THIRD AMENDMENT TO CORPORATE RESEARCH AGREEMENT

                                THIRD AMENDMENT TO
                          CORPORATE RESEARCH AGREEMENT



         This third Amendment to Corporate Research Agreement is entered into as
of  this  2nd  day  of  April,  1998  by and  between  SUNPHARM  CORPORATION,  a
corporation  duly organized under the laws of Delaware and currently  having its
principal office at 0000 Xxxxxxxxx Xxxx, Xxxxx 000, Xxxxxxxxxxxx,  Xxxxxxx 00000
(hereinafter  referred to as "Sponsor") and the  UNIVERSITY OF FLORIDA  RESEARCH
FOUNDATION, INC., a not-for-profit corporation duly organized and existing under
the laws of  Florida  and  having  its  principal  office at 223  Xxxxxxx  Xxxx,
University  of Florida,  Xxxxxxxxxxx,  Xxxxxxx  00000-0000,  U.S.A  (hereinafter
referred to as "UFRFI").

                                   WITNESSETH:

         WHEREAS,  Sponsor  and UFRFI have  entered  into a  Corporate  Research
Agreement  dated April 30, 1993 to be effective  March 26, 1993,  (the "Research
Agreement"),  which  Research  Agreement  superseded  in its entirety an earlier
Corporate Research Agreement between the parties dated December 9, 1991;

         WHEREAS,  Sponsor  and  UFRFI  entered  into a First  Amendment  to the
Research  Agreement  as of May 16, 1994 and a Second  Amendment  to the Research
Agreement on September 9, 1996 in order to extend the term of the period covered
by such Research Agreement;

         WHEREAS,  the parties desire to enter into this Third  Amendment to the
Research Agreement in order to extend the term thereof,

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


         1. The  definition of "Contract  Period"  contained in Section 2 of the
Second Amendment to the Research Agreement is hereby deleted in its entirety and
the following is inserted in place thereof:

                  "1.3 "Contract  Period"  will  be  December  9,  1991  through
         December31, 1998, during which time the UFRFI shall perform the Project
         Work;  which  period shall be extended on December 31 of each year on a
         thirty-six  month basis without  further  action of the parties  unless
         either  party  notified  the  other of its  desire  to  terminate  this
         Agreement on written  notice to the other given at least twelve  months
         in advance of the then-current period."

         2. Except as amended hereby, the Research Agreement shall be and remain
in full force and effect.



         3. This Third Amendment to Corporate Research Agreement may be executed
in one or more  counterparts,  each of which shall be deemed an original and all
of which shall be taken together as one instrument.

         IN WITNESS  WHEREOF,  the parties  have caused this Third  Amendment to
Corporate  Research Agreement to be executed as of the date and year first above
written.



                                    SPONSOR:

                                    SunPharm Corporation


                                    By:/s/ XXXXXX XXXX
                                       -------------------------------
                                           Xxxxxx Xxxx,Preside



                                    UFRFI:

                                    University of Florida 
                                    Research Foundation, Inc.


                                    By: /s/ X. XXXXX
                                        ------------------------------
                                    Name:   Xxxxxx X. Xxxxx
                                    Title:  Secretary


READ AND ACKNOWLEDGED 

/s/ XXXXXXX X. XXXXXXXX 
-------------------------------
    Xxxxxxx X. Xxxxxxxx