000.

7. STOCK OPTION PLANS AND STOCK PURCHASE PLAN

EMPLOYEE STOCK PURCHASE PLAN

The Company's Employee Stock Purchase Plan (the "Purchase Plan") was adopted
by the Board on August 30, 1996, was subsequently approved by the stockholders
on September 5, 1996, and became effective November 1, 1996. The Purchase Plan
is designed to allow eligible employees of the Company to purchase shares of
Common Stock, at semi-annual intervals, through periodic payroll deductions
under the Purchase Plan. A reserve of 300 shares of Common Stock has been
established for this purpose. The Purchase Plan will be implemented in a series
of successive offering periods, each with a maximum duration of twenty-four (24)
months. Payroll deductions may not exceed 10% of the participant's base salary
for each semi-annual period of participation, and the accumulated payroll
deductions will be applied to the purchase of shares on the participant's behalf
on each semi-annual purchase date (the last business day of February and August
each year, with the first purchase date occurring on the last business day of
February 1997) at a purchase price per share not less than 85% of the LOWER of
(i) the fair market value of

F-13
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

7. STOCK OPTION PLANS AND STOCK PURCHASE PLAN (CONTINUED)
the Common Stock on the participant's entry date into the offering period or
(ii) the fair market value of the Common Stock on the semi-annual purchase date.
Should the fair market value of the Common Stock on any semi-annual purchase
date be less than the fair market value of the Common Stock on the first day of
the offering period, then the current offering period will automatically end and
a new twenty-four month offering period will begin, based on the lower fair
market value. The shares vest immediately upon issuance.

During 1997, the Company issued 14 shares in conjunction with the Purchase
Plan. At December 31, 1997, the Company held payroll deductions of $84 which
will be converted to shares of Common Stock in 1998. The Purchase Plan had
insignificant impact on the Company's 1997 and 1996 operating results and pro
forma fair value disclosure as required under SFAS 123.

SALARY INVESTMENT OPTION GRANT PROGRAM

The Company's Salary Investment Option Grant Program (the "Investment Plan")
was activated by the Compensation Committee of the Board on December 13, 1996
for the calendar year 1997 and on December 4, 1997 for calendar year 1998. The
Investment Plan allows executive officers and other highly compensated employees
of the Company to reduce their base salary for that calendar year by a specified
dollar amount not less than $10 nor more than $50. Participants are issued a
non-statutory option to purchase that number of shares of Common Stock
determined by dividing the total salary reduction amount by an amount equal to
one-third of the fair market value per share of Common Stock on the grant date.
The option will be exercisable at a price per share equal to the difference
between the amount paid by the optionee for the option and the fair market value
of the option shares on the grant date. As a result, upon exercise of the
options issued under the Investment Plan, the optionee will have paid 100% of
the fair market value of the option shares as of the grant date. The option will
become vested and exercisable in a series of twelve (12) equal monthly
installments over the calendar year for which the salary reduction is in effect
and will become fully exercisable and vested upon certain changes in the
ownership or control of the Company. Options have a maximum term of ten years
from the date of grant.

DIRECTOR COMPENSATION

During 1997, all eligible non-employee directors received an option to
purchase 1.334 shares of Common Stock for the first year of the director's Board
term and 1.333 shares of Common Stock for each additional year remaining on the
director's Board term following the automatic option grant. These options have
an exercise price equal to 100% of the fair market value of the Common Stock on
the grant date and will become exercisable in annual installments after the
completion of each year of service following such grant. Options vest on the day
immediately preceding the next annual Board meeting and have a maximum term of
ten years from the date of grant, or one year from the cessation of Board
service.

1996 STOCK INCENTIVE PLAN

The Company's 1996 Stock Incentive Plan (the "1996 Plan") serves as the
successor equity incentive program to the Company's 1996 Stock Option/Stock
Issuance Plan (the "Predecessor Plan"). The 1996 Plan became effective on August
30, 1996 upon adoption by the Board and was subsequently approved by the
stockholders on September 5, 1996. 2,200 shares of Common Stock have been
authorized for issuance

F-14
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

7. STOCK OPTION PLANS AND STOCK PURCHASE PLAN (CONTINUED)
under the 1996 Plan. This initial share reserve is comprised of (i) the shares
that remain available for issuance under the Predecessor Plan, including the
shares subject to outstanding options thereunder, plus (ii) an additional
increase of 500 shares. However, in no event may any one participant receive
option grants or direct stock issuances for more than 500 shares in the
aggregate per calendar year. The shares vest over a four or five year period.

In accordance with the provisions of SFAS 123, the Company has chosen to
continue to account for stock-based compensation using the intrinsic value
method.

The following table summarizes the stock option activity for the Company's
plans:

<TABLE>
<CAPTION>
WEIGHTED
AVERAGE WEIGHTED
NUMBER EXERCISE AVERAGE
OF SHARES PRICE FAIR VALUE
----------- ------------- -----------
<S> <C> <C> <C>
Options outstanding, December 31, 1995......................... -- -- --

Granted below fair value....................................... 1,168 $ 0.320 $ 0.234
Granted at fair value.......................................... 283 $ 7.025 $ 1.579
Exercised...................................................... (317) $ 0.075 --
Forfeited...................................................... (38) $ 0.075 --
----- ------------- -----------
Options outstanding, December 31, 1996......................... 1,096 $ 2.129 --

Granted at fair value.......................................... 626 $ 21.166 $ 11.682
Exercised...................................................... (13) $ 0.075 --
Forfeited...................................................... -- -- --
----- ------------- -----------
Options outstanding, December 31, 1997......................... 1,709 $ 9.121 --
----- ------------- -----------
----- ------------- -----------
</TABLE>

In December 1997, the Board approved an amendment to the 1996 Plan
increasing the total number of shares of Common Stock available for issuance
under the 1996 Plan by 1,000 shares. The amendment is subject to stockholder
approval at the Company's 1998 Annual Meeting of Stockholders and consequently,
such shares have not been included in the table above.

F-15
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

7. STOCK OPTION PLANS AND STOCK PURCHASE PLAN (CONTINUED)
The following table summarizes information concerning options outstanding at
December 31, 1997 and 1996:

<TABLE>
<CAPTION>
WEIGHTED WEIGHTED AVERAGE
AVERAGE REMAINING
NUMBER EXERCISE CONTRACTUAL LIFE
OF SHARES PRICE (IN YEARS)
----------- ------------- -----------------
<S> <C> <C> <C>
Options outstanding-
Price range:
$0.075........................................................... 752 $ 0.075 8.13
$6.000--$15.750.................................................. 460 $ 9.341 8.87
$17.625--$21.500................................................. 115 $ 19.217 8.74
$23.625.......................................................... 382 $ 23.625 9.36
----------- -------------
Options outstanding, December 31, 1997........................... 1,709 $ 9.121
----------- -------------
----------- -------------
Exercisable options outstanding-
Price range:
$0.075........................................................... 752 $ 0.075
$6.000--$15.750.................................................. 331 $ 6.876
$17.625--$21.500................................................. 9 $ 20.750
$23.625.......................................................... 0 $ 0.000
----------- -------------
Exercisable options outstanding, December 31, 1997............... 1,092 $ 2.312
----------- -------------
----------- -------------
Exercisable options:
December 31, 1996................................................ 1,096 $ 2.129
----------- -------------
----------- -------------
</TABLE>

To determine the impact of SFAS 123, the fair value of each option grant is
estimated on the date of grant using the Black-Scholes option pricing model with
the following assumptions:

<TABLE>
<CAPTION>
1997 1996
------------ ------------
<S> <C> <C>
Expected dividend yield.................................................... 0.00% 0.00%
Expected stock price volatility............................................ 65.00% 0.00%
Risk-free interest rate.................................................... 5.70-5.72% 6.01-6.07%
Expected life of options................................................... 4-5 years 4-5 years
</TABLE>

For purposes of pro forma disclosures, the estimated fair value of equity
instruments is amortized to expense over their respective vesting period. If the
Company had elected to recognize compensation cost

F-16
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

7. STOCK OPTION PLANS AND STOCK PURCHASE PLAN (CONTINUED)
based on the fair value of stock-based instruments granted at grant date, as
prescribed by SFAS 123, its pro forma net loss and net loss per common share
would have been as follows:

<TABLE>
<CAPTION>
1997 1996
----------- -----------
<S> <C> <C>
Net loss--as reported...................................................... $ (37,668) $ (10,917)
Net loss--pro forma........................................................ $ (38,981) $ (11,120)
Net loss per common share--as reported..................................... $ (2.00) $ (1.89)
Net loss per common share--pro forma....................................... $ (2.07) $ (1.92)
</TABLE>

8. LICENSING AGREEMENTS

The Company has entered into seven license agreements for drug candidates as
of December 31, 1997. In the aggregate, these agreements required payments of
$3,101 upon execution or satisfaction of certain financing milestones, and may
require future payments of up to $43,250 contingent upon the achievement of
certain development milestones. One of the Company's licensors has the option to
receive $2,000 of such future milestone payments in shares of Common Stock
(based on the then current market price) in lieu of a cash payment. The Company
is also obligated to to issue up to 2,100 shares of Common Stock upon the
achievement of certain development milestones relating to DMP-450 or another
compound acquired in the acquisition of Avid Corporation and its wholly-owned
subsidiary (collectively, "Avid"). Additionally, the Company will pay royalties
based on a percentage of net sales of each licensed product incorporating these
drug candidates. Substantially all of the agreements require minimum royalty
payments commencing three years after regulatory approval. Depending on the
Company's success and timing in obtaining regulatory approval, aggregate annual
minimum royalties could range from $500 (if only a single drug candidate is
approved for one indication) to $49,500 (if all drug candidates are approved for
all indications). Under the terms of one of the license agreements, the Company
has been reimbursed $1,515 in 1997 and $485 in 1996 associated with certain
development work. Development expenses for the year ended December 31, 1997 and
1996 have been reduced by approximately $1,168 and $832, respectively.
Additionally, under the terms of certain of these agreements, the Company
granted 700 shares of Common Stock to the licensors.

9. INCOME TAXES

There is no current income tax provision or benefit recorded in any period
as the Company has generated net operating losses for income tax purposes for
which there is no carryback potential. There is no deferred income tax provision
or benefit recorded in any period as the Company is in a net deferred tax asset
position for which a full valuation allowance has been recorded due to
uncertainty of realization.

At December 31, 1997 and 1996, the Company had net operating loss
carryforwards of approximately $40,775 and $8,624, respectively, and a research
credit carryforward of approximately $1,951 and $147, respectively, which will
expire in years 2006 to 2012. The Company's ability to utilize its carryforwards
may be subject to an annual limitation in future periods pursuant to the "change
in ownership" provisions under Section 382 of the Internal Revenue Code. The
Company increased the valuation allowance by $4,300 during 1996.

F-17
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

9. INCOME TAXES (CONTINUED)
In connection with Triangle's acquisition of Avid, the Company acquired
transferable net operating loss carryforwards, research and development credits
and capitalized start-up costs which may be used to offset certain future
income. Net operating loss carryforwards associated with Avid will have an
annual limitation on the amount available to reduce certain future taxable
income.

The components of deferred taxes are as follows:

<TABLE>
<CAPTION>
DECEMBER 31,
----------------------
<S> <C> <C>
1997 1996
---------- ----------
Loss carryforwards................................................. $ 15,982 $ 3,363
Research tax credit................................................ 1,951 147
License fees....................................................... 1,270 1,204
Start-up costs..................................................... 1,531 --
---------- ----------
Deferred tax assets................................................ 20,734 4,714
Deferred tax assets valuation allowance............................ (20,734) (4,714)
---------- ----------
Net deferred tax asset............................................. $ -- $ --
---------- ----------
---------- ----------
</TABLE>

10. AVID ACQUISITION

On August 28, 1997 (the "Acquisition Date"), the Company acquired Avid.
Pursuant to the merger agreement, Triangle issued 400 shares of Common Stock in
exchange for all outstanding capital stock of Avid. Triangle also agreed to
issue up to 2,100 additional shares of Common Stock, the issuance of 1,600
shares of which is contingent upon Triangle initiating pivotal Phase II clinical
trials with DMP-450 before February 28, 1999, or electing on or before that date
to continue the development of DMP-450 even if such clinical trials have not
been initiated. The issuance of the remaining 500 shares is contingent upon the
attainment of other development milestones with DMP-450 or one of Avid's other
compounds. Issuance of any of these contingent shares will be recorded as
additional purchase price and will be allocated upon resolution of the
underlying contingency. The 400 shares issued had an aggregate fair market value
of approximately $8,117 and direct transaction costs were approximately $1,100,
primarily comprised of investment banking and legal fees. The total purchase
price of $9,217 has been allocated to the assets purchased and liabilities
assumed based on their respective fair market values. In connection with the
acquisition, the Company incurred a charge of $11,261 in the third quarter of
1997 for acquired in-process research and development as it assumed operating
and other liabilities of Avid totaling approximately $1,250 and certain
development liabilities totaling approximately $1,000. The merger was accounted
for as a purchase and the operating results of Avid have been included in the
Company's consolidated financial statements from the Acquisition Date.

Avid's principal assets consist of worldwide license rights to DMP-450, a
protease inhibitor, for the treatment of human immunodeficiency virus infection,
early preclinical stage compounds for the treatment of hepatitis B virus ("HBV")
infection, proprietary assays to screen compounds for the treatment of HBV and
assay technology for potential use in screening compounds for the treatment of
hepatitis C virus infection.

F-18
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

10. AVID ACQUISITION (CONTINUED)
The following unaudited pro forma consolidated results of operations have
been prepared as if the acquisition of Avid had occurred at the beginning of
1997 and 1996:

<TABLE>
<CAPTION>
(UNAUDITED) (UNAUDITED)
1997 1996
----------- -----------
<S> <C> <C>
Revenues........................................................ $ -- $ --
Net loss........................................................ $ (40,821) $ (26,889)
Net loss per common share....................................... $ (2.13) $ (4.35)
</TABLE>

The pro forma net loss and net loss per share amounts for each period above
include the acquired in-process research and development charge. The pro forma
consolidated results do not purport to be indicative of results that would have
occurred had the acquisition been in effect for the periods presented, nor do
they purport to be indicative of the results that will be obtained in the
future.

11. LITIGATION AND OTHER CONTINGENCIES

The Company is indirectly involved in several opposition and interference
proceedings and one lawsuit filed in Australia regarding the patent rights
related to three of its licensed drug candidates, including FTC. Although the
Company is not a named party in any of these proceedings, it is obligated to
reimburse its licensors for certain legal expenses associated with these
proceedings. The Company cannot predict the outcome of these proceedings. The
Company believes that an adverse judgment would not result in a material
financial obligation to the Company, nor would the Company have to recognize an
impairment under Statement of Financial Accounting Standards No. 121 "ACCOUNTING
FOR IMPAIRMENT OF LONG-LIVED ASSETS" as no amounts have been capitalized related
to these drug candidates. However, any development in these proceedings adverse
to the Company's interests could have a material adverse effect on the Company's
future consolidated financial position, results of operations and cash flow.

12. SUBSEQUENT EVENTS

LICENSE AGREEMENT

On February 27, 1998, the Company executed a license agreement with Bukwang
Pharm. Ind. Co., Ltd. ("Bukwang") for L-FMAU, the Company's eighth licensed drug
candidate, for the treatment of HBV and all other human antiviral applications.
The Company paid a license initiation fee of $6.0 million and will be required
to make development milestone payments of up to $32.5 million and sales
milestone payments of up to $30.0 million. The Company is also required to make
annual minimum royalty payments beginning the third year after FDA registration
is granted for the first product. Payment of the license initiation fee resulted
in the Company incurring a $6.0 million charge in the first quarter of 1998. The
license agreement grants Triangle exclusive worldwide rights, except for Korea.
The Company will be required to meet certain milestone obligations and to
conduct and fund certain development work with respect to L-FMAU.

F-19
<PAGE>
TRIANGLE PHARMACEUTICALS, INC.
(A DEVELOPMENT STAGE COMPANY)

DECEMBER 31, 1997

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

12. SUBSEQUENT EVENTS (CONTINUED)
STOCK OFFERING (UNAUDITED)

Subsequent to March 3, 1998, the Company expects to file a registration
statement with the Securities and Exchange Commission for the sale of 3,000
shares of its Common Stock. The Company intends to use the proceeds for general
corporate purposes, including the Company's drug development programs such as
preclinical testing and clinical trials, the payment of license fees, the costs
of obtaining patent protection and other payments to licensors, the potential
acquisition of additional drug candidates, the development of computerized
systems to support clinical trials and general working capital needs.

F-20
<PAGE>
No dealer, salesperson or other individual has been authorized to give any
information or to make any representation not contained in this Prospectus in
connection with the Offering. If given or made, such information or
representation must not be relied upon as having been authorized by the Company
or any of the Underwriters. This Prospectus does not constitute an offer to
sell, or a solicitation of an offer to buy, the Common Stock in any jurisdiction
where, or to any person to whom, it is unlawful to make such offer or
solicitation. Neither the delivery of this Prospectus nor any sale made
hereunder shall, under any circumstances, create an implication that there has
not been any change in the facts set forth in this Prospectus or in the affairs
of the Company since the date hereof.

TABLE OF CONTENTS
- -------------------------------------------

<TABLE>
<CAPTION>
<S> <C>
Prospectus Summary..................... 3

Risk Factors........................... 7

Special Note Regarding Forward-Looking
Statements........................... 20

Use of Proceeds........................ 21

Price Range of Common Stock............ 21

Capitalization......................... 22

Dilution............................... 23

Selected Consolidated Financial Data... 24

Management's Discussion and Analysis of
Financial Condition and Results of
Operations........................... 25

Business............................... 30

Management............................. 57

Principal Stockholders................. 61

Description of Capital Stock........... 64

Underwriting........................... 67

Legal Matters.......................... 68

Experts................................ 68

Available Information.................. 69

Information Incorporated by
Reference............................ 69

Index to Consolidated Financial
Statements........................... F-1
</TABLE>

PROSPECTUS April 9, 1998

3,500,000 Shares

[LOGO]

Common Stock

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