LICENSE AGREEMENT

            THIS LICENSE AGREEMENT is made and entered into this 25th day of
August, 1993 between THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL having an
address at 300 Bynum Hall, Chapel Hill, N.C. (hereinafter referred to as
"University") and PHARM-ECO LABORATORIES, INC., a corporation organized and
existing under the laws of California and having an address at 128 Spring
Street, Lexington, MA 02173, (hereinafter referred to as "Licensee").

                                   WITNESSETH

            WHEREAS, University owns and controls an invention known as "Methods
of Combatting Pneumocystis carinii Pneumonia ("PCP") and Compounds Useful
Therefor" (file #ORS93-17) as well as other compounds described in Exhibit A
that may have potential for the treatment of PCP as well as other indications
such as HIV, anti-fungal, anti-inflammatory, anti-bacterial, anti-viral and the
like, all of which compounds, including the compounds in file #ORS93-17 are
hereinafter referred to as "the compounds" and, together with the methods
described in file #ORS93-17, are referred to as the "Invention"; and

            WHEREAS,  University  owns  the  Invention  and has the  power  to
license it exclusively to Licensee; and


            WHEREAS,  the Invention was developed by or under the direction of
Dr. Richard Tidwell (hereafter, "Inventor") of the University; and

            WHEREAS, Licensee is desirous of producing, using and selling
products using the Invention and is willing to expend reasonable efforts and
resources to do so if it is granted the exclusive license to use the Invention
under the terms and conditions set forth herein; and

            WHEREAS, University desires to facilitate a timely transfer of its
information and technology concerning the Invention for the ultimate benefit of
the public; and

            WHEREAS, in the opinion of the University, this transfer can best be
accomplished consistent with its mission by affiliation with Licensee;

            NOW, THEREFORE, for and in consideration of the covenants,
conditions, and undertakings hereinafter set forth, it is agreed by and between
the parties as follows:

1.   Definitions

     1.1 "University Technology" means any unpublished research and development
information, unpatented inventions, know-how and technical data in the
possession of the University prior to the effective date of this Agreement or
which comes into the possession of University during the term of this Agreement
which relates to and is necessary for the practice of the Invention or the use
of the Compounds for therapeutic purposes to the extent that University has the
right to provide such information to Licensee. Should Dr. Richard Tidwell's lab
produce any unpublished research and development information, unpatented
inventions, know-how or technical data which is useful for the practice of the
Invention or the use of the Compounds for therapeutic purposes, then such shall
also be considered University Technology, to the extent that University has the
right to provide such information to Licensee.

     1.2 "Licensed Products" means products whose manufacture or sale includes
any use of University Technology or Patent Rights.

     1.3 "Patent Rights" means any and all patents and applications for patents
(including, but not limited to U.S. Application No. 07/958,695) covering the
Invention or the University Technology and which are owned by University during
the term of this Agreement, including all patents and reissue patents issuing on
said patent applications and any divisions, continuations or
continuations-in-part thereof.

     1.4 "Net Sales Price" means the invoiced sales price charged for Licensed
Products sold to distributors or other third parties by Licensee or its
sublicensees and/or their sublicensees, less any charges for (a) sales taxes or
other taxes separately stated on the invoice and (b) shipping, handling and
insurance charges.

     1.5 "Net Sales" means the total Net Sales Price of Licensed Products, less
any returns, rebates, trade allowances or discounts. Licensed Products will be
considered sold when they would be determined to be sold under generally
accepted accounting principles. Because Licensee and its sublicensees will not
be able to market Products for commercial use prior to appropriate FDA approval,
no royalties shall be payable on sales for pre-clinical or clinical trial
purposes. No royalties shall be payable on any transfer of products between
Licensee and its sublicensees and/or their sublicensees or affiliates. Only one
royalty shall be paid for the disposition of any Licensed Product. In case a
Licensed Product is sold in combination with Products containing active
ingredients which are not covered by this License ("Combination Products"), Net
Sales shall be adjusted to reflect only that portion of the Net Sales Price of
Combination Products attributable to the Licensed Product by reducing the Net
Sales Price of the Combination Product in accordance with the proportion which
the weight of the active ingredients in the Licensed Product bears to the total
weight of the active ingredients in the Combined Product, unless the entire
Combination Product is covered by a valid claim of a patent covering the
Invention or the University Technology.

     1.6 "Licensed Territory" means the World.

     1.7 "Licensed Field" means a field described in Exhibit B.

2.   Grant of License and Term

     2.1  University grants to Licensee to the extent of the Licensed Territory
an exclusive right and license to use University Technology in the Licensed
Field, subject to all the terms and conditions of this Agreement.

     2.2  University grants to Licensee to the extent of the Licensed Territory,
an exclusive license under the Patent Rights and the right to make, use and sell
Licensed Products in the Licensed Field, upon the terms and conditions set forth
herein.

     2.3  Any license granted herein is exclusive for a term beginning on the
date of execution of this Agreement and, unless terminated sooner as herein
provided, ending at the expiration of the twentieth anniversary of such date or
the last to expire of any patent claim included in the Patent Rights, whichever
is later.

     2.4  Licensee shall not disclose any unpublished University Technology
furnished by University pursuant to Paragraph 2.1 above to third parties during
the term of this Agreement or any time thereafter, provided, however, that
disclosure may be made of any such University Technology at any time: (1) with
the prior written consent of University which shall not be unreasonably
withheld, or (2) after the same shall have become public through no fault of
Licensee, or (3) which was known by the Licensee at the time of the disclosure
as shown by documents in existence at such time, or (4) to any sub-licensee(s)
who have agreed to terms essentially equivalent to those in this paragraph.

     2.5  Notwithstanding the foregoing, any and all licenses granted hereunder
are subject to the rights of the United States Government which arise out of its
sponsorship of the research which led to the Invention.

     2.6  If the Licensee provides funds to the University with respect to a
field not described in Exhibit B under a Sponsored Research Agreement or
otherwise for the purpose of investigating the use of Inventions in such field,
the Parties agree that such field shall be thereby added to Exhibit B and the
Licensed Field herein shall thereupon be deemed expanded to include such field.

     2.7  If the Licensee provides funds to the University under a Sponsored
Research Agreement or otherwise for the purpose of investigating the use of the
patents listed in Exhibit C in a Licensed Field, then the Parties agree that
such patent shall be thereby added to the Patent Rights.

 3.  License Fee and Royalties

     3.1  As part of the consideration for granting the license herein, Licensee
will reimburse the University for its reasonable expenditures (including
attorney's fees) arising out of the patenting of the Invention pursuant to
Article 10 of this Agreement. The reimbursement of patenting costs shall be
non-refundable and shall not be a credit against any other amounts due
hereunder. Reimbursement of patenting costs shall be due upon monthly billings
from University.

     3.2  (a) Beginning on the effective date of this Agreement and continuing
for the life of this Agreement, Licensee will pay University a running royalty
of six percent (6%) of all Net Sales of the Licensed Product(s). In the event of
sales of Licensed Product(s) in any country where a patent has not issued or
wherever a competitor has commenced marketing a product generically equivalent
to a Licensed Product, said royalty rate shall be reduced by 50%.

          (b) In the event a Licensed Product is a product in which the active
compound is an invention of the University and the use thereof is not an
invention of the University, in whole or in part, then the royalty set forth in
3.2(a) shall be 4% rather than 6%. No royalty shall be owed for sales of any
product wherein the University has no composition of matter patent protection or
the active ingredient and the use thereof is not an invention of the University,
in whole or in part.

     3.3  Licensee agrees to make quarterly written reports to University within
30 days after the first days of each January, April, July, and October during
the life of this Agreement and as of such dates, stating in each such report the
number, description, and aggregate Net Selling Prices of Licensed Products sold
or otherwise disposed of during the preceding three calendar months and upon
which royalty is payable as provided in Article 3.2 hereof. The first such
report shall include all such Licensed Products so sold or otherwise disposed of
prior to the date of such report.

     3.4  Concurrently with the making of each such report, Licensee shall pay
to the University royalties at the rate specified in this Agreement on the
Licensed Products included therein.

     3.5  If in any calendar year during the term of this Agreement after
approval of a New Drug Application for a Licensed Product, total amounts payable
under paragraph 3.2 hereof are less than $50,000.00, Licensee shall pay the
University within thirty (30) days after the end of such calendar year, the
difference between the amounts payable for such calendar year and said minimum
amount.

     3.6  Should this Agreement become effective or terminate or expire during a
calendar year, the minimum royalty under paragraph 3.5 for such portion of a
year shall be determined by multiplying the minimum royalty set forth in said
paragraph for the year in which this Agreement becomes effective, terminates or
expires, by a fraction, the numerator of which shall be the number of days
during such calendar year for which this Agreement shall be in effect and the
denominator of which shall be 365.

     3.7  To the extent the University shall have received payments pursuant to
a Sponsored Research Agreement ("Sponsored Research Funds") in connection with a
Licensed Field, the amount of royalty payments due hereunder with respect to Net
Sales of a Licensed Product within such Licensed Field shall be reduced by the
amount of such Sponsored Research Funds up to 50% of the royalties due for such
quarter, and such reduction shall continue until all applicable Sponsored
Research Funds have been credited against such royalties.

 4.  Diligence

     4.1  Licensee will use reasonable efforts to meet the schedule of
performance milestones set forth in Exhibit D, which is attached hereto. Failure
to achieve said milestones in accordance with such schedule will result in
conversion of the License Agreement to a non-exclusive license or to termination
of the License, in the University's discretion, subject to appropriate grace
periods and exhaustion of good faith efforts on the part of the parties to
adjust such milestones in the light of conditions experienced by Licensee in the
performance of its duties hereunder.

 5.  Sub-Licenses

     5.1  Subject to this Article, Licensee may grant a sub-license hereunder to
persons or entities previously specifically approved in writing by University,
which approval shall not be unreasonably withheld, provided that each
sub-license contains a provision that such sub-license and the rights thereby
granted are personal to the sub-licensee thereunder and such sub-license cannot
be further sub-licensed, without the written approval of both University and
Licensee, which approval shall not be unreasonably withheld.

     5.2  Unless otherwise provided or agreed, any sub-license granted pursuant
to this Article shall be in accordance with the terms and conditions of this
Agreement.

6.   Cancellation by University

     6.1  It is expressly agreed that, notwithstanding the provisions of any
other paragraph of this contract, if Licensee should fail to deliver to
University any royalty at the time or times that the same should be due to
University or if Licensee should in any material respect violate or fail to keep
or perform any covenant, condition, or undertaking of this Agreement on its part
to be kept or performed hereunder, then and in such event University shall have
the right to cancel and terminate this Agreement, and, the license herein
provided for, by written notice to Licensee if Licensee has failed to cure any
such breach within 60 days of receipt of written notice from University
describing such breach.

     6.2  Alternatively, instead of such termination, should Licensee be in
breach or default as set forth above, and should University be in a position
where it could rightfully terminate this Agreement, then in its sole discretion,
University may convert this exclusive license to a non-exclusive license upon
giving notice of such decision to Licensee.

     6.3  If Licensee should be adjudged bankrupt or enter into a composition
with or assignment to its creditors, then in such event University shall have
the right to cancel and terminate this Agreement, and the license herein
provided for, by written notice to Licensee.

     6.4  Any termination or cancellation under any provision of this Agreement
shall not relieve Licensee of its obligation to pay any royalty or other fees
(including attorney's fees pursuant to Article 3.1 hereof) due or owing at the
time of such cancellation or termination.

7.   Disposition of Licensed Products On Hand Upon Cancellation or Termination

     7.1  Upon cancellation of this Agreement or upon termination in whole or in
part, Licensee shall provide University with a written inventory of all Licensed
Products in Licensee's possession which are in process of manufacture, in use or
in stock. Licensee shall have the privilege of disposing of the inventory of
such licensed products upon conditions most favorable to University that
Licensee can reasonably obtain. Licensee will also have the right to complete
performance of all contracts requiring use of the University Technology, Patent
Rights or Licensed Products provided that the remaining term of any such
contract does not exceed one year. All Licensed products which are not disposed
of as provided above shall delivered to University or otherwise disposed of, in
University's sole discretion, and at Licensee's sole expense.

8.   Use Of University's Name

     8.1  The use of the name of University, or any contraction thereof, in any
manner in connection with the exercise of this license is expressly prohibited
except with prior written consent of University, which shall not be unreasonably
withheld.

9.   University Use

     9.1  It is expressly agreed that, notwithstanding any provisions herein,
University is free to use University Technology, Patent Rights and Licensed
Products for its own research, public service, clinical, teaching and
educational purposes shall be free without payment of royalties. Furthermore,
University shall be free to publish University Technology, as it sees fit.

10.  Patents and Infringements

     10.1  Licensee shall bear the cost of filing and prosecuting U.S. patent
applications included within the Patent Rights. Such filings and prosecution
shall be by counsel of University's choosing and shall be in the name of
University. University shall keep Licensee advised as to the prosecution of such
applications by forwarding to Licensee copies of all official correspondence,
(including, but not limited to, Applications, Office Actions, responses, etc.)
relating thereto. Licensee shall have the right to advise University as to such
prosecution, and further, shall have the right to make reasonable requests as to
the conduct of such prosecution.

     10.2  As regards filing of foreign patent applications corresponding to the
U.S. applications described in paragraph 10.1 above, Licensee shall designate
that country or those countries, if any, in which Licensee desires such
corresponding patent application(s) to be filed. Licensee shall pay all costs
and legal fees associated with the preparation and filing of such designated
foreign patent applications and such applications shall be in the University's
name. University may elect to file corresponding patent applications in
countries other than those designated by Licensee, but in that event University
shall be responsible for all costs associated with such non-designated filings.
In such event, Licensee shall forfeit its rights under this license in the
country(ies) where University exercises its option to file such corresponding
patent applications. In the event of such filings by the University, it is
agreed that before rights to patents in such foreign countries are granted to
any third party, Licensee shall be given a right of first refusal to the rights
on the same terms and conditions agreed to by said third party.

     10.3  If the production, sale or use of Licensed Products under this
Agreement by Licensee results in any claim for patent infringement against
Licensee, Licensee shall promptly notify the University thereof in writing,
setting forth the facts of such claim in reasonable detail. As between the
parties to this Agreement, Licensee shall have the first and primary right and
responsibility at its own expense to defend and control the defense of any such
claim against Licensee, by counsel of its own choice. It is understood that any
settlement of such actions must be approved by University. Such approval shall
not be unreasonably withheld. University agrees to cooperate with Licenses in
any reasonable manner deemed by Licensee to be necessary in defending any such
action. Licensee shall reimburse University for any out-of-pocket expenses
incurred in providing such assistance.

     10.4  In the event that any Patent Rights licensed to Licensee are
infringed by a third party, Licensee shall have the primary right, but not
the obligation, to institute, prosecute and control any action or proceeding
with respect to such infringement, by counsel of its choice, including any
declaratory judgment action arising from such infringement.

     10.5  Notwithstanding the foregoing, and in University's sole discretion,
University shall be entitled to participate through counsel of its own choosing
in any legal action involving the Invention. Nothing in the foregoing sections
shall be construed in any way which would limit the authority of the Attorney
General of North Carolina.

11.  Waiver

     11.1  It is agreed that no waiver by either party hereto of any breach or
default of any of the covenants or agreements herein set forth shall be deemed a
waiver as to any subsequent and/or similar breach or default.

 12. License Restrictions

     12.1 It is agreed that the rights and privileges granted to Licensee are
each and all expressly conditioned upon the faithful performance on the part of
the Licensee of every requirement herein contained, and that each of such
conditions and requirements may be and the same are specific license
restrictions.

13.  Assignments

     13.1  This Agreement is binding upon and shall inure to the benefit of the
University, its successors and assigns. However, this Agreement shall be
personal to Licensee and it is not assignable by Licensee to any other entity
without the written consent of University, which consent shall not be withheld
unreasonably.

14.  Indemnity

     14.1  The Licensee shall defend, indemnify and hold the University, its
officers, directors, employees and agents from and against any and all claims,
damages, losses or expenses (including lawyers' fees) arising out of or in
connection with this Agreement (the "Indemnified Losses").

     14.2  The Indemnified Losses include, without restriction:

           (a) product liability claims;

           (b) claims resulting from the design, manufacture, testing,
modification, packaging, distribution, sale or other disposition of the Licensed
Product by the Licensee;

           (c) claims resulting from the manufacture, distribution, sale or
other disposition of the Licensee's affiliates, related companies and
sublicensees;

           (d) claims resulting from the failure of the Licensee to comply with
applicable governmental regulations relating to the Licensed Product;

           (e) claims resulting from the Licensee's breach of this Agreement;

           (f) claims resulting from alleged patent, copyright or trademark
infringement, or other proprietary rights of any person as a result of the
manufacture, distribution or sale of the Licensed Product; and

           (g) clinical trials conducted by or on behalf of the Licensee using
the Licensed Product, including (without limitation) claims by or on behalf of a
human subject of any clinical trial and any claim arising from the protocol
procedures required or used in any clinical trial or any deviation (whether or
not authorized) from such procedures and any claim arising from the design,
manufacture, distribution and sale by other person; off any substance
administered in any clinical trial.

     14.3  The Licensee shall pay to the University the amount of any and all
claims, damages, losses and expenses referred to in this provision, promptly
following written notice by the University.

     14.4  The indemnification rights set out in this provision shall survive
the termination or expiration of this Agreement.

     14.5  The Indemnification rights contained in this provision are in
addition to all rights which the Licensor may have at law or in equity.

     14.6  The Licensee will warn its customers and sublicensees that the
Licensed Products are experimental and advise them to take all reasonable
precautions to warn persons against the dangers of the use or misuse of the
same.

 15.  Liability Insurance

     15.1  No later than the first commercial sale of a Licensed Product,
Licensee shall carry a product liability insurance policy protecting the
University with respect to such Licensed Product which lists the University as
an additional insured with respect thereto and requires that the University be
given thirty (30) days written notice prior to any cancellation or lateral
change thereof, in an amount of not less than five million dollars ($5,000,000)
per occurrence with an aggregate of 10 million dollars ($10,000,000) for
personal injury or death, and Licensee shall supply the University with
certificates of such coverage. Notwithstanding the foregoing, Licensee shall
only be obligated to purchase insurance to the extent that it is reasonably
available at commercially reasonable rates.

 16.  Independent Contractor Status

     16.1  Neither party hereto is an agent of the other for any purpose.

 17.  Late Payments

     17.1  In the event royalty payments or fees are not paid by Licensee when
due, Licensee shall be liable for interest on said royalties or fees, the
interest rate to be calculated based on the prime interest rate plus 2% as
established by NationsBank of North Carolina on the date such amounts were due.

18.   Warranties

     18.1 University makes no warranties that any patent will issue on
University Technology or invention. University further makes no warranties,
express or implied as to any matter whatever, including, without limitation, the
condition of any invention(s) or product(s), that are the subject or this
Agreement; or the merchantability or fitness for a particular purpose of any
such invention or product. University shall not be liable for any direct,
consequential, or other damages suffered by Licensee or any others resulting
from the use of the Invention or Licensed Products.

19.  Accounting and Records

     19.1  Licensee will keep complete, true and accurate books of account and
records for the purpose of showing the derivation of all amounts payable to
University under this Agreement. Such books and records will be kept at
Licensee's principal place of business for at least three (3) years following
the end of the calendar quarter to which they pertain, and will be open at all
reasonable times for inspection by a representative of University for the
purpose of verifying Licensee's royalty statements, or Licensee's compliance in
other respects with this Agreement. The representative will be obliged to treat
as confidential all relevant matters.

     19.2  Such inspections shall be at the expense of University, unless a
variation or error exceeding U.S. $l,000, or the equivalent, is discovered in
the course of any such inspection, whereupon all reasonable costs directly
relating thereto paid by Licensee.

     19.3  Licensee will promptly pay to University the full amount of any such
underpayment, together with interest thereon at the maximum rate of interest
allowed by law.

20.  Compliance with Laws

     20.1  In exercising its rights under this license, Licensee shall exercise
all reasonable efforts to comply with the requirements of any and all applicable
laws, regulations, rules and orders of any governmental body having jurisdiction
over the exercise of rights under this license. To the extent permitted by
public policy, Licensee farther agrees to indemnify, and hold University
harmless from and against any costs, expenses, attorneys' fees, citation, fine,
penalty and liability of every kind and nature which might be imposed by reason
of any asserted or established violation of any such laws, order, rules and/or
regulations.

21.  U.S. Manufacture

     21.1  It is agreed that any Licensed Products sold in the United States
shall be substantially manufactured in the United States.

22.   Notices

     22.1  Any notice required or permitted to be given to the parties hereto
shall be deemed to have been properly given i delivered in person or mailed by
first-class certified mail to the other party at the appropriate address as set
forth below or to such other addresses as may be designated in writing by the
parties from time to time during the term of this Agreement.

UNIVERSITY                               LICENSEE

Office of Research Services              Pharm-Eco Laboratories, Inc.
CB #4100 Bynum Hall                      128 Spring Street
UNC-CH                                   Lexington, MA  02173
Chapel Hill, NC  27599-4100

23.  Governing Laws

     23.1  This Agreement shall be interpreted and construed in accordance with
the laws of the State of North Carolina.

 24.  Complete Agreement

     24.1  It is understood and agreed between University and Licensee that this
license constitutes the entire Agreement, both written and oral, between the
parties, and that all prior agreements between the parties respecting the
subject matter hereof, either written or oral, expressed or implied, shall be
abrogated, canceled, and are null and void and of no effect.

25.  Survival of Terms

     25.1 The provisions of Articles 7, 8, 9, 10, 14, 16, 20, 22, 23, and 24
shall survive the expiration or termination of this Agreement.


<PAGE>
            IN WITNESS WHEREOF, both University and Licensee have executed this
Agreement in duplicate originals, by their respective officers hereunto duly
authorized, the day and year first above written. Inventors, have likewise
indicated their acceptance of the terms hereof by signing below.

THE UNIVERSITY OF NORTH CAROLINA        PHARM-ECO LABORATORIES, INC.
   AT CHAPEL HILL



By: /s/ Wayne R. Jones                       By: /s/ David J. Wade
    -------------------                          ------------------
   Wayne R. Jones                                Name: David J. Wade
   Vice Chancellor,                              Title: President
   Business and Finance
   Business and Finance


INVENTORS:



/s/  Richard R. Tidwell
--------------------------------
    Professor Richard R. Tidwell


<PAGE>


                                                                       EXHIBIT A

                              [graphic omitted]



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

NO.                    R                                  X
--------------------------------------------------------------------------------
1         amidine                           -CH2-
--------------------------------------------------------------------------------
2         imidazoline                       -CH2-
--------------------------------------------------------------------------------
3         monoamidine                       -CH2-
--------------------------------------------------------------------------------
4         amidine                           -(CH2)2-
--------------------------------------------------------------------------------
5         imidazoline                       -(CH2)2-
--------------------------------------------------------------------------------
6         H                                 -(CH2)2-
--------------------------------------------------------------------------------
7         nitro                             -(CH2)2-
--------------------------------------------------------------------------------
8         amine                             -(CH2)2-
--------------------------------------------------------------------------------
9         morpholine                        -(CH2)2-
--------------------------------------------------------------------------------
10        iminoethanol                      -(CH2)2-
--------------------------------------------------------------------------------
11        aminomethyl                       -(CH2)2-
--------------------------------------------------------------------------------
12        1,4,5,6-tetrahydro-2-             -(CH2)2-
--------------------------------------------------------------------------------
13        pyrimidine
--------------------------------------------------------------------------------
14        1,4,5,6-tetrahydro-1-             -(CH2)2-
--------------------------------------------------------------------------------
15        methylpyrimidine
--------------------------------------------------------------------------------
16        N-isopropylamidine                -(CH2)2-
--------------------------------------------------------------------------------
17        amidine                           -CH-CH-(trans)
--------------------------------------------------------------------------------
18        N-isopropylamidine                -CH-CH-(trans)
--------------------------------------------------------------------------------
19        amidine                           -C(CH3)-C(CH3)-(trans)
--------------------------------------------------------------------------------
20        amidine                           -(CH2)3-
--------------------------------------------------------------------------------
21        imidazoline                       -(CH2)3-
--------------------------------------------------------------------------------
22        amidine                           -(CH2)4-
--------------------------------------------------------------------------------
23        imidazoline                       -(CH2)4-
--------------------------------------------------------------------------------
24        amidine                           -(CH2)6-
--------------------------------------------------------------------------------
25        amidine                           -(CH2)6-
--------------------------------------------------------------------------------
26        amidine                           -(CH2)8-
--------------------------------------------------------------------------------
27        amidine                           1,3-phenylene
--------------------------------------------------------------------------------
28        amidine                           1,4-phenylene
--------------------------------------------------------------------------------
29        N-isopropylamidine                1,4-phenylene
--------------------------------------------------------------------------------
30        amidine                           2,5-dimethyl-1, 4-phenylene
--------------------------------------------------------------------------------


<PAGE>



                                    EXHIBIT B

              Treatment of Pneumocystis carinii Pneumonia in Humans


<PAGE>



                                    EXHIBIT C

           U.S. PATENT NO.                               TITLE
-------------------------------------    ---------------------------------------

1.    4,324,794                          Inhibition of Respiratory Syncytial
                                         Virus-Induced Cell Fusion by Amidino
                                         Compounds

2.    4,397,863                          Inhibition of Respiratory Syncytial
                                         Virus-Induced Cell Fusion by Amidino
                                         Compounds

3.    4,619,942                          Inhibition of Respiratory Syncytial
                                         Virus-Induced Cell Fusion by Amidino
                                         Compounds

4.    4,940,723                          Use of

                                         Bis-(5-Amindino-2-Benzimidazolyl)
                                         Methane (BABIM) in Treating Arthritis
                                         and Cancer

5.    4,933,347                          Diamidines and Bis (Imidazolines) for
                                         the Treatment of and Prophylaxis
                                         Against Pneumocystis Carinii Pneumonia

6.    5,202,320                          Method for Treating Leishmaniasis

7.    4,963,589                          Methods for Treating Giardia Lamblia

8.    5,206,236                          Methods of Treating Malaria

NOTE:  SOME OR ALL OF THE LISTED PATENTS MAY NOT BE AVAILABLE FOR LICENSING IN
       SOME OR ALL FIELDS AT THIS TIME BECAUSE OF PRIOR LEGAL COMMITMENTS TO
       OTHER PARTIES.



<PAGE>



                                    EXHIBIT D

Licensee will use reasonable efforts to meet the following schedule of
performance milestones, counting from the date when a lead compound is selected
for clinical development by mutual agreement between the parties.


                                                  YEARS AFTER SELECTION
               MILESTONE                            OF LEAD COMPOUND
---------------------------------------    -------------------------------------

Completion of pre-clinical trials                           2

Filing of IND                                              2.5

Completion of phase I clinical trials                      4.5

Completion of phase II clinical trials                     6.5

Completion of phase III clinical trials                    9.5

Filing of NDA                                              10

These milestones represent Licensee's realistic estimate of the schedule it will
be able to keep in the event there are no unexpected technical or clinical
obstacles. Adverse results at any stage could significantly extend the periods
required to meet any or all of the milestones listed.



<PAGE>


                  [LETTERHEAD OF PHARM-ECO LABORATORIES, INC.]



March 15, 1995



Dr. Richard Tidwell
Department of Pathology
The University of North Caroline at Chapel Hill
Chapel Hill, NC  27599

Ref.: Filing of Patent Applications for inventions OTD95-48
      OTD95-49; OTD95-50 and OTD95-51

Dear Dr. Tidwell:

In consideration for the grant to Pharm-Eco of a license to the University's
rights to the above inventions on similar terms as our current license of
Tidwell Technology, please instruct the UNC patent counsel to file applications
on the above inventions immediately. Pharm-Eco will reimburse the University
upon the grant of the license, in accordance with its terms.

We would also appreciate your advising your patent counsel to provide copies of
their filings to our attorney, Scott McNeil, of Hamilton, Brook, Smith &
Reynolds, 4 Militia Drive, Lexington, MA 02173.

If you have any questions or concerns please do not hesitate to call me.

Sincerely,


/s/ Richard Gabriel

Richard Gabriel
Director, Commercial Development

cc:   Dr. Christine Dykstra
      Mr. T. Peterson, Esq. Pharm-Eco
      Mr. D. Parker
      Ms. Susan Ehringhaus
      Mr. Scott McNeil, Esq.