Wyeth-Ayerst Laboratories

September 30, 1997
Page 5






                                                              September 30, 1997




Wyeth-Ayerst Laboratories
P.O. Box 8299
Philadelphia, PA 19101-1245

Dear Sirs:

         This  letter  sets  forth  the  proposed  terms and  conditions  for an
extension of the  Agreement  between  Ostex  International,  Inc.  ("OSTEX") and
Wyeth-Ayerst  Laboratories ("W-A") dated September 20, 1995, regarding detailing
of diagnostic  testing,  prevention and treatment of osteoporosis to health care
professionals.

1.       OSTEX  grants  W-A  a   world-wide,   non-exclusive   right  to  detail
         osteoporosis   diagnostic   tests  developed  by  OSTEX  together  with
         technology,  data,  test results,  clinical and other  studies  related
         thereto  and  sales  materials,  medical  education  programs,  disease
         management  programs  and sample  tests so as to  promote  the sale and
         utilization of OSTEX's osteoporosis tests.

2.       W-A  grants  OSTEX  the  non-exclusive  right to  detail  W-A  products
         marketed  by W-A  together  with  promotional,  educational  and  sales
         materials so as to  encourage  the use of W-A's  Premarin(R)  family of
         products in the prevention and treatment of osteoporosis.

3.       It is  understood  and agreed that each party shall  determine,  in its
         sole discretion, the detailing activities it shall undertake, including
         frequency, detail position,  physician targets, field force commitment,
         call plan and whether or not to detail.

4.       The parties  shall  appoint  coordinators  who shall meet  regularly to
         develop  advertising,  marketing and sales  programs,  including  sales
         training  programs,  for the  OSTEX  and W-A  products  to be  detailed
         hereunder.  Such programs may include medical education for health care
         professionals,  disease management  programs for managed care audiences
         and  convention  exhibits  for key target  audiences.  Each party shall
         provide  appropriate  training  materials  and  trainers to educate the
         trainers and/or sales representatives of the other party.

5.       OSTEX  agrees  to  conduct  or  arrange  for the  conduct  of assays to
         generate data derived from  osteoporosis  diagnostic tests developed by
         OSTEX and utilized in patients receiving W-A products. OSTEX grants W-A
         the  non-exclusive  right to utilize  OSTEX test data in detailing  W-A
         products.


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6.       Neither  party shall be obligated to make payments to the other for any
         rights granted or services to be performed hereunder.  Each party shall
         be responsible  for its own expenses in connection  with  negotiations,
         documents, or transactions, services or performance contemplated hereby
         and additionally  neither party shall have any liability whatsoever for
         any fees or expenses of the other party owed to third parties.

7.        Neither party shall have any  responsibility  for the hiring,  
     firing,  compensation or employee benefits of the other party's  employees.
Except as  specifically  set forth herein,  no employee or  representative  of a
party shall have any  authority  to bind or obligate the other party for any sum
or in any manner  whatsoever,  or to create or impose any  contractual  or other
liability on the other party without such other party's written approval.  OSTEX
and W-A's legal  relationship under this Agreement shall be that the parties are
independent of each other and not that of partners or joint  venturers.  Neither
party's  representatives  shall have any authority  regarding sales of the other
party's products or to bind or obligate the other party for any orders,  prices,
discounts,  rebates,  allowances,  etc.,  or  any  other  commercial  terms  and
conditions of sale.

8.       Each  party  hereby  represents  and  warrants  to the  other  that its
         products  shall be  approved  by FDA for  marketing;  that  neither the
         products'  applications  for market  approval nor any other filing with
         FDA or other reports or records shall contain any misrepresentations of
         material fact.  Each party further  represents and warrants that in the
         performance   of  its   obligations   hereunder   each  party  and  its
         representatives  shall at all times  comply with all  applicable  laws,
         rules,  and  regulations  issued  or  promulgated  by any  governmental
         authority  having   jurisdiction   over  the  activities   contemplated
         hereunder.

9.       Each  party  shall give the other  party  notice of all  complaints  or
         adverse experiences associated with the products of the other party. If
         the information  obtained  indicates a serious or unusual experience or
         complaint,  it shall be reported to the other party by  telephone or in
         writing  within   twenty-four   hours  after  initial  receipt.   Other
         information  shall be reported within five working days.  Reports shall
         contain the name,  address and telephone  number of the source,  and an
         indication of the adverse drug experience or other complaint.

10.      All  advertising,  marketing  and sales  promotion  materials  utilized
         hereunder  shall be created by or on behalf of or approved by the party
         whose products are being  described.  Such materials  shall be reviewed
         and  approved  by the other party prior to use by the other party which
         approval shall not be unreasonably withheld. All advertising, marketing
         and sales promotion materials, detailing and other activities by either
         party shall be in  accordance  with approved  product  labeling and all
         applicable laws and regulations.


<PAGE>

11.      No  advertising,   promotional,  sales  or  publicity  concerning  this
         Agreement or the business  relationship  between  OSTEX and W-A created
         hereby or  wherein  the name of the  other  party or its  products  are
         mentioned  shall be released or made use of by anyone  acting on behalf
         of a party  without  the prior  approval  of the other  party.  Nothing
         contained in this  Section 11 shall be deemed to prohibit  either party
         (a)  from  detailing  with  respect  to the  products  of the  other as
         provided herein or (b) from notifying appropriate governmental agencies
         in accordance with, or otherwise complying with the requirements of any
         applicable law or regulation.

12.       The  term of this  Agreement  shall  be for one (1)  year  from  the 
     date  hereof  in  accordance  with  the  provisions  of  Section  12 of the
Agreement  dated  September  20,  1995.  This  Agreement  may  be  extended  for
additional  terms of one (1) year each upon the mutual agreement of the parties.
Either party may terminate this Agreement by thirty (30) days' notice in writing
to the other. Upon the effective date of termination,  the detailing  activities
specified  herein  shall  cease  and  promotional  materials  utilized  shall be
guarantied until disposition is agreed upon by the parties.  Termination of this
Agreement  shall not relieve the parties  hereto of any liability  which accrued
hereunder  prior to the effective date of such  termination  nor preclude either
party from  pursuing all rights and remedies it may have  hereunder or at law or
in equity with  respect to any breach of this  Agreement  nor  prejudice  either
party's  right to obtain  performance  of any  obligation  provided  for in this
Agreement which expressly survives termination.

13.      Nothing  contained  herein  shall be deemed  to grant to OSTEX,  either
         expressly  or  impliedly,  a license or other  right or interest in any
         patent, trademark, trade name or logo or other similar property of W-A,
         except as may be necessary for OSTEX to detail W-A products  hereunder.
         Nothing  contained  herein  shall be  deemed  to  grant to W-A,  either
         expressly  or  impliedly,  a license or other  right or interest in any
         patent,  trademark,  trade name or logo or other  similar  property  of
         OSTEX,  except as may be necessary  for W-A to perform its  obligations
         hereunder.

14.       Each party  shall  indemnify,  defend  and hold  harmless  the other 
     and its officers, directors, agents, servants and employees against any and
all claims,  losses,  damages and liabilities,  including reasonable  attorneys'
fees, but excluding  loss of profits and  consequential  damages,  to the extent
that any such claim,  loss,  damage or liability is based on or  determined by a
court of competent  jurisdiction  to result from or arise out of  utilization of
such party's products.  Provided, however, that a party shall have no obligation
to  indemnify  the other party for any act or omission of the other party or any
employee,  representative  or agent thereof or any product of the other party or
unapproved advertising,  marketing,  promotion or selling activity or warranties
or representations of the other party or any violation of any applicable statute
or regulation, or breach of this Agreement by the other party.


<PAGE>

15.      Except as otherwise expressly provided under this Agreement, each party
         shall hold in confidence all confidential  information  provided by the
         other  party  in   furtherance   of  this   Agreement.   The  foregoing
         confidentiality obligations shall not apply to:

         a)        any information  which at the time of disclosure or 
                   acquisition is part of the public  knowledge or
                   literature,  or  thereafter  becomes part of the public  
                   knowledge or literature  otherwise  than by
                   unauthorized disclosure by the recipient;

         b)        any information  which at the time of disclosure or 
                  acquisition  was in the recipient's  possession
                  as evidenced by its written records; or

         c)        any  information  which  becomes  available  to the  
                   recipient  from any other  source not bound to
                  secrecy to the disclosing party with respect to such 
                  information.

16.      If  the  performance  by  either  party  is  prevented,  restricted  or
         interfered with by reason of any event or cause  whatsoever  beyond the
         reasonable  control  of the  party so  affected,  such  party  shall be
         excused from performance to the extent of such prevention,  restriction
         or interference; provided that such cause is not the result of a breach
         of this  Agreement.  In any such case,  prompt  written notice shall be
         given by the affected party to the other of the existence of such cause
         and of readiness to resume performance.  Labor disputes shall be deemed
         to be events beyond the reasonable  control of the party affected,  and
         neither party shall be required to settle a labor  dispute  against its
         will.

17.       Neither  party may assign  this  Agreement  or rights  granted  
     hereunder  in whole or in part  without  the  written  consent of the other
party  except  to their  affiliates  or  subsidiaries  or to a  successor  to or
assignee of all or substantially all of the pharmaceutical interests, assets and
good will of the assigning  party;  provided,  however,  that W-A shall have the
right to  terminate  this  Agreement  at any time on not less than  fifteen (15)
days'  notice in writing  to OSTEX upon the  occurrence  of any  transaction  or
series of  transactions  which  results in the transfer of ownership or control,
directly or indirectly,  of a majority of the capital stock, with right to vote,
or of  substantially  all of the  assets of OSTEX or of any  parent  company  of
OSTEX.

18.      These  terms and  conditions  constitute  the  complete  and  exclusive
         understanding  of OSTEX  and W-A with  respect  to the  subject  matter
         hereof, and no statements or agreements, oral or written, made prior to
         or at the signing hereof shall modify the written terms hereof. Neither
         party shall claim any  modification or revision of any provision hereof
         unless such modification or revision is in writing, signed by the other
         party and states it is an amendment to this Agreement.


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19.      The  failure on the part of OSTEX or W-A to  exercise  or  enforce  any
         rights  conferred  hereunder  shall not be deemed to be a waiver of any
         such rights nor operate to bar the exercise or  enforcement  thereof at
         any time or times thereafter.

20.      The  construction,  validity and performance of this Agreement shall be
         governed  in all  respects  by the  laws  of  Pennsylvania,  excluding,
         however, its laws respecting choice of law.

          If the foregoing terms and conditions meet with your approval,  please
signify your  acceptance  by signing,  dating and returning the enclosed copy of
this letter.

                                                    Very truly yours,



                                                    OSTEX INTERNATIONAL, INC.

                                                    By: /S/ Thomas A. Bologna
                                                        Thomas A. Bologna
                                                  President and Chief Executive
                                                           Officer

Accepted:

WYETH-AYERST LABORATORIES


By:  /S/ Susan Jasper

Title:  Group Product Director

Date:  October 20, 1997