<PAGE>

                                                               Exhibit 10.13

                                  CONFIDENTIAL TREATMENT HAS BEEN SOUGHT FOR
                             PORTIONS OF THIS EXHIBIT PURSUANT TO RULE 24B-2
                       UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED


                                                              EXECUTION COPY


                                LICENSE AGREEMENT


                                     BETWEEN


                           PHOTOGEN TECHNOLOGIES, INC.


                                       AND


                               PHOTOGEN NEWCO LTD.


<PAGE>

                               TABLE OF CONTENTS
<TABLE>

<S>      <C>
1.       DEFINITIONS

2.       ELAN LICENSE TO NEWCO

3.       INTELLECTUAL PROPERTY

4.       [****]/AFTER ACQUIRED TECHNOLOGY

5.       FINANCIAL PROVISIONS

6.       RIGHT OF INSPECTION AND AUDIT

7.       REPRESENTATIONS AND WARRANTIES

8.       TERM AND TERMINATION

9.       CONFIDENTIAL INFORMATION

10.      GOVERNING LAW AND ARBITRATION

11.      IMPOSSIBILITY OF PERFORMANCE - FORCE MAJEURE

12.      ASSIGNMENT

13.      NOTICES

14.      MISCELLANEOUS
</TABLE>

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

THIS AGREEMENT made this 20th October 1999

BETWEEN:

(1)      PHOTOGEN TECHNOLOGIES, INC., a corporation duly incorporated and
         validly existing under the laws of Nevada and having its principal
         place of business at 7327 Oak Ridge, Knoxville, TN. 37931, United
         States of America; and

(2)      PHOTOGEN NEWCO, LTD., an exempted limited liability company
         incorporated under the laws of Bermuda and having its registered
         office at Clarendon House, 2 Church Street, Hamilton, Bermuda
         ("NEWCO"); and

(3)      ELAN PHARMA INTERNATIONAL LIMITED incorporated under the laws of
         Ireland, and having its registered office at WIL House, Shannon
         Business Park, Shannon, County Clare, Ireland ("EPIL").

RECITALS:

A.       Simultaneously herewith, Photogen, Elan, EIS, and Newco are entering
         into the JDOA for the purpose of recording the terms and conditions of
         the joint venture and of regulating their relationship with each other
         and certain aspects of the affairs of, and their dealings with Newco.

B.       Newco desires to enter into this Agreement with Photogen so as to
         permit Newco to utilize the Photogen Intellectual Property in making,
         having made, importing, using, offering for sale and selling the
         Products in the Field in the Territory.

C.       Simultaneously herewith Newco and Elan are entering into the Elan
         License Agreement relating to Newco's use of the Elan Intellectual
         Property.

1        DEFINITIONS

1.1      In this Agreement unless the context otherwise requires:

         "AFFILIATE" shall mean any corporation or entity controlling,
         controlled or under the common control of Elan or Photogen, as the case
         may be. For the purpose of this definition, "control" shall mean direct
         or indirect ownership of fifty percent (50%) or more of the stock or
         shares entitled to vote for the election of directors. Newco is not an
         Affiliate of Photogen, Elan or EIS.

         "AGREEMENT" shall mean this license agreement (which expression shall
         be deemed to include the Recitals and Schedules hereto).

<PAGE>

         "ALLIANCE" shall mean Alliance Pharmaceutical Corp., whose principal
         place of business is at 3040 Science Park Road, San Diego, California.

         "ALLIANCE AGREEMENT" shall mean the Agreement dated 9 August 1999,
         between Alliance, Photogen and Dr. Gerald Wolf ("DR WOLF"), which
         agreement, inter alia, assigned the Method Patents from Alliance and
         Dr. Wolf to Photogen.

         "[****]"

         "[****]"

         "BUSINESS PLAN" shall have the meaning, as such term is defined in
         the JDOA.

         "COMPOUNDS" shall mean the [****].

         "CONFIDENTIAL INFORMATION" shall have the meaning, as such term is
         defined in Clause 9.

         "CONTROL" shall mean the ability to grant a license or sublicense as
         contemplated herein without violating the terms of any agreement with
         any third party.

         "DEFINITIVE DOCUMENTS" shall mean the definitive agreements relating to
         the transaction between the Parties and Elan including finance, stock
         purchase, research and license agreements.

         "ELAN " shall mean EPIL (a wholly owned subsidiary of Elan Corporation,
         Plc., which owns the Nanocrystal-TM- technology formerly Controlled by
         NanoSystems LLC, formerly a subsidiary of the Eastman Kodak Company)
         and Affiliates and subsidiaries of Elan Corporation, Plc. within the
         division of Elan Corporation, Plc. carrying on business as Elan
         Pharmaceutical Technologies but shall not include Affiliates and
         subsidiaries (present or future) of Elan Corporation Plc within the
         division of Elan Corporation, Plc carrying on business as Elan
         Pharmaceuticals which incorporates, inter alia, Targon Corporation,
         Athena Neurosciences, Inc., Elan Pharmaceuticals, Inc., Elan
         Diagnostics, Carnrick Laboratories, and Elan Europe Limited.

         "EIS" shall mean Elan International Services, Limited, an exempted
         limited liability company incorporated under the laws of Bermuda and
         having its registered office at Clarendon House, 2 Church Street,
         Hamilton, Bermuda and a subsidiary of Elan.

         "EFFECTIVE DATE" shall mean the date of this Agreement.

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

     EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         "ELAN INTELLECTUAL PROPERTY" shall mean the Elan Know-How, the Elan
         Patents and the Elan Improvements, as such terms are defined in the
         Elan License Agreement.

         "ELAN LICENSE" shall have the meaning set forth in Clause 2.1 of the
         Elan License Agreement.

         "ELAN LICENSE AGREEMENT" shall mean that certain license agreement, of
         even date herewith, entered into between EPIL and Newco.

         "ELAN PATENTS" shall have the meaning as such term is defined in the
         Elan License Agreement.

         "FIELD" shall mean the research, development, manufacture and
         commercialization of nanoparticulate x-ray, CT, and/or MRI diagnostic
         imaging agents using radio-opaque molecules containing Iodine that
         passively target to lymphnodes involved in a disease state following
         parenteral administration to a mammal to locate, diagnose and/or treat
         cancer and/or other diseases.

         For the avoidance of doubt, the Field does not include:

         (iv)     active targeting agents, including but not limited to
                  monoclonal antibodies, short-chain antibodies or any other
                  active targeting agents including protein, peptide or
                  peptidomimetic targeting agents; or

         (ii)     ultrasound diagnostic imaging agents.

         "GENERAL NYCOMED AGREEMENT" shall mean the License Agreement dated 30
         September, 1999 between The General Hospital Corporation (acting, inter
         alia, as agent for Nycomed) and Photogen which agreement licenses,
         inter alia, certain rights with respect to the Compounds [****] and
         [****] to Photogen.

         "GENERAL NYCOMED PATENTS" shall mean the patents included in the
         GenNyc Intellectual Property.

         "GENNYC INTELLECTUAL PROPERTY" shall mean all the rights to and under
         the General Patent Rights, the Joint Patent Rights and the [****]
         Patent Rights (as those terms are defined in the General Nycomed
         Agreement) which were licensed to Photogen pursuant to the General
         Nycomed Agreement.

         The primary examples of GenNyc Intellectual Property existing as of the
         Effective Date are set forth on Schedule 2, which listing is not
         necessarily exhaustive.

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

<PAGE>

[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         "IN-LICENSE AGREEMENTS" shall mean collectively the General Nycomed
         Agreement and the Alliance Agreement.

         "JDOA" shall mean that certain joint development and operating
         agreement, of even date herewith, by and between Elan, Photogen, EIS
         and Newco.

         "KNOW-HOW" shall mean information and know-how, whether patentable or
         not, including but not limited to any and all discoveries, inventions,
         substances, data, techniques, processes, systems, formulations, designs
         and commercial information relating to design, development,
         manufacture, assembly, use or sale.

         "LICENSED TECHNOLOGIES" shall mean the Elan Intellectual Property, the
         Photogen Intellectual Property and the GenNyc Intellectual Property.

         "LICENSES" shall mean the Elan License, the Photogen License and the
         General Nycomed Sublicense.

         "MANAGEMENT COMMITTEE" shall have the meaning, as such term is
         defined in the JDOA.

         "METHOD PATENTS" shall mean the patent family that contains the [****]
         Patent, the [****] Patent, [****] and others as described in Exhibit B
         of the Alliance Agreement.

         "NEWCO INTELLECTUAL PROPERTY" shall mean all Patent Rights and Know-How
         and other intellectual property arising pursuant to the Project by any
         person, that does not constitute Elan Intellectual Property or Photogen
         Intellectual Property and any technology licensed or acquired by Newco
         from a third party.

         For avoidance of doubt, Newco Intellectual Property includes that
         portion of all improvements developed pursuant to the Project relating
         solely and specifically to Product(s).

         "NEWCO PATENTS" shall mean any and all Patent Rights now existing,
         currently pending or hereafter filed or obtained relating to the Newco
         Intellectual Property.

         "NYCOMED" shall mean Nycomed Imaging AS doing business as Nycomed
         Amersham, whose principal place of business is at 101 Carnegie Center,
         Princeton, NJ 08540, USA.

         "PARTY" shall mean Photogen or Newco, as the case may be, and
         "PARTIES" shall mean Photogen and Newco.

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<PAGE>

[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         "PATENT RIGHTS" shall mean any and all patents and patent applications,
         including all divisonals, continuations, continuations-in-part,
         extensions, patents-of-additions, re-examinations, re-issues,
         supplementary protection certificates and foreign counterparts of such
         patents and patent applications and any patents issuing thereon and
         extensions thereon.

         "PHOTOGEN" shall mean Photogen Technologies, Inc. and its
         Affiliates, excluding Newco.

         "PHOTOGEN INTELLECTUAL PROPERTY" shall mean the Photogen Know-How, the
         Photogen Patents and the Photogen Improvements.

         "PHOTOGEN KNOW-HOW" shall mean any and all rights owned, licensed or
         Controlled by Photogen to Know-How other than Know-How included in the
         GenNyc Intellectual Property, relating to medical diagnostic imaging
         agents, methods of treatment using medical diagnostic imaging agents
         and related compositions.

         The primary examples of the Photogen Know-How existing as of the
         Effective Date are set forth on Schedule 1 attached hereto, which
         listing is not necessarily exhaustive, and includes Know-How owned,
         licensed or Controlled by Photogen related to the Method Patents.

         "PHOTOGEN LICENSE" shall have the meaning set forth in Clause 2.1.

         "PHOTOGEN PATENTS" shall mean any and all Patent Rights owned or
         Controlled by Photogen other than Patent Rights included in the GenNyc
         Intellectual Property, now existing, currently pending or hereafter
         filed by Photogen relating to nanoparticulate medical diagnostic
         imaging agents including medical diagnostic imaging agents, methods of
         treatment using medical diagnostic imaging agents and related
         compositions.

         The primary examples of Photogen Patents existing as of the Effective
         Date are set forth on Schedule 1 attached hereto, which listing is not
         necessarily exhaustive, and includes the Method Patents.

         "PHOTOGEN IMPROVEMENTS" shall mean improvements relating to the
         Photogen Patents and/or the Photogen Know-How, developed (i) by
         Photogen not pursuant to the Project, (ii) by Photogen pursuant to the
         Project except for that portion of improvements relating solely and
         specifically to Product(s) (iii) by Newco or Elan or by a third party
         (under contract with Newco) pursuant to the Project except for that
         portion of improvements relating solely and specifically to Product(s),
         and/or (iv) jointly by any combination of Photogen, Elan or Newco
         pursuant to the Project except for that portion of improvements
         relating solely and specifically to Product(s), except as limited by
         agreements with unaffiliated third parties.

         Subject to third party agreements with unaffiliated third parties,
         Photogen Improvements

<PAGE>

         shall constitute part of Photogen Intellectual Property and be
         included in the license of the Photogen Intellectual Property
         pursuant to Clause 2.1 solely for the purposes set forth therein. If
         the inclusion of a Photogen Improvement in the license of Photogen
         Intellectual Property is restricted or limited by a third party
         agreement, Photogen shall use reasonable commercial efforts to
         minimize any such restriction or limitation.

         "PRODUCT" shall mean a formulation containing one or more x-ray, CT,
         and/or MRI Compounds in nanoparticulate form developed by or on behalf
         of Newco pursuant to the Project.

         "PHOTOGEN TRADEMARK(S)" shall mean one or more trademarks, trade names,
         or service marks that are owned or licensed by or on behalf of Photogen
         which Photogen may nominate and approve in writing from time to time
         and Newco may accept for use in connection with the sale or promotion
         of the Products by Newco

         "PROJECT" shall mean all activities as undertaken by Elan, Photogen and
         Newco in order to develop the Products.

         "R&D COMMITTEE" shall have the meaning, as such term is defined in
         the JDOA.

         "R&D PLAN" shall have the meaning, as such term is defined in the
         JDOA.

         "R&D PROGRAM" shall mean any research and development program
         commenced by Newco pursuant to the Project.

         "TERM" shall have the meaning set forth in Clause 8.

         "TERRITORY" shall mean all the countries of the world.

         "UNITED STATES DOLLAR" and "US$" shall mean the lawful currency for the
         time being of the United States of America.

1.2      In this Agreement:

         1.2.1    The singular includes the plural and vice versa, and the
                  masculine includes the feminine and vice versa and the neuter
                  includes the masculine and the feminine.

         1.2.2    Any reference to a Clause or Schedule shall, unless otherwise
                  specifically provided, be to a Clause or Schedule of this
                  Agreement.

         1.2.3    The headings of this Agreement are for ease of reference only
                  and shall not affect its construction or interpretation.

<PAGE>

2.       PHOTOGEN LICENSE TO NEWCO

2.1      Photogen hereby grants to Newco for the Term an [****] license
         (including the right to grant sublicenses under Clause 2.7) (the
         "PHOTOGEN LICENSE") of the Photogen Intellectual Property solely in the
         Field to make, have made, import, use, offer for sale and sell the
         Products in the Field in the Territory.

2.2      Photogen hereby grants to Newco for the Term an [****] sublicense
         (including the right to grant sublicenses under Clause 2.7) (the
         "GENERAL NYCOMED SUBLICENSE") of all Photogen's rights to the GenNyc
         Intellectual Property solely in the Field solely to make, have made,
         import, use, offer for sale and sell the Products in the Field in the
         Territory.

2.3      Save only the specific royalty obligations of Photogen to Nycomed under
         Clause 5.1(c) and Clause 5.1(d) of the General Nycomed Agreement in
         respect of Newco's sales of Products as a "SUB-LICENSEE" as defined in
         the General Nycomed Agreement for which Newco will be responsible,
         Photogen shall be responsible for payments related to the financial
         provisions and obligations of any third party agreement with respect to
         the Photogen Intellectual Property to which it is a party on the
         Effective Date (including amendments thereto) (the "PHOTOGEN EFFECTIVE
         DATE AGREEMENTS"), including without limitation, any royalty or other
         compensation obligations triggered thereunder on the Effective Date, or
         triggered thereunder after the Effective Date.

         For the avoidance of doubt, royalties, milestones or other payments
         which arise from the process of the commercialization or exploitation
         of products under the Photogen Effective Date Agreements (for example,
         a milestone payment payable upon successful completion of Phase II
         clinical trials, the filing of an NDA application, obtaining NDA
         approval, or first commercial sale) shall be payments for which
         Photogen will be responsible under this Clause 2.3.

2.4      To the extent royalty or other compensation obligations that are
         payable to third parties with respect to the Photogen Intellectual
         Property would be triggered after the Effective Date under any third
         party agreement entered into by Photogen after the Effective Date (the
         "PHOTOGEN POST-EFFECTIVE DATE AGREEMENTS"), by a proposed use of such
         Photogen Intellectual Property in connection with the Project, Photogen
         will inform Newco of such royalty or compensation obligations. [****]

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         For the avoidance of doubt, royalties, milestones or other payments
         which arise from the process of the commercialization or exploitation
         of products under the Photogen Post-Effective Date Agreements (for
         example, a milestone payment payable upon successful completion of
         Phase II clinical trials, the filing of an NDA application, obtaining
         NDA approval, or first commercial sale) shall be payments for which
         Newco will be responsible under this Clause 2.4.

2.5      Elan shall be a third party beneficiary under this Agreement and shall
         have the right to cause Newco to enforce Newco's rights under this
         Agreement against Photogen.

2.6      Notwithstanding anything contained in this Agreement to the contrary,
         Photogen shall have the right outside the Field and subject to the
         non-competition provisions of Clause 4 to exploit and grant licenses
         and sublicenses of the Photogen Intellectual Property. For the
         avoidance of doubt, Newco shall have no right to use the Photogen
         Intellectual Property outside the Field.

2.7      Newco shall not be permitted to assign or sublicense any of its rights
         under the Photogen Intellectual Property without the prior written
         consents of Photogen and Elan, which consents shall not be unreasonably
         withheld or delayed.

2.8      Any agreement between Newco and any permitted third party for the
         development or exploitation of the Photogen Intellectual Property shall
         require such third party to maintain the confidentiality of all
         information concerning the Photogen Intellectual Property.

Insofar as the obligations owed by Newco to Photogen are concerned, Newco
shall remain responsible for all acts and omissions of any permitted
sub-licensee, including Elan, as if they were acts and omissions by Newco.

3        INTELLECTUAL PROPERTY

3.1      OWNERSHIP OF INTELLECTUAL PROPERTY:

         3.1.1 Newco shall own the Newco Intellectual Property.

         3.1.2 Photogen shall own the Photogen Intellectual Property.

3.2      TRADEMARKS:

         3.2.1    Photogen hereby grants to Newco for the Term a [****]
                  license in the Territory to

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER


<PAGE>

         THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

                  use and display the Photogen Trademarks to promote, offer
                  for sale and sell the Products in the Field in the
                  Territory and the following provisions shall apply as
                  regards the use of the Photogen Trademarks by Newco
                  hereunder:

                  (1)      Newco shall ensure that each reference to and use of
                           a Photogen Trademark by Newco is in a manner approved
                           by Photogen and accompanied by an acknowledgement, in
                           a form approved by Photogen, that the same is a
                           trademark (or registered trademark) of Photogen.

                           From time to time, upon the reasonable request of
                           Photogen, Newco shall submit samples of the Product
                           to Photogen or its duly appointed agent to ensure
                           compliance with quality standards and specifications.
                           Photogen, or its duly appointed agent, shall have the
                           right to inspect the premises of Newco where the
                           Product is manufactured, held or stored, and Newco
                           shall permit such inspection, upon advance notice at
                           any reasonable time, of the methods and procedures
                           used in the manufacture, storage and sale of the
                           Product. Newco shall not sell or otherwise dispose of
                           any Product under the Photogen Trademarks that fails
                           to comply with the quality standards and
                           specifications referred to in this Clause 3.2, as
                           determined by Photogen.

                  (2)      Newco shall not use an Photogen Trademark in any way
                           which might materially prejudice its distinctiveness
                           or validity or the goodwill of Photogen therein.

                  (3)      The parties recognize that the Photogen Trademarks
                           have considerable goodwill associated therewith.
                           Newco shall not use in relation to the Products any
                           trademarks other than the Photogen Trademarks (except
                           the Photogen Trademarks (as defined in the Photogen
                           License Agreement) licensed to Newco under the
                           Photogen License Agreement) without obtaining the
                           prior consent in writing of Photogen, which consent
                           may not be unreasonably withheld. However, such use
                           must not conflict with the use and display of the
                           Photogen Trademark and such use and display must be
                           approved by Photogen.

                  (4)      Newco shall not use in the Territory any trademarks
                           or trade names so resembling the Photogen Trademark
                           as to be likely to cause confusion or deception.

                  (5)      Newco shall promptly notify Photogen in writing of
                           any alleged infringement or unauthorised use of which
                           it becomes aware by a third party of the Photogen
                           Trademarks and provide Photogen with any applicable
                           evidence of infringement or unauthorised use.

                  (6)      Newco shall favourably consider promoting and using
                           the Photogen

<PAGE>

                           Trademarks in each country of the Territory and
                           provide proof of such use upon request by Photogen.

                  (7)      Newco shall not be permitted to assign or sublicense
                           any of its rights under the Photogen Trademarks
                           without the prior written consent of Photogen, which
                           consent shall not be unreasonably withheld or
                           delayed.

         3.2.2    Photogen shall, [****], file and prosecute applications to
                  register and maintain registrations of the Photogen Trademarks
                  in the Territory. Newco shall reasonably co-operate with
                  Photogen in such efforts. In the event Photogen decides not to
                  file or prosecute such Photogen Trademark, Newco may request
                  Photogen to do the same at Newco's expense, and Photogen shall
                  file or prosecute such Photogen Trademark at Newco's request
                  and expense unless Photogen believes such action is without
                  merit.

         3.2.3    Photogen will be entitled to conduct all enforcement
                  proceedings relating to the Photogen Trademarks and shall
                  at its [****] discretion decide what action, if any, to
                  take in respect to any enforcement proceedings of the
                  Photogen Trademarks or any other claim or counter-claim
                  brought in respect to the use or registration of the
                  Photogen Trademarks. Any such proceedings shall be
                  conducted at Photogen's [****] and for its own benefit.
                  Newco and Elan shall reasonably cooperate with Photogen in
                  such efforts. In the event Photogen decides not to engage
                  in enforcement proceedings of the Photogen Trademarks Newco
                  may request Photogen to do the same at Newco's expense
                  unless Photogen believes the basis for such enforcement
                  proceedings is without merit. In such a case, Photogen
                  shall have the sole discretion not to engage in any such
                  enforcement proceedings.

         3.2.4    Newco shall promptly notify Photogen in writing in the
                  event that any Photogen Trademark has been challenged by a
                  third party in a judicial or administrative proceeding in a
                  country in the Territory as infringing on the rights of a
                  third party and Photogen shall have the first right to
                  decide whether or not to defend such allegations, or to
                  adopt an alternative mark, or allow Newco to adopt an
                  alternative mark. If Photogen decides not to defend the
                  Photogen Trademark, then Newco may request Photogen to
                  defend the Photogen Trademark, at Newco's expense, unless
                  such requested defense is believed by Photogen to be
                  unsubstantiated and without merit. In such a case, Photogen
                  may elect not initiate defence proceedings.

         3.2.5    Save where Newco adopts its own mark under Clause 3.2.4, Newco
                  will have no ownership rights in respect of the Photogen
                  Trademarks or of the goodwill

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES


<PAGE>

         EXCHANGE ACT OF 1934, AS AMENDED.

                  associated therewith, and Newco hereby acknowledges that,
                  except as expressly provided in this Agreement, it shall
                  not acquire any rights in respect thereof and that all such
                  rights and goodwill are, and will remain, vested in
                  Photogen.

         3.2.6    Nothing in this Agreement shall be construed as a warranty on
                  the part of Photogen regarding the Photogen Trademarks,
                  including without limitation, that use of the Photogen
                  Trademarks in the Territory will not infringe the rights of
                  any third parties. Accordingly, Newco acknowledges and agrees
                  that Photogen makes no such warranty.

         3.2.7    Photogen assumes no liability to Newco or to any third parties
                  with respect to the quality, performance or characteristics of
                  any of the goods manufactured or sold by Newco under the
                  Photogen Trademarks pursuant to this Agreement.

          4       [****]/AFTER ACQUIRED TECHNOLOGY

4.1      [****]

         [****]

4.2      If, after the Effective Date, Photogen acquires know-how or patent
         rights relating to the Field, or acquires or merges with a third
         party entity that has know-how or patent rights relating to the
         Field, Photogen shall offer to license such know-how and patent
         rights to Newco (subject to existing contractual obligations), on
         [****] terms on an arm's length basis for a [****] period under the
         prevailing circumstances.

         If Newco determines that Newco should not acquire such license,
         Photogen shall be free to fully exploit such know-how and patent rights
         with the Photogen Intellectual Property then licensed to Newco, whether
         inside or outside the Field, and to grant to third parties licenses and
         sublicenses with respect thereto.

5        FINANCIAL PROVISIONS

5.1      MILESTONE PAYMENTS AND ROYALTIES:

         Prior to the commercialization of the Products, the Management
         Committee shall consider and if appropriate, determine reasonable
         royalties and milestone payments with respect to the commercialization
         of the Products by Newco that shall be payable by Newco to Elan and
         Photogen, and shared by Elan and Photogen [****] (whether common stock
         and/or preferred stock) in Newco.

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<PAGE>

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         At such time, the Management Committee will agree to an appropriate
         definition of "Net Sales" as such term is used in this Agreement.

5.2      Payment of any royalties pursuant to Clause 5.1 shall be made quarterly
         in arrears during each Financial Year within 30 days after the expiry
         of the calendar quarter. The method of payment shall be by wire
         transfer to an account specified by Photogen. Each payment made to
         Photogen shall be accompanied by a true accounting of all Products sold
         by Newco's permitted sublicensees, if any, during such quarter.

         Such accounting shall show, on a country-by-country and
         Product-by-Product basis, Net Sales (and the calculation thereof) and
         each calculation of royalties with respect thereto, including the
         calculation of all adjustments and currency conversions.

5.3      Newco shall maintain and keep clear, detailed, complete, accurate and
         separate records for a period of [****]:

         5.3.1 to enable any royalties on Net Sales that shall have accrued
               hereunder to be determined; and

         5.3.2 to enable any deductions made in the Net Sales calculation to be
               determined.

5.4      All payments due hereunder shall be made in United States Dollars.
         Payments due on Net Sales of any Product for each calendar quarter made
         in a currency other than United States Dollars shall first be
         calculated in the foreign currency and then converted to United States
         Dollars on the basis of the exchange rate in effect on the last working
         day for such quarter for the purchase of United States Dollars with
         such foreign currency quoted in the Wall Street Journal (or comparable
         publication if not quoted in the Wall Street Journal) with respect to
         the currency of the country of origin of such payment, determined by
         averaging the rates so quoted on each business day of such quarter.

5.5      If, at any time, legal restrictions in the Territory prevent the prompt
         payment when due of royalties or any portion thereof, the Parties shall
         meet to discuss suitable and reasonable alternative methods of paying
         Photogen the amount of such royalties. In the event that Newco is
         prevented from making any payment under this Agreement by virtue of the
         statutes, laws, codes or government regulations of the country from
         which the payment is to be made, then such payments may be paid by
         depositing them in the currency in which they accrue to Photogen's
         account in a bank acceptable to Photogen in the country the currency of
         which is involved or as otherwise agreed by the Parties.

5.6      Photogen and Newco agree to co-operate in all respects necessary to
         take advantage of any double taxation agreements or similar agreements
         as may, from time to time, be available.

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         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER

<PAGE>

         THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

5.7      Any taxes payable by Photogen on any payment made to Photogen pursuant
         to this Agreement shall be for the account of Photogen. If so required
         by applicable law, any payment made pursuant to this Agreement shall be
         made by Newco after deduction of the appropriate withholding tax, in
         which event the Parties shall co-operate to obtain the appropriate tax
         clearance as soon as is practicable. On receipt of such clearance,
         Newco shall forthwith arrange payment to Photogen of the amount so
         withheld.

6        RIGHT OF INSPECTION AND AUDIT

6.1      [****] during each Financial Year, or more often not to exceed
         quarterly as reasonably requested by Photogen, Newco shall permit
         Photogen or its duly authorised representatives, upon reasonable notice
         and at any reasonable time during normal business hours, to have access
         to inspect and audit the accounts and records of Newco and any other
         book, record, voucher, receipt or invoice relating to the calculation
         of the royalty payments on Net Sales submitted to Photogen.

         Any such inspection of Newco's records shall be at the expense of
         Photogen, except that if any such inspection reveals a deficiency in
         the amount of the royalty actually paid to Photogen hereunder in any
         Financial Year of [****]% or more of the amount of any royalty actually
         due to Photogen hereunder, then the expense of such inspection shall be
         borne [****] by Newco. Any amount of deficiency shall be paid promptly
         to Photogen by Newco.

         If such inspection reveals a surplus in the amount of royalties
         actually paid to Photogen by Newco, Photogen shall reimburse Newco the
         surplus within 15 days after determination.

6.2      In the event of any unresolved dispute regarding any alleged deficiency
         or overpayment of royalty payments hereunder, the matter will be
         referred to an independent firm of chartered or public accountants
         chosen by agreement of Elan and Photogen for a resolution of such
         dispute. Any decision by the said firm of chartered accountants shall
         be binding on the Parties.

7        REPRESENTATIONS AND WARRANTIES

7.1      Photogen represents and warrants to Newco and Elan as of the
         Effective Date, as set forth below:

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER

<PAGE>

         THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         7.1.1    Photogen has the right to grant the Photogen License and
                  the General Nycomed Sublicense;

         7.1.2    there are no agreements between Photogen and any third parties
                  that conflict with the Photogen License and/or the General
                  Nycomed Sublicense;

         7.1.3    to Photogen's knowledge, there is no agreement to which
                  Photogen is a party, or otherwise, or by which it is bound
                  that restricts the use by Newco of the Photogen License or the
                  General Nycomed Sublicense;

         7.1.4    the patents and patent applications included in the Photogen
                  Patents and, to Photogen's knowledge, the General Nycomed
                  Patents, are free and clear of encumbrances and liens except
                  for the lien on the Method Patents in favour of Imperial Bank
                  which Alliance is obliged to discharge and remove pursuant to
                  the Alliance Agreement and, if not released by the Effective
                  Date, Photogen will use its continuing best efforts to procure
                  that Alliance shall discharge its obligations to Imperial Bank
                  and obtain all releases relevant hereto; and

         7.1.5    to the best of Photogen's knowledge, there are no proceedings
                  or threatened proceedings or substantive grounds for
                  proceedings against Photogen in connection with the Photogen
                  Intellectual Property or, to Photogen's knowledge, the General
                  Nycomed Sublicense in relation to the Field or, to Photogen's
                  knowledge, against General Nycomed or Alliance in connection
                  with the General Nycomed Sublicense or the Method Patents in
                  relation to the Field;

         7.1.6    to Photogen's best knowledge there is no infringement by third
                  parties of any Photogen Intellectual Property or, to
                  Photogen's knowledge, the General Nycomed Patents;

         7.1.7    to Photogen' s knowledge, there is no patent of others which
                  contains claims that they dominate the Photogen Patents or the
                  General Nycomed Patents;

         7.1.8    to Photogen's knowledge, neither the Photogen Patents nor the
                  General Nycomed Patents nor any products, methods, or other
                  inventions related thereto interferes, infringes,
                  misappropriates or conflicts with the intellectual property
                  rights, contact or other rights of any third party;

         7.1.9    Photogen has paid all payments due to relevant third parties
                  which have become payable on or prior to the date hereof
                  relating to the Photogen Intellectual Property.

7.2      Photogen further agrees and represents and warrants to Newco and
         Elan as follows:

         7.2.1    as of the Effective Date, each of the In-License Agreements is
                  valid and in full

<PAGE>

                  force and effect;

         7.2.2    as of the Effective Date, there are no existing or claimed
                  defaults by Photogen, and to Photogen's best knowledge by any
                  other party, under any of the In-License Agreements and no
                  event, act or omission has occurred which (with or without
                  notice, lapse of time or the happening or occurrence of any
                  other event) would result in a default under the In-License
                  Agreements by Photogen, or to Photogen's best knowledge by any
                  other party except Alliance's obligation to Photogen to
                  discharge the lien on the Method Patents as described in
                  Clause 7.1.4;

         7.2.3    during the Term, Photogen will fully comply with all of the
                  terms and conditions of the In-License Agreements. Photogen
                  will enforce its rights under the In-License Agreements and
                  Photogen will not assign its rights under the In-License
                  Agreements; and

         7.2.4    during the Term, Photogen will keep Newco and Elan reasonably
                  fully informed with respect to Photogen's transactions,
                  arrangements and business under the In-License Agreements that
                  relate to Newco and/or the transactions contemplated
                  hereunder, and Photogen shall provide Newco and Elan with any
                  written notices delivered by any party thereunder that relate
                  to Newco and/or the transactions contemplated hereunder, or
                  that may affect Newco;

         7.2.5    Photogen to warrant to Newco in identical terms to any and all
                  warranties provided to Photogen in the In-License Agreements.

         7.2.6    The phrase "TO PHOTOGEN'S KNOWLEDGE" in this Clause 7 is to
                  Photogen's actual knowledge based on reasonable investigation.

7.3      During the Term, Photogen shall not amend, modify, or waive any of its
         rights under the In-License Agreements without the prior written
         consent of the Management Committee (by the unanimous vote of its
         members).

         For the avoidance of doubt, Photogen shall not terminate any of its
         rights under the In-License Agreements without the prior written
         consent of the Management Committee (by the unanimous vote of its
         members).

7.4      Photogen shall indemnify and hold harmless Newco and Elan against all
         costs, claims and liabilities in respect of any claims or proceedings
         which may be taken by a third party against Newco and/or Elan, or which
         may arise in any way, in relation to or in connection with the
         In-License Agreements except for any wilful wrongful act of Elan or
         Newco.

         In addition, Photogen shall indemnify and hold harmless Newco and Elan
         against all costs, claims and liabilities in respect of any claims or
         proceedings which may be taken by a third party against Newco and/or
         Elan that any Product infringes the patent rights of

<PAGE>

         such third party by virtue of the Photogen Patents or the General
         Nycomed Patents.

         For the avoidance of doubt, the provisions of Clause 7.9 shall not
         exclude or limit Newco's and Elan's rights to be fully indemnified by
         Photogen hereunder against the full extent of any third party claim,
         whether or not such third party claim, includes a claim for the
         recovery of consequential loss or incidental or punitive loss or damage
         (whether for loss of profits or otherwise).

7.5      In addition to any other indemnities provided for herein, Photogen
         shall indemnify and hold harmless Elan, Newco and its Affiliates and
         their respective employees, agents, officers and directors from and
         against any claims, losses, liabilities or damages (including
         reasonable attorney's fees and expenses) incurred or sustained by Elan
         or Newco arising out of or in connection with any:

         7.5.1    breach of any representation, covenant, warranty or
                  obligation by Photogen hereunder; or

         7.5.2    act or omission on the part of Photogen or any of its
                  respective employees, agents, officers and directors in the
                  performance of this Agreement.

7.6      In addition to any other indemnities provided for herein, Newco shall
         indemnify and hold harmless Photogen and its Affiliates and their
         respective employees, agents, officers and directors from and against
         any claims, losses, liabilities or damages (including reasonable
         attorney's fees and expenses) incurred or sustained by Photogen arising
         out of or in connection with any:

         7.6.1    breach of any representation, covenant, warranty or
                  obligation by Newco hereunder; or

         7.6.2    act or omission on the part of Newco or any of its agents or
                  employees in the performance of this Agreement.

7.7      The Party seeking an indemnity shall:

         7.7.1    fully and promptly notify the other Party of any claim or
                  proceeding, or threatened claim or proceeding;

         7.7.2    permit the indemnifying Party to take full care and control
                  of such claim or proceeding;

         7.7.3    co-operate in the investigation and defence of such claim
                  or proceeding;

         7.7.4    not compromise or otherwise settle any such claim or
                  proceeding without the prior written consent of the other
                  Party, which consent shall not be unreasonably

<PAGE>

                  withheld conditioned or delayed; and

         7.7.5    take all reasonable steps to mitigate any loss or liability in
                  respect of any such claim or proceeding.


7.8      EXCEPT AS SET FORTH IN THIS CLAUSE 7, PHOTOGEN IS GRANTING THE LICENSE
         HEREUNDER ON AN "AS IS" BASIS WITHOUT REPRESENTATION OR WARRANTY
         WHETHER EXPRESS OR IMPLIED INCLUDING WARRANTIES OF MERCHANTABILITY OR
         FITNESS FOR A PARTICULAR PURPOSE, OR INFRINGEMENT OF THIRD PARTY
         RIGHTS, AND ALL SUCH WARRANTIES ARE EXPRESSLY DISCLAIMED.

7.9      EXCEPT AS SET FORTH IN CLAUSE 7.4, NOTWITHSTANDING ANYTHING TO THE
         CONTRARY IN THIS AGREEMENT, PHOTOGEN AND NEWCO SHALL NOT BE LIABLE TO
         THE OTHER BY REASON OF ANY REPRESENTATION OR WARRANTY, CONDITION OR
         OTHER TERM OR ANY DUTY OF COMMON LAW, OR UNDER THE EXPRESS TERMS OF
         THIS AGREEMENT, FOR ANY CONSEQUENTIAL, SPECIAL OR INCIDENTAL OR
         PUNITIVE LOSS OR DAMAGE (WHETHER FOR LOSS OF PROFITS OR OTHERWISE) AND
         WHETHER OCCASIONED BY THE NEGLIGENCE OF THE RESPECTIVE PARTIES, THEIR
         EMPLOYEES OR AGENTS OR OTHERWISE.

7.10     On the Effective Date, Newco shall open a special purpose account (the
         "SPECIAL PURPOSE ACCOUNT") with Bank of Bermuda and Photogen shall
         lodge $100,000 to the Special Purpose Account which will be held by
         Newco and applied by Newco to discharge the financial obligations of
         Photogen to Alliance set forth in the Alliance Agreement, subject to
         the following conditions:

         7.10.1   each payment shall be made by Newco to Alliance from the
                  Special Purpose Account upon a determination by the Management
                  Committee that the relevant payment is due and owing to
                  Alliance in accordance with the Alliance Agreement;

         7.10.2   each payment shall be made by Newco to Alliance within the
                  payment period specified for the relevant payment in the
                  Alliance Agreement;

         7.10.3   in the event of a dispute within the Management Committee as
                  to whether any payment described in this Clause 7.10 should be
                  made to Alliance in accordance with the Alliance Agreement,
                  the representatives of Elan and Photogen on the Management
                  Committee will use best efforts to resolve such dispute
                  swiftly PROVIDED THAT in the event that any such dispute is
                  not settled within the Management Committee within 5 days,
                  Elan shall have absolute discretion and full signing authority
                  to forthwith make the relevant payment from the Special
                  Purpose Account to Alliance;

<PAGE>

         7.10.4   all interest which is paid by Bank of Bermuda to Newco on the
                  Special Purpose Account shall promptly be paid by Newco to
                  Photogen.

7.11     On the Effective Date, Photogen will deliver to Newco a fully executed
         irrevocable Letter of Direction to its transfer agent, Harris Trust and
         Savings Bank, to issue and deliver that number of shares of common
         stock of Photogen in the name of Alliance if and to the extent that the
         formula set forth in Section 9(b) of the Alliance Agreement (a copy of
         which will be attached to the Letter of Direction) requires the
         issuance of such contingent shares.

         The Letter of Direction shall be delivered by Newco to Harris Trust and
         Savings Bank hereunder upon a determination by the Management Committee
         that Photogen is obliged to deliver the shares of common stock of
         Photogen to Alliance in accordance with the formula set forth in
         Section 9(b) of the Alliance Agreement.

         In the event of a dispute within the Management Committee as to whether
         the Letter of Direction should be delivered by Newco to Harris Trust
         and Savings Bank hereunder, the representatives of Elan and Photogen on
         the Management Committee will use best efforts to resolve such dispute
         swiftly PROVIDED THAT in the event that any such dispute is not settled
         within the Management Committee within 5 days, Elan shall have absolute
         discretion to cause Newco to deliver the Letter of Direction to Harris
         Trust and Savings Bank for the purposes contemplated herein.

         If the Management Committee determines that the formula set forth in
         Section 9(b) of the Alliance Agreement does not call for the issuance
         of any contingent shares to Alliance, Newco shall promptly return the
         Letter of Direction to Photogen.

8.       TERM AND TERMINATION

8.1      The term of this Agreement shall commence as of the Effective Date and
         shall, subject to the rights of termination outlined in this Clause 8,
         expire on a Product-by-Product basis and on a country-by-country basis
         on the last to occur of:

         8.1.1    [****] starting from the date of the launch of the Product in
                  the country concerned; or

         8.1.2    the date of expiration of the last to expire of the patents
                  included in the Elan Patents and the Elan Improvements and/or
                  the Photogen Patents and the Photogen Improvements

("THE TERM")

<PAGE>

8.2      If either Party commits a Relevant Event, the other Party shall have,
         in addition to all other legal and equitable rights and remedies
         hereunder, the right to terminate this

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[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         Agreement upon 30 days' prior written notice to the defaulting Party.

8.3      For the purpose of this Clause 8, a "RELEVANT EVENT" is committed or
         suffered by a Party if:

         8.3.1    it commits a material breach of its obligations under
                  this Agreement and fails to remedy it within 60 days of being
                  specifically required in writing to do so by the other Party;
                  provided, that if the breaching Party has proposed a course of
                  action to rectify the breach and is acting in good faith to
                  rectify same but has not cured the breach by the 60th day,
                  such period shall be extended by such period as is reasonably
                  necessary to permit the breach to be rectified;

         8.3.2    a distress, execution, sequestration or other process is
                  levied or enforced upon or sued out against a material part of
                  its property which is not discharged or challenged within 30
                  days;

         8.3.3    it is unable to pay its debts in the normal course
                  of business;

         8.3.4    it ceases wholly or substantially to carry on its
                  business, otherwise than for the purpose of a reconstruction
                  or amalgamation, without the prior written consent of the
                  other Party (such consent not to be unreasonably withheld);

         8.3.5    the appointment of a liquidator, receiver, administrator,
                  examiner, trustee or similar officer of such Party or over all
                  or substantially all of its assets under the law of any
                  applicable jurisdiction, including without limitation, the
                  United States of America, Bermuda or Ireland;

         8.3.6    an application or petition for bankruptcy, corporate
                  re-organisation, composition, administration, examination,
                  arrangement or any other procedure similar to any of the
                  foregoing under the law of any applicable jurisdiction,
                  including without limitation, the United States of America,
                  Bermuda or Ireland, is filed, and is not discharged within 60
                  days, or a Party applies for or consents to the appointment of
                  a receiver, administrator, examiner or similar officer of it
                  or of all or a material part of its assets, rights or revenues
                  or the assets and/or the business of a Party are for any
                  reason seized, confiscated or condemned.

8.4      Upon expiration or termination of the Agreement:

         8.4.1.   any sums that were due from Newco to Photogen on Net
                  Sales in the Territory or in such particular country or
                  countries in the Territory (as the case may be) prior to the
                  expiration or termination of this Agreement as set forth
                  herein shall be paid in full within 60 days after the
                  expiration or termination of this Agreement for the Territory
                  or for such particular country or countries in the Territory
                  (as the case may be);

<PAGE>

         8.4.2    any provisions that expressly survive termination or
                  expiration of this Agreement, including without limitation
                  this Clause 8, shall remain in full force and effect;

         8.4.3    all representations, warranties and indemnities shall
                  insofar as are appropriate remain in full force and effect;

         8.4.4    the rights of inspection and audit set out in Clause 6
                  shall continue in force for a period of one year; and

         8.4.5    all rights and licenses granted pursuant to this Agreement
                  and to the Photogen Intellectual Property pursuant to the
                  JDOA (including the rights of Newco pursuant to Clause
                  11 of the JDOA) shall cease for the Territory or for such
                  particular country or countries in the Territory (as the case
                  may be) and shall revert to or be transferred to Photogen, and
                  Newco shall not thereafter use in the Territory or in such
                  particular country or countries in the Territory (as the case
                  may be) any rights covered by this Agreement;

         8.4.6    subject to Clause 8.4.7 and to such license, if any, granted
                  by Newco to Photogen pursuant to the provisions of Clause 12
                  of the JDOA, all rights to Newco Intellectual Property shall
                  be transferred to and jointly owned by Photogen and Elan and
                  may be exploited by both Elan and Photogen separately
                  pursuant to a perpetual [****], world-wide fully paid
                  license granted to each of Elan and Photogen with the
                  right to sublicense;

         8.4.7    the rights of permitted third party sub-licensees in and to
                  the Photogen Intellectual Property shall survive the
                  termination of the license and sublicense agreements
                  granting said intellectual property rights to Newco; and
                  Newco, Elan and Photogen shall in good faith agree upon
                  the form most advantageous to Elan and Photogen in which
                  the rights of Newco under any such licenses and sublicenses
                  are to be held (which form may include continuation of
                  Newco solely as the holder of such licenses or assignment
                  of such rights to a third party or parties, including an
                  assignment to both Elan and Photogen).

                  Any sublicense agreement between Newco and such permitted
                  sublicensee shall permit an assignment of rights by Newco and
                  shall contain appropriate confidentiality provisions.

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         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

9        CONFIDENTIAL INFORMATION

9.1      The Parties agree that it will be necessary, from time to time, to
         disclose to each other confidential and proprietary information,
         including without limitation, inventions, works of authorship, trade
         secrets, specifications, designs, data, know-how and other proprietary
         information relating to the Field, the Products, processes, services
         and business of the disclosing Party.

         The foregoing shall be referred to collectively as "CONFIDENTIAL
         INFORMATION".

9.2      Any Confidential Information disclosed by one Party to another Party
         shall be used by the receiving Party exclusively for the purposes of
         fulfilling the receiving Party's obligations under this Agreement and
         the JDOA and for no other purpose.

9.3      Each Party shall disclose Confidential Information of the other Party
         only to those employees, representatives and agents requiring knowledge
         thereof in connection with fulfilling the Party's obligations under
         this Agreement. Each Party further agrees to inform all such employees,
         representatives and agents of the terms and provisions of this
         Agreement and their duties hereunder and to obtain their agreement
         hereto as a condition of receiving Confidential Information. Each Party
         shall exercise the same standard of care as it would itself exercise in
         relation to its own confidential information (but in no event less than
         a reasonable standard of care) to protect and preserve the proprietary
         and confidential nature of the Confidential Information disclosed to it
         by the other Party. Each Party shall, upon request of the other Party,
         return all documents and any copies thereof containing Confidential
         Information belonging to, or disclosed by, such other Party.

9.4      Any breach of this Clause 9 by any person informed by one of the
         Parties is considered a breach by the Party itself.

9.5      Confidential Information shall not be deemed to include:

         9.5.1    information that is in the public domain;

         9.5.2    information which is made public through no breach of this
                  Agreement;

         9.5.3    information which is independently developed by a Party as
                  evidenced by such Party's records;

         9.5.4    information that becomes available to a Party on a
                  non-confidential basis, whether directly or indirectly, from a
                  source other than a Party, which source did not acquire this
                  information on a confidential basis; or

         9.5.5    information which the receiving Party is required to disclose
                  pursuant to:

<PAGE>

                  (i)      a valid order of a court or other governmental
                           body; or

                  (ii)     any other requirement of law;

                  provided that if the receiving Party becomes legally required
                  to disclose any Confidential Information, the receiving Party
                  shall give the disclosing Party prompt notice of such fact so
                  that the disclosing Party may obtain a protective order or
                  other appropriate remedy concerning any such disclosure. The
                  receiving Party shall fully co-operate with the disclosing
                  Party in connection with the disclosing Party's efforts to
                  obtain any such order or other remedy. If any such order or
                  other remedy does not fully preclude disclosure, the receiving
                  Party shall make such disclosure only to the extent that such
                  disclosure is legally required.

9.6      The provisions relating to confidentiality in this Clause 9 shall
         remain in effect during the term of this Agreement, and for a period of
         [****] following the expiration or earlier termination of this
         Agreement.

9.7      The Parties agree that the obligations of this Clause 9 are necessary
         and reasonable in order to protect the Parties' respective businesses,
         and each Party agrees that monetary damages would be inadequate to
         compensate a Party for any breach by the other Party of its covenants
         and agreements set forth herein.

         Accordingly, the Parties agree that any such violation or threatened
         violation shall cause irreparable injury to a Party and that, in
         addition to any other remedies that may be available, in law and equity
         or otherwise, each Party shall be entitled to obtain injunctive relief
         against the threatened breach of the provisions of this Clause 9, or a
         continuation of any such breach by the other Party, specific
         performance and other equitable relief to redress such breach together
         with its damages and reasonable counsel fees and expenses to enforce
         its rights hereunder, without the necessity of proving actual or
         express damages.

10       GOVERNING LAW AND ARBITRATION

10.1     This Agreement shall be governed by and construed in accordance with
         the laws of the State of New York.

10.2     The Parties will attempt in good faith to resolve any dispute
         arising out of or relating to this Agreement promptly by negotiation
         between executives of the Parties. In the event that such
         negotiations do not result in a mutually acceptable resolution, the
         Parties agree to consider other dispute resolution mechanisms
         including mediation.

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         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

         In the event that the Parties fail to agree on a mutually acceptable
         dispute resolution mechanism within 180 days of written notice of a
         dispute by one Party to the other Party, any such dispute shall be
         finally settled by arbitration pursuant to Clause 10.3.

10.3     Save any dispute under Clause 6.2 which will be resolved in accordance
         with the provisions of Clause 6.2, any dispute under this Agreement
         which is not settled by mutual consent under Clause 10.2 shall be
         finally settled by binding arbitration, conducted in accordance with
         the Commercial Arbitration Rules of the American Arbitration
         Association by one arbitrator appointed in accordance with said rules.
         Such arbitrator shall be reasonably satisfactory to each of the
         Parties; provided, that if the Parties are unable to agree upon the
         identity of such arbitrator within 15 days of demand by either Party,
         then either Party shall have the right to petition a presiding justice
         of the Supreme Court of New York, New York County, to appoint an
         arbitrator.

         The arbitration shall be held in New York, New York.

         The arbitrator shall determine what discovery will be permitted,
         consistent with the goal of limiting the cost and time which the
         Parties must expend for discovery; provided the arbitrator shall permit
         such discovery as he deems necessary to permit an equitable resolution
         of the dispute.

         Any written evidence originally in a language other than English shall
         be submitted in English translation accompanied by the original or a
         true copy thereof.

         The costs of the arbitration, including administrative and arbitrator's
         fee, shall be shared equally by the Parties and each Party shall bear
         its own costs and attorneys' and witness' fees incurred in connection
         with the arbitration.

         In rendering judgement, the arbitrator shall be instructed by the
         Parties that he shall be permitted to select solely from between the
         proposals for resolution of the relevant issue presented by each Party,
         and not any other proposal.

         A disputed performance or suspended performances pending the resolution
         of the arbitration must be completed within 30 days following the final
         decision of the arbitrator or such other reasonable period as the
         arbitrator determines in a written order.

         The Parties will co-operate and use reasonable efforts to ensure that
         any arbitration any arbitration hereunder shall be completed swiftly
         and in any event within one year from the filing of notice of a request
         for such arbitration.

         The arbitration proceedings and the decision shall not be made public
         without the joint consent of the Parties and each Party shall maintain
         the confidentiality of such proceedings and decision unless otherwise
         permitted by the other Party.

<PAGE>

         The Parties agree that the decision shall be the sole, exclusive and
         binding remedy between them regarding any and all disputes,
         controversies, claims and counterclaims presented to the arbitrator.
         Application may be made to any court having jurisdiction over the Party
         (or its assets) against whom the decision is rendered for a judicial
         recognition of the decision and an order of enforcement.


11       IMPOSSIBILITY OF PERFORMANCE - FORCE MAJEURE

         Neither Photogen nor Newco shall be liable for delay in the performance
         of any of its obligations hereunder if such delay results from causes
         beyond its reasonable control, including, without limitation, acts of
         God, fires, strikes, acts of war, intervention of a government
         authority, but any such delay or failure shall be remedied by such
         Party as soon as practicable.

12       ASSIGNMENT

         This Agreement may not be assigned by either Party without the prior
         written consent of the other, save that either Party may assign this
         Agreement to its Affiliates or subsidiaries without such prior written
         consent provided that such assignment does not have any adverse tax
         consequences on the other Party and that the assignee shall be
         obligated to the other Party for all of the assignor Party's
         obligations hereunder which assignee shall be capable of fulfilling
         such obligations.

13       NOTICES

13.1     Any notice to be given under this Agreement shall be sent in writing in
         English by registered airmail or telefaxed to the following addresses:

         If to Newco at:

         Clarendon House,
         2 Church Street,
         Hamilton,
         Bermuda,
         Attention: Secretary
         Telephone: 441 292 9169
         Fax:       441 292 2224

         with a copy to Elan at:

         Elan Corporation, plc
         Lincoln House,

<PAGE>

         Lincoln Place,
         Dublin 2,
         Ireland.

         Attention: Vice President, General Counsel,
         Elan Pharmaceutical Technologies,
         a division of Elan Corporation, plc
         Telephone:  + 353 1 709 4000
         Telefax:    + 353 1 709 4124

         If to Photogen at:
         7327 Oak Ridge,
         Knoxville,
         TN. 3793
         USA.

         Attn: Chief Executive Officer
         Telephone  001 423 769 4011
         Fax:       001 423 769 4013

         with a copy to:

         Grippo & Elden
         Suite 3600
         227 West Monroe
         Chicago
         Illinois 60606
         USA

         Attention:  Theodore W Grippo
         Telephone   001 312 704 7720
         Fax:        001 312 558 1195

         If to Elan at:

         Elan Corporation, plc
         Lincoln House,
         Lincoln Place,
         Dublin 2,
         Ireland.

         Attention: Vice President, General Counsel,
         Elan Pharmaceutical Technologies,
         a division of Elan Corporation, plc
         Telephone:  + 353 1 709 4000

<PAGE>

         Telefax:    + 353 1 709 4124

         or to such other address(es) and telefax numbers as may from time to
         time be notified by either Party to the other hereunder.

13.2     Any notice sent by mail shall be deemed to have been delivered within
         seven 7 working days after dispatch and any notice sent by telex or
         telefax shall be deemed to have been delivered within twenty 24 hours
         of the time of the dispatch. Notice of change of address shall be
         effective upon receipt.

14       MISCELLANEOUS

14.1     WAIVER:

         No waiver of any right under this Agreement shall be deemed effective
         unless contained in a written document signed by the Party charged with
         such waiver, and no waiver of any breach or failure to perform shall be
         deemed to be a waiver of any other breach or failure to perform or of
         any other right arising under this Agreement.

14.2     SEVERABILITY:

         If any provision in this Agreement is agreed by the Parties to be, or
         is deemed to be, or becomes invalid, illegal, void or unenforceable
         under any law that is applicable hereto:

         14.2.1   such provision will be deemed amended to conform to applicable
                  laws so as to be valid and enforceable; or

         14.2.2   if it cannot be so amended without materially altering the
                  intention of the Parties, it will be deleted, with effect from
                  the date of such agreement or such earlier date as the Parties
                  may agree, and the validity, legality and enforceability of
                  the remaining provisions of this Agreement shall not be
                  impaired or affected in any way.

14.3     FURTHER ASSURANCES:

         At the request of any of the Parties, the other Party or Parties shall
         (and shall use reasonable efforts to procure that any other necessary
         parties shall) execute and perform all such documents, acts and things
         as may reasonably be required subsequent to the signing of this
         Agreement for assuring to or vesting in the requesting Party the full
         benefit of the terms hereof.

14.4     SUCCESSORS:

<PAGE>

         This Agreement shall be binding upon and enure to the benefit of the
         Parties hereto, their successors and permitted assigns.

14.5     NO EFFECT ON OTHER AGREEMENTS/CONFLICT:

         No provision of this Agreement shall be construed so as to negate,
         modify or affect in any way the provisions of any other agreement
         between the Parties unless specifically referred to, and solely to the
         extent provided herein.

         In the event of a conflict between the provisions of this Agreement and
         the provisions of the JDOA, the terms of the JDOA shall prevail unless
         this Agreement specifically provides otherwise.

14.6     AMENDMENTS:

         No amendment, modification or addition hereto shall be effective or
         binding on any Party unless set forth in writing after the Effective
         Date and executed by a duly authorised representative of each Party.

14.7     COUNTERPARTS:

         This Agreement may be executed in any number of counterparts, each of
         which when so executed shall be deemed to be an original and all of
         which when taken together shall constitute this Agreement.

14.8     GOOD FAITH:

         Each Party undertakes to do all things reasonably within its power
         which are necessary or desirable to give effect to the spirit and
         intent of this Agreement.

14.9     NO RELIANCE:

         Each Party hereby acknowledges that in entering into this Agreement it
         has not relied on any representation or warranty save as expressly set
         out herein or in any document referred to herein.

14.10    RELATIONSHIP OF THE PARTIES:

         Nothing contained in this Agreement is intended or is to be construed
         to constitute Photogen and Newco as partners, or Photogen as an
         employee of Newco, or Newco as an employee of Photogen.

         Neither Party hereto shall have any express or implied right or
         authority to assume or create any obligations on behalf of or in the
         name of the other Party or to bind the other

<PAGE>

         Party to any contract, agreement or undertaking with any third party.


                                SCHEDULE I
                                ----------

                PHOTOGEN PATAENTS AND PHOTOGEN KNOW-HOW

                            PHOTOGEN PATENTS
                            ----------------

[****]


                            PHOTOGEN KNOW-HOW
                            -----------------

[****]


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

[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

                                   SCHEDULE 2

                          GENNYC INTELLECTUAL PROPERTY
                                     [****]


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

[****]   REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST
         FOR CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE
         SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

<PAGE>

IN WITNESS WHEREOF the Parties hereto have executed this Agreement.

SIGNED BY                              /s/ John Smolik
for and on behalf of
PHOTOGEN TECHNOLOGIES, INC


SIGNED BY                              /s/ John Smolik
For and on behalf of
PHOTOGEN NEWCO LIMITED


AGREED TO AND ACCEPTED BY              /s/ Kevin Insley
ELAN PHARMA INTERNATIONAL LIMITED