AMENDMENT
                                       TO
                        STRATEGIC COLLABORATION AGREEMENT

     THIS AMENDMENT ("Amendment") is made and entered into this 13th day of May,
2002, by and between MALLINCKRODT INC., a Delaware corporation, with its
principal place of business at 675 McDonnell Boulevard, P.O. Box 5840, St.
Louis, Missouri 63134 ("Mallinckrodt"), and PALATIN TECHNOLOGIES, INC., a
Delaware corporation, with its principal place of business at 103 Carnegie
Center, Suite 200, Princeton, New Jersey 08540 ("Palatin").

                                    RECITALS

A. Mallinckrodt and Palatin are parties to a Strategic Collaboration Agreement,
dated as of August 17, 1999 (the "Collaboration Agreement"), under which they
entered into a joint collaboration for the development of a commercial product
or products from LeuTech(TM), a radiopharmaceutical product useful for imaging
infection and inflammation.

B. Palatin has notified Mallinckrodt that additional funding will be required to
complete the development of LeuTech and to address issues raised by the United
States Food and Drug Administration ("FDA") in connection with its review of the
previously filed Biologics License Application ("BLA") for LeuTech.

C. Mallinckrodt and Palatin have agreed upon the terms and conditions under
which Mallinckrodt will provide additional funding for the above-stated
purposes.

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<PAGE>


                               TERMS OF AGREEMENT

     NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties agree to amend the Collaboration Agreement as follows:

1. Definitions of Certain Terms.

     (a) Unless otherwise specifically provided herein, all capitalized terms
undefined herein and used in this Amendment will be defined in the same manner
as provided for in Article 1 of the Collaboration Agreement.

     (b) These defined terms as set forth in Article 1 of the Collaboration
Agreement are hereby amended and restated in their entireties as follows:

          (i) 1.46 [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION
          UNDER RULE 24b-2.]

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<PAGE>


2. Payment of Up-Front Product Costs. The obligation of Mallinckrodt to pay
fifty percent (50%) of Palatin's direct costs incurred in connection with a
purchase order submitted by Mallinckrodt for Product Units is hereby eliminated.
Accordingly, Section 2.3(f) of the Collaboration Agreement is hereby amended and
restated as follows:

     (f) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER
RULE 24b-2.]

3. Waiver of Section 3.2 of Collaboration Agreement. Subject to the following
sentence, the parties hereto affirm that any rights, obligations or conditions
imposed by Section 3.2 of the Collaboration Agreement with respect to either
Mallinckrodt or Palatin shall hereby be waived in the event that any such right,
condition or obligation shall have been breached or shall not have been
satisfied in accordance with the provisions of such Section 3.2. Notwithstanding
the preceding sentence, Palatin represents and warrants to, and covenants with
Mallinckrodt that:

     (a) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER
RULE 24b-2.];

     (b) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER
RULE 24b-2.]; and

     (c) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER
RULE 24b-2.].

4. Agreements with Subcontractors. Without limiting the generality of any other
provision in the Collaboration Agreement, Palatin covenants and agrees

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<PAGE>


that it will not make any change in the subcontractors it has currently engaged
for the manufacture of LeuTech, without the prior written consent of
Mallinckrodt.

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<PAGE>


5. License Payments. The parties have agreed to restructure the License Payments
to Palatin provided for in Section 5.1 of the Collaboration Agreement. Section
5.1 is hereby amended and restated in its entirety, as follows:

     5.1 License Payments. In consideration of the license rights granted by
     Palatin to Mallinckrodt and its Affiliates in accordance with Section 2.1
     above, Mallinckrodt hereby agrees to make the following License Payments to
     Palatin:

          (a) Mallinckrodt will pay [INFORMATION OMITTED AND FILED SEPARATELY
     WITH THE COMMISSION UNDER RULE 24b-2.] on and as of the date of execution
     of this Agreement [Palatin acknowledges that this payment has been made, in
     full],

          (b) Mallinckrodt will pay [INFORMATION OMITTED AND FILED SEPARATELY
     WITH THE COMMISSION UNDER RULE 24b-2.] within thirty (30) days after the
     approval by the FDA of a BLA for any LeuTech Product useful for the imaging
     of appendicitis, and

          (c) Mallinckrodt will pay [INFORMATION OMITTED AND FILED SEPARATELY
     WITH THE COMMISSION UNDER RULE 24b-2.] within thirty (30) days after
     [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER RULE
     24b-2.].

          (d) Mallinckrodt will pay [INFORMATION OMITTED AND FILED SEPARATELY
     WITH THE COMMISSION UNDER RULE 24b-2.] within thirty (30) days after
     [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER RULE
     24b-2.].

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<PAGE>


     Remittance of each of the License Payments will be made by wire transfer of
     immediately available United States funds to an account designated by
     Palatin to Mallinckrodt at least three (3) business days prior to the date
     on which any such payment is due.

6. [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER RULE
24b-2.]

7. Funding of Additional Development Costs. Section 5.7(d) of the Collaboration
Agreement is hereby amended and restated in its entirety as follows:

          (d) (i) Notwithstanding the provisions of Section 5.7(b) above, and
     other than as may be determined by the Joint Steering Committee and the
     Board of Directors of each of Palatin and Mallinckrodt, no Development
     Payments will be made for any costs incurred after the termination of the
     Development Phase in any portion of the Territory with respect to a LeuTech
     Indication which is being developed in accordance with the Development
     Program.

          (ii) Mallinckrodt will provide additional funding for Development
     Costs in the aggregate amount of up to $3.2 million (the "Additional
     Funding"). Upon execution of this Amendment, $800,000 of the Additional
     Funding shall be paid to Palatin in immediately available funds as payment
     for the achievement of [INFORMATION OMITTED AND FILED SEPARATELY WITH THE
     COMMISSION UNDER RULE 24b-2.]. Mallinckrodt's obligation to provide the
     remainder of the Additional Funding, in such amounts identified below, will
     be contingent upon Palatin's achievement of the applicable Milestones
     identified below: [INFORMATION OMITTED AND FILED SEPARATELY WITH THE

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<PAGE>


     COMMISSION UNDER RULE 24b-2.]

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<PAGE>


     With respect to the milestone payments [INFORMATION OMITTED AND FILED
     SEPARATELY WITH THE COMMISSION UNDER RULE 24b-2.] Palatin will provide
     Mallinckrodt with a letter, executed by the Chief Executive Officer or the
     Chief Financial Officer of Palatin, certifying the successful completion of
     the appropriate milestone. With respect to the milestone payments
     [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER RULE
     24b-2.] Palatin will provide Mallinckrodt with a request for payment,
     executed by the Chief Executive Officer or the Chief Financial Officer of
     Palatin, certifying the successful completion of the appropriate milestone.
     Mallinckrodt shall have the right to verify the achievement of the
     milestone and Palatin shall cooperate with Mallinckrodt in this regard. Any
     dispute between the parties regarding the achievement of a milestone shall
     be resolved pursuant to the dispute resolution procedures described in
     Section 10.6 of the Collaboration Agreement.

          (iii) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION
     UNDER RULE 24b-2.]

          (iv) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION
     UNDER RULE 24b-2.]

          (v) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION
     UNDER RULE 24b-2.]

          (vi) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION
     UNDER RULE 24b-2.]

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<PAGE>


8. Security Interest.

     (a) Palatin and its wholly-owned subsidiary, Rhomed Incorporated, a New
     Mexico corporation, shall grant Mallinckrodt a first priority security
     interest in (i) all of its patents, patent rights, registrations,
     applications for registration, licenses or other contract rights and
     know-how relating to LeuTech and (ii) the trademark LeuTech(TM), all
     registrations relating thereto, and all related goodwill, pursuant to the
     Security Agreement attached hereto as Exhibit A.

     (b) Upon final FDA approval of a BLA for any LeuTech Product useful for the
     imaging of appendicitis [INFORMATION OMITTED AND FILED SEPARATELY WITH THE
     COMMISSION UNDER RULE 24b-2.] such security interest conveyed pursuant to
     the provisions of Exhibit A will terminate, and Mallinckrodt, at such time,
     agrees to take any or all actions and filings which may be desirable or
     necessary to effectuate the termination of such security interests,
     including any actions and filings as may be reasonably requested by
     Palatin.

     (c) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER
     RULE 24b-2.].

     (d) [INFORMATION OMITTED AND FILED SEPARATELY WITH THE COMMISSION UNDER
     RULE 24b-2.].

9. Monthly Reporting Obligation. In addition to the reporting obligations
imposed on Palatin under the Collaboration Agreement, Palatin shall also provide
Mallinckrodt with written monthly reports updating the status of Palatin's
manufacturing and clinical programs for LeuTech. Palatin shall provide each such
report to Mallinckrodt within fifteen (15) days following the last day of each
month. Each report shall contain such information as is necessary to provide
Mallinckrodt with a true and complete status report regarding such programs as
of the end of the month in question. Notwithstanding anything contained herein

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<PAGE>


or in the Collaboration Agreement to the contrary, Palatin's reporting
obligations pursuant to this Section 9 shall terminate upon receipt of FDA
approval of LeuTech for equivocal appendicitis.

10. FDA Submissions and Reviews. In addition to any other rights afforded to
Mallinckrodt under the Collaboration Agreement, Mallinckrodt shall be given the
opportunity of prior review and comment upon any and all submissions to the FDA
relating to LeuTech. Mallinckrodt shall also have the right to designate one
individual to represent Mallinckrodt at FDA meetings and conferences.

11. Public Disclosure. Neither Palatin nor Mallinckrodt will issue a press
release or make any other public disclosure regarding the terms of this
Amendment without the prior written approval of the other party, which approval
will not be unreasonably withheld.

12. Collaboration Agreement Survival. Except to the extent provided for in this
Amendment, the Collaboration Agreement shall continue in full force and effect.

13. Governing Law. The validity and interpretation of this Amendment and the
rights and obligations of the parties shall be governed by the internal laws of
the State of New York.

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<PAGE>



     IN WITNESS WHEREOF, the parties have executed this Amendment by their duly
authorized officers on the date first above-written.


MALLINCKRODT INC.


By:____________________
     Mark A. Thom
     President Imaging Group


PALATIN TECHNOLOGIES, INC.


By:____________________
     Stephen T. Wills
     Chief Financial Officer



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<PAGE>


EXHIBIT A

                               SECURITY AGREEMENT

     THIS SECURITY AGREEMENT (this "Agreement") dated as of May 13, 2002, is
entered into by and between PALATIN TECHNOLOGIES, INC., a Delaware corporation
("Palatin"), including its wholly-owned subsidiary, RHOMED INCORPORATED, a New
Mexico corporation (Palatin and RhoMed Incorporated are hereinafter collectively
referred to as the "Company"), and MALLINCKRODT INC., a Delaware corporation
(the "Secured Party").

                             PRELIMINARY STATEMENTS

     Palatin and the Secured Party are parties to a Strategic Collaboration
Agreement, dated as of August 17, 1999, which is being amended by an Amendment,
dated of even date herewith (the "Amendment"). The Amendment provides that the
performance by Palatin of its obligations thereunder shall be secured by the
security interest contemplated by this Agreement. Capitalized terms used in this
Agreement and not otherwise defined herein shall have the meanings set forth in
the Amendment.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

                             STATEMENT OF AGREEMENT

     1. Grant of Security.

          1.1 In order to secure the complete and timely satisfaction by Palatin
     of its obligation to receive final United States Food and Drug
     Administration approval of a Biologics License Application for any LeuTech
     Product useful for the imaging of appendicitis [INFORMATION OMITTED AND
     FILED SEPARATELY WITH THE COMMISSION UNDER RULE 24b-2.] (the
     "Obligations"), the Company hereby grants to the Secured Party a security
     interest in and to all of the Company's right, title and interest in and to
     all of the patents and trademarks, including the goodwill of the business
     of the Company associated with the trademark of LeuTech for equivocal
     appendicitis, currently held, and as may be acquired during the term
     hereof, by the Company necessary for the use of LeuTech for equivocal
     appendicitis, all as identified on Schedule A attached hereto
     (collectively, the "Intellectual Property").


          1.2 The amount of the Obligations secured by the security interest
     granted by this Agreement shall not exceed $3.2 million, plus the amount
     identified in Section 6 herein, and in the event the Company is unable to
     satisfy the Obligations, the Secured Party shall enforce its rights under
     this Agreement pursuant to and subject to Section 5.

     2. Representations and Warranties. The Company represents and warrants to
the Secured Party as follows:

          2.1 Schedule A sets forth a complete and correct list of all
     Intellectual Property owned by the Company on the date hereof. Except as
     set forth on Schedule A, the Company has the right to use all Intellectual
     Property which is necessary for the


<PAGE>


     development of LeuTech for equivocal appendicitis. Except as set forth on
     Schedule A, there is no pending or, to the Company's knowledge, threatened
     claim or litigation against or affecting the Company contesting the
     validity of any of the Intellectual Property.

          2.2 This Agreement creates a valid lien in the Intellectual Property,
     securing the timely satisfaction of the Obligations, and all other actions
     as are reasonably necessary or desirable to perfect and protect such
     security interest have been duly taken or will be taken in the requisite
     period of time.

          2.3 Except for financing statements and such filings with the U.S.
     Department of Commerce Patent and Trademark Office required to be filed in
     favor of the Secured Party pursuant to this Agreement, no authorization,
     approval or other action by, and no notice to or filing with, any
     governmental or regulatory agency or authority is required (i) for the
     grant by the Company of the security interest granted hereby or (ii) for
     the execution, delivery or performance of this Agreement by the Company.


          2.4 Except as set forth on Schedule A, the Company is the sole and
     exclusive owner of the entire unencumbered right, title and interest in and
     to the Intellectual Property, free and clear of any liens, charges and
     encumbrances, including without limitation pledges, assignments, licenses
     and covenants by the Company not to sue third parties.


          2.5 All corporate action on the part of the Company necessary for the
     authorization, execution and delivery of this Agreement has been taken.

     3. Further Assurances.

          3.1 To the extent reasonably requested by the Secured Party, the
     Company agrees that from time to time, at the expense of the Company, the
     Company will promptly execute and deliver all further instruments and
     documents, and take all further action, that may be necessary or desirable,
     in order to perfect and protect any security interest granted or purported
     to be granted hereby or to enable the Secured Party to exercise and enforce
     its rights and remedies hereunder with respect to any Intellectual
     Property. Without limiting the generality of the foregoing, the Company
     will execute and file such financing or continuation statements, or
     amendments thereto, and such other instruments or notices, as may be
     reasonably necessary or desirable, or as the Secured Party may reasonably
     request, in order to perfect and preserve the security interest granted or
     purported to be granted hereby.

          3.2 The Company hereby authorizes the Secured Party to file one or
     more financing or continuation statements, and amendments thereto, relative
     to the Intellectual Property without the signature of the Company where
     permitted by law. A carbon, photographic or other reproduction of this
     Agreement or any financing statement


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<PAGE>


     covering the Intellectual Property or any part thereof shall be sufficient
     as a financing statement where permitted by law.

          3.3 The Company will defend the Intellectual Property against all
     claims and demands of all persons (other than the Secured Party) claiming
     an interest therein. The Company will pay promptly when due all property
     and other taxes, assessments and governmental charges or levies imposed
     upon, and all claims (including claims for labor, materials and supplies)
     against, the Intellectual Property, except to the extent where there is a
     good faith contest to the validity thereof. In connection with any such
     good faith contest the Company will, at the request of the Secured Party,
     promptly provide a bond, cash deposit or other security, in an amount not
     to exceed $3.2 million, reasonably satisfactory to protect the security
     interest of the Secured Party should such good faith contest be
     unsuccessful.

          3.4 The Company shall take all reasonable steps to maintain and
     enforce the Intellectual Property, including but not limited to (i) payment
     of all fees and (ii) take all actions as are necessary, including
     prosecuting infringers, to prevent a material diminution in the value of
     the Intellectual Property.

          3.5 The Company shall not sell, assign (by operation of law or
     otherwise) or otherwise dispose of any of the Intellectual Property without
     the prior written consent of the Secured Party, except in the ordinary
     course of business.

     4. The Secured Party's Duties. The powers conferred on the Secured Party
hereunder are solely to protect its interest in the Intellectual Property and
shall not impose any duty upon it to exercise any such powers. The Secured Party
shall not have any duty as to any Intellectual Property or as to the taking of
any necessary steps to preserve rights against prior parties or any other rights
pertaining to any Intellectual Property.

     5. Default and Remedies. If the Company fails to timely satisfy the
Obligation, and the Company has elected not to pay the Milestone Amount, as such
term is defined in the Amendment, to the Secured Party pursuant to Section 8(c)
of the Amendment, the Secured Party may foreclose upon the security interest
granted herein, and the Secured Party shall have those rights and remedies
allowed by law and the rights and remedies of a secured party under the Uniform
Commercial Code as enacted in any applicable jurisdiction up to an amount not to
exceed the amount specified in Section 1.2 of this Agreement.

     6. Expenses. Other than with respect to the initial filing or recording
fees incurred upon execution of this Agreement, which expenses shall be borne by
the Company, each of the parties hereto shall bear their own fees and expenses
incurred in connection with this Agreement; provided, however, the Company
hereby agrees to pay the expenses, in an amount not to exceed $25,000, of the
Secured Party which may be incurred in connection with the foreclosure of the
security interests pursuant to this Agreement.

     7. Amendments. No amendment or waiver of any provision of this Agreement
nor consent to any departure by the Company herefrom shall in any event be
effective unless the


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same shall be in writing and signed by the Secured Party, and then such waiver
or consent shall be effective only in the specific instance and for the specific
purpose for which given.

     8. Continuing Security Interest; Termination. This Agreement shall create a
continuing security interest in the Intellectual Property and shall (i) remain
in full force and effect until satisfaction by the Company of the Obligations,
(ii) be binding upon the Company, its successors and assigns, and (iii) inure to
the benefit of the Secured Party and its successors, transferees and assigns.
The security interest granted hereby shall terminate and all rights to the
Intellectual Property shall revert to the Company (i) upon satisfaction of the
Obligations by the Company or (ii) upon failure of the Secured Party to provide
Additional Funding, as applicable, upon completion by the Company of each of the
Milestones . Upon any such termination, the Secured Party will, at the Company's
expense, execute and deliver to the Company such termination agreement and
Uniform Commercial Code termination statements and such other documentation as
the Company shall reasonably request to effect the termination and release of
the security interest on the Intellectual Property.

     9. Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of New York (without regard to the
conflicts of laws provisions thereof).

     10. Miscellaneous. This Agreement is in addition to and not in limitation
of any other rights and remedies the Secured Party may have by virtue of any
other instrument or agreement heretofore, contemporaneously herewith or
hereafter executed by the Company or by law or otherwise. If any provision of
this Agreement is contrary to applicable law, such provision shall be deemed
ineffective without invalidating the remaining provisions hereof. If and to the
extent that applicable law confers any rights in addition to any of the
provisions of this Agreement, the affected provision shall be considered amended
to conform thereto. The Secured Party shall not by any act, delay, omission or
otherwise be deemed to have waived any of its rights or remedies hereunder. A
waiver by the Secured Party of any right or remedy hereunder on any one
occasion, shall not be construed as a bar to or waiver of any such right or
remedy which the Secured Party would have had on any future occasion nor shall
the Secured Party be liable for exercising or failing to exercise any such right
or remedy. This Agreement may be executed in any number of counterparts, all of
which taken together shall constitute one and the same instrument and the
parties hereto may execute this Agreement by signing any such counterpart.
Facsimile execution and delivery of this Agreement shall be legal, valid and
binding execution and delivery for all purposes.

                                    * * * * *
            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]


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     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and delivered as of the date first above written.

                                                     PALATIN technologies, inc.


                                                     By:
                                                              ___________
                                                              ___________



                                                     RHOMED INCORPORATED


                                                     By:
                                                              ___________
                                                              ___________



                                                     MALLINCKRODT INC.


                                                     By:
                                                     Title:   ___________





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<PAGE>



CERTIFICATE OF ACKNOWLEDGEMENT

STATE OF __________________)
                           )  SS
COUNTY OF _________________)

     Before me, the undersigned, a Notary Public in and for the County and State
aforesaid, on this ___ day of ___________, 2002, personally appeared Carl Spana,
Ph.D. to me known personally, and who, being by me duly sworn, deposes and says
that he is the Chief Executive Officer and President of PALATIN TECHNOLOGIES,
INC., a Delaware corporation and that said instrument was signed on behalf of
said corporation by authority of its Board of Directors, and said individual
acknowledged said instrument to be the free act and deed of said corporation.

                                            ____________________________________
                                            Notary Public
(SEAL)
                                                     My commission expires:



STATE OF __________________)
                           )  SS
COUNTY OF _________________)

     Before me, the undersigned, a Notary Public in and for the County and State
aforesaid, on this ___ day of ___________, 2002, personally appeared__________,
to me known personally, and who, being by me duly sworn, deposes and says that
he is the __________________________of RHOMED INCORPORATED, a New Mexico
corporation and that said instrument was signed on behalf of said corporation by
authority of its Board of Directors, and said individual acknowledged said
instrument to be the free act and deed of said corporation.

                                            ____________________________________
                                            Notary Public
(SEAL)
                                                     My commission expires:





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<PAGE>




                                   SCHEDULE A


Patents:

U.S. Patent 6,261,536, issued July 17, 2001, Post-Labeling Stabilization of
Radiolabeled Proteins and Peptides (Assignee of record RhoMed Incorporated)

U.S. Patent 6,066,309, issued May 23, 2000, Post-Labeling Stabilization of
Radiolabeled Proteins and Peptides (Assignee of record RhoMed Incorporated)

U.S. Patent No. 5,346,687, issued September 13, 1994, Direct Radiolabeling of
Antibody against Stage Specific Embryonic Antigen for Diagnostic Imaging
(Assignee of record RhoMed Incorporated)

U.S. Patent No. RE35,500, issued May 6, 1997, Direct Radiolabeling of Antibodies
and Other Proteins with Technetium or Rhenium (Assignee of record RhoMed
Incorporated)

U.S. Patent No. RE35,457, issued February 18, 1997, Radiolabeling Antibodies and
Other Proteins with Technetium or Rhenium by Regulated Reduction (Assignee of
record RhoMed Incorporated)


Trademarks:

Registered Trademarks:

LEUTECH, Registration No. 2,260,726 (Owner Palatin Technologies, Inc.)



The Patents and Trademarks identified on this Schedule A shall include all
reissues, divisions, continuations, renewals and extensions of such Patents and
Trademarks identified above.