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                                                                Exhibit 10.1


                         COMMON STOCK PURCHASE AGREEMENT

                                  BY AND AMONG

                          PHOTOGEN TECHNOLOGIES, INC.,

                                       AND

                                    MI3 L.P.,

                       OXFORD BIOSCIENCE PARTNERS IV L.P.,

                                MRNA FUND II L.P.

                     NEW ENGLAND PARTNERS CAPITAL, L.P., AND

                                  TANNEBAUM LLC

                           DATED AS OF AUGUST 2, 2002

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                                TABLE OF CONTENTS

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<S>                                                                                                              <C>
1.   Purchase and Sale of Common Stock............................................................................1
   1.1.   Offering................................................................................................1
   1.2.   Purchase Price..........................................................................................2
   1.3.   Proceeds................................................................................................2
2.   The Closing..................................................................................................3
3.   Representations of the Company...............................................................................3
   3.1.   Organization; Amended Articles..........................................................................3
   3.2.   Corporate Power.........................................................................................3
   3.3.   Authorization...........................................................................................4
   3.4.   Capitalization..........................................................................................4
   3.5.   Subsidiaries............................................................................................5
   3.6.   SEC Filings; Business...................................................................................5
   3.7.   No Material Adverse Change..............................................................................6
   3.8.   Financial Statements....................................................................................6
   3.9.   Contracts and Commitments...............................................................................7
   3.10.     Proprietary Rights, Employee Restrictions............................................................7
   3.11.     Litigation; Compliance with Law......................................................................8
   3.12.     Leasehold Interests..................................................................................9
   3.13.     Insurance............................................................................................9
   3.14.     Loans and Advances...................................................................................9
   3.15.     Assumptions, Guaranties, Etc. of Indebtedness of Other Persons.......................................9
   3.16.     Governmental Approvals...............................................................................9
   3.17.     Tax Matters.........................................................................................10
   3.18.     Title to Properties.................................................................................10
   3.19.     No Labor Disputes...................................................................................10
   3.20.     Environmental Matters...............................................................................10
   3.21.     Compliance with Nasdaq Continued Listing Requirements...............................................10
   3.22.     Brokers.............................................................................................11
   3.23.     No Directed Selling Efforts or General Solicitation.................................................11
   3.24.     No Integrated Offering..............................................................................11
   3.25.     Transactions With Affiliates........................................................................11
   3.26.     Questionable Payments...............................................................................11
   3.27.     Information Supplied to Purchasers..................................................................12
4.   Representations of the Purchasers...........................................................................12
   4.1.   Validity...............................................................................................12
   4.2.   Accredited Investor....................................................................................12
   4.3.   Investment.............................................................................................12
   4.4.   Investment Experience..................................................................................12
   4.5.   Restricted Securities..................................................................................12
   4.6.   Access to Management...................................................................................12
   4.7.   No General Solicitation................................................................................13
5.   Pre-Closing Covenants; Conditions to the Obligations of the Purchasers......................................13
   5.1.   Pre-Closing Covenants..................................................................................13
   5.1.1.    Exclusivity.........................................................................................13
   5.1.2.    Break up Fee........................................................................................13
   5.1.3.    Mi3 Termination.....................................................................................13
   5.1.4.    Dealings with Affiliates............................................................................13
   5.1.5.    Distributions.......................................................................................13
   5.1.6.    Extraordinary Corporate Transactions................................................................14
   5.1.7.    Option Pool.........................................................................................15
   5.2.   Conditions to the Obligations of the Purchasers........................................................15
   5.2.1.    Accuracy of Representations and Warranties..........................................................15
</Table>

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<Table>
<S>                                                                                                              <C>
   5.2.2.    Consents............................................................................................15
   5.2.3.    Preferred Stock.....................................................................................15
   5.2.4.    Voting, Drag-Along and Right of First Refusal Agreement.............................................15
   5.2.5.    Certificates and Documents..........................................................................16
   5.2.6.    Opinion.............................................................................................16
   5.2.7.    Non-Competition Agreements..........................................................................16
   5.2.8.    Election of Directors...............................................................................16
   5.2.9.    Expenses............................................................................................16
   5.2.10.   Split-off...........................................................................................16
   5.2.11.   SEC approvals; Effective Registration; Blue Sky.....................................................17
   5.2.12.   Conversion of Tannebaum Credit Line.................................................................17
   5.2.13.   Reverse Stock Split.................................................................................17
   5.2.14.   Syndicate...........................................................................................17
   5.2.15.   Fairness Opinion....................................................................................17
   5.2.16.   Conversion of Elan Debt.............................................................................17
   5.2.17.   AmeriCal Securities.................................................................................17
   5.2.18.   Registration Rights.................................................................................17
6.   Conditions to the Obligations of the Company................................................................17
   6.1.   Accuracy of Representations and Warranties.............................................................18
   6.2.   Performance............................................................................................18
7.   Post Closing Covenants......................................................................................18
   7.1.   Affirmative Covenants of the Company...................................................................18
   7.1.1.    Inspection Rights...................................................................................18
   7.1.2.    Meetings of Directors, Committees and Observer Rights...............................................18
   7.1.3.    Reports.............................................................................................19
   7.1.4.    Management Disclosure to the Board..................................................................19
   7.2.   Key Person Insurance; Directors' Liability and Other Insurance.........................................19
   7.3.   No Integration.........................................................................................20
   7.4.   Shareholder Purchase Offering..........................................................................20
   7.5.   Registration of Shares.................................................................................20
   7.6.   Non-Contravention......................................................................................20
   7.7.   Listing of Shares......................................................................................20
8.   General.....................................................................................................21
   8.1.   Successors and Assigns.................................................................................21
   8.2.   Survival of Representations and Warranties.............................................................21
   8.3.   Indemnification........................................................................................21
   8.4.   Conduct of Indemnification Proceedings.................................................................21
   8.5.   Notices................................................................................................22
   8.6.   Entire Agreement.......................................................................................22
   8.7.   Amendments and Waivers.................................................................................22
   8.8.   Counterparts...........................................................................................23
   8.9.   Captions...............................................................................................23
   8.10.     Severability........................................................................................23
   8.11.     Governing Law.......................................................................................23
   8.12.     Exculpation Among Purchasers........................................................................23
</Table>

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                         COMMON STOCK PURCHASE AGREEMENT

     THIS AGREEMENT dated as of August 2, 2002 is entered into by and among
Photogen Technologies, Inc., a Nevada corporation (the "COMPANY"), and Mi3 L.P.,
a Delaware limited partnership ("Mi3"), OXFORD BIOSCIENCE PARTNERS IV L.P., a
Delaware limited partnership, New England Partners Capital, L.P., a Delaware
limited partnership, and Tannebaum LLC, a Delaware limited liability company
(together with Mi3, the "PURCHASERS").

     WHEREAS, the Company and the Purchasers are executing and delivering this
Agreement in reliance upon the exemption from securities registration afforded
by the provisions of Regulation D ("REGULATION D"), as promulgated by the U.S.
Securities and Exchange Commission (the "SEC") under the Securities Act of 1933,
as amended (the "1933 ACT"); and

     WHEREAS, the Purchasers wish to purchase from the Company, and the Company
wishes to sell and issue to the Purchasers, shares of Common Stock of the
Company, $0.001 par value per share (the "COMMON STOCK"), upon the terms and
conditions set forth in this Agreement;

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained in this Agreement, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, intending to be
legally bound by the terms and conditions of this Agreement, the parties hereto
hereby agree as follows.

1.   PURCHASE AND SALE OF COMMON STOCK.

     1.1.   OFFERING. Subject to the terms and conditions of this Agreement, at
the Closing the Company shall sell and issue to each of the Purchasers, and each
of the Purchasers shall severally, and not jointly, purchase from the Company,
the number of shares of Common Stock (the "SHARES") equal to the investment
amount set forth opposite the Purchaser's name on Exhibit I divided by the Per
Share Purchase Price (as defined below). Additional investors mutually
acceptable to Mi3 and the Company may be added to Exhibit I at or prior to the
Closing, and upon execution by such additional investors of a counterpart
signature page to this Agreement, such additional investors shall be deemed a
Purchaser hereunder and shall be subject to and may rely upon the
representations, warranties, terms and conditions contained herein.
Additionally, Purchasers may assign a portion of their subscription hereunder to
additional investors at or prior to the Closing, whereupon Exhibit I will be
adjusted accordingly and upon execution by such additional investors of a
counterpart signature page to this Agreement, such additional investors shall be
deemed a Purchaser hereunder and shall be subject to and may rely upon the
representations, warranties, terms and conditions contained herein.

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     1.2.   PURCHASE PRICE. Immediately prior to the Closing, the per share
purchase price for the Shares (the "PER SHARE PURCHASE PRICE") shall be
determined as follows, payable as set forth in Section 2 of this Agreement:

            $14,000,000 divided by the sum of:

            (a)   the number of shares of issued and outstanding Common Stock
                  less 4,070,000; plus

            (b)   the number of shares of Common Stock reserved and available
                  for issuance pursuant to the Option Plans (as defined below
                  and assuming the increase contemplated herein); plus

            (c)   the number of shares of Common Stock issuable pursuant to all
                  subscriptions, warrants, options, convertible securities and
                  other rights (contingent or otherwise) to purchase or acquire
                  any shares of capital stock of the Company.

The per share purchase price shall be calculated by the Company and subject to
verification and acceptance by the Purchasers.

     1.3.   PROCEEDS. Proceeds from the sale of the Shares and from the
Shareholder Purchase Offering will be used only for the following purposes and
appropriately related administrative costs, in the following order of priority,
subject to changes authorized by a majority of the Directors after the Closing:

          -  all necessary steps to obtain approval by the Food and Drug
             Administration (the "FDA") for the use of PH-50 as a CT contrast
             agent, including the cost of reformulation and toxicity testing in
             the event that the initial Phase 1 trials uncover an adverse effect
             in humans;

          -  all necessary steps to obtain approval by the FDA for the use of
             N-1177 as a lymphography contrast agent;

          -  pre-clinical exploration of the use of PH-50 to identify vulnerable
             plaque; and

          -  acquisition or licensing of compounds to build a product pipeline
             for the Company.

Pending use of the proceeds in accordance with the preceding sentence, the
proceeds will be invested in securities issued or guaranteed by the United
States, national bank repurchase agreements secured by such securities or such
other types of investments as may be approved by a majority of the Directors
after the Closing, but in no event in such a manner that would cause the Company
to be deemed an Investment Company as defined in the Investment Company Act of
1940, as amended.

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2.   THE CLOSING. The closing of the sale and purchase of the Shares pursuant to
this Agreement shall take place at the offices of Epstein Becker & Green, P.C.,
111 Huntington Avenue, Boston, Massachusetts 02199 as soon as practicable upon
approval of the transactions contemplated herein by the stockholders of the
Company, or at such other time, date, and place as are mutually agreeable to the
Company and the Purchasers (the "CLOSING"). The date of the Closing is
hereinafter referred to as the "CLOSING DATE." At the Closing, the Company shall
deliver to each Purchaser a certificate representing the Shares purchased by
such Purchaser of Common Stock registered in the name of such Purchaser. The
purchase price for the Shares shall be paid by wire transfer, certified or
cashier's check or another method acceptable to the Company, including
conversion of outstanding debt. If at the Closing any of the conditions
specified in Section 5 of this Agreement shall not have been fulfilled, each
Purchaser shall, at its election, be relieved of all of its obligations under
this Agreement without thereby waiving any other right it may have by reason of
such failure or such non-fulfillment. If at the Closing any of the conditions
specified in Section 6 of this Agreement shall not have been fulfilled, the
Company shall, at its election, be relieved of all of its obligations under this
Agreement without thereby waiving any other right it may have by reason of such
failure or such non-fulfillment.

3.   REPRESENTATIONS OF THE COMPANY. Except as disclosed in the Disclosure
Schedule attached hereto (which Disclosure Schedule makes explicit reference to
the particular Section containing the representation or warranty as to which
exception is taken), the Company hereby represents and warrants to the
Purchasers as follows:

     3.1.   ORGANIZATION; AMENDED ARTICLES. The Company is a corporation duly
organized, validly existing and in corporate good standing under the laws of the
State of Nevada and is qualified to do business as a foreign corporation in each
jurisdiction in which such qualification is required, except where the failure
to be so qualified would not have, either individually or in the aggregate, a
material adverse effect on the business, operations, financial condition,
assets, prospects, liabilities or contractual rights of the Company, whether
individually or taken as a whole (a "MATERIAL ADVERSE EFFECT"). The Company has,
or prior to the Closing will have, duly authorized the sale and issuance,
pursuant to the terms of this Agreement an adequate number shares of its Common
Stock authorized and available for purchase hereunder, having the rights,
restrictions, privileges and preferences set forth in the Amended and Restated
Certificate of Incorporation in the form set forth in Exhibit A hereto (the
"AMENDED ARTICLES"). The Company has, or prior to the Closing will have, filed
the Amended Articles with the Secretary of State of the State of Nevada.

     3.2.   CORPORATE POWER. The Company has all required corporate power and
authority to own its property, to carry on its business as presently conducted
or contemplated, to enter into and perform this Agreement, the Voting,
Drag-Along and Right of First Refusal Agreement by and among the Company, the
Purchasers and the other parties thereto, in the form attached as Exhibit B (the
"VOTING, DRAG-ALONG AND RIGHT OF FIRST REFUSAL AGREEMENT") and the other
agreements, documents and instruments contemplated hereby (collectively with
this Agreement, the "FINANCING DOCUMENTS"), and generally to carry out the
transactions contemplated hereby. The copies of the Certificate of Incorporation
and Bylaws of the Company, as amended to date,

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which have been furnished by the Company to counsel for the Purchasers, are
correct and complete at the date hereof. The Company is not in violation of any
term of its Certificate of Incorporation or Bylaws, each as amended, or in
violation of any term of any agreement, instrument, judgment, decree, order,
statute, rule or government regulation applicable to the Company or to which the
Company is a party, where any violation, noncompliance or default would result
in a Material Adverse Effect.

     3.3.   AUTHORIZATION. The Financing Documents are valid and binding
obligations of the Company, enforceable in accordance with their terms. The
execution, delivery and performance of the Financing Documents have been duly
authorized by all necessary corporate or other action of the Company. The
issuance, sale and delivery of the Shares in accordance with this Agreement have
been, or will be prior to the Closing, duly authorized by all necessary
corporate action on the part of the Company. The Shares when so issued, sold and
delivered against payment therefor in accordance with the provisions of this
Agreement will be duly and validly issued, fully paid and non-assessable. No
consent, approval or authorization of, or designation, declaration or filing
with, any governmental authority or any other person or entity is required of
the Company in connection with the execution and delivery of the Financing
Documents, or the issuance, sale and delivery of the Shares in accordance with
the terms of this Agreement, or the consummation of any other transaction
contemplated hereby or by the other Financing Documents.

     3.4.   CAPITALIZATION. The authorized capital stock of the Company consists
of 14,547.52 shares of Series A Preferred Stock, $0.001 par value per share, of
which 14,547.52 shares are issued and outstanding, 402,000 shares of Series B
Preferred Stock, $0.01 par value per share, of which 391,024.40 shares are
issued and outstanding, and 150,000,000 shares of Common Stock, $0.001 par value
per share, of which 38,842,298 shares are issued and outstanding]. All of the
issued and outstanding shares of the Company's capital stock have been duly
authorized and validly issued and are fully paid and non-assessable. The Company
will have reserved, immediately prior to the Closing, a total of 24,270,500
shares of its Common Stock for issuance pursuant to the Option Plans. Except as
contemplated by this Agreement, the other Financing Documents, the Amended
Articles, or as otherwise disclosed in the Disclosure Schedule (i) no
subscription, warrant, option, convertible security or other right (contingent
or otherwise) to purchase or acquire any shares of capital stock of the Company
is authorized or outstanding, (ii) there is not any commitment or offer of the
Company to issue any subscription, warrant, option, convertible security or
other such right or to issue or distribute to holders of any shares of its
capital stock any evidences of indebtedness or assets of the Company, (iii) the
Company has no obligation (contingent or otherwise) to purchase, redeem or
otherwise acquire any shares of its capital stock or any interest therein or to
pay any dividend or make any other distribution in respect thereof, and (iv)
there are no restrictions on the transfer of the Company's capital stock other
than those arising from securities laws or contemplated by this Agreement and
the other Financing Documents. Except for the Voting, Drag-Along and Right of
First Refusal Agreement or as otherwise disclosed in the Disclosure Schedule,
there are no voting trusts or agreements, stockholders' agreements, pledge
agreements, buy-sell agreements, rights of first refusal, preemptive rights or
proxies relating to any securities of the Company, whether or not the Company is
a party thereto. All of the outstanding securities of the Company were issued in
compliance with all applicable federal and state securities laws. Set forth in
the Disclosure

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Schedule is a capitalization table for the Company showing (i) the
capitalization of the Company on a fully diluted basis immediately prior to the
issuance of the Shares; and (ii) the capitalization of the Company on a fully
diluted basis giving effect to the issuance of the Shares. For the purposes of
this Agreement, the term "on a fully diluted basis" means that for purposes of
calculating the percentage interest of the Company's capital stock represented
by a specified number of shares, there shall be deemed outstanding (i) all
shares of Common Stock, $0.001 per value per share, of the Company currently
outstanding; (ii) all shares of Common Stock issuable pursuant to the exercise
of options granted and capable of being granted under the Company's 1998 Long
Term Incentive Compensation Plan, 2000 Long Term Incentive Compensation Plan,
and Senior Executive Long Term Incentive Compensation Plan, copies of which have
been supplied to Purchasers' counsel (the "OPTION PLANS"); and (iii) all shares
of Common Stock issuable pursuant to other existing options, warrants,
convertible debt securities and other instruments and agreements whatsoever.

     3.5.   SUBSIDIARIES. Except as set forth in the Disclosure Schedule, the
Company does not control, directly or indirectly, any other entity (a
"SUBSIDIARY") and does not own of record or beneficially, directly or
indirectly, any shares of capital stock or securities convertible into capital
stock of any other corporation, or any participating interest in any
partnership, joint venture or other non-corporate business enterprise.

     3.6.   SEC FILINGS; BUSINESS. The Company has provided the Purchasers with
copies of the Company's most recent Annual Report on Form 10-K for the fiscal
year ended December 31, 2001 (the "2001 10-K"), and all other reports filed by
the Company pursuant to the Securities Exchange Act of 1934, as amended (the
"1934 ACT") since the filing of the 2001 10-K and prior to the date hereof
(collectively, the "SEC FILINGS"). The SEC Filings are the only filings required
of the Company pursuant to the 1934 Act for such period. At the time of filing
thereof, the SEC Filings complied as to form in all material respects with the
requirements of the 1934 Act and did not contain any untrue statement of a
material fact or omit to state any material fact necessary in order to make the
statements made therein, in the light of the circumstances under which they were
made, not misleading. During the preceding two years, each registration
statement and any amendment thereto filed by the Company pursuant to the 1933
Act and the rules and regulations thereunder, as of the date such statement or
amendment became effective, complied as to form in all material respects with
the 1933 Act and did not contain any untrue statement of a material fact or omit
to state any material fact required to be stated therein or necessary in order
to make the statements made therein, in light of the circumstances under which
they were made, not misleading; and each prospectus filed pursuant to Rule
424(b) under the 1933 Act, as of its issue date and as of the closing of any
sale of securities pursuant thereto did not contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary in order to make the statements made therein, in the light of the
circumstances under which they were made, not misleading. The Company and its
Subsidiaries are engaged only in the business described in the SEC Filings and
the SEC Filings contain a complete and accurate description in all material
respects of the business of the Company and its Subsidiaries, taken as a whole,
as required to be disclosed.

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     3.7.   NO MATERIAL ADVERSE CHANGE. Since December 31, 2001, except as
identified and described in the SEC Filings or as disclosed in the Disclosure
Schedule, there has not been:

            (a)   any change in the consolidated assets, liabilities, financial
condition or operating results of the Company from that reflected in the
financial statements included in the 2001 10-K, except for changes in the
ordinary course of business which have not and could not reasonably be expected
to have a Material Adverse Effect, individually or in the aggregate;

            (b)   any declaration or payment of any dividend, or any
authorization or payment of any distribution, on any of the capital stock of the
Company, or any redemption or repurchase of any securities of the Company;

            (c)   any material damage, destruction or loss, whether or not
covered by insurance to any assets or properties of the Company;

            (d)   any waiver, not in the ordinary course of business, by the
Company or any Subsidiary of a material right or of a material debt owed to it;

            (e)   any satisfaction or discharge of any lien, claim or
encumbrance or payment of any obligation by the Company or a Subsidiary, except
in the ordinary course of business and which is not material to the assets,
properties, financial condition, operating results or business of the Company
and its Subsidiaries taken as a whole (as such business is presently conducted
and as it is proposed to be conducted);

            (f)   any change or amendment to the Company's Certificate of
Incorporation or Bylaws, or material change to any material contract or
arrangement by which the Company or any Subsidiary is bound or to which any of
their respective assets or properties is subject;

            (g)   any material labor difficulties or labor union organizing
activities with respect to employees of the Company or any Subsidiary;

            (h)   any transaction entered into by the Company or a Subsidiary
other than in the ordinary course of business;

            (i)   any loss of the services of any key employee, or material
change in the composition or duties of the senior management of the Company or
any Subsidiary;

            (j)   any loss or threatened loss of any customer which has had or
could reasonably be expected to have a Material Adverse Effect; or

            (k)   any other event or condition of any character that has had or
could reasonably be expected to have a Material Adverse Effect.

     3.8.   FINANCIAL STATEMENTS. The financial statements included in each SEC
Filing present fairly, in all material respects, the consolidated financial
position of the Company as of

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the dates shown and its consolidated results of operations and cash flows for
the periods shown, and such financial statements have been prepared in
conformity with United States generally accepted accounting principles applied
on a consistent basis (except as may be disclosed therein or in the notes
thereto, and, in the case of quarterly financial statements, as permitted by
Form 10-Q under the 1934 Act). Except as set forth in the financial statements
of the Company included in the SEC Filings filed prior to the date hereof or as
described on the Disclosure Schedule neither the Company nor any of its
Subsidiaries has incurred any liabilities, contingent or otherwise, except those
incurred in the ordinary course of business, consistent (as to amount and
nature) with past practices since the date of such financial statements, none of
which, individually or in the aggregate, have had or could reasonably be
expected to have a Material Adverse Effect.

     3.9.   CONTRACTS AND COMMITMENTS. Except as identified and described in the
SEC Filings or as disclosed in the Disclosure Schedule, the Company (i) is not a
party to any oral or written contract, obligation, instrument, corporate
restriction or commitment which involves a potential obligation or liability in
excess of $5,000 and which is otherwise material and not entered into in the
ordinary course of business, (ii) does not have any oral or written employment
contracts, financing agreements, licenses, distributor or sales representative
agreements, agreements with officers, directors, employees or shareholders of
the Company or persons or organizations related to or affiliated with any such
persons, leases, agreements relating to product development; and (iii) does not
have any pension, profit sharing, retirement or stock option plans other than
the Option Plans and the Company's 401(k) Plan.

     3.10.  PROPRIETARY RIGHTS, EMPLOYEE RESTRICTIONS.

            (a)   The Company has disclosed on the Disclosure Schedule all
copyrights, copyright registrations and copyright applications, trademark
registrations and applications for registration, patents and patent
applications, trademarks, service marks, trade names, trade secrets or other
proprietary rights (collectively, "INTELLECTUAL PROPERTY RIGHTS") used or useful
in the Company's business as presently conducted or currently contemplated to be
conducted and all licenses, assignments and releases of Intellectual Property
Rights of others in material works embodied in the Company's products. All
Intellectual Property Rights held by any employee, officer or consultant have
been assigned to the Company. The Company has exclusive ownership of, or
exclusive license to use, all Intellectual Property Rights identified in the
Disclosure Schedule. The Company has obtained any licenses, releases or
assignments necessary to use all third parties' Intellectual Property Rights in
works embodied in its products. All such licenses, releases and assignments are
specifically identified in the Disclosure Schedule. To the Company's knowledge,
neither the present nor currently contemplated business activities or products
of the Company infringe any Intellectual Property Rights of others. The Company
has not received any notice or other written claim from any person asserting
that any of the Company's present or currently contemplated activities infringe
or may infringe any Intellectual Property Rights of such person. The Company has
the right to use, free and clear of known or asserted claims or rights of
others, all trade secrets, customer lists, hardware designs, programming
processes, software and other information required for or incident to its
products or its business as presently conducted or contemplated to be conducted,
except for claims which

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would not have a Material Adverse Effect. The Company has taken all reasonable
measures to protect and preserve the security, confidentiality and value of its
Intellectual Property Rights, including its trade secrets and other confidential
information. The Company is not aware of any infringement by others of its
copyrights or other Intellectual Proprietary Rights in any of its products,
technology or services, or any violation of the confidentiality of any of its
proprietary information. The activities of the Company's employees on behalf of
the Company do not violate any agreements or arrangements known to the Company
which any such employees have with former employers or any other entity to whom
such employees may have rendered consulting services. For the purposes of this
Section 3.10, Intellectual Property Rights also includes any and all material
licenses, databases, computer programs and other computer software user
interfaces (other than those generally available to the public), know-how, trade
secrets, customer lists, proprietary technology, processes and formulae, source
code, object code, algorithms, architecture, structure, display screens,
layouts, development tools, instructions, templates, marketing materials,
inventions, trade dress, logos and designs and all documentation and media
constituting, describing or relating to the foregoing.

            (b)   All key employees, including all consultants (contract or
otherwise), of or to the Company have executed and delivered to and in favor of
the Company an agreement regarding the protection of confidential and
proprietary information and the assignment to the Company of all Intellectual
Property Rights arising from the services performed for the Company by such
Persons (collectively, the "CONFIDENTIALITY AGREEMENTS") in the form prepared by
counsel to the Company in substantially the form attached as Exhibit C.

     3.11.  LITIGATION; COMPLIANCE WITH LAW. There is no (i) action, suit,
claim, proceeding or investigation pending or, to the best of the Company's
knowledge, threatened against or affecting the Company, at law or in equity, or
before or by any federal, state, municipal or other governmental department,
commission, board, bureau, agency or instrumentality, domestic or foreign, (ii)
arbitration or mediation proceeding relating to the Company, pending or, to the
best of the Company's knowledge, threatened, or (iii) governmental inquiry
pending or, to the best of the Company's knowledge, threatened against or
affecting the Company (including without limitation any inquiry as to the
qualification of the Company to hold or receive any license or permit). The
Company has not received any opinion or memorandum or legal advice from legal
counsel to the effect that it is exposed, from a legal standpoint, to any
liability which may have a Material Adverse Effect. The Disclosure Schedule also
lists any other legal memoranda, letters and other legal documents provided to
the Company with respect to the Company's compliance with any and all applicable
laws, rules and regulations relating to its business, copies of all of which
legal memoranda, letters and other documents having previously been supplied to
the Purchasers. The Company is not in default with respect to any order, writ,
injunction or decree known to or served upon the Company of any court or of any
federal, state, municipal or other governmental department, commission, board,
bureau, agency or instrumentality, domestic or foreign. There is no action or
suit by the Company, and to the best of the Company's knowledge, pending,
threatened or contemplated against others. To the best of the Company's
knowledge, the Company has complied and will continue to comply, in all material
respects, with all laws, rules, regulations and orders applicable to its present
and contemplated business, operations, properties, assets, products and
services. The Company has all necessary permits, licenses and

                                        8
<Page>

other authorizations required to conduct its business as conducted and as
proposed to be conducted, except where the failure to obtain such permits,
licenses or authorization would not have a Material Adverse Effect, and the
Company has been and will continue to be operating its business pursuant to and
in compliance with the terms of all such permits, licenses and other
authorizations, except where the failure to so operate the business would not
have a Material Adverse Effect. The Company has all franchises, permits,
licenses and other rights and privileges necessary to permit it to own its
property and to conduct its business as it is presently conducted or proposed to
be conducted. The Company is not subject to any pending or threatened
investigation, inquiry or proceeding by the SEC, any state securities commission
or any other federal, state, municipal or other governmental department,
commission, board, bureau, agency or instrumentality, domestic or foreign, or
any securities exchange or securities market, with respect to any matter,
including but not limited to the Company's relationship or transactions with
Elan International Services, Ltd. ("ELAN"), Sentigen Ltd. or any of their
successors or affiliates.

     3.12.  LEASEHOLD INTERESTS. Each lease or agreement to which the Company is
a party under which it is a lessee of any property, real or personal, is a valid
and subsisting agreement, duly authorized and entered into, without any default
of the Company thereunder and, to the best of the Company's knowledge, without
any default thereunder of any other party thereto. No event has occurred and is
continuing which, with due notice or lapse of time or both, would constitute a
default or event of default by the Company under any such lease or agreement or,
to the best of the Company's knowledge, by any other party thereto. The
Company's possession of such property has not been disturbed and, to the best of
the Company's knowledge, no claim has been asserted against the Company adverse
to its rights in such leasehold interests.

     3.13.  INSURANCE. The Company and each Subsidiary maintain in full force
and effect insurance coverage that is customary for comparably situated
companies for the business being conducted and properties owned or leased by the
Company and each Subsidiary, and the Company reasonably believes such insurance
coverage to be adequate against all liabilities, claims and risks against which
it is customary for comparably situated companies to insure.

     3.14.  LOANS AND ADVANCES. The Company does not have any outstanding loans
or advances to any person and is not obligated to make any such loans or
advances.

     3.15.  ASSUMPTIONS, GUARANTIES, ETC. OF INDEBTEDNESS OF OTHER PERSONS. The
Company has not assumed, guaranteed, endorsed or otherwise become directly or
contingently liable on any indebtedness of any other person (including, without
limitation, liability by way of agreement, contingent or otherwise, to purchase,
to provide funds for payment, to supply funds to or otherwise invest in the
debtor, or otherwise to assure the creditor against loss), except for guaranties
by endorsement of negotiable instruments for deposit or collection in the
ordinary course of business.

     3.16.  GOVERNMENTAL APPROVALS. Subject to the accuracy of the
representations and warranties of the Purchasers set forth in Section 4, no
registration or filing with, or consent or approval of or other action by, any
federal, state or other governmental agency or instrumentality

                                        9
<Page>

is or will be necessary for the valid execution, delivery and performance by the
Company of any of the Financing Documents, the issuance, sale and delivery of
the Shares other than filings pursuant to federal and state securities laws (all
of which filings have been made by the Company, other than those which are
required to be made after the Closing and which will be duly made on a timely
basis) in connection with the sale of the Shares.

     3.17.  TAX MATTERS. Each of the Company and each Subsidiary has timely
prepared and filed all tax returns required to have been filed by the Company or
such Subsidiary with all appropriate governmental agencies and timely paid all
taxes shown thereon or otherwise owed by it. The charges, accruals and reserves
on the books of the Company in respect of taxes for all fiscal periods are
adequate in all material respects, and there are no material unpaid assessments
against the Company or any Subsidiary nor any basis for the assessment of any
additional taxes, penalties or interest for any fiscal period or audits by any
federal, state or local taxing authority except for any assessment which is not
material to the Company and its Subsidiaries, taken as a whole. All taxes and
other assessments and levies that the Company or any Subsidiary is required to
withhold or to collect for payment have been duly withheld and collected and
paid to the proper governmental entity or third party when due. There are no tax
liens or claims pending or threatened against the Company or any Subsidiary or
any of their respective assets or property. There are no outstanding tax sharing
agreements or other such arrangements between the Company and any Subsidiary or
other corporation or entity.

     3.18.  TITLE TO PROPERTIES. The Company and each Subsidiary has good and
marketable title to all real properties and all other properties and assets
owned by it, in each case free and clear from any and all liens, security
interests, encumbrances and defects, and the Company and each Subsidiary holds
any leased real or personal property under valid and enforceable leases with no
exceptions that would materially interfere with the use made or currently
planned to be made thereof by them.

     3.19.  NO LABOR DISPUTES. No material labor dispute with the employees of
the Company or any Subsidiary exists or is imminent.

     3.20.  ENVIRONMENTAL MATTERS. Neither the Company nor any Subsidiary is in
violation of any statute, rule, regulation, decision or order of any
governmental agency or body or any court, domestic or foreign, relating to the
use, disposal or release of hazardous or toxic substances or relating to the
protection or restoration of the environment or human exposure to hazardous or
toxic substances (collectively, "ENVIRONMENTAL LAWS"), owns or operates any real
property contaminated with any substance that is subject to any Environmental
Laws, is liable for any off-site disposal or contamination pursuant to any
Environmental Laws, and is subject to any claim relating to any Environmental
Laws, which violation, contamination, liability or claim has had or could
reasonably be expected to have a Material Adverse Effect, individually or in the
aggregate; and there is no pending or threatened investigation that might lead
to such a claim.

     3.21.  COMPLIANCE WITH NASDAQ CONTINUED LISTING REQUIREMENTS. The Company
is in compliance with applicable Nasdaq SmallCap Market continued listing
requirements. There are no proceedings pending or threatened against the Company
relating to the continued listing of

                                       10
<Page>

the Company's Common Stock on the Nasdaq SmallCap Market and the Company has not
received any notice of, nor is there any basis for, the delisting of the Common
Stock from the Nasdaq SmallCap Market.

     3.22.  BROKERS. The Company has no contract, arrangement or understanding
with any broker, finder or similar agent with respect to the transactions
contemplated by this Agreement. No person or entity will have, as a result of
the transactions contemplated by this Agreement, any right, interest or claim
against or upon the Company, any Subsidiary or a Purchaser for any commission,
fee or other compensation pursuant to any agreement, arrangement or
understanding entered into by or on behalf of the Company.

     3.23.  NO DIRECTED SELLING EFFORTS OR GENERAL SOLICITATION. Neither the
Company nor any person or entity acting on its behalf has conducted any general
solicitation or general advertising (as those terms are used in Regulation D) in
connection with the offer or sale of any of the Shares.

     3.24.  NO INTEGRATED OFFERING. Neither the Company nor any of its
affiliates, nor any person or entity acting on its or their behalf has, directly
or indirectly, made any offers or sales of any Company security or solicited any
offers to buy any security, under circumstances that would adversely affect
reliance by the Company on Section 4(2) of the 1933 Act for the exemption from
registration for the transactions contemplated hereby or would require
registration of the Shares under the 1933 Act.

     3.25.  TRANSACTIONS WITH AFFILIATES. Except as identified and described in
the SEC Filings, no director, officer, employee or stockholder of the Company,
or member of the family of any such person, or any corporation, partnership,
trust or other entity in which any such person, or any member of the family of
any such person, has a substantial interest or is an officer, director, trustee,
partner or holder of more than 5% of the outstanding capital stock thereof, is a
party to any transaction with the Company, including any contract, agreement or
other arrangement providing for the employment of, furnishing of services by,
rental of real or personal property from or otherwise requiring payments to any
such person or firm, other than employment-at-will arrangements in the ordinary
course of business.

     3.26.  QUESTIONABLE PAYMENTS. Neither the Company nor any of its
Subsidiaries nor any of their respective current or former shareholders,
directors, officers, employees, agents or other persons or entities acting on
behalf of the Company or any Subsidiary, has on behalf of the Company or any
Subsidiary or in connection with their respective businesses: (a) used any
corporate funds for unlawful contributions, gifts, entertainment or other
unlawful expenses relating to political activity; (b) made any direct or
indirect unlawful payments to any governmental officials or employees from
corporate funds; (c) established or maintained any unlawful or unrecorded fund
of corporate monies or other assets; (d) made any false or fictitious entries on
the books and records of the Company or any Subsidiary; or (e) made any unlawful
bribe, rebate, payoff, influence payment, kickback or other unlawful payment of
any nature.

                                       11
<Page>

     3.27.  INFORMATION SUPPLIED TO PURCHASERS. Neither this Agreement, the
Disclosure Schedule and Exhibits attached hereto nor any other Financing
Documents furnished to the Purchasers by or on behalf of the Company contains
any untrue statement of a material fact, and none of this Agreement, the
Disclosure Schedule and Exhibits attached hereto, or such other Financing
Documents omits to state a material fact necessary in order to make the
statements contained herein or therein not misleading. None of the matters
described on the Disclosure Schedules have had, or could reasonably be expected
to have, a Material Adverse Effect, individually or in the aggregate.

4.   REPRESENTATIONS OF THE PURCHASERS. Each of the Purchasers represents and
warrants to the Company as follows:

     4.1.   VALIDITY. Assuming the due execution and delivery by the Company of
this Agreement and the Financing Documents, the Agreement and the Financing
Documents to which the Purchaser is a party constitute legal, valid and binding
obligations of the Purchaser, enforceable against the Purchaser in accordance
with their respective terms.

     4.2.   ACCREDITED INVESTOR. The Purchaser is an "accredited investor" as
such term is defined in Regulation D under the 1933 Act.

     4.3.   INVESTMENT. The Shares to be received by the Purchaser hereunder
will be acquired for the Purchaser's own account, not as nominee or agent, and
not with a view to the resale or distribution of any part thereof in violation
of the 1933 Act, and the Purchaser has no intention of selling, granting any
participation in, or otherwise distributing the same in violation of the 1933
Act. The Purchaser is not a registered broker dealer or an entity engaged in the
business of being a broker dealer.

     4.4.   INVESTMENT EXPERIENCE. The Purchaser acknowledges that it can bear
the economic risk and complete loss of its investment in the Shares and has such
knowledge and experience in financial or business matters that it is capable of
evaluating the merits and risks of the investment contemplated hereby.

     4.5.   RESTRICTED SECURITIES. The Purchaser understands that the Shares are
characterized as "restricted securities" under the U.S. federal securities laws
inasmuch as they are being acquired from the Company in a transaction not
involving a public offering and that under such laws and applicable regulations
such securities may be resold without registration under the 1933 Act only in
certain limited circumstances.

     4.6.   ACCESS TO MANAGEMENT. The Purchaser has had an opportunity to
receive additional information related to the Company requested by it and to ask
questions of and receive answers from the Company regarding the Company, its
business and the terms and conditions of the offering of the Shares. The
Purchaser acknowledges receipt of copies of the SEC Filings. Neither such
inquiries nor any other due diligence investigation conducted by the Purchaser
shall modify, amend or affect the Purchaser's right to rely on the Company's
representations and warranties contained in this Agreement.

                                       12
<Page>

     4.7.   NO GENERAL SOLICITATION. The Purchaser did not learn of the
investment in the Shares as a result of any public advertising or general
solicitation.

5.   PRE-CLOSING COVENANTS; CONDITIONS TO THE OBLIGATIONS OF THE PURCHASERS.

     5.1.   PRE-CLOSING COVENANTS. The parties covenant and agree that they will
perform and observe the following covenants and provisions until the Closing
Date, as applicable.

            5.1.1.  EXCLUSIVITY. The Company will not, without the prior written
consent of the Purchasers, enter into or continue discussions with any third
party, whether agent or principal, concerning a possible investment, private
placement, merger, acquisition or other business accommodation.

            5.1.2.  BREAK UP FEE. Other than this Agreement with the parties
hereto or the Shareholder Purchase Offering, the Company shall not accept any
offer or proposal from or enter into any agreement, written or otherwise, with
any third party relating in any manner to any debt or equity financing of the
Company or any merger, acquisition or related transaction involving the capital
stock or assets of the Company prior to October 31, 2002. In the event the
Company breaches the provisions of this Section, the Company shall immediately
pay Mi3 $3,000,000 in cash. Except as set forth in Section 5.1.3, this Section
5.1.2 shall survive termination of this Agreement and the Closing.

            5.1.3.  Mi3 TERMINATION. Mi3 shall provide the Company immediate
written notice in the event that Mi3 elects to not proceed with consummation of
the transactions contemplated hereunder, whereupon (a) the Company shall pay all
reasonable fees and expenses incurred by Mi3 in connection with the preparation
and negotiation of this Agreement and the Financing Documents and the closing of
the transactions contemplated hereby, including but not limited to expenses
incurred in the due diligence process and legal fees of Epstein Becker & Green,
P.C., in an aggregate amount not to exceed $60,000 (collectively "DEAL
EXPENSES") up to the date of such notice, and (b) the restrictions set forth in
Sections 5.1.1 and 5.1.2 shall terminate.

            5.1.4.  DEALINGS WITH AFFILIATES. Except as contemplated herein, the
Company will not enter into any transaction, including, without limitation, any
loans, leases, extension of credit or royalty agreements with any employee,
officer or director of the Company or holder of three percent or more of any
class of capital stock of the Company, or any member of their respective
immediate families or any corporation or other entity directly or indirectly
controlled by one or more of such employees, officers, directors or stockholders
or members of their immediate families.

            5.1.5.  DISTRIBUTIONS. Except as contemplated herein, the Company
will not declare or pay any dividends, purchase, redeem, retire, or otherwise
acquire for value any of its capital stock (or rights, options or warrants to
purchase such shares) now or hereafter outstanding, return any capital to its
stockholders as such, or make any distribution of assets to its

                                       13
<Page>

stockholders as such, or pay into or set aside a sinking fund for such purpose
(such transactions being hereinafter referred to as "DISTRIBUTIONS"); provided,
however, that nothing herein contained shall prevent the Company from:

                    (i)    complying with any specific provision of the terms of
this Agreement;

                    (ii)   redeeming any stock of a deceased stockholder out of
insurance held by the Company on that stockholder's life; or

                    (iv)   repurchasing any stock of an officer, employee or
consultant subject to a stock repurchase agreement under which the Company has
the right or obligation to repurchase such shares in the event of termination of
employment or of a consulting arrangement.

            5.1.6.  EXTRAORDINARY CORPORATE TRANSACTIONS. Except as contemplated
herein, the Company will not take any corporate action, enter into any agreement
to take such action, or obligate itself to take any such action, if such action
would:

                    (i)    cause the Company to create, authorize or issue any
class or series of capital stock with equity features or convertible into equity
ranking senior to the Common Stock with respect to liquidation preferences,
dilution protection, redemption rights, or payment of dividends, or otherwise
having terms and conditions superior to the terms of the Common Stock, or that
would impair or limit the Company's obligations under this Agreement;

                    (ii)   enter into any transaction that expressly prohibits
or limits the Company's right to perform its obligations under this Agreement;

                    (iii)  cause or authorize any transaction, whether by
consolidation or merger of the Company, which results in the holders of the
Company's capital stock holding less than 50% of the voting securities of the
resulting or surviving entity, or a sale of all or substantially all of the
capital stock or assets of the Company, or any other form of business
combination or acquisition in which the Company is the object of the acquisition
and in which control of the voting securities or assets of the Corporation are
transferred in any way;

                    (iv)   transfer, sell, pledge, encumber, mortgage, dispose
of, assign, lease, license or convey any ownership or interest in, or material
rights relating to, any of its technology, or other Intellectual Property Rights
to any person where the loss of such rights would have a Material Adverse
Effect;

                    (v)    create or incur any indebtedness for money borrowed
which is secured by assets of the Company or any subsidiary or otherwise
mortgage or pledge, or create a security interest in all or substantially all of
the property of the Company;

                                       14
<Page>

                    (vi)   change the principal business of the Company, enter
new lines of business, or exit its current and proposed line of business;

                    (vii)  make investments in, or loans to, any third parties
other than for employee travel or relocation;

                    (viii) make any single capital expenditure in excess of
$50,000; or

                    (ix)   except as contemplated herein, issue more than 10,000
shares of Common Stock individually, or 25,000 shares of Common Stock in the
aggregate.

            5.1.7.  OPTION POOL. The Company shall reserve an additional number
of shares of Common Stock under the Option Plans so that the aggregate number of
shares of Common Stock available for exercise and issuance under such Option
Plans equals 20% of the aggregate number of shares of Common Stock issued and
outstanding on the Closing Date.

     5.2.   CONDITIONS TO THE OBLIGATIONS OF THE PURCHASERS. The obligations of
the Purchasers under this Agreement are subject to the fulfillment, or the
waiver by the Purchasers, of the conditions set forth in this Section 5 on or
before the Closing Date. All such documents and actions shall be satisfactory in
form and substance to the Purchasers and its counsel.

            5.2.1.  ACCURACY OF REPRESENTATIONS AND WARRANTIES. Each
representation and warranty of the Company contained in this Agreement shall be
true on and as of the Closing Date, with the same effect as though such
representation and warranty had been made on and as of that date.

            5.2.2.  CONSENTS. The Company shall have obtained in a timely
fashion any and all consents, permits, approvals, registrations and waivers
necessary or appropriate for consummation of the purchase and sale of the
Shares. No judgment, writ, order, injunction, award or decree of or by any
court, or judge, justice or magistrate, including any bankruptcy court or judge,
or any order of or by any governmental authority, shall have been issued, and no
action or proceeding shall have been instituted by any governmental authority,
enjoining or preventing the consummation of the transactions contemplated hereby
or in the other Financing Documents.

            5.2.3.  PREFERRED STOCK. The rights and preferences of the Series A
Preferred Stock of the Company shall be amended, modified or canceled in form
and substance satisfactory to the Purchasers. All shares of Series B Preferred
Stock of the Company shall have been converted to Common Stock.

            5.2.4.  VOTING, DRAG-ALONG AND RIGHT OF FIRST REFUSAL AGREEMENT.
The Voting, Drag-Along and Right of First Refusal Agreement shall have been duly
executed and delivered by all parties thereto.

                                       15
<Page>

            5.2.5.  CERTIFICATES AND DOCUMENTS. The Company shall have
delivered to counsel to the Purchasers:

            (a)     evidence of filing of the Amended Articles, certified by
the Secretary of State of the State of Nevada;

            (b)     a certificate, as of the most recent practicable date, of
the Secretary of State of the State of Nevada as to the Company's legal
existence and corporate good standing;

            (c)     evidence of approval of an amendment and restatement of the
Bylaws of the Company, in substantially the form attached hereto as Exhibit D in
effect on and as of the Closing Date; and

            (d)     a copy of the resolutions of the Board of Directors (the
"BOARD") and stockholders of the Company authorizing and approving the Company's
execution, delivery and performance of the Financing Documents, all matters in
connection with the Financing Documents, and the transactions contemplated
thereby.

            5.2.6.  OPINION. The Company shall have delivered to counsel to the
Purchasers an original opinion from Grippo & Elden, counsel to the Company,
dated as of the Closing Date, addressed to the Purchasers, and substantially in
the form attached hereto as Exhibit E and in such final form as reasonably
acceptable to the Purchasers and their counsel..

            5.2.7.  NON-COMPETITION AGREEMENTS. The Company shall have
delivered to counsel to the Purchasers copies of Noncompetition Agreements
signed by and between the Company and each of Taffy Williams, Brooks Boveroux
and Reinhard Koenig, together with such other key employees designated by the
Purchasers, in the form attached hereto as Exhibit F.

            5.2.8.  ELECTION OF DIRECTORS. The number of Directors constituting
the entire Board shall have been fixed at seven and the persons designated
pursuant to the Voting, Drag-Along and Right of First Refusal Agreement shall
have been elected as Directors and shall each hold such position as of the
Closing Date.

            5.2.9.  EXPENSES. The Company shall have paid all Deal Expenses.

            5.2.10. SPLIT-OFF. The Company shall have effected a split-off of
its therapeutic line of business to Craig Dees, Ph.D. and Dees Family
Foundation, Eric A. Wachter, Ph.D. and Eric A. Wachter 1998 Charitable Remainder
Unitrust, Timothy D. Scott, Ph.D. and Scott Family Investment Limited
Partnership; Walter Fisher, Ph.D., Fisher Family Investment Limited Partnership,
and Walt Fisher 1998 Charitable Remainder Unitrust, and John A. Smolik and
Smolik Family LLP (the "Founders") in exchange for the redemption of all of the
capital stock of the Company held by such Founders (the "ASSET SPLIT-OFF"). In
the event the Company does not satisfy this condition, then:

            (a)     No Founder shall be a member of the Board;

                                       16
<Page>

            (b)     Each Founder shall be a required party to the Voting,
Drag-Along and Right of First Refusal Agreement; and

            (c)     All capital stock of the Company held by the Founders shall
remain subject to the Lockup Agreements dated May 9, 2001, and such Lockup
Agreements shall be amended to extend the term thereof by an additional two
years and as otherwise requested by the Purchasers.

            5.2.11. SEC APPROVALS; EFFECTIVE REGISTRATION; BLUE SKY. Any SEC
approval required to consummate the transactions contemplated by the Financing
Documents shall have been obtained. Issuance and sale of the Shares shall be in
compliance with all applicable Federal securities and State "Blue Sky" laws.

            5.2.12. CONVERSION OF TANNEBAUM CREDIT LINE. The Company shall have
converted $2,000,000 of its $2,500,000 line of credit granted to the Company by
Tannebaum LLC into Common Stock at the same price per share as the Per Share
Purchase Price in consideration for the purchase of Shares by Tannebaum LLC
hereunder.

            5.2.13. REVERSE STOCK SPLIT. The Board shall have recommended and
the shareholders of the Company shall have approved a 1:4 reverse split of the
Common Stock, to be effective as of the Closing.

            5.2.14. SYNDICATE. The Purchasers shall have arranged for committed
investment hereunder by a syndicate in minimum amount of $15,000,000.

            5.2.15. FAIRNESS OPINION. The Company shall have received a
fairness opinion from Valuation Counselors in form and substance satisfactory to
the Purchasers regarding this financing and the Asset Split-off.

            5.2.16. CONVERSION OF ELAN DEBT. The amount then outstanding,
including principal and all accrued interest, on the convertible promissory note
dated as of October 20, 1999 initially held by Elan International Services, Ltd.
shall have been amended, modified or canceled in form and substance satisfactory
to the Purchasers.

            5.2.17. AMERICAL SECURITIES. The Company shall have terminated in
writing all business development and unit sale agreements, as amended, with
AmeriCal Securities, Inc.

            5.2.18. REGISTRATION RIGHTS. The Company shall have executed and
delivered to the Purchasers the Registration Rights Agreement in substantially
the form attached hereto as Exhibit G.

6.   CONDITIONS TO THE OBLIGATIONS OF THE COMPANY. The obligations of the
Company under this Agreement are subject to the fulfillment, or the waiver in
writing by the Company, of the conditions set forth in this Section 6 on or
before each Closing Date.

                                       17
<Page>

     6.1.   ACCURACY OF REPRESENTATIONS AND WARRANTIES. The representations and
warranties of the Purchasers contained in Section 4 shall be true on and as of
the Closing Date, with the same effect as though such representations and
warranties had been made on and as of that date.

     6.2.   PERFORMANCE. The Purchasers shall have performed and complied with
all agreements contained in this Agreement required to be performed and complied
with by it prior to or at the Closing.

7.   POST CLOSING COVENANTS.

     7.1.   AFFIRMATIVE COVENANTS OF THE COMPANY. Subject to the terms of the
Voting, Drag-Along and Right of First Refusal Agreement and without limiting any
other covenants and provisions hereof or thereof (the terms of the Voting,
Drag-Along and Right of First Refusal Agreement to take precedence), and
provided that the Purchasers in the aggregate hold at least ten percent of the
Shares originally purchased by Purchasers hereunder, the Company covenants and
agrees that it will perform and observe the following covenants and provisions,
and will cause each of its subsidiaries to perform and observe such of the
following covenants and provisions as are applicable to such subsidiary, if and
when such subsidiary exists:

            7.1.1.  INSPECTION RIGHTS. The Company will permit during normal
business hours, upon reasonable request and at least five days' prior notice,
and without undue disruption of the Company's business, the Purchasers to
examine and make copies of and extracts from the records and books of account
of, and visit and inspect the properties, assets, operations and business of the
Company, and to discuss the affairs, finances and accounts of the Company with
any of its officers, directors, employees, attorneys or independent accountants;
provided, however, that the Purchasers and if through a designated
representative then the designated representative as well as the Purchasers
shall agree in writing prior to the receipt of any information to hold all
information confidential and not use such information for any purpose other than
with respect to the Purchasers' investment in the Company.

            7.1.2.  MEETINGS OF DIRECTORS, COMMITTEES AND OBSERVER RIGHTS. The
Company will:

            (a)     hold not less than five meetings of the Board per each
fiscal year;

            (b)     convene one or more special meetings of the Board at any
time, with agendas to be prepared by management upon the request of any two
directors;

            (c)     hold meetings of each of the Compensation Committee and
Audit Committee of the Board (as established by the Board) not less than two
times a year;

                                       18
<Page>

            (d)     send the Purchasers the notice of the time and place of all
meetings of the Board and Board committees in the same manner and at the same
time as it shall send such notice to its directors or committee members, as the
case may be;

            (e)     hold two separate meetings with representatives of the
Purchasers during each fiscal year;

            (f)     permit the Purchasers or their designees, including but not
limited to representatives of Mi3, to attend and observe all meetings of the
Board and Board committees, and to participate in all discussions during each
such meeting; provided (i) that such individuals attending the meetings agree to
hold all information confidential and not use such information for any purpose
other than with respect to the Purchasers' investment in the Company; and (ii)
that such individuals shall be subject to exclusion from portions of meetings as
necessary to preserve attorney-client privilege with respect to pending or
threatened litigation.

            (g)     reimburse members of the Board for reasonable out-of-pocket
expenses related to attendance at Board and Board committee meetings and
discharge of their duties; and

            (h)     indemnify and hold members of the Board harmless from all
costs and liabilities incurred in the course of their duties pursuant to
indemnification agreements in form and substance acceptable to such members.

            7.1.3.  REPORTS The Company will furnish to the Purchasers as soon
as available and in any event at least 30 days before the beginning of each
fiscal year of the Company, a business plan and monthly and quarterly operating
budgets for the forthcoming fiscal year, and as soon as available and in any
event within 20 days after the end of each calendar month, revisions to the
business plan and monthly operating budgets, monthly comparisons against the
original and revised business plans and original and revised monthly operating
budgets; and such other information as the Purchasers may reasonably request
which directly relates to the business of the Company. The Company shall not
furnish such reports to any Purchaser that elects, in its sole discretion, to
not receive such reports, provided that such election shall not act as a waiver
or release of the right to receive subsequent reports.

            7.1.4.  MANAGEMENT DISCLOSURE TO THE BOARD. The Board or, at its
direction, the executive officers of the Company will undertake to advise key
managerial employees of the Company of their respective obligations to disclose
all material technological or financial developments affecting the Company's
business, financial condition, prospects, assets, contractual rights or
liabilities to the Board in a timely manner.

     7.2.   KEY PERSON INSURANCE; DIRECTORS' LIABILITY AND OTHER INSURANCE. The
Company shall obtain and maintain on a continuous basis, "key person" term life
insurance on the life of Taffy Williams in a face amount equal to $2,000,000.
The proceeds of such insurance shall at all times be payable to the Company and
shall be used as the Board shall determine. In addition, the Company shall
obtain and maintain on a continuous basis, directors' liability

                                       19
<Page>

insurance in form and substance satisfactory to Mi3 with aggregate coverage of
at least $15,000,000.

     7.3.   NO INTEGRATION. Neither the Company nor any of its affiliates, nor
any person or entity acting on its or their behalf will make any offers or sales
of any Company security or solicit any offers to buy any security, under
circumstances that would adversely affect reliance by the Company on Section
4(2) of the 1933 Act for the exemption from registration for the transactions
contemplated hereby or would require registration of the Shares under the 1933
Act.

     7.4.   SHAREHOLDER PURCHASE OFFERING. Promptly following the Closing,
and provided it will not be integrated under SEC rules and interpretations
with the transactions contemplated by this Agreement, the Company shall offer
its Common Shareholders the opportunity to purchase shares of Common Stock of
the Shares at the Per Share Purchase Price and subject to the limitations
herein (the "SHAREHOLDER PURCHASE OFFERING"). A "COMMON SHAREHOLDER" shall
mean a holder of record of Common Stock as of the record date set by the
Company's Board of Directors in connection with the Shareholder Purchase
Offering (the "RECORD DATE"). The aggregate number of shares of Common Stock
offered in the Shareholder Purchase Offering shall be limited to the leser of
(i) the aggregate number of shares of Common Stock held by all Common
Shareholders on the Record Date, or (ii) $5,000,000 divided by the Per Share
Purchase Price. The Company shall not be required to sell and issue less than
$15,000,000 worth of Common Stock at the Per Share Purchase Price (the
"MINIMUM THRESHOLD") or more than $20,000,000 worth Common Stock Per Share
Purchase Price (the "MAXIMUM AMOUNT"), in the aggregate, upon both the
issuance of the Shares and the closing of the Shareholder Purchase Offering.
To the extent that the sum of the aggregate number of Shares plus the
aggregate shares of Common Stock issued in the Shareholder Purchase Offering
equals less than the Maximum Amount, the Purchasers shall have the right but
not the obligation to purchase a number of shares of Common Stock up to the
amount of such difference, allocated pro-rata among the Purchasers or as
otherwise determined by them, provided that such right does not cause the
Shareholder Purchase Offering to be integrated under SEC rules and
interpretations with the transactions contemplated by this Agreement.

     7.5.   REGISTRATION OF SHARES. The Company will file a registration
statement on Form S-1 with the SEC as contemplated by the Registration Rights
Agreement within 20 days after the Closing and make any and all post-effective
filings pursuant to applicable state and federal securities laws within the
applicable time periods so that all Shares are and remain freely tradable as
soon as practicable after the Closing.

     7.6.   NON-CONTRAVENTION. The Company will not take any action, enter into
any agreement or make any commitment that would conflict or interfere with the
obligations to the Purchasers under the Financing Documents.

     7.7.   LISTING OF SHARES. The Company shall take such action as may be
required to cause the Shares to be listed on the Nasdaq SmallCap Market no later
than the date on which the Registration Statement is first declared effective by
the SEC. Further, if the Company applies to have its Common Stock or other
securities traded on any other principal stock exchange or

                                       20
<Page>

market, it shall include the Shares in such application and will take such other
action as is necessary to cause such Common Stock to be so listed. The Company
will use commercially reasonable efforts to continue the listing and trading of
its Common Stock on The Nasdaq SmallCap Market and, in accordance, therewith,
will use commercially reasonable efforts to comply in all respects with the
Company's reporting, filing and other obligations under the bylaws or rules of
such exchange, as applicable.

8.   GENERAL.

     8.1.   SUCCESSORS AND ASSIGNS. The provisions of this Agreement shall bind
and inure to the benefit of the respective successors, assigns, heirs,
executors, and administrators of the parties hereto, including but not limited
to assigns of the Purchasers pursuant to Section 1.1 of this Agreement.

     8.2.   SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All representations and
warranties shall survive and remain in full force and effect after the Closing
with respect to the Company.

     8.3.   INDEMNIFICATION. The Company agrees to indemnify and hold harmless
each Purchaser and its affiliates and their respective directors, officers,
employees and agents from and against any and all losses, claims, damages,
liabilities and expenses (including without limitation reasonable attorney fees
and disbursements and other expenses incurred in connection with investigating,
preparing or defending any action, claim or proceeding, pending or threatened
and the costs of enforcement hereof) to which such person or entity may become
subject as a result of and will reimburse any such person or entity for all such
amounts as they are incurred by such person or entity as a result of (a) any
breach of representation, warranty, covenant or agreement made by or to be
performed on the part of the Company under the Financing Documents, (b) any
claim that any outstanding capital stock of the Company is not duly and validly
issued, fully paid and non-assessable, including but not limited to capital
stock issued to Ballsbridge Finance Limited and/or Elan or their affiliates,
and/or (c) any claim, investigation or proceeding by the SEC or any other
governmental authority with respect to the Company's relationship or
transactions with Elan, Sentigen Ltd. or their affiliates.

     8.4.   CONDUCT OF INDEMNIFICATION PROCEEDINGS. Promptly after receipt by
any person or entity (the "INDEMNIFIED PERSON") of notice of any demand, claim
or circumstances which would or might give rise to a claim or the commencement
of any action, proceeding or investigation by a third party in respect of which
indemnity may be sought pursuant to Section 8.3 hereof, such Indemnified Person
shall promptly notify the Company in writing and the Company shall assume the
defense thereof, including the employment of counsel reasonably satisfactory to
such Indemnified Person, and shall assume the payment of all fees and expenses;
provided, however, that the failure of any Indemnified Person so to notify the
Company shall not relieve the Company of its obligations hereunder except to the
extent that the Company is materially prejudiced by such failure to notify. In
any such proceeding, any Indemnified Person shall have the right to retain its
own counsel, but the fees and expenses of such counsel shall be at the expense
of such Indemnified Person unless: (i) the Company and the Indemnified Person
shall have mutually agreed to the retention of such counsel; or (ii) in the
reasonable judgment of

                                       21
<Page>

counsel to such Indemnified Person representation of both parties by the same
counsel would be inappropriate due to actual or potential differing interests
between them. The Company shall not be liable for any settlement of any
proceeding effected without its written consent, which consent shall not be
unreasonably withheld, but if settled with such consent, or if there be a final
judgment for the plaintiff, the Company shall indemnify and hold harmless such
Indemnified Person from and against any loss or liability (to the extent stated
above) by reason of such settlement or judgment. Without the prior written
consent of the Indemnified Person, which consent shall not be unreasonably
withheld, the Company shall not effect any settlement of any pending or
threatened proceeding in respect of which any Indemnified Person is or could
have been a party and indemnity could have been sought hereunder by such
Indemnified Party, unless such settlement includes an unconditional release of
such Indemnified Person from all liability arising out of such proceeding.

     8.5.   NOTICES. All notices, requests, consents and other communications
under this Agreement shall be in writing and shall be delivered by hand, by
telecopier, by express overnight courier service or mailed by first class mail,
postage prepaid, to the respective addresses set forth on the signature pages of
this Agreement, as such addresses may be modified by notice given pursuant to
this Section 8.5, with copies provided simultaneously to counsel as set forth on
the signature pages of this Agreement. Notices provided in accordance with this
Section 8.5 shall be deemed delivered upon personal delivery, receipt by
telecopy or overnight mail, or 48 hours after deposit in the mail in accordance
with the above.

     8.6.   ENTIRE AGREEMENT. This Agreement, together with the instruments and
other documents hereby contemplated to be executed and delivered in connection
herewith, contains the entire agreement and understanding of the parties hereto,
and supersedes any prior agreements or understandings between or among them,
with respect to the subject matter hereof. Except as expressly set forth in this
Agreement, the Disclosure Schedule attached hereto, and the other agreements
between the Company and the Purchasers, the Company makes no representation or
warranty, express or implied, with respect to the transactions contemplated by
this Agreement or such other agreements, the business of the Company, the
Company, the Company's assets or its future prospects. No party is relying on
any understandings, agreements or representations other than those expressly
contained in this Agreement, the Disclosure Schedule attached hereto or such
other agreements.

     8.7.   AMENDMENTS AND WAIVERS. Except as otherwise expressly set forth in
this Agreement, any term of this Agreement may be amended and the observance of
any term of this Agreement may be waived (either generally or in a particular
instance and either retroactively or prospectively), with the written consent of
the Company and the Purchasers. No waivers of or exceptions to any term,
condition or provision of this Agreement, in any one or more instances, shall be
deemed to be, or construed as, a further or continuing waiver of any such term,
condition or provision.

     8.8.   COUNTERPARTS. This Agreement may be executed in several
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

                                       22
<Page>

     8.9.   CAPTIONS. The captions of the sections, subsections and paragraphs
of this Agreement have been added for convenience only and shall not be deemed
to be a part of this Agreement.

     8.10.  SEVERABILITY. Each provision of this Agreement shall be interpreted
in such manner as to validate and give effect thereto to the fullest lawful
extent, but if any provision of this Agreement is determined by a court of
competent jurisdiction to be invalid or unenforceable under applicable law, such
provision shall be ineffective only to the extent so determined and such
invalidity or unenforceability shall not affect the remainder of such provision
or the remaining provisions of this Agreement.

     8.11.  GOVERNING LAW. This Agreement shall be governed by and interpreted
and construed in accordance with the laws of the Commonwealth of Massachusetts;
provided, however, that matters relating to the authorization, issuance and
enforceability of the terms of the Common Stock shall be governed and
interpreted and construed in accordance with the Nevada General Corporation Law.
The Company irrevocably submits to the exclusive jurisdiction of the state and
federal courts located in Boston, Massachusetts for the purpose of any suit,
action, proceeding or judgment relating to or arising out of this Agreement and
the transactions contemplated hereby. Service of process in connection with any
such suit, action or proceeding may be served on each party hereto anywhere in
the world by the same methods as are specified for the giving of notices under
this Agreement. The Company irrevocably consents to the jurisdiction of any such
court in any such suit, action or proceeding and to the laying of venue in such
court. The Company irrevocably waives any objection to the laying of venue of
any such suit, action or proceeding brought in such courts and irrevocably
waives any claim that any such suit, action or proceeding brought in any such
court has been brought in an inconvenient forum.

     8.12.  EXCULPATION AMONG PURCHASERS. Each Purchaser acknowledges that it is
not relying upon any person, firm or corporation, other than the Company and its
officers and directors, in making its investment or decision to invest in the
Company. Each Purchaser agrees that no Purchaser nor the respective controlling
persons, officers, directors, partners, agents, or employees of any Purchaser
shall be liable for any action heretofore or hereafter taken or omitted to be
taken by any of them in connection with the Common Stock.

                         [NEXT PAGE IS SIGNATURE PAGE.]

                                       23
<Page>

     IN WITNESS WHEREOF, the parties have executed this Common Stock Purchase
Agreement as of the day and year first above written.

                         PHOTOGEN TECHNOLOGIES, INC.

                         By:
                            -----------------------------------------
                            Taffy J. Williams, Ph.D., President

                         Notice Address:   140 Union Square Drive
                                           New Hope, PA 18938

                         MI3 L.P.

                               By: MI3 Services L.L.C., its General Partner

                               By:
                                  -----------------------------------------
                                  William D. McPhee, President

                               Notice Address:   One Hollis Street, Suite 232
                                                 Wellesley, MA 02482

                               With a copy to:   Susan E. Pravda, Esquire
                                                 Epstein Becker & Green, P.C.
                                                 111 Huntington Avenue
                                                 Boston, MA  02199

                         OXFORD BIOSCIENCE PARTNERS IV L.P.

                               By: OBP Management IV L.P.

                               By:
                                  -----------------------------------------
                               Jonathan J. Fleming - General Partner

                               Notice Address:   222 Berkeley Street, Suite 1650
                                                 Boston, MA  02216

                         MRNA FUND II L.P.

                               By:  OBP Management IV L.P.

                               By:
                                  -----------------------------------------
                               Jonathan J. Fleming - General Partner

                               Notice Address:   222 Berkeley Street, Suite 1650
                                                 Boston, MA  02216

                                       24
<Page>

                         NEW ENGLAND PARTNERS CAPITAL, L.P.

                               By: NEP Capital LLC, its General Partner

                               By:
                                  ----------------------------------------------
                                  John Rousseau, President

                               Notice Address:   One Boston Place, Suite 2100
                                                 Boston, MA 02108

                         TANNEBAUM LLC

                         By:
                            ------------------------------------------
                         Name:
                         Title:

                               Notice Address:

                                       25
<Page>

                   EXHIBIT A To Common Stock Purchase Agreement
                                  (SECTION 3.1)
                AMENDED AND RESTATED CERTIFICATE OF INCORPORATION


                              AMENDED AND RESTATED
                            ARTICLES OF INCORPORATION
                                       OF
                           PHOTOGEN TECHNOLOGIES, INC.

     We, the undersigned, for the purpose of amending and restating the
Restated Articles of Incorporation of Photogen Technologies, Inc. filed May
17, 2000 with the Nevada Secretary of State, and subject to the requirements
of Title 7, Chapter 78 of the Nevada Revised Statutes, and the acts
amendatory thereof, and hereinafter sometimes referred to as the General
Corporation Law of the State of Nevada, hereby adopt and make the following
Amended and Restated Articles of Incorporation:

     FIRST: The name of the corporation (hereinafter called the "Corporation")
is: Photogen Technologies, Inc.

     SECOND: The resident agent of the Corporation within the State of Nevada is
The Corporation Trust Company of Nevada, whose address is One East First Street,
Reno, Nevada 89501.

     THIRD: The nature of the business of the Corporation and the objects or the
purposes to be transacted, promoted, or carried on by it are to engage in any
lawful act or activity for which corporations may be organized under the General
Corporation Law of the State of Nevada.

     FOURTH:

     (a)   The total number of shares of all classes of stock which the
Corporation shall have the authority to issue is one hundred fifty-five million
(155,000,000) of which

           (i)  one hundred fifty million (150,000,000) shares shall be Common
Stock, par value $.001 per share ("Common Stock"), and

           (ii) five million (5,000,000) shares shall be Preferred Stock, par
value $.01 per share ("Preferred Stock"), which Preferred Stock may be issued
from time to time by the Board of Directors. The Board of Directors is
authorized to prescribe the classes, series and the number

                                        1
<Page>

of each class or series of Preferred Stock and the voting powers, designations,
preferences, limitations, restrictions and relative rights of each class or
series of Preferred Stock. The voting powers, designations, preferences,
limitations, restrictions, relative rights and distinguishing designation of
each class or series of Preferred Stock shall be described in one or more
resolutions of the Board of Directors authorizing the issuance of such class or
series of Preferred Stock.

     (b)   Effective as of the close of business on the date of filing these
Amended and Restated Articles of Incorporation with the Nevada Secretary of
State (the "Effective Time"), the filing of this Amendment shall effect a
reverse split (the "Reverse Split") pursuant to which each four shares of Common
Stock, par value $.001 per share, issued and outstanding and held by a single
holder, shall be combined into one validly issued, fully paid and nonassessable
share of Common Stock, par value $.001 per share. Each stock certificate that
prior to the Effective Time represented shares of Common Stock shall, following
the Effective Time, represent the number of shares into which the shares of
Common Stock represented by such certificate shall be combined as a result of
the Reverse Split. The Corporation shall not issue fractional shares or scrip as
a result of the Reverse Split, but shall round up to the nearest whole share any
fractional share that would otherwise result from the Reverse Split. After the
Reverse Split, the number of authorized shares of Common Stock shall continue to
be 150,000,000; and the par value of the Common Stock shall be $.001 per share.

     (c)   No holder of any of the shares of any class or series of capital
stock of the Corporation shall have a preemptive right to acquire unissued
shares, treasury shares or securities convertible into or carrying a right to
subscribe for or acquire any such shares.

     (d)   Any paid-up shares of stock of the Corporation and any shares of
stock of the Corporation issued as fully paid-up shall not be assessable or
assessed in any manner or for any cause.


                                        2
<Page>

     FIFTH:

     (a)   The governing board of the Corporation shall be styled as a "Board of
Directors," and any member of said Board shall be styled as a "director."

     (b)   The authorized number of members constituting the Board of Directors
of the Corporation is seven (7).

     (c)   All vacancies on the Board of Directors, including those caused by an
increase in the number of directors, shall only be filled in the manner provided
by the Bylaws.

                                        3
<Page>

     SIXTH: The Corporation shall have perpetual existence.

     SEVENTH: The personal liability of the directors to the Corporation or its
stockholders is hereby eliminated to the fullest extent permitted by the General
Corporation Law of the State of Nevada, as the same may be amended and
supplemented. No amendment to or repeal of this Article Seventh shall apply to
or have any effect on the liability or alleged liability of any director of the
Corporation for or with respect to any acts or omissions of such director
occurring prior to the effective date of such amendment or repeal.

     EIGHTH: The Corporation shall, to the fullest extent permitted by the
General Corporation Law of the State of Nevada, as the same may be amended and
supplemented, indemnify each person who is or was a director of the Corporation
and each person who serves or served at the request of the Corporation as a
director of another enterprise. The indemnification provided for herein shall
not be deemed exclusive of any other rights to which such person may be entitled
under any Bylaw, agreement, vote of stockholders or disinterested directors or
otherwise. No amendment to or repeal of this Article Eighth shall apply to or
have any effect on the rights of any person referred to in this Article Eighth
for or with respect to acts or omissions of such person occurring prior to such
amendment or repeal. The indemnification provided in this Article Eighth shall
continue as to a person who has ceased to be a director and shall inure to the
benefit of the heirs, executors and administrators of such person.

     NINTH: The Corporation reserves the right to amend, alter, change, or
repeal any provision contained in these Restated Articles of Incorporation in
the manner now or hereafter prescribed by statute, and all rights conferred upon
stockholders herein are granted subject to this reservation.

     We, the undersigned President and Secretary, respectively, of the
Corporation, hereby certify that the amendment to the Restated Articles of
Incorporation of the Corporation was adopted by the holders of at least ______
shares of Common Stock eligible to vote thereon which represents approximately
at least _______% of the shares Common Stock of the Corporation eligible to vote
thereon; and the amendment to the Amended and Restated Certificate of
Designations, Preferences and Rights of Series A Preferred Stock was approved
the sole record and beneficial owner of the Series A Preferred Stock.

     IN WITNESS WHEREOF, we hereby execute these Amended and Restated Articles
of Incorporation on this [   ] day of [      ], 2002.


                                         ---------------------------------------
                                         Taffy Williams, Ph.D., President


                                         ---------------------------------------
                                         Brooks Boveroux, Secretary

                                        4
<Page>

STATE OF ILLINOIS   )
                    ) SS.
COUNTY OF COOK      )

On this [   ] day of [    ], 2002, personally appeared before me, a Notary
Public in and for the State and County aforesaid Taffy Williams, Ph.D. and
Brooks Boveroux, known to me to be the persons described in and who executed the
foregoing Amended and Restated Articles of Incorporation, and who acknowledged
to me that they, respectively, executed the same freely and voluntarily and for
the uses and purposes therein mentioned.

WITNESS my hand and official seal, the day and year first above written.


---------------------------------------
Notary Public

(Notarial Seal)

                                       5
<Page>

                              AMENDED AND RESTATED
               CERTIFICATE OF DESIGNATION, PREFERENCES AND RIGHTS
                                       OF
                            SERIES A PREFERRED STOCK
                                       OF
                           PHOTOGEN TECHNOLOGIES, INC.

     We, the undersigned, for the purpose of amending and restating the Amended
and Restated Certificate of Designation, Preferences and Rights of the Series A
Preferred Stock of Photogen Technologies, Inc., a corporation organized and
existing under the laws of the State of Nevada (the "Corporation") and in
accordance with the provisions of Title 7, Chapter 78 of the Nevada Revised
Statutes, hereby certify:

     That pursuant to the authority conferred upon the Board of Directors of the
Corporation (the "Board of Directors") by the Amended and Restated Articles of
Incorporation of the Corporation, the Board of Directors on ________________,
2002 adopted the following resolution, pursuant to Article FOURTH of the
Corporation's Amended and Restated Articles of Incorporation, thereby amending
and restating a series of shares of Preferred Stock designated as Series A
Preferred Stock:

     "RESOLVED, that pursuant to Article FOURTH of the Corporation's Amended and
Restated Articles of Incorporation, the Series A Preferred Stock is hereby
amended in its entirety and the Amended and Restated Certificate of Designation,
Preferences and Rights of the Series A Preferred Stock, filed on November 5,
1999 with the Secretary of State of Nevada, is hereby amended and restated in
its entirety as follows:

     1.   DESIGNATION. 12,015 shares of Preferred Stock shall be designated and
known as the "Series A Preferred Stock." Such number of shares may be increased
or decreased by resolution of the Board of Directors after obtaining the consent
of a majority in interest of the holder(s) of the then-outstanding shares of
Series A Preferred Stock; provided, that no decrease shall reduce the number of
shares of Series A Preferred Stock to a number less than the number of shares
then outstanding plus the number of such shares issuable upon exercise of
outstanding rights, options or warrants or upon conversion of outstanding
securities issued by the Corporation.

     2.   DIVIDEND PROVISIONS.

          (A)  From and after the date hereof, when and if the Board of
Directors shall declare a dividend or distribution payable with respect to the
then-outstanding shares of Common Stock of the Corporation, the holders of the
Series A Preferred Stock shall be entitled to the amount of dividends per share
in the same form as such Common Stock dividends that would be payable on the
largest number of whole shares of Common Stock into which a holder's aggregate
shares of Series A Preferred Stock could then be converted pursuant to Section 4
hereof (such number to be determined as of the record date for the determination
of holders of Common Stock entitled to receive such dividend).

<Page>

          (B)  In addition to Section 2(A) above, each share of Series A
Preferred Stock, for a period of six years from the date of first issuance of
the Series A Preferred Stock, shall be entitled to receive a mandatory dividend
equal to 7.0% per year of the Original Issue Price (as defined below) thereof.
Such dividend shall (1) be cumulative and shall compound on a semi-annual basis,
the first compounding to commence six months from the date hereof and (2) be
payable semi-annually solely by the issuance of additional shares of Series A
Preferred Stock, at a price per share equal to the Original Issue Price thereof,
and not in cash. Fractional shares of Series A Preferred Stock shall be issuable
for purposes hereunder.

     3.   NO LIQUIDATION PREFERENCE. In the event of any liquidation,
dissolution or winding-up of the affairs of the Corporation, whether voluntary
or involuntary (collectively, a "Liquidation"), the holders of the Series A
Preferred Stock shall not be entitled to receive any liquidation preference, out
of the assets of the Corporation legally available for distribution to its
shareholder. In the event of any Liquidation, the Series A Preferred shall rank
parri passu with the Common Stock in any distribution of the assets of the
Corporation to stockholders in their capacities as such.

     4.   CONVERSION. The holders of the Series A Preferred Stock shall have
conversion rights, through and including the Conversion Termination Date (as
defined below), as follows (the "Conversion Rights"):

          (A)  RIGHT TO CONVERT.

               (i)    Each share of Series A Preferred Stock shall be
convertible, at the option of the holder thereof, at any time that is two years
after the issuance thereof, at the office of the Corporation or any transfer
agent for such stock, into such number of fully paid and non-assessable shares
of Common Stock as is determined by dividing (x) the sum of the Original Issue
Price of such share of Series A Preferred Stock (including all shares issued as
dividends thereon) and all accrued and unpaid dividends thereon by (y) the
Series A Conversion Price (as defined below). The "Series A Conversion Price"
shall initially be $3.00 and shall be subject to adjustment as set forth below
in this Section 4(a); provided, however, that the Series A Conversion Price
shall not exceed $3.00.

               (ii)   Before any holder of Series A Preferred Stock shall be
entitled to convert such shares into shares of Common Stock, such holder shall
surrender the certificate or certificates therefor, duly endorsed, at the office
of the Corporation or of any transfer agent for the Series A Preferred Stock,
and shall give written notice to the Corporation at its principal corporate
office, of the election to convert the same and shall state therein the name or
names in which the certificate or certificates for shares of Common Stock are to
be issued. The Corporation shall, as soon as practicable thereafter, issue and
deliver at such office to such holder of Series A Preferred Stock, or to the
nominee or nominees of such holder, a certificate or certificates for the number
of shares of Common Stock to which such holder shall be entitled as set forth
above. Such conversion shall be deemed to have been made immediately prior to
the close of business on the date of such surrender of the shares of Series A
Preferred Stock to be converted, and the person or persons entitled to receive
the shares of Common Stock issuable

                                       -2-
<Page>

upon such conversion shall be treated for all purposes as the record holder or
holders of such shares of Common Stock as of such date.

               (iii)  In the event the Corporation should at any time fix a
record date for the effectuation of a split or subdivision of the outstanding
shares of Common Stock or the determination of holders of Common Stock entitled
to receive a dividend or other distribution payable in additional shares of
Common Stock or other securities or rights convertible into, or entitling the
holder thereof to receive directly or indirectly, additional shares of Common
Stock (hereinafter referred to as "Common Stock Equivalents") without payment of
any consideration by such holder for the additional shares of Common Stock or
the Common Stock Equivalents (including the additional shares of Common Stock
issuable upon conversion or exercise thereof) or with payment that is less than
the then-market price of the Common Stock (including, in the case of Common
Stock Equivalents, on an as-converted basis) then, as of such record date (or
the date of such dividend distribution, split or subdivision if no record date
is fixed), the Series A Conversion Price of the Series A Preferred Stock shall
be appropriately decreased so that the number of shares of Common Stock issuable
on conversion of each share of such series shall be increased in proportion to
such increase of the aggregate of (a) shares of Common Stock outstanding and (b)
those issuable with respect to such Common Stock Equivalents, with the number of
shares issuable with respect to Common Stock Equivalents determined from time to
time as provided in Section 4(a)(v) below.

               (iv)   If the number of shares of Common Stock outstanding at any
time is decreased by a combination of the outstanding shares of Common Stock,
then, following the record date of such combination, the Series A Conversion
Price for the Series A Preferred Stock shall be appropriately increased so that
the number of shares of Common Stock issuable on conversion of each share of
such series shall be decreased in proportion to such decrease in outstanding
shares.

               (v)    The following provisions shall apply for purposes of this
Section 4(a):

                      (a)    The aggregate maximum number of shares of Common
Stock deliverable upon conversion or exercise of Common Stock Equivalents
(assuming the satisfaction of any conditions to convertibility or
exercisability, including, without limitation, the passage of time, but without
taking into account potential antidilution adjustments) shall be deemed to have
been issued at the time such Common Stock Equivalents were issued.

                      (b)    In the event of any change in the number of shares
of Common Stock deliverable or in the consideration payable to the Corporation
upon conversion or exercise of such Common Stock Equivalents including, but not
limited to, a change resulting from the antidilution provisions thereof, the
Series A Conversion Price of the Series A Preferred Stock, to the extent in any
way affected by or computed using such Common Stock Equivalents, shall be
recomputed to reflect such change, but no further adjustment shall be made for
the actual issuance of Common Stock or any payment of such consideration upon
the exercise of any such options or rights or the conversion or exchange of such
securities.

                                       -3-
<Page>

                      (c)    Upon the termination or expiration of the
convertibility or exercisability of any such Common Stock Equivalents, the
Series A Conversion Price of the Series A Preferred Stock, to the extent in any
way affected by or computed using such Common Stock Equivalents, shall be
recomputed to reflect the issuance of only the number of shares of Common Stock
(and Common Stock Equivalents which remain convertible or exercisable) actually
issued upon the conversion or exercise of such Common Stock Equivalents.

          5.   EXCHANGE RIGHT. Provided that (a) all shares of Series A
Preferred Stock initially issued and sold by the Corporation to Elan
International Services, Ltd. or its successors and assigns ("EIS") have not been
converted and (b) the Exchange Termination Date (as defined below) shall not
have occurred, the holders of the Series A Preferred Stock (acting by act of the
majority holders thereof) shall have the right to exchange all of their shares
of Series A Preferred Stock (the "Exchange Right") of the Corporation for such
number of shares of Common Shares (as adjusted for any combinations or divisions
or similar recapitalizations) of Sentigen, Ltd., a Bermuda exempted limited
liability company ("Sentigen") held by the Corporation, so that, after giving
effect to the exercise of the Exchange Right, EIS and the Corporation will each
hold 50% of the total outstanding share capital of Sentigen assuming that
neither EIS nor the Corporation has sold any shares of Sentigen; provided, that
if EIS exercises the Exchange Right prior to a date that is three years after
the date hereof, the Corporation shall deliver to Sentigen for exchange the
number of Common Shares of Sentigen that would otherwise be delivered to EIS
pursuant to this Section 5, and EIS shall receive from Sentigen, upon the
exchange of such Common Shares, a number of shares of a newly-created non-voting
convertible preferred stock of Sentigen equal to such number of Common Shares
delivered to Sentigen by the Corporation. Such non-voting preferred stock shall
be convertible into Common Shares of Sentigen on a one-for-one basis at any time
after such three-year period. Upon exercise of the Exchange Right, the shares of
Series A Preferred Stock originally purchased from the Corporation, but not
including any of the accrued and unpaid dividends thereon, shall be canceled and
shall no longer be entitled to any rights in the Corporation. If any shares of
the Series A Preferred Stock are converted pursuant to Section 4(a), to shares
of Common Stock, the Exchange Right with respect to the shares of Series A
Preferred Stock originally purchased from the Corporation, but not including any
of the accrued and unpaid dividends thereon, shall be canceled and shall no
longer be entitled to any rights in the Corporation. In order to exercise the
Exchange Right, the holders shall provide written notice thereof to the
Corporation, setting forth (a) the fact that such holders intend to exercise the
Exchange Right, and (b) the proposed date for such exercise (the "Exercise
Date"), which shall be between 10 and 30 days after the date of such notice,
provided, however, that if the Corporation shall deliver the holders a written
request to delay the date for such exercise by no more than 45 days, the
Exercise Date will be as set forth in that request. During the period after the
receipt of such written request, and before the Exercise Date, the holders shall
negotiate with the Corporation in good faith an alternative mechanism for the
transfer of the Common Shares or Preferred Stock of Sentigen that will reduce
the Corporation's tax liability, provided that the holders shall not be required
to agree to any transaction which is financially disadvantageous to them. On the
Exercise Date, (y) the holders shall tender their shares of Series A Preferred
Stock to the Corporation for cancellation, and (z) the Corporation shall cause
to be delivered to EIS, acting on behalf of such holders, such shares of
Sentigen. The holders and the

                                       -4-
<Page>

Corporation shall take all other necessary or appropriate actions in connection
with or to effect such closing.

          6.   TERMINATION DATE.

               (A)   The rights of the holders to convert the shares of Series A
Preferred Stock into shares of Common Stock, shall terminate and be of no
further force and effect on the date that is six years after the date of the
first issuance of any shares of Series A Preferred Stock hereunder (the
"Conversion Termination Date").

               (B)   The rights of the holders to exercise the Exchange Right
shall terminate and be of no further force and effect on the date that is six
years after the date of the first issuance of any shares of the Series A
Preferred Stock hereunder (the "Exchange Termination Date").

          7.   OTHER DISTRIBUTIONS. On or prior to the Conversion Termination
Date, in the event the Corporation shall declare a distribution payable in
securities of other persons, evidences of indebtedness issued by the Corporation
or other persons, assets (excluding cash dividends) or options or rights not
referred to in Section 4, then, in each such case for the purpose of this
Section 7, the holders of the Series A Preferred Stock shall be entitled to a
proportionate share of any such distribution as though they were the holders of
the number of shares of Common Stock of the Corporation into which their shares
of Series A Preferred Stock would be convertible as of the record date fixed for
the determination of the holders of Common Stock of the Corporation entitled to
receive such distribution.

          8.   RECAPITALIZATIONS. On or prior to the Conversion Termination
Date, if at any time or from time to time there shall be a recapitalization of
the Common Stock (other than a subdivision, combination or merger or sale of
assets provided for in Section 3 or Section 4 hereof) provision shall be made so
that the holders of the Series A Preferred Stock shall thereafter be entitled to
receive upon conversion of the Series A Preferred Stock the number of shares of
stock or other securities or property of the Corporation or otherwise, to which
a holder of Common Stock deliverable upon conversion would have been entitled on
such recapitalization. In any such case, appropriate adjustment shall be made in
the application of the provisions of Section 4 with respect to the rights of the
holders of the Series A Preferred Stock after the recapitalization to the end
that the provisions of Section 4 (including adjustment of the Series A
Conversion Price then in effect and the number of shares purchasable upon
conversion of the Series A Preferred Stock) shall be applicable after that event
as nearly equivalent as may be practicable.

          9.   NO IMPAIRMENT. The Corporation will not, by amendment of its
Articles of Incorporation or through any reorganization, recapitalization,
transfer of assets, consolidation, merger, dissolution, issuance or sale of
securities or any other voluntary action, avoid or seek to avoid the observance
or performance of any of the terms to be observed or performed hereunder by the
Corporation, but will at all times in good faith assist in the carrying out of
all the provisions hereof and in the taking of all such action as may be
necessary or appropriate in order

                                      -5-
<Page>

to protect the Series A Conversion Rights and Exchange Right of the holders of
the Series A Preferred Stock against impairment.

          10.  NO FRACTIONAL SHARES AND CERTIFICATE AS TO ADJUSTMENTS.

               (A)   No fractional shares shall be issued upon the conversion of
any share or shares of the Series A Preferred Stock, and the number of shares of
Common Stock to be issued shall be rounded to the nearest whole share. Whether
or not fractional shares are issuable upon such conversion shall be determined
on the basis of the aggregate number of shares of Series A Preferred Stock each
holder is at the time converting into Common Stock and the aggregate number of
shares of Common Stock issuable to each such holder upon such conversion. No
fractional shares shall be issued upon the conversion of any share or shares of
the Series A Preferred Stock, and the number of shares of Common Stock to be
issued shall be rounded to the nearest whole share. Whether or not fractional
shares are issuable upon such conversion shall be determined on the basis of the
total number of shares of Series A Preferred Stock the holder is at the time
converting into Common Stock and the number of shares of Common Stock issuable
upon such aggregate conversion.

               (B)   Upon the occurrence of each adjustment or readjustment of
the Series A Conversion Price pursuant to Section 4, the Corporation, at its
expense, shall promptly compute such adjustment or readjustment in accordance
with the terms hereof and prepare and furnish to each holder of shares of Series
A Preferred Stock a certificate setting forth such adjustment or readjustment
and showing in detail the facts upon which such adjustment or readjustment is
based. The Corporation shall, upon the written request at any time of any holder
of Series A Preferred Stock, furnish or cause to be furnished to such holder a
like certificate setting forth (i) such adjustment and readjustment, (ii) the
Series A Conversion Price at the time in effect, and (iii) the number of shares
of Common Stock and the amount, if any, of other property which at the time
would be received upon the conversion of a share of Series A Preferred Stock.

          11.  RESERVATION OF STOCK ISSUABLE UPON CONVERSION. The Corporation
shall at all times reserve and keep available out of its authorized but unissued
shares of Common Stock, solely for the purpose of effecting the conversion of
the shares of the Series A Preferred Stock, such number of its shares of Common
Stock that shall from time to time be sufficient to effect the conversion of all
outstanding shares of the Series A Preferred Stock; and if at any time the
number of authorized but unissued shares of Common Stock not otherwise reserved
for issuance shall not be sufficient to effect the conversion of all then
outstanding shares of the Series A Preferred Stock, in addition to such other
remedies as shall be available to the holders of such Series A Preferred Stock,
the Corporation will take such corporate action that may, in the opinion of its
counsel, be necessary to increase its authorized but unissued shares of Common
Stock to such number of shares as shall be sufficient for such purposes,
including without limitation, engaging in best efforts to obtain the requisite
shareholder approval of any necessary amendment to its Articles of
Incorporation.

          12.  NOTICES. Any notice required by the provisions hereof to be given
to the holders of shares of Series A Preferred Stock shall be deemed given on
the date of service if

                                       -6-
<Page>

served personally on the party to whom notice is to be given, or on the date of
transmittal of services by facsimile transmission to the party to whom notice is
to be given, and addressed to each holder of record at his address appearing on
the books of the Corporation.

          13.  VOTING RIGHTS. Subject to Section 14 below, holders of Series A
Preferred Stock shall not be entitled to vote, including with respect to the
election of directors of the Corporation.

          14.  PROTECTIVE PROVISIONS. Subject to the rights of any series of
preferred stock that may from time to time come into existence, so long as any
shares of Series A Preferred Stock are outstanding, the Corporation shall not
without first obtaining the approval (by vote or written consent, as provided by
law) of the holders of at least a majority of the then-outstanding shares of
Series A Preferred Stock, voting separately as a series:

               (A)   amend its Restated Articles of Incorporation so as to
affect adversely the shares of Series A Preferred Stock or any holder thereof
(including by creating any additional classes or series of preferred stock with
a liquidation preference senior to or PARI PASSU with the Series A Preferred
Stock); or

               (B)   change the rights of the holders of the Series A Preferred
Stock in any other respect.

          15.  STATUS OF CONVERTED STOCK. In the event any shares of Series A
Preferred Stock shall be converted pursuant to Section 4 or exchanged pursuant
to Section 5 hereof, the shares so converted or exchanged shall be canceled and
shall not be reissuable by the Corporation. The Restated Articles of
Incorporation of the Corporation shall be appropriately amended to effect the
corresponding reduction in the Corporation's authorized capital stock.

          IN WITNESS WHEREOF, the Corporation has caused this Amended and
Restated Certificate of Designation, Preferences and Rights of Series A
Preferred Stock to be duly executed by its President and duly attested to by its
Secretary as of ___________________, 2002.


                                         ---------------------------------------
                                         Taffy  Williams, Ph.D., President


                                         ---------------------------------------
                                         Brooks Boveroux, Secretary

                                       -7-
<Page>

STATE OF ____________       )
                            ) SS.
COUNTY OF ___________       )

          On this ____ day of __________, 2002, personally appeared before me, a
Notary Public in and for the State and County aforesaid, Taffy J. Williams,
Ph.D., known to me to be the person described in and did say that he is the
President of Photogen Technologies, Inc., a Nevada corporation, and that the
foregoing Amended and Restated Certificate of Designation, Preferences and
Rights of Series A Preferred Stock was signed on behalf of said corporation by
authority of its board of directors, and acknowledged to me that said instrument
to be the free act and deed of said corporation.

          WITNESS my hand and official seal, the day and year first above
written.

                                         ------------------------------------
                                         Notary Public

(Notarial Seal)

STATE OF ____________       )
                            ) SS.
COUNTY OF ___________       )

          On this ____ day of __________, 2002, personally appeared before me, a
Notary Public in and for the State and County aforesaid, Brooks Boveroux, known
to me to be the person described in and did say that he is the Secretary of
Photogen Technologies, Inc., a Nevada corporation, and that the foregoing
Amended and Restated Certificate of Designation, Preferences and Rights of
Series A Preferred Stock was signed on behalf of said corporation by authority
of its board of directors, and acknowledged to me that said instrument to be the
free act and deed of said corporation.

          WITNESS my hand and official seal, the day and year first above
written.

                                         ------------------------------------
                                         Notary Public

(Notarial Seal)

                                       -8-
<Page>

               CERTIFICATE OF DESIGNATION, PREFERENCES AND RIGHTS
                                       OF
                      SERIES B CONVERTIBLE PREFERRED STOCK
                                       OF
                           PHOTOGEN TECHNOLOGIES, INC.

          We, the undersigned, for the purpose of terminating the Certificate of
Designation, Preferences and Rights of the Series B Convertible Preferred Stock
of Photogen Technologies, Inc., a corporation organized and existing under the
laws of the State of Nevada (the "Corporation") and in accordance with the
provisions of Title 7, Chapter 78 of the Nevada Revised Statutes, hereby
certify:

          That pursuant to the authority conferred upon the Board of Directors
of the Corporation (the "Board of Directors") by the Amended and Restated
Articles of Incorporation of the Corporation, the Board of Directors on
________________, 2002 adopted the following resolution, pursuant to Article
FOURTH of the Corporation's Amended and Restated Articles of Incorporation,
thereby canceling one series of shares of Preferred Stock designated as Series B
Convertible Preferred Stock:

          "RESOLVED, that pursuant to Article FOURTH of the Corporation's
Amended and Restated Articles of Incorporation, the Series B Convertible
Preferred Stock is hereby cancelled and the Certificate of Designation,
Preferences and Rights of the Series B Convertible Preferred Stock, filed on
February 11, 2000 with the Secretary of State of Nevada, is hereby terminated in
its entirety."

          IN WITNESS WHEREOF, the Corporation has caused this Certificate of
Designation, Preferences and Rights of Series B Convertible Preferred Stock to
be duly executed by its President and duly attested to by its Secretary as of
____________________, 2002.

                                         ---------------------------------------
                                         Taffy  Williams, Ph.D., President

                                         ---------------------------------------
                                         Brooks Boveroux, Secretary

<Page>

STATE OF ____________       )
                            ) SS.
COUNTY OF ___________       )

          On this ____ day of __________, 2002, personally appeared before me, a
Notary Public in and for the State and County aforesaid, Taffy J. Williams,
Ph.D., known to me to be the person described in and did say that he is the
President of Photogen Technologies, Inc., a Nevada corporation, and that the
foregoing Certificate of Designation, Preferences and Rights of Series B
Preferred Stock was signed on behalf of said corporation by authority of its
board of directors, and acknowledged to me that said instrument to be the free
act and deed of said corporation.

          WITNESS my hand and official seal, the day and year first above
written.

                                         ------------------------------------
                                         Notary Public

(Notarial Seal)


STATE OF ____________       )
                            ) SS.
COUNTY OF ___________       )

          On this ____ day of __________, 2002, personally appeared before me, a
Notary Public in and for the State and County aforesaid, Brooks Boveroux, known
to me to be the person described in and did say that he is the Secretary of
Photogen Technologies, Inc., a Nevada corporation, and that the foregoing
Certificate of Designation, Preferences and Rights of Series B Preferred Stock
was signed on behalf of said corporation by authority of its board of directors,
and acknowledged to me that said instrument to be the free act and deed of said
corporation.

          WITNESS my hand and official seal, the day and year first above
written.

                                         ------------------------------------
                                         Notary Public

(Notarial Seal)

                                       -2-




<Page>

                 EXHIBIT B To the Common Stock Purchase Agreement
                                  (SECTION 3.2)
             VOTING, DRAG-ALONG AND RIGHT OF FIRST REFUSAL AGREEMENT

     THIS AGREEMENT ("AGREEMENT") is entered into as of July [ ], 2002 by and
among

     -    Robert J. Weinstein, M.D. (individually and as Director of the Robert
          and Lois Weinstein Family Foundation, Inc. and as Trustee of the
          Robert and Lois Weinstein Joint Revocable Trust) ("WEINSTEIN"),
     -    Stuart Levine (individually and as Trustee of the Theodore Tannebaum
          Trust) ("TANNEBAUM"),
     -    Tannebaum LLC, a Delaware limited liability company ("TLLC"),
     -    Mi3 L.P., a Delaware limited partnership ("MI3"),
     -    [Oxford BioScience, a Delaware limited partnership] ("OXFORD"), and
     -    New England Partners Capital, L.P., a Delaware limited partnership
          ("NEP").

Weinstein, Tannebaum and TLLC are sometimes collectively referred to herein as
the "CHICAGO STOCKHOLDERS;" Mi3, Oxford and NEP and are sometimes collectively
referred to herein as the "VENTURE STOCKHOLDERS;" and the Chicago Stockholders,
and/or the Venture Stockholders are each sometimes collectively referred to
herein as the "STOCKHOLDERS."

     WHEREAS, Photogen Technologies, Inc., a Nevada corporation (the "COMPANY")
is issuing to the Venture Stockholders shares of common stock, $.001 par value
per share (the "COMMON STOCK") pursuant to a Common Stock Purchase Agreement
dated July [ ], 2002 (the "STOCK PURCHASE AGREEMENT"). The shares of Common
Stock, together with all other capital stock or securities of the Company,
whether authorized or outstanding as of the date hereof or at any time
hereafter, are collectively referred to as the "SHARES."

     WHEREAS, certain of the Stockholders are parties to that certain Amended
and Restated Voting Agreement dated June 17, 1998, as amended on September 4,
2001 (the "ORIGINAL VOTING AGREEMENT").

     WHEREAS, one of the conditions to the investment by the Venture
Stockholders pursuant to the Stock Purchase Agreement is the execution of an
agreement relating to the election of members to the Company's Board of
Directors, a compulsory sale of shares in the event of a sale of all or
substantially all of the assets or equity of the Company, and a right of first
refusal with respect to dispositions of Shares by the Chicago Stockholders.

     NOW, THEREFORE, in consideration of the mutual promises herein and other
good and valuable consideration, the receipt and adequacy of which is
acknowledged, the parties hereby agree as follows.

1.        VOTING AGREEMENT.

     1.1       The agreement in Section 1.2 shall be deemed to constitute a
voting agreement among the Stockholders pursuant to Section 78.365(3) of the
Nevada General

<Page>

Corporation Law. As used in this Agreement, the definition and determination of
a "Beneficial Owner" or "Beneficial Ownership" shall be governed by Regulation
13d-3 under the Securities Exchange Act of 1934, as amended.

     1.2       At each annual meeting or special meeting of the stockholders of
the Company, and at any other time at which stockholders of the Company will
have the right to or will vote for or render consent in writing, then and in
each event, each Stockholder hereby agrees:

          A.      To take all necessary and appropriate actions to cause all
Shares he or it Beneficially Owns to be represented at any such meeting or in
any such written consent and to cause a quorum to be present in any such event.

          B.      To vote or cause to be voted all Shares of which he or it is
the Beneficial Owner as follows:

               (i)      To amend, alter, modify or repeal the Articles of
Incorporation or the By-Laws of the Company (if at all) only in accordance with
the recommendation of five of the seven Directors of the Company (whether or not
any Board or stockholder action is required by law);

               (ii)     To fix and maintain the number of directors of the
Company at seven (7);

               (iii)    To elect or cause the election to and to maintain the
election to the Company's Board of Directors of the following:

               -        one (1) person nominated by Mi3, who shall initially be
                        William D. McPhee;

               -        one (1) person nominated by the holders of 80% of the
                        aggregate Shares Beneficially Owned by the Venture
                        Stockholders excluding Mi3, who shall initially be [ ];

               -        one (1) person nominated by the holders of 80% of the
                        aggregate Shares Beneficially Owned by the Chicago
                        Stockholders, who shall initially be Robert J.
                        Weinstein, M.D.;

               -        one (1) person appointed by the Company's Board of
                        Directors as the Chief Executive Officer of the Company,
                        who shall initially be Taffy Williams, Ph.D.;

               -        one (1) person nominated by Elan International Services,
                        Ltd. ("ELAN"), who shall initially be Aidan King, in
                        accordance with and subject to that certain Securities
                        Purchase Agreement dated as

                                        2
<Page>

                        of October 20, 1999 pursuant to which Elan has the right
                        to nominate one director to the Company's Board of
                        Directors; and

               -        two (2) persons (or in upon the event Elan no longer has
                        a right to nominate a director to the Company's Board of
                        Directors, three (3) persons) with relevant industry
                        experience in the healthcare, biotech or pharmaceutical
                        industries, as nominated by the Company's Board of
                        Directors and approved by 80% of the aggregate Shares
                        Beneficially Owned by the Venture Stockholders, who
                        shall initially be Gene Golub and Lester McKeever, Jr.

               (iv)     To remove from the Company's Board of Directors any
director nominated pursuant to paragraph 1.2(b)(iii) only at the request of the
entity or group nominating or approving such director, as applicable; and

               (v)      To fix and maintain an Audit Committee and Compensation
Committee of the Company's Board of Directors, each to consist of three (3)
directors, and to appoint one person nominated by the holders of 80% of the
aggregate Shares Beneficially Owned by the Venture Stockholders to serve on such
committees who shall initially be [     ];

     1.3       The Company shall provide the Stockholders entitled to nominate
directors hereunder prior notice of any intended mailing of notice to
Stockholders for a meeting at which any of the actions subject to paragraph 1.2
are to be acted upon. Thereafter, Stockholders entitled to nominate directors
hereunder shall notify the Company in writing, prior to such mailing, of the
person(s) nominated by him or it to be director(s); provided, that if a
Stockholder fails to give such notice to the Company, it shall be deemed that
the nominee(s) of such party for such meeting is the person(s) then serving as
director(s) pursuant to such Stockholders' previous nomination(s). If a
representative of Mi3 is not a director of the Company at any time, Mi3 shall
have the right to designate one person who shall be entitled to attend all Board
meetings as an observer and shall be provided with all notices of Board meetings
and all Board reports as if he or she were a member of the Company's Board of
Directors, provided (i) that such individual agrees to hold all information
confidential and not use such information for any purpose other than with
respect to the Mi3's investment in the Company; and (ii) that such individual
shall be subject to exclusion from portions of meetings as necessary to preserve
attorney-client privilege with respect to pending or threatened litigation..

2.        DRAG-ALONG AGREEMENT.

     2.1       If at any time after the third year anniversary of this Agreement
the Company receives an offer from a third party to purchase all or
substantially all of the assets or equity of the Company, and the Venture
Stockholders propose to sell a majority of their shares at that time, and the
sale has been approved by a majority of the Company's Board of Directors (with
the Chicago Stockholder nominee director recusing himself) (a "COMPANY SALE"),
then the Venture Stockholders shall have the right to require all, but not less
than all, of the Chicago Stockholders to sell to the prospective purchaser of
the Venture Stockholders' shares, a pro-rata

                                        3
<Page>

portion of such Chicago Shareholders' shares at the same time and on the same
conditions as the Venture Stockholders are selling their shares.

     2.2       The rights and obligations created in this Section 2 shall
terminate upon the consummation of an underwritten public offering pursuant to
an effective registration statement under the Securities Act of 1933, as
amended, covering the offering and sale of Common Stock for the account of the
Corporation on a firm commitment basis in which the gross proceeds received by
the Corporation at the public offering price equals or exceeds $20,000,000 (a
"TERMINATION EVENT").

     2.3       If the Venture Stockholders elect to exercise their rights under
this Section 2, the Venture Stockholders shall furnish a written notice (the
"DRAG ALONG NOTICE") to each Chicago Stockholder. The Drag Along Notice shall
set forth the principal terms of the proposed Company Sale insofar as it relates
to such Shares including (i) the number of Shares to be acquired from the
Venture Stockholders, (ii) the form and amount of the per share consideration to
be received in the proposed Company Sale, (iii) the name and address of the
prospective buyer and (iv) the proposed date of consummation of the proposed
Company Sale. If the Company Sale is consummated as described in the Drag Along
Notice, each Chicago Stockholder shall be bound and obligated to sell his or its
Shares in the proposed Sale on the same terms and conditions with respect to
each Share sold as the Venture Stockholders shall sell their Shares in the
Company Sale. Without limiting the generality of the foregoing, each Chicago
Stockholder agrees to execute and deliver such agreements as may be reasonably
specified by the Venture Stockholders to which such Venture Stockholders will
also be party, including, without limitation, agreements to (a) (i) make
individual representations, warranties, covenants and other agreements as to the
unencumbered title to his or its Shares and the power, authority and legal right
to transfer such Shares and the absence of any adverse claim with respect to
such Shares and (ii) be liable without limitation as to such representations,
warranties, covenants and other agreements, and (b) be liable (whether by
purchase price adjustment, indemnity payments or otherwise) in respect of
representations, warranties, covenants and agreements in respect of the Company
and its subsidiaries up to his or its pro-rata portion of the proceeds of such
Sale.

3.        RIGHT OF FIRST REFUSAL AGREEMENT. The provisions of this Section 3
shall not apply to transactions pursuant to Rule 144 of the Securities Act of
1933, as amended, or transactions pursuant to any registration statement under
the Securities Act.

     3.1       SALES TO THIRD PARTIES. If a Stockholder desires to transfer (a
"SELLING STOCKHOLDER") all or any part of the Shares beneficially owned by him
or it (the "OFFERED SHARES") in a privately-negotiated transaction pursuant to a
bona fide offer or proposed offer (the "PROPOSED OFFER SALE") from a third party
or a proposed offer to a third party (the "PROPOSED TRANSFEREE"), the Selling
Stockholder shall first submit a written offer (the "OFFER") to sell such
Offered Shares first to the Company, and second to the Venture Stockholders
(together, the "OFFEREES"), if applicable, on terms and conditions, including
without limitation price, not less favorable to the Company and the Offerees
than those on which the Selling Stockholder proposes to sell such Offered Shares
to the Proposed Transferee or otherwise pursuant to the Proposed Offer Sale in
accordance with the provisions of this Agreement.

                                        4
<Page>

          The Offer shall disclose the identity of and, if available,
information about the Proposed Transferee, and the terms of the Proposed Offer
Sale, the number of Offered Shares proposed to be sold, the total number of
Shares owned by the Selling Stockholder, the terms and conditions, including
without limitation, price, of the proposed sale, and any other material terms
and facts relating to the proposed sale which may be requested by the Company
and the Offerees, as the case may be. The Offer shall further state that the
Company and the Offerees may acquire, in accordance with the provisions of this
Agreement, all of the Offered Shares (but not less than all of the Offered
Shares) for the price indicated in the Offer and upon the other terms and
conditions, including deferred or installment payment (if applicable), set forth
therein.

          In the event the terms of the Proposed Offer Sale contemplate the
payment to the Selling Stockholder of consideration other than cash, the value
of such non-cash consideration shall be determined in good faith by the
disinterested members of the Company's Board of Directors; provided that if the
Proposed Transferee offers the Selling Stockholder (i) securities that are
traded on a nationally-recognized stock exchange or quoted on the Nasdaq
National Market, then the value of such consideration shall be the average
closing sale prices for the 10 consecutive trading days preceding the date of
the Offer, or (ii) securities that are traded on the Nasdaq over-the-counter
market or Small-Cap market, the value of such consideration shall be the average
of the closing bid and closing asked prices for the 20 consecutive trading days
preceding the date of the Offer as reported in the Wall Street Journal or by any
market maker.

     3.2       COMPANY'S RIGHT OF FIRST REFUSAL. Upon receipt of the Offer, the
Company shall deliver a written notice of its election to purchase, or not to
purchase, such shares to the Selling Stockholder and the Offerees. The notice
shall be delivered in person or mailed to the Selling Stockholder and the
Offerees within 15 days of the date of receipt by the Company of the Offer. Such
notice, if to purchase the Offered Shares, shall, when taken in conjunction with
the Offer, be deemed to constitute a valid, legally binding and enforceable
agreement for the sale to, and purchase by, the Company of the number of Offered
Shares specified by the Company in such notice and on the terms of the Offer.
The Company's election not to participate in an Offer shall be without prejudice
to the Company's rights to participate in any future Offers in accordance with
this Section 3.

     The closing of the sale of Offered Shares to the Company pursuant to this
Section shall be made at the offices of the Company on such date as may be
agreed upon by the Company and the Selling Stockholder, but no later than on or
before the 45th day following the date the Offer is received by the Company (or
if such 45th day is not a business day, then on the next succeeding business
day). Such sale shall be effected by the Selling Stockholder's delivery to the
Company of a certificate(s) evidencing the Offered Shares (or any portion
thereof) to be purchased by the Company, duly endorsed for transfer to the
Company, against payment to the Selling Stockholder of the purchase price by the
Company.

     3.3       OFFEREES' RIGHT OF SECOND REFUSAL. Upon receipt of the Offer, and
subject to the prior right of the Company under Section 3.2 above, if the
Offerees also desire to purchase all or any part of the Offered Shares not so
purchased by the Company, the Offerees shall deliver a written notice of its
election to purchase or not to purchase such shares to the Selling Stockholder
and the Company. In the event that one or more of the Offerees wish to

                                        5
<Page>

purchase all or any part of the Offered Shares, not so purchased by the Company,
then each such of the Offerees shall have the right to purchase that number of
shares equal to the number of such Offered Shares to be sold multiplied by a
fraction, the numerator of which shall be the number of shares of capital stock
of the Company (calculated on an as-converted basis, and assuming the conversion
or exercise of all rights, options, warrants or convertible securities) then
owned by such Offeree desiring to purchase the Offered Shares, as the case may
be, and the denominator of which shall be the aggregate number of shares of
capital stock of the Company (calculated on an as-converted basis, and assuming
the conversion or exercise of all rights, options, warrants or convertible
securities) owned by all of the Offerees. An Offeree's election not to
participate in an Offer shall be without prejudice to the Offeree's rights to
participate in any future Offers in accordance with this Section 3.

          The notice shall be delivered in person or mailed to the Selling
Stockholder and the Company within fifteen (15) days of the date of receipt by
the Offerees of the Offer. Such notice, if to purchase the Offered Shares,
shall, when taken in conjunction with the Offer, and subject to the prior right
of the Company under Section 3.2 above, be deemed to constitute a valid, legally
binding and enforceable agreement for the sale to, and purchase by, the Offerees
of the number of Offered Shares specified by the Offerees in such notice and on
the terms of the Offer.

          The closing of the sale of Offered Shares to the Offerees pursuant to
this Section 3.3 shall be made at the offices of the Company on such date as may
be agreed upon by the Offerees and the Selling Stockholder, but no later than on
or before the 45th day following the date the Offer is received by the Company
(or if such 45th day is not a business day, then on the next succeeding business
day). Such sale shall be effected by the Selling Stockholder's delivery to the
Offerees of a certificate(s) evidencing the Offered Shares (or any portion
thereof) to be purchased by the Offerees, duly endorsed for transfer to the
Offerees, against payment to the Selling Stockholder of the purchase price by
the Offerees.

     3.4       SALES TO PROPOSED TRANSFEREE. In order for the provisions of
Section 3.1 to be valid and binding on the Selling Stockholder to restrict
transfers to a third party, the Company and the Offerees, must, as amongst
themselves, purchase all, and not less than all, of the Offered Shares. If the
Company and the Offerees do not purchase all (and, as amongst themselves, not
less than all) of the Offered Shares, the Offered Shares may be sold by the
Selling Stockholder to the Proposed Transferee at any time within 180 days after
the date the Offer was made pursuant to the Proposed Offer Sale. Any such sale
shall be at the same or greater price and upon other terms and conditions, if
any, not more favorable to the transferee than those specified in the Offer. Any
Offered Shares not sold within the permitted time period shall continue to be
subject to the requirements of a prior offer and right of first refusal pursuant
to Section 3.1.

     3.5       NO OTHER TRANSFERS. A Stockholder shall not sell, assign,
transfer, grant an option to or for, pledge, hypothecate, mortgage, encumber or
dispose of all or any of his or its shares of capital stock of the Company
except as expressly provided in this Agreement. If a Stockholder becomes
obligated to sell to a Venture Stockholder any Shares as a Selling Stockholder
under this Agreement and fails to deliver the Shares in accordance with the
terms of

                                        6
<Page>

this Agreement, such Venture Stockholder may, at its option, upon ten days'
prior written notice to the Company and the Selling Stockholder, in addition to
all other remedies it may have, send to the Company for the benefit of the
Selling Stockholder the purchase price for such shares as is herein specified.
Thereupon, the Company upon written notice to the Selling Stockholder shall (a)
cancel on its books the certificate(s) representing the shares to be sold, (b)
issue, in lieu thereof, in the name of such Venture Stockholder(s), a new
certificate(s) representing such shares, and (c) pay or tender the proceeds paid
by the Venture Stockholder to the Selling Stockholder, and thereupon all of the
Selling Stockholder's rights in and to such shares shall terminate. The Company
may exercise a similar remedy in enforcing its rights under Section 3.1. If a
Selling Stockholder transfers any shares to a Proposed Transferee in violation
of this Agreement, the Company may, at the election of a majority of the
disinterested members of the Company's Board of Directors, cancel on the books
of the Company any shares of capital stock then held by such Proposed Transferee
and compel such Selling Stockholder to purchase from the Proposed Transferee the
shares of capital stock so transferred in violation of this Agreement.

     3.6       TERM. The rights and obligations created in this Section 3 shall
terminate upon the consummation of a Termination Event.

4.        LEGEND ON STOCK CERTIFICATE. Each certificate representing Shares
covered by this Agreement is subject to and shall bear the restrictive legend
set forth below:

     The stock evidenced by this certificate is subject to a Voting,
     Drag-Along and Right of First Refusal Agreement dated as of July
     [ ], 2002, as amended from time to time. Copies of the Agreement
     may be obtained from the Secretary of the Company at no cost by
     written request of the holder of record of this certificate.

5.        GENERAL PROVISIONS.

     5.1       Each of the parties hereto agrees that he or it will do (or cause
to be done) any act or thing and will execute (or cause to be executed) any and
all instruments necessary and/or proper to make effective the provisions of this
Agreement. Each Stockholder represents and warrants to, and agrees with, each
other party hereto that (a) any transferee holding Shares over which such
Stockholder remains the Beneficial Owner shall execute and deliver a counterpart
of this Agreement and shall be bound by the provisions hereof as if such
transferee was an original party hereto; and (b) such Stockholder shall provide
each other party hereto true and complete information concerning the Beneficial
Ownership of Shares in the hands of transferees. The parties are executing this
Agreement in all applicable individual and representative capacities (including
as attorney-in-fact or joint tenant, and as stockholder, officer, director,
trustee, general partner or limited partner of any entity which Beneficially
Owns Common Stock of the Company attributable to that party). This Agreement
shall be binding upon and inure to the benefit of the parties hereto and their
legal representatives, heirs and legatees.

     5.2       The section headings in this Agreement are inserted for
convenience of reference only, and shall not affect the construction or
interpretation of this Agreement.

                                        7
<Page>

     5.3       The failure at any time to enforce any of the provisions of this
Agreement shall not be construed as a waiver of such provisions and shall not
affect the right of any party thereafter to enforce each and every provision of
this Agreement in accordance with its terms.

     5.4       This Agreement shall be governed by and construed in accordance
with the laws of the Commonwealth of Massachusetts without giving effect to
conflict of laws principles thereof, except to the extent the Nevada General
Corporation Law govern portions hereof.

     5.5       It is acknowledged that it will be impossible to measure the
damages that would be suffered by any party if another party fails to comply
with the provisions of this Agreement and that in the event of any such failure,
the non-defaulting party will not have an adequate remedy at law. The
non-defaulting party shall, therefore, be entitled to obtain specific
performance of any defaulting party's obligations hereunder and to obtain
immediate injunctive relief. The defaulting party shall not argue, as a defense
to any proceeding for such specific performance or injunctive relief, that the
non-defaulting party has an adequate remedy at law.

     5.6       This Agreement may be executed in one or more counterparts, each
of which shall be deemed to be an original and shall be enforceable against the
party executing the same, and all of which together shall constitute a single
Agreement. In making proof of this Agreement, it shall not be necessary to
produce or account for more than one such counterpart.

     5.7       Whenever possible, each provision of this Agreement shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Agreement shall be held to be invalid by a court of
competent jurisdiction, the remaining provisions shall remain in full force and
effect and the provision held invalid shall be modified to the extent necessary
to be valid and shall be enforced as modified.

     5.8       Any notice to be served under this Agreement shall be in writing
and shall be deemed to be delivered or given upon receipt if delivered
personally, by overnight courier or by telecopier, or two days after mailing by
registered mail, return receipt requested, addressed as follows:

     If to the Company:                 Photogen Technologies, Inc.
                                        To its then current address
                                        Attention: President

     If to any Stockholder:             To such Stockholder's address on file in
                                        the stock records of the Company

or to such other place as a party may specify in writing, delivered in
accordance with the provisions of this subsection.

     5.9       This Agreement constitutes the full and entire understanding and
agreement of the parties with regard to the subject hereof, and supersedes any
prior agreement or understanding, written or oral, with respect to such subject
matter. No party shall be liable or

                                        8
<Page>

bound by any representations, warranties or agreements, or any other information
or materials previously delivered, whether written or oral, regarding such
subject matter.

     5.10      This Agreement may be modified or amended in any respect upon the
written approval of the holders of 90% of the Shares held by the parties hereto,
and as so modified or amended, this Agreement shall continue to bind all
Stockholders regardless of whether they consented to such modification or
amendment.

                         [Next Page is Signature Page.]

                                        9
<Page>

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first written above.



                                      ------------------------------------------
                                      ROBERT J. WEINSTEIN, M.D.,
                                      individually and as Director of the Robert
                                      and Lois Weinstein Family Foundation, Inc.
                                      and as Trustee of the Robert and Lois
                                      Weinstein Joint Revocable Trust



                                      ------------------------------------------
                                      STUART LEVINE, individually and as Trustee
                                      of the Theodore Tannebaum Trust



                                      ------------------------------------------
                                      TANNEBAUM LLC
                                      By:
                                      Its:


                                      Mi3 L.P.

                                            By: MI3 Services L.L.C., its General
                                                 Partner

                                            By:
                                               ---------------------------------
                                            William D. McPhee, President


                                      OXFORD BIOSCIENCE PARTNERS IV L.P.

                                            By: OBP Management IV L.P.

                                            By:
                                               ---------------------------------
                                            Jonathan J. Fleming - General
                                             Partner

                                      MRNA FUND II L.P.

                                            By:  OBP Management IV L.P.

                                            By:
                                               ---------------------------------
                                            Jonathan J. Fleming - General
                                             Partner


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

                                       10
<Page>

                                      NEW ENGLAND PARTNERS CAPITAL, L.P.

                                            By: NEP Capital LLC, its General
                                                 Partner

                                            By:
                                               ---------------------------------
                                            John Rousseau, President

                                       11



<Page>


                EXHIBIT C to the Common Stock Purchase Agreement
                                (SECTION 3.10(B))
                        FORM OF CONFIDENTIALITY AGREEMENT

                   Proprietary Rights, Employee Restrictions*

                    [Photogen Technologies, Inc. letterhead]

                                     [Date]


          RE:    EMPLOYEE CONFIDENTIALITY, INVENTIONS AND
                 NONCOMPETITION AGREEMENT ("AGREEMENT")

Dear _________________:

          In the course of your work for Photogen Technologies, Inc. or any of
its subsidiaries existing on and after the date hereof (collectively,
"Photogen"), you may have access to Photogen's confidential and proprietary
information and/or you may create Developments (defined below). For legally
sufficient consideration, the receipt and adequacy of which you acknowledge, you
and Photogen agree as follows:

          1.     Definitions. The following terms are defined for purposes of
this Agreement:

          (a)    "Confidential Information" means any and all information that
has or could have value or utility to Photogen, whether or not reduced to
written or other tangible form and all copies thereof, relating to Photogen's
private or proprietary matters, confidential matters or trade secrets.
Confidential Information includes, but is not limited to, the following:

          (i)    technical information (whether or not subject to patent
     registration or protection), such as research and development, methods,
     trade secrets, know-how, formulas, compositions, protocols, processes and
     techniques, discoveries, machines, inventions, ideas, computer programs
     (including software and data used in all such programs), drawings,
     specifications;

          (ii)   except to the extent publicly disclosed by Photogen without any
     fault by you or any other person or entity, information relating to
     Photogen's patents, patent applications, and patent disclosures, together
     with all reissuances, continuations, continuations-in-part, revisions,
     extensions, and reexaminations thereof, and all improvements and inventions
     related thereto;

          (iii)  business information, such as information concerning any
     products, customers, suppliers, production, developments, costs,
     purchasing,

----------
* Employees and consultants have signed non-disclousure and inventions
agreements in substance comparable to the Exhibit C.

<Page>


     pricing, profits, markets, sales, accounts, customers, financing,
     acquisitions, strategic alliances or collaborations, expansions; and

          (iv)   other information relating to Photogen's business practices,
     strategies or policies.

          (b)    "Competitive Business" means engaging in the research,
development, sale, lease, marketing, financing or distribution of technology,
products or services similar to or competitive with Photogen's actual or
proposed products or services anywhere in the world.

          (c)    "Development" means any invention, discovery, improvement,
know-how, method, technique, work, copyrightable work or other intellectual
property (whether or not patentable or subject to registration with any
governmental office) you conceive, reduce to practice, discover or make, alone
or with others, during your employment and for twelve (12) months after
termination (regardless of the reason for termination) that either is (i)
related to or may be useful in the business or demonstrably anticipated business
of Photogen, (ii) includes, or is a product or extension of, any Confidential
Information, or (iii) results from duties assigned to you by Photogen or from
the use of any of Photogen's assets or facilities.

          (d)    "Restricted Period" means a period (i) starting when you begin
working for Photogen, and (ii) ending on the earlier of: (A) twenty-four (24)
months after termination of your employment (regardless of the reason for
termination), or (B) if you work less than a total of 24 months, that number of
months after termination of your employment which equals the total number of
months you worked for Photogen (for example, if you work for Photogen for a
total of six months, the Restricted Period will end six months after your
employment terminates), or (C) the longest period (if any) permitted by
applicable law after termination of your employment which is less than 24
months.

          2.     Confidential Information. (a) During your employment by
Photogen and at all times thereafter, you will hold in trust, keep confidential
and not disclose, directly or indirectly, to any third parties or make any use
of Confidential Information (defined below) for any purpose except for the
benefit of Photogen in the performance of your employment duties. Confidential
Information will not be subject to these restrictions if it becomes generally
known to the public or in the industry without any fault by you or any other
person or entity, or if Photogen ceases to have a legally protectable interest
in it. If you are required by valid subpoena or similar legal requirement to
disclose Confidential Information, you will promptly notify Photogen in writing
and cooperate with Photogen's efforts to obtain a protective order or similar
relief, and you will only disclose the minimum amount of Confidential
Information necessary. Upon termination of your employment (regardless of the
reason for termination), you will immediately return to Photogen all tangible
Confidential Information and any other material made or derived from
Confidential Information, including information stored in electronic format and
handwritten notes, which is in your possession or which you delivered to others.

<Page>


          3.     Developments. You agree to promptly and fully disclose in
writing to Photogen, Inc.'s President any Development when created or developed.
You hereby assign and transfer to Photogen, Inc. all of your right, title and
interest in and to all Developments, including all patents, patent applications
and related patent rights. You agree to sign and deliver to Photogen, Inc.
(during and after employment) other documents Photogen, Inc. considers necessary
or desirable to evidence its ownership of Developments. All copyrightable works
that are Developments, whether or not works made for hire (as defined in 17
U.S.C. Section 101), shall be owned by Photogen, Inc. and it may file and own
the same as the author throughout the world. If Photogen, Inc. is unable for any
reason to secure your signature on any document necessary or desirable to apply
for, prosecute, obtain, or enforce any patent, trademark, service mark,
copyright, or other right or protection relating to any Development, you hereby
irrevocably designate and appoint Photogen, Inc. and each of its duly authorized
officers and agents, as your agent and attorney-in-fact to act for and in your
behalf and stead to execute and file any such document and to do all other
lawfully permitted acts to further the prosecution, issuance, and enforcement of
patents, trademarks, service marks, copyrights, or other rights or protections
with the same force and effect as if personally executed and delivered by you.
You agree that this power of attorney is irrevocable and is coupled with an
interest and thereby survives your death or disability.

          4.     Noncompetition.

          (a)    You acknowledge that you may have access to a significant
amount of highly sensitive and valuable Confidential Information, you may be
involved in formulating Photogen's business strategies or in its research and
development activities, and you may be involved in important aspects of
relationships with employees, consultants, suppliers, customers and others and
you will be expected to promote Photogen's business and goodwill. You also
acknowledge that Photogen's business is international in scope and that
Photogen's employees and customers in any location can be solicited and serviced
from any other location in the world.

          (b)    You therefore agree that during the Restricted Period, you will
not, directly or indirectly through any other person or entity:

          (i)    own, manage, control, participate in, consult with, be employed
     by, or render services for, any person or entity engaged in a Competitive
     Business or in any other manner or in any other capacity (except as owner
     of 2% or less of stock of a publicly registered and traded entity) engage
     in any Competitive Business;

<Page>


          (ii)   solicit, induce or attempt to influence any other person or
     entity to engage in any Competitive Business or to curtail or cease any
     business or business relationship with the Company, its affiliates,
     employees or independent contractors;

          (iii)  solicit any other employee or independent contractor to
     terminate any employment or engagement with the Company and engage in a
     Competitive Business; or

          (iv)   disparage the Company, its affiliates, employees, independent
     contractors or their services or products.

          5.     No Conflicts. You represent and warrant to, and agree with
Photogen that:

          (a)    You are under no contractual or other obligation or restriction
which is inconsistent with your obligations under this Agreement or the
performance of your employment duties for Photogen. Without limiting the
generality of the foregoing, performing your employment duties for Photogen will
not cause you to breach any agreement or other duty which obligates you to keep
in confidence any confidential, proprietary, trade secret or similar information
of any third party or to refrain from competing, directly or indirectly, with
the business of any third party.

          (b)    You have set forth in a separate list attached to this
Agreement as Exhibit A an accurate and complete list of all confidential,
proprietary or trade secret information (including invention disclosures and
patent applications), including a brief description thereof (without revealing
any confidential or proprietary information of any other party), which you made
or conceived prior to your employment with Photogen and for which you claim
ownership or which is in the physical possession of a former employer or other
person or entity and which are therefore excluded from the scope of this
Agreement. If there are no such exclusions, you have so indicated by writing
"none."

          (c)    Neither you nor any third party has any ownership or other
interest in any idea, invention or other item of intellectual property that will
be used in performing your duties for Photogen, and all Developments will be
free and clear of any encumbrances or claims of third parties. In performing
your duties for Photogen, you will not disclose to Photogen or use any
confidential or proprietary information or trade secret of any third party, and
you will not interfere with the business of any third party in any way contrary
to applicable law.

          (d)    In performing your duties for Photogen, you will comply with
applicable laws and regulations.

          6.     No Employment Rights. Nothing in this Agreement shall affect
your or Photogen's right to terminate your employment or Photogen's right modify
the

<Page>


terms of your employment, nor will this Agreement confer on you any other rights
or benefits in connection with your employment.

          7.     Severability; Choice of Law; Injunction. If any provision of
this Agreement is deemed by a court of competent jurisdiction to be
unenforceable or invalid, the enforceability and validity of all other
provisions shall not be affected and that court shall modify the unenforceable
or invalid provision to the extent necessary to render it enforceable and valid
and that provision shall be enforced as modified. You agree that the time
period, geographic scope and other terms of the covenants and restrictions in
this Agreement are reasonable and appropriate under the circumstances of
Photogen's business. This Agreement shall be governed and interpreted in
accordance with the laws of the State of Tennessee without regard to its
provisions on conflicts of law. Without limiting any other available remedies at
law or in equity, Photogen will be entitled to injunctive relief restraining any
individual or entity from participating in any breach or threatened breach of
this Agreement without having to post a bond or security.

          8.     Miscellaneous. This Agreement may not be amended or modified
except by a written instrument signed by both parties after the date of this
Agreement. This Agreement may be assigned by Photogen and shall inure to the
benefit of Photogen, its successors and assigns, but may not be assigned or
delegated by you. This Agreement supersedes all prior agreements, negotiations
and representations, written or oral, between the parties with respect to the
subject matter contained herein. Any waiver of any breach of, or failure to
enforce, any of the provisions of this Agreement shall not operate as a waiver
of any other breach or waiver of performance of such provisions or any other
provisions. Any waiver must be in writing signed by Photogen. Your obligations
under this Agreement survive termination of your employment, regardless of the
manner or reason for termination. During, and upon termination of your
employment (regardless of the reason therefor), you will certify to Photogen in
writing that you have fully complied with each provision of this Agreement and
that you will continue to comply with all provisions herein that survive
termination.

          Please indicate your agreement to the foregoing by signing a copy of
this letter below and returning it to me. I look forward to working with you.

                                        Very truly yours,


                                        Taffy J. Williams, Ph.D., President

Accepted and Agreed to
as of __________, 2002.

By:
   ----------------------------------
Print name:
           --------------------------

<Page>


                EXHIBIT A (TO FORM OF CONFIDENTIALITY AGREEMENT)
               EMPLOYEE'S INTELLECTUAL PROPERTY EXCLUDED FROM THIS
                                    AGREEMENT


Describe:


(If none, write "none" above.)


Signed:
       -----------------------------
Dated:
      -------------------------------

<Page>

                 EXHIBIT D to the Common Stock Purchase Agreement
                               (SECTION 5.2.5(c))
                           AMENDED AND RESTATED BYLAWS


                           AMENDED AND RESTATED BYLAWS
                                       OF
                           PHOTOGEN TECHNOLOGIES, INC.

                                ARTICLE I OFFICES

     Section 1. PRINCIPAL EXECUTIVE OFFICE. The principal executive office of
the corporation may be located within or without the State of Nevada. The Board
of Directors (herein called the "Board") is hereby granted full power and
authority to change the principal executive office or the location of any other
corporate office from one location to another.

     Section 2. OTHER OFFICES. Branch or subordinate offices may at any time be
established by the Board at any place or places.

                             ARTICLE II STOCKHOLDERS

     Section 1. PLACE OF MEETINGS. Meetings of stockholders shall be held either
at the principal executive office of the corporation or at any other place
within or without the State of Nevada which may be designated either by the
Board or by the written consent of all persons entitled to vote thereat, given
either before or after the meeting and filed with the Secretary.

     Section 2. ANNUAL MEETINGS. The annual meetings of stockholders shall be
held on the last Tuesday of each April, at 10:00 o'clock a.m., local time, or
such other date or such other time as may be fixed by the Board. At such
meetings, directors shall be elected and any other proper business may be
transacted.

     Section 3. SPECIAL MEETINGS. Special meetings of the stockholders may be
called at any time by the Board, the Chairman of the Board, the President, or by
the holders of shares entitled to cast not less than ten percent of the votes at
such meeting. Upon request in writing to the Chairman of the Board, the
President, any Vice President or the Secretary by any person (other than the
Board) entitled to call a special meeting of stockholders, the officer forthwith
shall cause notice to be given in writing to the stockholders entitled to vote
that a meeting will be held at a time requested by the person or persons calling
the meeting, not less than ten nor more than sixty days after the receipt of the
request.

     Section 4. NOTICE OF ANNUAL OR SPECIAL MEETINGS. Written notice of each
annual or special meeting of stockholders shall be given not less than ten nor
more than sixty days before the date of the meeting to each stockholder entitled
to vote thereat. Such notice shall state the place, date, and hour of the
meeting and (a) in the case of a special meeting, the general nature of the
business to be transacted, and no other business may be transacted, or (b) in
the case of the annual meeting, those matters which the

<Page>

Board, at the time of the mailing of the notice, intends to present for action
by the stockholders, but, subject to the provisions of applicable law, any
proper matter may be presented at the meeting for such action. The notice of any
meeting at which directors are to be elected shall include the names of nominees
intended at the time of the notice to be presented by management for election.
Notice of a stockholders' meeting shall be given either by mail or by other
means of written communication, addressed to the stockholder at the address of
such stockholder appearing on the books of the corporation or given by the
stockholder to the corporation for the purpose of notice, or, if no such address
appears or is given, at the place where the principal executive office of the
corporation is located or by publication at least once in a newspaper of general
circulation in the county in which the principal executive office is located.
Notice by mail shall be deemed to have been given at the time a written notice
is deposited in the United States mails, postage prepaid. Any other written
notice shall be deemed to have been given at the time it is personally delivered
to the recipient or is delivered to a common carrier for transmission, or
actually transmitted by the person giving the notice by electronic means, to the
recipient.

     Section 5. QUORUM. A majority of the shares entitled to vote, represented
in person or by proxy, shall constitute a quorum at any meeting of stockholders.
If a quorum is present, the affirmative vote of the majority of the shares
represented at the meeting and voting at the meeting (which shares voting
affirmatively also constitute at least a majority of the required quorum) shall
be the act of the stockholders, unless the vote of a greater number or voting by
classes is required by law, by the Articles of Incorporation or the Bylaws and
except as provided in the following sentence. The stockholders present at a duly
called or held meeting at which a quorum is present may continue to do business
until adjournment, notwithstanding the withdrawal of enough stockholders to
leave less than a quorum, if any action taken (other than adjournment) is
approved by at least a majority of the shares required to constitute a quorum.

     Section 6. ADJOURNED MEETINGS AND NOTICE THEREOF. Any stockholders'
meeting, whether or not a quorum is present, may be adjourned from time to time
by the vote of a majority of the shares, represented either in person or by
proxy, but in the absence of a quorum (except as provided in Section 5 of this
Article) no other business may be transacted at such meeting. It shall not be
necessary to give any notice of the time and place of the adjourned meeting or
of the business to be transacted thereat, other than by announcement at the
meeting at which such adjournment is taken; provided, however, when any
stockholders' meeting is adjourned for more than forty-five days, or if after
adjournment a new record date is fixed for the adjourned meeting, notice of the
adjourned meeting shall be given as in the case of an original meeting.

     Section 7. VOTING. The stockholders entitled to notice of any meeting or to
vote at any such meeting shall be only persons in whose name shares stand on the
stock records of the corporation on the record date determined in accordance
with Section 8 of this Article. Voting shall in all cases be subject to the
provisions of Title 7 of the Nevada Revised Statutes and to the following
provisions:

                                        2
<Page>

     (a)   Shares held by an administrator, executor, guardian, conservator or
custodian may be voted by such holder either in person or by proxy, without a
transfer of such shares into the holder's name; and shares standing in the name
of a trustee may be voted by the trustee, either in person or by proxy, but no
trustee shall be entitled to vote shares held by such trustee without a transfer
of such shares into the trustee's name.

     (b)   Shares standing in the name of a receiver may be voted by such
receiver, and shares held by or under the control of a receiver may be voted by
such receiver without the transfer thereof into the receiver's name if authority
to do so is contained in an order of the court by which such receiver was
appointed.

     (c)   Subject to the provisions of Title 7 of the Nevada Revised Statutes,
and except where otherwise agreed in writing between the parties, a stockholder
whose shares are pledged shall be entitled to vote such shares until the shares
have been transferred into the name of the pledgee, and thereafter the pledgee
shall be entitled to vote the shares so transferred.

     (d)   Shares standing in the name of a minor may be voted and the
corporation may treat all rights incident thereto as exercisable by the minor,
in person or by proxy, whether or not the corporation has notice, actual or
constructive, of the minority, unless a guardian of the minor's property has
been appointed and written notice of such appointment given to the Secretary of
the corporation.

     (e)   Shares standing in the name of another corporation, domestic or
foreign, may be voted by such officer, agent or proxyholder as the bylaws of
such other corporation may prescribe or, in the absence of such provision, as
the Board of Directors of such other corporation may determine or, in the
absence of such determination, by the chairman of the board, president or any
vice president of such other corporation. Shares which are purported to be voted
or any proxy purported to be executed in the name of a corporation (whether or
not any title of the person signing is indicated) shall be presumed to be voted
or the proxy executed in accordance with the provisions of this clause, unless
the contrary is shown.

     (f)   If shares stand of record in the names of two or more persons,
whether fiduciaries, members of a partnership, joint tenants, tenants in common,
husband and wife as community property, tenants by the entirety, voting
trustees, persons entitled to vote under a stockholder voting agreement or
otherwise, or if two or more persons (including proxyholders) have the same
fiduciary relationship respecting the same shares, unless the Secretary of the
corporation is given written notice to the contrary and is furnished with a copy
of the instrument or order appointing them or creating the relationship wherein
it is so provided, their acts with respect to voting shall have the following
effect:

           (i)    If only one votes, such act binds all;

           (ii)   If more than one vote, the act of the majority so voting binds
all; and

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           (iii)  If more than one vote, but the vote is evenly split on any
particular matter, each faction may vote the securities in question
proportionately. If the instrument so filed or the registration of the shares
shows that any such tenancy is held in unequal interests, a majority or even
split for the purpose of this section shall be a majority or even split in
interest.

     (g)   No stockholder shall be entitled to cumulate votes at any election of
directors. Elections need not be by ballot; provided, however, that all
elections for directors must be by ballot upon demand made by the Chairman of
the Board or by a majority of the outstanding shares entitled to vote therefor
at the meeting and before the voting begins.

     Section 8. RECORD DATE. The Board may fix, in advance, a record date for
the determination of the stockholders entitled to notice of any meeting or to
vote, or entitled to receive payment of any dividend or other distribution, or
any allotment of rights, or to exercise rights in respect of any other lawful
action. The record date so fixed shall be not more than sixty days prior to the
date of the meeting nor more than sixty days prior to any other action. When a
record date is so fixed, only stockholders of record on that date are entitled
to notice of and to vote at the meeting or to receive the dividend,
distribution, or allotment of rights, or to exercise of the rights, as the case
may be, notwithstanding any transfer of shares on the books of the corporation
after the record date. A determination of stockholders of record entitled to
notice of or to vote at a meeting of stockholders shall apply to any adjournment
of the meeting unless the Board fixed a new record date for the adjourned
meeting. The Board shall fix a new record date if the meeting is adjourned for
more than forty-five days. If no record date is fixed by the Board, the record
date for determining stockholders entitled to notice of or to vote at a meeting
of stockholders shall be at the close of business on the business day next
preceding the day on which notice is given or, if notice is waived, at the close
of business on the business day next preceding the day on which the meeting is
held. The record date for determining stockholders for any purpose other than as
set forth in this Section 8 or Section 10 of this Article shall be at the close
of business on the day on which the Board adopts the resolution relating
thereto, or the sixtieth day prior to the date of such other action, whichever
is later.

     Section 9. CONSENT OF ABSENTEES. The transactions of any meeting of
stockholders, however called and noticed, and wherever held, are as valid as
though had at a meeting duly held after regular call and notice, if a quorum is
present either in person or by proxy, and if, either before or after the
meeting, each of the persons entitled to vote, not present in person or by
proxy, signs a written waiver of notice, or a consent to the holding of the
meeting or an approval of the minutes thereof. All such waivers, consents, or
approvals shall be filed with the corporate records or made a part of the
minutes of the meeting. Attendance of a person shall constitute a waiver of
notice of and presence at such meeting, except when the person objects, at the
beginning of the meeting, to the transaction of any business because the meeting
is not lawfully called or convened and except that attendance at a meeting is
not a waiver of any right to object to the consideration of matters required by
Title 7 of the Nevada Revised Statutes to be

                                        4
<Page>

included in the notice but not so included, if such objection is expressly made
at the meeting. Neither the business to be transacted at nor the purpose of any
regular or special meeting of stockholders need be specified in any written
waiver of notice, consent to the holding of the meeting or approval of the
minutes thereof, except as provided in Title 7 of the Nevada Revised Statutes.

     Section 10. ACTION WITHOUT MEETING. Any action which under any provision of
Title 7 of the Nevada Revised Statutes may be taken at any annual or special
meeting of stockholders, may be taken without a meeting and without prior notice
if a consent in writing, setting forth the action so taken, shall be signed by
the holders of outstanding shares having not less than the minimum number of
votes that would be necessary to authorize or take such action at a meeting at
which all shares entitled to vote thereon were present and voted. Unless a
record date for voting purposes be fixed as provided in Section 8 of this
Article, the record date for determining stockholders entitled to give consent
to pursuant to this Section 10, when no prior action by the Board has been
taken, shall be the day on which the first written consent is given.

     Section 11. PROXIES. Every person entitled to vote shares has the right to
do so either in person or by one or more persons authorized by a written proxy
executed by such stockholder and filed with the Secretary. Any proxy duly
executed is not revoked and continues in full force and effect until revoked by
the person executing it prior to the vote pursuant thereto by a writing
delivered to the Secretary of the corporation stating that the proxy is revoked
or by a subsequent proxy executed by the person executing the prior proxy and
presented to the meeting, or by attendance at the meeting and voting in person
by the person executing the proxy.

     Section 12. INSPECTORS OF ELECTION. In advance of any meeting of
stockholders, the Board may appoint inspectors of election to act at such
meeting and any adjournment thereof. If inspectors of election be not so
appointed, or if any persons so appointed fail to appear or refuse to act, the
chairman of any such meeting may, and on the request of any stockholder or
stockholder's proxy shall, make such appointment at the meeting. The number of
inspectors shall be either one or three. If appointed at a meeting on the
request of one or more stockholders or proxies, the majority of shares present
shall determine whether one or three inspectors are to be appointed. The duties
of such inspectors shall be as prescribed by Title 7 of the Nevada Revised
Statutes and shall include: determining the number of shares outstanding and the
voting power of each; determining the shares represented at the meeting;
determining the existence of a quorum; determining the authenticity, validity,
and effect of proxies; receiving votes, ballots, or consents; hearing and
determining all challenges and questions in any way arising in connection with
the right to vote; counting and tabulating all votes or consents, determining
when the polls shall close; determining the result; and doing such acts as may
be proper to conduct the election or vote with fairness to all stockholders. If
there are three inspectors of election, the decision, act, or certificate of a
majority is effective in all respects as the decision, act, or certificate of
all.

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     Section 13. CONDUCT OF MEETING. The Chairman of the Board shall preside as
Chairman at all meetings of the stockholders. The Chairman shall conduct each
such meeting in a businesslike and fair manner, but shall not be obligated to
follow any technical, formal or parliamentary rules or principles of procedure.
The Chairman's rulings on procedural matters shall be conclusive and binding on
all stockholders, unless at the time of a ruling a request for a vote is made to
the stockholders entitled to vote and represented in person or by proxy at the
meeting, in which case the decision of a majority of such shares shall be
conclusive and binding on all stockholders. Without limiting the generality of
the foregoing, the Chairman shall have all of the powers usually vested in the
chairman of a meeting of stockholders.

     Section 14. PARTICIPATION IN MEETING BY CONFERENCE TELEPHONE. Stockholders
may participate in a meeting of the stockholders by means of conference
telephone or similar method of communication by which all persons participating
in the meeting can hear one another.

                              ARTICLE III DIRECTORS

     Section 1. POWERS. Subject to limitations of the Articles of Incorporation,
these Bylaws, and Title 7 of the Nevada Revised Statutes relating to action
required to be approved by the stockholders or by the outstanding shares, the
business and affairs of the corporation shall be managed and all corporate
powers shall be exercised by or under the direction of the Board. The Board may
delegate the management of the day-to-day operation of the business of the
corporation to its officers, provided that the business and affairs of the
corporation shall be managed and all corporate powers shall be exercised under
the ultimate direction of the Board. Without prejudice to such general powers,
but subject to the same limitations, it is hereby expressly declared that the
Board shall have the following powers in addition to the other powers enumerated
in these Bylaws:

     (a)   To select and remove all the officers, agents, and employees of the
corporation, prescribe the powers and duties for them as may not be inconsistent
with law, the Articles of Incorporation or these Bylaws, fix their compensation,
and require from them security for faithful service.

     (b)   To conduct, manage, and control the affairs and business of the
corporation and to make such rules and regulations therefor not inconsistent
with law, the Articles of Incorporation or these Bylaws.

     (c)   To adopt, make, and use a corporate seal, and to prescribe the forms
of certification of stock, and to alter the form of such seal and of such
certificates from time to time.

     (d)   To authorize the issuance of shares of stock of the corporation from
time to time, upon such terms and for such consideration as may be lawful.

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     (e)   To borrow money and incur indebtedness for the purposes of the
corporation, and to cause to be executed and delivered therefor, in the
corporate name, promissory notes, bonds, debentures, deeds of trust, mortgages,
pledges, hypothecations, or other evidence of debt and securities therefor.

     Section 2. VACANCIES.

     (a)   Any director may resign effective upon giving written notice to the
Chairman of the Board, the President, or the Secretary, unless the notice
specifies a later time for the effectiveness of such resignation. If the
resignation is effective at a future time, a successor may be elected to take
office when the resignation becomes effective.

     (b)   Directors shall hold office until the next annual election and until
their successors shall have been elected and shall have qualified, unless sooner
displaced. Whenever any vacancy shall have occurred in the Board of Directors,
by reason of death, resignation, increase in the authorized number of directors,
or otherwise, other than removal of a director with or without cause by a vote
of the stockholders, it shall be filled by the vote or consent of a majority of
the remaining directors, though less than a quorum (except as otherwise provided
by law), or by the stockholders, and the person so chosen shall hold office
until the next annual election and until his successor is duly elected and has
qualified. If one or more directors is removed by a vote of stockholders
pursuant to the laws of the State of Nevada, the term of such director or
directors shall forthwith terminate and there shall be a vacancy or vacancies in
the Board of Directors, to be filled by a vote of the stockholders as provided
in these Bylaws.

     (c)   A vacancy or vacancies in the Board shall be deemed to exist in case
of the death, resignation, or removal of any director, or if the authorized
number of directors is increased.

     (d)   The Board may declare vacant the office of a director who has been
declared of unsound mind by an order of court or convicted of a felony.

     (e)   No reduction of the authorized number of directors shall have the
effect of removing any director prior to the expiration of the director's term
of office.

     Section 3. PLACE OF MEETING. Regular or special meetings of the Board shall
be held at any place within or without the State of Nevada which has been
designated from time to time by the Board. In the absence of such designation,
regular meetings shall be held at the principal executive office of the
corporation.

     Section 4. REGULAR MEETINGS. Immediately following each annual meeting of
stockholders the Board shall hold a regular meeting for the purpose of
organization, election of officers, and the transaction of other business.

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<Page>

     Section 5. SPECIAL MEETINGS.

     (a)   Special meetings of the Board for any purpose or purposes may be
called at any time by the Chairman of the Board, the President, any Vice
President, the Secretary, or by any two directors.

     (b)   Special meetings of the Board shall be held upon two days' written
notice or 24 hours' notice given personally or by telephone, telegraph, telex,
or other similar means of communication. Any such written notice shall be
addressed or delivered to each director at such director's address as it is
shown upon the records of the corporation or as may have been given to the
corporation by the director for purposes of notice or, if such address is not
shown on such records or is not readily ascertainable, at the place in which the
meetings of the directors are regularly held.

     (c)   Notice by mail shall be deemed to have been given at the time a
written notice is deposited in the United States mails, postage prepaid. Any
other written notice shall be deemed to have been given at the time it is
personally delivered to the recipient or is delivered to a common carrier for
transmission, or actually transmitted by the person giving the notice by
electronic means, to the recipient. Oral notice shall be deemed to have been
given at the time it is communicated, in person or by telephone, to the
recipient.

     Section 6. QUORUM. A majority of the authorized number of directors
constitutes a quorum of the Board for the transaction of business, except (a)
where the Articles of Incorporation or Bylaws require action by a greater number
of directors, in which case a quorum shall consist of such greater number of
directors, and (b) to adjourn as hereinafter provided. Every act or decision
done or made by a majority of the directors present at a meeting duly held at
which a quorum is present shall be regarded as the act of the Board; except
where a greater number is required by law, the Articles of Incorporation or
elsewhere in these Bylaws, in which case such act or decision shall be done or
made by approval or consent of such greater number of directors.

     Section 7. PARTICIPATION IN MEETINGS BY CONFERENCE TELEPHONE. Members of
the Board may participate in a meeting through use of conference telephone or
similar communications equipment, so long as all members participating in such
meeting can hear one another.

     Section 8. WAIVER OF NOTICE. Notice of a meeting need not be given to any
director who signs a waiver of notice or a consent to holding the meeting or an
approval of the minutes thereof, whether before or after the meeting, or who
attends the meeting without protesting, prior thereto or at its commencement,
the lack of notice to such director. All such waivers, consents and approvals
shall be filed with the corporate records or made a part of the minutes of the
meeting.

     Section 9. ADJOURNMENT. A majority of the directors present, whether or not
a quorum is present, may adjourn any directors' meeting to another time and
place.

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Notice of the time and place of holding an adjourned meeting need not be given
to absent directors if the time and place be fixed at the meeting adjourned,
except as provided in the next sentence. If the meeting is adjourned for more
than twenty-four hours, notice of any adjournment to another time or place shall
be given prior to the time of the adjourned meeting to the directors who were
not present at the time of the adjournment.

     Section 10. FEES AND COMPENSATION. Directors and members of committees may
receive such compensation, if any, for their services, and such reimbursement
for expenses, as may be fixed or determined by the Board.

     Section 11. ACTION WITHOUT MEETING. Any action required or permitted to be
taken by the Board may be taken without a meeting if all members of the Board
shall individually or collectively consent in writing to such action. Such
consent or consents shall have the same effect as a unanimous vote of the Board
and shall be filed with the minutes of the proceedings of the Board.

     Section 12. RIGHTS OF INSPECTION. Every director shall have the absolute
right at any reasonable time to inspect and copy all books, records, and
documents of every kind and to inspect the physical properties of the
corporation and also of its subsidiary corporations, domestic or foreign. Such
inspection by a director may be made in person or by agent or attorney and
includes the right to copy and obtain extracts of documents.

     Section 13. COMMITTEES.

     (a)   By vote or consent of a majority of the authorized number of
directors, the Board may designate one or more committees, each consisting of
one or more directors, and delegate to such committees any of the authority of
the Board except with respect to:

           (i)    The approval of any action for which Title 7 of the Nevada.
Revised Statutes also requires stockholders' approval or approval of the
outstanding shares;

           (ii)   The filling of vacancies on the Board or in any committee;

           (iii)  The fixing of compensation of the directors for serving on the
Board or on any committee;

           (iv)   The amendment or repeal of the Bylaws or the adoption of new
bylaws;

           (v)    The amendment or repeal of any resolution of the Board which
by its express terms is not so amendable or repealable;

           (vi)   A distribution to the stockholders of the corporation except
at a rate or in a periodic amount or within a price range determined by the
Board; or

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<Page>

           (vii)  The appointment of other committees of the Board of the
members thereof.

Any such committee must be designated, and the members or alternate members
thereof appointed, by resolution adopted by a majority of the authorized number
of directors, and any such committee may be designated by such name as the Board
shall specify. The Board, acting through a majority of the authorized number of
directors, shall have the power to prescribe the manner in which the proceeding
of any such committee shall be conducted. Unless the Board, acting through a
majority of the authorized number of directors, shall otherwise provide, the
regular and special meetings and other actions of any such committee shall be
governed by the provisions of this Article applicable to meetings and actions of
the Board. Minutes shall be kept of each meeting of each committee.

     (b)   There shall be an Executive Committee consisting of three (3)
directors who may exercise the authority of the Board to the extent permitted by
law and these Bylaws, and all actions of such Executive Committee shall be made
upon approval or consent of a majority of the members of such Committee.

                               ARTICLE IV OFFICERS

     Section 1. OFFICERS. The officers of the corporation shall be a President,
a Secretary, and a Treasurer. The corporation may also have, at the discretion
of the Board, a Chairman of the Board, one or more Vice-Presidents, one or more
Assistant Secretaries, one or more Assistant Treasurers, and such other officers
as may be elected or appointed in accordance with the provisions of Section 3 of
this Article.

     Section 2. ELECTION. The officers of the corporation, appointed in
accordance with the provisions of Section 3 or Section 5 of this Article, shall
be chosen annually by, and shall serve at the pleasure of, the Board, and shall
hold their respective offices until their resignation, removal, or other
disqualification from service, or until their respective successors shall be
elected.

     Section 3. SUBORDINATE OFFICERS. The Board may elect, and may appoint, such
other officers as the business of the corporation may require, each of whom
shall hold office for such period, have such authority, and perform such duties
as are provided in these Bylaws or as the Board may from time to time determine.

     Section 4. REMOVAL AND RESIGNATION. Any officer may be removed, either with
or without cause, by the Board at any time or, except in the case of an officer
chosen by the Board, by any officer upon whom such power of removal may be
conferred by the Board. Any such removal shall be without prejudice to the
rights, if any, of the officer under any contract of employment of the officer.
Any officer may resign at any time by giving written notice to the corporation,
but without prejudice to the rights, if any, of the corporation under any
contract to which the officer is a party. Any such

                                       10
<Page>

resignation shall take effect at the date of the receipt of such notice or at
any later time specified therein and, unless otherwise specified therein, the
acceptance of such resignation shall not be necessary to make it effective.

     Section 5. VACANCIES. A vacancy in any office because of death,
resignation, removal, disqualification, or any other cause shall be filled in
the manner prescribed in these Bylaws for regular election or appointment to
such office.

     Section 6. CHAIRMAN OF THE BOARD. The Chairman of the Board, if there shall
be such an officer, shall, if present, preside at all meetings of the Board and
stockholders and exercise and perform such other powers and duties as may be
from time to time assigned by the Board.

     Section 7. PRESIDENT. Subject to such powers, if any, as may be given by
the Board to the Chairman of the Board, if there be such an officer, the
President is the chief executive officer of the corporation and has, subject to
the control of the Board, general supervision, direction, and control of the
business and affairs of the corporation. In the absence of the Chairman of the
Board, the President shall preside at all meetings of the stockholders and at
all meetings of the Board. The President has the general powers and duties of
management usually vested in the office of president of a corporation and such
other powers and duties as may be prescribed by the Board.

     Section 8. VICE PRESIDENTS. In the absence or disability of the President,
the Vice Presidents in order of their rank as fixed by the Board or, if not
ranked, the Vice President designated by the Board, shall perform all the duties
of the President, and when so acting shall have all the powers of, and be
subject to all the restrictions upon, the President. The Vice Presidents shall
have such other powers and perform such other duties as from time to time may be
prescribed for them respectively by the Board.

     Section 9. SECRETARY. The Secretary shall keep or cause to be kept, at the
principal executive office and such other place as the Board may order, a book
of minutes of all meetings of stockholders, the Board, and its committees, with
the time and place of holding, whether regular or special and, if special, how
authorized, the notice thereof given, the names of those present at Board and
committee meetings, the number of shares present or represented at stockholders'
meetings, and the proceedings thereof. The Secretary shall keep, or cause to be
kept, a copy of the Bylaws of the corporation at the principal executive office
or business in accordance with Title 7 of the Nevada Revised Statutes. The
Secretary shall keep, or cause to be kept, at the principal executive office or
at the office of the corporation's transfer agent or registrar, if one be
appointed, a share register, or a duplicate share register, showing the names of
the stockholders and their addresses, the number and classes of shares held by
each, the number and date of cancellation of every certificate surrendered for
cancellation. The Secretary shall give, or cause to be given, notice of all the
meetings of the stockholders and of the Board and of any committees thereof
required by these Bylaws or by law to be given, shall keep the seal of the
corporation in safe custody, and shall have such other powers and perform such
other duties as may be prescribed by the Board.

                                       11
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     Section 10. TREASURER. Unless the Board has elected or appointed another
person to be the corporation's chief financial officer, the Treasurer shall be
the chief financial officer of the corporation and shall keep and maintain, or
cause to be kept and maintained, adequate and correct accounts of the properties
and business transactions of the corporation, and shall send or cause to be sent
to the stockholders of the corporation such financial statements and reports as
are by law or these Bylaws required to be sent to them. The books of account
shall at all times be open to inspection by any director. The Treasurer shall
deposit all moneys and other valuables in the name and to the credit of the
corporation with such depositaries as may be designated by the Board. The
Treasurer shall disburse the funds of the corporation as may be ordered by the
Board, shall render to the President and directors, whenever they request it, an
account of all transactions as Treasurer and of the financial condition of the
corporation, and shall have such other powers and perform such other duties as
may be prescribed by the Board.

                            ARTICLE V INDEMNIFICATION

     Section 1. INDEMNIFICATION IN ACTIONS BY THIRD PARTIES. The corporation
shall indemnify any person who was or is a party or is threatened to be made a
party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative, except an action by or
in the right of the corporation, by reason of the fact that he or she is or was
a director or officer, of the corporation, or is or was serving at the request
of the corporation as a director, officer, partner, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise, against
expenses, including attorneys' fees, judgments, fines and amounts paid in
settlement actually and reasonably incurred by him or her in connection with the
action, suit or proceeding if he or she acted in good faith and in a manner
which he or she reasonably believed to be in or not opposed to the best
interests of the corporation, and with respect to any criminal action or
proceeding, had no reasonable cause to believe his or her conduct was unlawful.
The termination of any action, suit or proceeding by judgment, order,
settlement, conviction, or upon a plea of NOLO CONTENDERE or its equivalent,
does not, of itself, create a presumption that the person did not act in good
faith and in a manner which he or she reasonably believed to be in or not
opposed to the best interests of the corporation, and that, with respect to any
criminal action or proceeding, he or she had reasonable cause to believe that
his or her conduct was unlawful.

     Section 2. INDEMNIFICATION IN ACTIONS BY OR IN THE RIGHT OF THE
CORPORATION. The corporation shall indemnity any person who was or is a party or
is threatened to be made a party to any threatened, pending or completed action
or suit by or in the right of the corporation to procure a judgment in its favor
by reason of the fact that he or she is or was a director or officer of the
corporation, or is or was serving at the request of the corporation as a
director, officer, partner, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise against expenses,
including amounts paid in settlement and attorneys' fees actually and reasonably
incurred by him or her in connection with the defense or settlement of the
action or suit if he or

                                       12
<Page>

she acted in good faith and in manner which he or she reasonably believed to be
in or not opposed to the best interests of the corporation. Indemnification may
not be made for any claim, issue or matter as to which such a person has been
adjudged by a court of competent jurisdiction, after exhaustion of all appeals
therefrom, to be liable to the corporation or for amounts paid in settlement to
the corporation, unless and only to the extent that the court in which the
action or suit was brought or other court of competent jurisdiction determines
upon application that, in view of all the circumstances of the case, the person
is fairly and reasonably entitled to indemnity for such expenses as the court
deems proper.

     Section 3. INDEMNIFICATION AGAINST EXPENSES. To the extent that a director,
officer, employee or agent of the corporation has been successful on the merits
or otherwise in defense of any action, suit or proceeding referred to in
Sections 1 or 2 of this Article, or in defense of any claim, issue or matter
therein, he or she must be indemnified by the corporation against expenses,
including attorneys' fees, actually and reasonably incurred by him or her in
connection with the defense.

     Section 4. REQUIRED DETERMINATIONS. Any indemnification under Sections 1
and 2 of this Article, unless ordered by a court or advanced pursuant to Section
5 of this Article, must be made by the corporation only as authorized in the
specific case upon a determination that indemnification of the director or
officer is proper in the circumstances. The determination must be made:

     (a)   By the stockholders;

     (b)   By the Board of Directors by majority vote of a quorum consisting of
directors who were not parties to the act, suit or proceeding;

     (c)   If a majority vote of a quorum consisting of directors who were not
parties to the act, suit or proceeding so orders, by independent legal counsel
in a written opinion; or

     (d)   If a quorum consisting of directors who were not parties to the act,
suit or proceeding cannot be obtained, by independent legal counsel in a written
opinion.

     Section 5. ADVANCE OF EXPENSES. Expenses of officers and directors incurred
in defending a civil or criminal action, suit or proceeding must be paid by the
corporation as they are incurred and in advance of the final disposition of the
action, suit or proceeding, upon receipt of an undertaking by or on behalf of
the director or officer to repay the amount if it is ultimately determined by a
court of competent jurisdiction that he or she is not entitled to be indemnified
by the corporation. The provisions of this Section 5 do not affect any rights to
advancement of expenses to which corporate personnel other than directors or
officers may be entitled under any contract or otherwise by law.

                                       13
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     Section 6. NONEXCLUSIVITY; CONTINUATION. The indemnification and
advancement of expenses authorized in or ordered by a court pursuant to this
Article VI:

     (a)   Does not exclude any other rights to which a person seeking
indemnification or advancement of expenses may be entitled under the Articles of
Incorporation or any agreement, vote of stockholders or disinterested directors
or otherwise, for either an action in his or her official capacity or an action
in another capacity while holding his or her office, except that
indemnification, unless ordered by a court pursuant to Section 2 of this Article
or for the advancement of expenses made pursuant to Section 5 of the Article,
may not be made to or on behalf of any director or officer if a final
adjudication establishes that his or her acts or omissions involved intentional
misconduct, fraud or a knowing violation of the law and was material to the
cause of action.

     (b)   Continues for a person who has ceased to be a director or officer and
inures to the benefit of the heirs, executors and administrators of such a
person.

     Section 7. INSURANCE.

     (a)   The corporation may purchase and maintain insurance or make other
financial arrangements on behalf of any person who is or was a director,
officer, employee or agent of the corporation, or is or was serving at the
request of the corporation as a director, officer, partner, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise for
any liability asserted against him or her and liability and expenses incurred by
him or her in his or her capacity as a director, officer, employee or agent, or
arising out of his or her status as such, whether or not the corporation has the
authority to indemnify him against such liability and expenses.

     (b)   The other financial arrangements made by the corporation pursuant to
subsection (a) of this Section 7 may include the following:

           (i)    The creation of a trust fund.

           (ii)   The establishment of a program of self-insurance.

           (iii)  The securing of its obligation of indemnification by granting
a security interest or other lien on any assets of the corporation.

           (iv)   The establishment of a letter of credit, guaranty or surety.
No financial arrangement made pursuant to this subsection(b) of this Section 7
may provide protection for any person adjudged by a court of competent
jurisdiction, after exhaustion of all appeals therefrom, to be liable for
intentional misconduct, fraud or a knowing violation of law, except with respect
to the advancement of expenses or indemnification ordered by a court.

                                       14
<Page>

     (c)   Any insurance or other financial arrangement made on behalf of a
person pursuant to this Section 7 may be provided by the corporation or any
other person approved by the Board of Directors, even if all or part of the
other person's stock or other securities is owned by the corporation.

                            ARTICLE VI MISCELLANEOUS

     Section 1. INSPECTION OF BYLAWS. The corporation shall keep in its
principal executive office the original or a copy of these Bylaws as amended to
date, which shall be open to inspection by stockholders at all reasonable times
during customary office hours. If the principal executive office of the
corporation is outside the State of Nevada and the corporation has no principal
business office in such state, it shall upon the written request of any
stockholder furnish to such stockholder a copy of these Bylaws as amended to
date.

     Section 2. ENDORSEMENT OF DOCUMENTS; CONTRACTS. Subject to the provisions
of applicable law, any note, mortgage, evidence of indebtedness, contract, share
certificate, conveyance, or other instrument in writing and any assignment or
endorsements thereof executed or entered into between the corporation and any
other person, when signed by the Chairman of the Board, the President or any
Vice President, and the Secretary, any Assistant Secretary, the Treasurer or any
Assistant Treasurer of the corporation shall be valid and binding on the
corporation in the absence of actual knowledge on the part of the other person
that the signing officers had no authority to execute the same. Any such
instruments may be signed by any other person or persons and in such manner as
from time to time shall be determined by the Board and, unless so authorized by
the Board, no officer, agent, or employee shall have any power or authority to
bind the corporation by any contract or engagement or to pledge its credit or to
render it liable for any purpose or amount.

     Section 3. CERTIFICATES OF STOCK. Every holder of shares of the corporation
shall be entitled to have a certificate signed in the name of the corporation by
the Chairman of the Board, the President or a Vice President and by the
Treasurer or an Assistant Treasurer or the Secretary or an Assistant Secretary,
certifying the number of shares and the class or series of shares owned by the
stockholder. Any or all of the signatures on the certificate may be facsimile.
If any officer, transfer agent, or registrar who has signed or whose facsimile
signature has been placed upon a certificate shall have ceased to be such
officer, transfer agent, or registrar before such certificate is issued, it may
be issued by the corporation with the same effect as if such person were an
officer, transfer agent, or registrar at the date of issue. Except as provided
in this Section, no new certificate for shares shall be issued in lieu of an old
one unless the latter is surrendered and canceled at the same time. The Board
may, however, if any certificate for shares is alleged to have been lost,
stolen, or destroyed, authorize the issuance of a new certificate in lieu
thereof, and the corporation may require that the corporation be given a bond or
other adequate security sufficient to indemnify it against any claim that may be
made against it (including expense or liability) on account of the alleged loss,
theft, or destruction of such certificate or the issuance of such new
certificate.

                                       15
<Page>

     Section 4. REPRESENTATION OF SHARES OF OTHER CORPORATIONS. The President or
any other officer or officers authorized by the Board or the President are each
authorized to vote, represent, and exercise on behalf of the corporation all
rights incident to any and all shares of any other corporation or corporations
standing in the name of the corporation. The authority herein granted may be
exercised either by any such officer in person or by any other person authorized
so to do by proxy or power of attorney duly executed by said officer.

     Section 5. STOCK PURCHASE PLANS. The corporation may adopt and carry out a
stock purchase plan or agreement or stock option plan or agreement providing for
the issue and sale for such consideration as may be fixed of its unissued
shares, or of issued shares acquired or to be acquired, to one or more of the
employees or directors of the corporation or of a subsidiary or to a trustee on
their behalf and for the payment for such shares in installments or at one time,
and may provide for aiding any such persons in paying for such shares by
compensation for services rendered, promissory notes, or otherwise. Any such
stock purchase plan or agreement or stock option plan or agreement may include,
among other features, the fixing of eligibility for participation therein, the
class and price of shares to be issued or sold under the plan or agreement, the
number of shares which may be subscribed for, the method of payment therefor,
reservation of title until full payment therefor, the effect of the termination
of employment, an option or obligation on the part of the corporation to
repurchase the shares upon termination of employment, restrictions upon transfer
of the shares, the time limits of and termination of the plan, and any other
matters, not in violation of applicable law, as may be included in the plan as
approved or authorized by the Board or any committee of the Board.

     Section 6. CONSTRUCTION AND DEFINITIONS. Unless the context otherwise
requires, the general provisions, rules of construction, and definitions
contained in the general provisions of Title 7 of the Nevada Revised Statutes
shall govern the construction of these Bylaws.

                                       16
<Page>



                  EXHIBIT E to the Common Stock Purchase Agreement
                                 (SECTION 5.2.6)
                                  LEGAL OPINION


<Page>

                           [Grippo & Elden letterhead]

                                     [Date]

[______________]
[______________]
[______________]

                 Re:    Purchase of Common Stock from
                        Photogen Technologies, Inc.

Ladies and Gentlemen:

          We have acted as counsel to Photogen Technologies, Inc., a Nevada
corporation (the "Company"), in connection with the Common Stock Purchase
Agreement dated August 2, 2002 (the "Purchase Agreement") between the Company,
Mi3, L.P., a Delaware limited partnership and certain other Purchasers
identified therein (collectively, the "Purchasers"), and the transactions
contemplated thereby. This opinion letter is furnished to you at the request of
the Company pursuant to Section 5.2.6 of the Purchase Agreement. Capitalized
terms not otherwise defined herein have the meanings specified in the Purchase
Agreement.

                               DOCUMENTS EXAMINED

          For purposes of rendering this opinion, with your consent, we have
limited our review of the documents to originals, or copies certified or
otherwise identified to our satisfaction, of the following: (a)(i) the Purchase
Agreement, (ii) the Voting, Drag-Along and Right of First Refusal Agreement
executed by the Company and certain other parties pursuant to the Purchase
Agreement (the "Voting Agreement"), (iii) the Registration Rights Agreement
executed by the Company and Purchasers pursuant to the Purchase Agreement (the
Voting Agreement and Registration Rights Agreement are collectively referred to
as the "Other Agreements") (b) the Company's Amended and Restated Articles of
Incorporation and Bylaws, as currently in effect and as proposed to be amended
pursuant to the Purchase Agreement, (c) resolutions of the Company's Board of
Directors and stockholders concerning the transactions contemplated by the
Purchase Agreement and Other Agreements, and (d) such other documents and
certificates of public officials and representatives of the Company as we have
deemed relevant or necessary as the basis for such opinions. Except as set forth
above, we have conducted no investigation of factual matters in connection with
this opinion.

                                    OPINIONS

          Based upon the foregoing, and subject to the assumptions,
qualifications, limitations and exceptions set forth below, we are of the
opinion that:

          (a)    The Company (i) is a corporation duly organized, validly
existing and in good corporate standing under the laws of the State of Nevada
and is duly qualified to do business as a foreign corporation in all
jurisdictions in which its ownership of property or the

<Page>

Page 2

character of its business requires such qualification, except where the failure
to so qualify would not have a material adverse effect on the Company, (ii) has
all corporate power and authority under its Articles of Incorporation and
Bylaws, each as amended to date, to carry on its business as now being
conducted, and (iii) has all corporate power and authority to own its property.

          (b)    The Purchase Agreement has been duly executed and delivered
by the Company and constitutes the legal, valid and binding obligations of the
Company, enforceable against it in accordance with its terms. Each of the Other
Agreements has been duly executed and delivered by the Company and constitutes
the legal, valid and binding obligations of the Company, enforceable against it
in accordance with their terms.

          (c)    The execution, delivery and the performance of the Purchase
Agreement and the Other Agreements has been authorized by all necessary
corporate action on the part of the Company and the Company has the corporate
power and authority necessary to make, execute, deliver and perform the Purchase
Agreement and the Other Agreements and to carry out the transactions
contemplated thereby and to issue and deliver the Shares. All corporate
proceedings required by law or by the provisions of the Purchase Agreement and
the Other Agreements to be taken by the Board of Directors and the stockholders
of the Company on or prior to the Closing Date in connection with the execution
and delivery of the Purchase Agreement and the Other Agreements, the adoption of
the Articles of Incorporation as proposed to be amended in the Purchase
Agreement and the offer, issuance and sale of the Shares, have been duly and
validly taken.

          (d)    The Separation Agreement by and among the Company and certain
stockholders dated July __, 2002, has been duly and validly authorized,
executed, delivered and consummated by the Company and, to our knowledge, the
other parties thereto; and constitutes the legal, valid and binding obligations
of the Company and, to our knowledge, the other parties thereto, enforceable
against the Company and, to our knowledge, each of the other parties thereto in
accordance with its terms. All shares of the Company's Series B Preferred Stock
have been converted into common stock.

          (e)    The authorized capital stock of the Company currently consists
of 150,000,000 shares of Common Stock, $0.001 par value per share, [     ] of
which are issued and outstanding, and 12,015 shares of Series A Preferred
Stock, $.01 par value per share, all of which are issued and outstanding
(excluding paid-in-kind dividends on such Series A Preferred Stock). The Shares
to be purchased at the Closing have been duly authorized and, when purchased in
the manner set forth in the Purchase Agreement, will be validly issued, fully
paid and non-assessable. The stock certificates evidencing the Shares comply as
to form with Nevada law. The respective rights, privileges, restrictions and
preferences of the Series A Preferred Stock and the Common Stock are as stated
in the Company's Amended Articles, as filed with the Secretary of State of the
State of Nevada. There are no statutory preemptive rights, and other than as set
forth in the capitalization table in Section 3.4 of the Disclosure Schedule, no
options, warrants, contractual preemptive rights, conversion privileges or other
rights (or agreements for any such rights) outstanding to purchase or otherwise
obtain from the Company any of the Company's

<Page>

Page 3

securities. All of the shares of Common Stock and Series A Preferred Stock of
the Company outstanding immediately prior to the transactions contemplated in
the Purchase Agreement were duly authorized, validly issued and delivered, and
are fully paid and nonassessable. Except for such shares of Common Stock and
Series A Preferred Stock, the Company has no other authorized series or class of
capital stock. Except for the warrants listed in Section 3.4 of the Disclosure
Schedule and the Series A Preferred Stock, neither the offer nor the issuance or
sale of the Shares constitutes an event under any anti-dilution provisions of
any securities issued (or issuable pursuant to outstanding rights, warrants or
options) by the Company which will either increase the number of shares issuable
pursuant to such provisions or decrease the consideration per share to be
received by the Company pursuant to such provisions.

          (f)    The consummation of the transactions contemplated by the
Purchase Agreement and the Other Agreements will not result in a breach of or
constitute a default under the Articles of Incorporation or Bylaws of the
Company, or any applicable statute, law, regulation, order or decree of any
court or governmental authority, or, conflict with, result in a breach or
termination of, constitute a default under, or result in the creation of any
material lien, charge, encumbrance or restriction of any of the assets of the
Company under any agreement or other instrument to which the Company is a party
or by which any of its assets are bound.

          (g)    All consents, approvals, permits, orders or authorizations, of
and all qualifications, registrations, designations, declarations or filings
with any federal or state governmental agencies or bodies required at or prior
to the Closing pursuant to any law, rule or regulation on pursuant to any order,
decree, judgment, agreement or other instrument, in connection with the
execution and delivery of the Purchase Agreement and the Other Agreements, and
the legal and valid offer, issuance and sale of the Shares and the performance
of the other obligations of the Company under the Purchase Agreement and the
Other Agreements have been obtained and are effective. No consent,
authorization, approval, permit or order of or filing with any governmental or
regulatory authority is required at or prior to the Closing under current laws
and regulations, including but not limited to all applicable Federal securities
and State "Blue Sky" laws, in connection with the execution and delivery of the
Purchase Agreement or the offer, issuance, sale or delivery of the Shares other
than the filing of the Form D pursuant to Regulation D under the Securities Act
of 1933 and compliance with comparable filing requirements under applicable Blue
Sky laws. The offer, issuance, sale and delivery of the Shares will not, under
current laws and regulations, require compliance with the prospectus delivery or
registration requirements of the Securities Act.

          (h)    There is no action, proceeding or governmental investigation
pending or, to our knowledge, overtly threatened against the Company, or any of
its officers or directors, that questions the validity of the Purchase Agreement
or the Other Agreements or the Company's right to enter into such agreements.
There is no action, proceeding, suit or investigation pending or, to our
knowledge, overtly threatened against the Company. The Company is not subject to
any pending or, to our knowledge, overtly threatened investigation, inquiry or
proceeding by the SEC, any state securities commission or any other federal,
state, municipal or other governmental department, commission, board, bureau,
agency or instrumentality, domestic or

<Page>

Page 4

foreign, or any securities exchange or securities market, with respect to any
matter, including but not limited to the Company's relationship or transactions
with Elan International Services, Ltd., Sentigen Ltd. or any of their successors
or affiliates.

          (i)    The Company is in material compliance with all applicable
Nasdaq SmallCap Market continued listing requirements. There are no proceedings
pending or, to our knowledge, overtly threatened against the Company relating to
the continued listing of the Company's Common Stock on the Nasdaq SmallCap
Market and the Company has not received any notice of the delisting of the
Common Stock from the Nasdaq SmallCap Market.

             ASSUMPTIONS, QUALIFICATIONS, LIMITATIONS AND EXCEPTIONS

          The foregoing opinions are subject to the following assumptions,
qualifications, exceptions and limitations:

     1.   In conducting our examination and rendering this opinion, we have
assumed:

          (a)    the genuineness and authenticity of all signatures and
     documents submitted to us as originals;

          (b)    the correctness of all certificates and representations,
     documents and records and the  representations  and warranties  made by the
     Company in the Purchase  Agreement and Other Agreements,  in each case with
     respect to the  factual  matters  set forth  therein.  For  purposes of the
     preceding sentence, in cases where representations and warranties have been
     made "to the best  knowledge" of a party or have been similarly  qualified,
     we have relied upon, and assumed the accuracy of, such  representations and
     warranties as if they were not so qualified;

          (c)    that all copies submitted to us are accurate, complete and
     conform to the originals;

          (d)    the legal capacity of all natural persons who are signatories
     to the documents, but we have no reason to believe that each natural person
     executing the documents does not have the legal capacity to do so;

          (e)    all parties to the Purchase Agreement and Other Agreements that
     are entities (other than the Company) are duly organized, validly existing,
     and in good standing under the laws of their  respective  jurisdictions  of
     organization  and have the requisite  corporate  power (as  applicable)  to
     enter into the Purchase Agreements and Other Agreements; and

          (f)    the execution and delivery of the Purchase Agreement and Other
     Agreements have been duly authorized by all necessary  corporate action (as
     applicable) and proceedings on the part of all such parties (other than the
     Company);  the  Purchase  Agreement  and  Other  Agreements  have been duly
     executed and delivered by all such

<Page>

Page 5

     parties  (other  than the  Company)  and  constitute  the valid and binding
     obligations of such parties, enforceable against such parties in accordance
     with their  respective  terms;  the respective  terms and provisions of the
     Purchase Agreement and Other Agreements do not, and the execution, delivery
     and  performance  of its  obligations  thereunder  by each of such  parties
     (other than the Company) will not,  violate the articles or  certificate of
     incorporation or other charter document, document of organization or bylaws
     of any such party or any law, order or decree of any court,  administrative
     agency or other governmental authority binding on any such party, or result
     in a breach of or cause a default  under any contract or indenture to which
     it is a party or by which it is bound.

     2.   The qualification of any opinion or statement herein by the use of the
words "counsel's knowledge" or "our knowledge" or words to similar effect means
that during the course of our representation of the Company in connection with
the transactions contemplated by the Purchase Agreement, Other Agreements or
other matter to which such phrase matters, no information has come to the
attention of any attorney in this firm involved in such transactions which would
give such attorney current actual knowledge of the existence of facts, opinions
or conclusions so qualified.

     3.   We call to your attention that (a) the Company's common stock has
traded at prices below $1.00 per share, (b) the Company is subject to a
contingent liability relating to sales of common stock to Ballsbridge, Ltd. as
described in Section 3.6 of the Disclosure Schedule, and (c) the Company's
registration statement pursuant to the Registration Rights Agreement must be
declared effective by the SEC:

     4.   Our opinions are subject to limitations imposed by any applicable
bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium and
similar laws affecting creditors' rights generally. Our opinions are also
subject to the effect of general principles of equity (regardless of whether
considered in a proceeding in equity or at law). In addition, a court may refuse
to enforce a provision of the Purchase Agreement or Other Agreements if it deems
such provision to violate public policy, including any provision indemnifying a
party against liability for its own wrongful or negligent acts or for securities
law violations.

     5.   Whenever we have stated that we have assumed any matter, it is
intended to indicate that we have assumed such matter without making any
factual, legal or other inquiry or investigations, and without expressing any
opinion or conclusion of any kind concerning such matter. However, we do not
have actual knowledge of any facts or circumstances which would cause us to
questions the validity of any such assumption.

     6.   We are members of the bar of the State of Illinois. We render no
opinion herein as to matters involving laws of any jurisdiction other than the
State of Illinois, the federal laws of the United States and the Nevada General
Corporation Law.

     7.   This opinion is limited to present laws and to the facts and
agreements as they presently exist. We assume no obligation to revise or
supplement this opinion should the present

<Page>

Page 6

laws of any jurisdiction be changed through legislative action, judicial
decision or otherwise, or should the facts change.

     8.   This opinion is rendered solely for the Purchasers' information in
connection with the transactions described in the Purchase Agreement and may not
in whole or in part be used or relied upon by any other person (except the
Purchasers) or in any other context or for any other purpose. This opinion may
not in whole or in part be circulated, quoted or referred to nor may copies of
it be delivered to any other person without our prior written consent.


                                        Very truly yours,


                                        Grippo & Elden

<Page>


                 EXHIBIT F to the Common Stock Purchase Agreement
                                 (SECTION 5.2.7)
                       FORM OF NON-COMPETITION AGREEMENTS


None.

<Page>


                 EXHIBIT G to the Common Stock Purchase Agreement
                                (SECTION 5.2.18)
                          REGISTRATION RIGHTS AGREEMENT


                          REGISTRATION RIGHTS AGREEMENT

     This Registration Rights Agreement (the "Agreement") is made and entered
into as of this ___ day of July, 2002 by and among Photogen Technologies, Inc.,
a Delaware corporation (the "Company"), and the "Purchasers" named in that
certain Common Stock Purchase Agreement, of even date herewith, by and among the
Company and the Purchasers (the "Purchase Agreement").

     The parties hereby agree as follows:

1.   Certain Definitions. As used in this Agreement, the following terms shall
     have the following meanings:

     "Affiliate" means, with respect to any person, any other person which
directly or indirectly controls, is controlled by, or is under common control
with, such person.

     "Agreement" has the meaning ascribed thereto in the preamble hereof.

     "Allowed Delay" has the meaning ascribed thereto in Section 2(c)(ii)
hereof.

     "Availability Date" has the meaning ascribed thereto in Section 3(k)
hereof.

     "Blackout Period" has the meaning ascribed thereto in Section 2(c)(i)
hereof.

     "Blue Sky Application" has the meaning ascribed thereto in Section 6(a)
hereof.

     "Business Day" means a day, other than a Saturday or Sunday, on which banks
in New York City are open for the general transaction of business.

     "Closing Date" has the meaning ascribed thereto in Section 2(a) hereof.

     "Closing Price" as of any date means (a) the closing bid price of one share
of Common Stock as reported on The Nasdaq SmallCap Market ("Nasdaq") on such
date, (b) if no closing bid price is available, the average of the high bid and
the low asked price quoted on Nasdaq on such date, or (c) if the shares of
Common Stock are not then quoted on Nasdaq, the value of one share of Common
Stock on such date as shall be determined in good faith by the Board of
Directors of the Company and the Purchasers, provided, that if the Board of
Directors of the Company and the Purchasers are unable to agree upon the value
of a share of Common Stock pursuant to this subpart (c), the Company and the
Purchasers shall jointly select an appraiser who is experienced in such matters
to determine the Closing Price. The decision of such appraiser shall be final
and conclusive, and the cost of such appraiser shall be borne one half by the
Company and one half by the Purchasers.

     "Common Stock" shall mean the Company's common stock, par value $0.001 per
share.

<Page>

     "Company" has the meaning ascribed thereto in the preamble hereof.

     "Nasdaq" has the meaning ascribed thereto in the definition of Closing
Price above.

     "Prospectus" shall mean the prospectus included in any Registration
Statement, as amended or supplemented by any prospectus supplement, with respect
to the terms of the offering of any portion of the Registrable Securities
covered by such Registration Statement and by all other amendments and
supplements to the prospectus, including post-effective amendments and all
material incorporated by reference in such prospectus.

     "Purchasers" shall mean the Purchasers identified in the Purchase Agreement
and any Affiliate or permitted transferee of any Purchaser who is a subsequent
holder of any Registrable Securities.

     "Purchase Agreement" has the meaning ascribed thereto in the preamble
hereof.

     "Register," "registered" and "registration" refer to a registration made by
preparing and filing a Registration Statement or similar document in compliance
with the 1933 Act, and the declaration or ordering of effectiveness of such
Registration Statement or document.

     "Registrable Securities" shall mean the shares of Common Stock issuable (i)
pursuant to the Purchase Agreement and (ii) pursuant to the provisions of
Sections 2(a) and 2(c) below, and any other securities issued or issuable with
respect to or in exchange for Registrable Securities; provided, that, a security
shall cease to be a Registrable Security upon (a) sale pursuant to a
Registration Statement or Rule 144 under the 1933 Act, or (b) such security
becoming eligible for sale by the Purchasers pursuant to Rule 144(k).

     "Registration Statement" shall mean any registration statement of the
Company filed under the 1933 Act that covers the resale of any of the
Registrable Securities pursuant to the provisions of this Agreement, amendments
and supplements to such Registration Statement, including post-effective
amendments, all exhibits and all material incorporated by reference in such
Registration Statement.

     "SEC" means the U.S. Securities and Exchange Commission.

     "1933 Act" means the Securities Act of 1933, as amended, and the rules and
regulations promulgated thereunder.

     "1934 Act" means the Securities Exchange Act of 1934, as amended, and the
rules and regulations promulgated thereunder.

2.   Registration.

     (a)  Registration Statements. Promptly following the closing of the
purchase  and sale of  shares  of  Common  Stock  contemplated  by the  Purchase
Agreement (the "Closing Date") (but

                                       -2-
<Page>

no later than twenty (20) days thereafter), the Company shall prepare and file
with the SEC one Registration Statement on Form S-1 covering the resale of the
Registrable Securities in an amount equal to the number of shares of Common
Stock issued to the Purchasers on the Closing Date. Such Registration Statement
also shall cover, to the extent allowable under the 1933 Act and the rules
promulgated thereunder (including Rule 416), such indeterminate number of
additional shares of Common Stock resulting from stock splits, stock dividends
or similar transactions with respect to the Registrable Securities. The Company
shall use its reasonable best efforts to obtain from each person who now has
piggyback registration rights a waiver of those rights with respect to the
Registration Statement. The Registration Statement (and each amendment or
supplement thereto, and each request for acceleration of effectiveness thereof)
shall be provided in accordance with Section 3(c) to the Purchasers and their
counsel prior to its filing or other submission. If a Registration Statement
covering the Registrable Securities is not filed with the SEC within twenty (20)
days of the Closing Date, the Company will make pro rata payments to each
Purchaser, as liquidated damages and not as a penalty, in an amount equal to
1.5% of the aggregate amount paid by such Purchaser on the Closing Date to the
Company for any 30-day period or pro rata for any portion thereof following the
date by which such Registration Statement should have been filed for which no
Registration Statement is filed with respect to the Registrable Securities. Such
payment shall be made to each Purchaser in additional fully paid and
non-assessable shares of Common Stock not later than three Business Days
following the end of any 30-day period. For this purpose, each share of Common
Stock shall be deemed to have a value equal to the arithmetic mean of the
Closing Prices for the ten (10) trading days beginning twenty (20) trading days
prior to the issuance of such shares.

     (b)  Expenses. The Company will pay all expenses associated with each
registration hereunder, including filing and printing fees, counsel and
accounting fees and expenses, costs associated with clearing the Registrable
Securities for sale under applicable state securities laws, listing fees and the
Purchasers' reasonable expenses in connection with the registration, but
excluding discounts, commissions, fees of underwriters, selling brokers, dealer
managers or similar securities industry professionals with respect to the
Registrable Securities being sold.

     (C)  Effectiveness.

          (i)    The Company shall use all commercially reasonable efforts to
have the Registration Statement declared effective as soon as practicable. If a
Registration Statement covering the Registrable Securities is not declared
effective by the SEC within sixty (60) days after the initial filing of the
Registration Statement (or ninety (90) days after the initial filing of the
Registration Statement if it is reviewed by the SEC), as such period may be
extended by Mi3 (as defined in the Purchase Agreement and on behalf of the
Purchasers) in its reasonable discretion for good cause, then the Company will
make pro rata payments to each Purchaser, as liquidated damages and not as a
penalty, in an amount equal to 1.5% of the aggregate amount invested by such
Purchaser in the shares of Common Stock for any 30-day period or pro rata for
any portion thereof following the date by which such Registration Statement
should have been effective (the "Blackout Period"). Such payments shall be in
partial compensation to the Purchasers, and shall not constitute the Purchasers'
exclusive remedy for such events. The amounts payable as liquidated damages
pursuant to this paragraph shall be paid monthly within three (3) Business Days
of the last day of each month following the commencement of the

                                       -3-
<Page>

Blackout Period until the termination of the Blackout Period. Such payment shall
be made to each Purchaser in additional fully paid and non-assessable shares of
Common Stock. Each share of Common Stock shall be deemed to have a value equal
to the arithmetic mean of the Closing Prices for the ten (10) trading days
beginning twenty (20) trading days prior to the issuance of such shares.

          (ii)   For not more than twenty (20) consecutive days or for a total
of not more than forty-five (45) days in any twelve (12) month period, the
Company may delay the disclosure of material non-public information concerning
the Company, by suspending the use of any Prospectus included in any
registration contemplated by this Section containing such information, the
disclosure of which at the time is not, in the good faith opinion of the
Company, in the best interests of the Company (an "Allowed Delay"); provided,
that the Company shall promptly (a) notify the Purchasers in writing of the
existence of (but in no event, without the prior written consent of a Purchaser,
shall the Company disclose to such Purchaser any of the facts or circumstances
regarding) material non-public information giving rise to an Allowed Delay, and
(b) advise the Purchasers in writing to cease all sales under the Registration
Statement until the end of the Allowed Delay.

     (d)  Underwritten Offering. If any offering pursuant to a Registration
Statement pursuant to Section 2(a) hereof involves an underwritten offering, the
Company shall have the right to select an investment banker and manager to
administer the offering, which investment banker or manager shall be reasonably
satisfactory to the Purchasers.

3.   Company Obligations. The Company will use all commercially reasonable
efforts to effect the registration of the Registrable Securities in accordance
with the terms hereof, and pursuant thereto the Company will, as expeditiously
as possible:

     (a)  use all commercially reasonable efforts to cause such Registration
Statement to become effective and to remain continuously effective for a period
that will terminate upon the earlier of (i) the date on which all Registrable
Securities covered by such Registration Statement as amended from time to time,
have been sold, and (ii) the date on which all Registrable Securities covered by
such Registration Statement may be sold pursuant to Rule 144(k);

     (b)  prepare and file with the SEC such amendments and post-effective
amendments to the Registration Statement and the Prospectus as may be necessary
to keep the Registration Statement effective for the period specified in Section
3(a) hereof and to comply with the provisions of the 1933 Act and the 1934 Act
with respect to the distribution of all of the Registrable Securities covered
thereby;

     (c)  provide copies to and permit counsel designated by the Purchasers to
review each Registration Statement and all amendments and supplements thereto no
fewer than seven (7) days prior to their filing with the SEC and not file any
document to which such counsel reasonably objects;

     (d)  furnish to the Purchasers and their legal counsel (i) promptly after
the same is prepared and publicly distributed, filed with the SEC, or received
by the Company (but not later

                                       -4-
<Page>

than two (2) Business Days after the filing date, receipt date or sending date,
as the case may be) one (1) copy of any Registration Statement and any amendment
thereto, each preliminary prospectus and Prospectus and each amendment or
supplement thereto, and each letter written by or on behalf of the Company to
the SEC or the staff of the SEC, and each item of correspondence from the SEC or
the staff of the SEC, in each case relating to such Registration Statement
(other than any portion of any thereof which contains information for which the
Company has sought confidential treatment), and (ii) such number of copies of a
Prospectus, including a preliminary prospectus, and all amendments and
supplements thereto and such other documents as each Purchaser may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such Purchaser that are covered by the related Registration Statement;

     (e)  in the event the Company selects an underwriter for the offering, the
Company shall enter into and perform its reasonable obligations under an
underwriting agreement, in usual and customary form, including, without
limitation, customary indemnification and contribution obligations, with the
underwriter of such offering;

     (f)  if required by the underwriter, or if any Purchaser is described in
the Registration Statement as an underwriter, the Company shall furnish, on the
effective date of the Registration Statement (except with respect to clause (i)
below) and on the date that Registrable Securities are delivered to an
underwriter, if any, for sale in connection with the Registration Statement
(including any Purchaser deemed to be an underwriter), (i) (a) in the case of an
underwritten offering, an opinion, dated as of the closing date of the sale of
Registrable Securities to the underwriters, from independent legal counsel
representing the Company for purposes of such Registration Statement, in form,
scope and substance as is customarily given in an underwritten public offering,
addressed to the underwriters and the Purchasers participating in such
underwritten offering or (b) in the case of an "at the market" offering, an
opinion, dated as of or promptly after the effective date of the Registration
Statement to the Purchasers, from independent legal counsel representing the
Company for purposes of such Registration Statement, in form, scope and
substance as is customarily given in a public offering, addressed to the
Purchasers, and (ii) a letter, dated as of the effective date of such
Registration Statement and confirmed as of the applicable dates described above,
from the Company's independent certified public accountants in form and
substance as is customarily given by independent certified public accountants to
underwriters in an underwritten public offering, addressed to the underwriters
(including any Purchaser deemed to be an underwriter);

     (g)  use all commercially reasonable efforts to (i) prevent the issuance of
any stop order or other suspension of effectiveness and, (ii) if such order is
issued, obtain the withdrawal of any such order at the earliest possible moment;

     (h)  prior to any public offering of Registrable Securities, use all
commercially reasonable efforts to register or qualify or cooperate with the
Purchasers and their counsel in connection with the registration or
qualification of such Registrable Securities for offer and sale under the
securities or blue sky laws of such jurisdictions requested by the Purchasers
and do any and all other commercially reasonable acts or things necessary or
advisable to enable the distribution in such jurisdictions of the Registrable
Securities covered by the Registration Statement;

                                       -5-
<Page>

     (i)  use all commercially reasonable efforts to cause all Registrable
Securities covered by a Registration Statement to be listed on each securities
exchange, interdealer quotation system or other market on which similar
securities issued by the Company are then listed;

     (j)  immediately notify the Purchasers, at any time when a Prospectus
relating to Registrable Securities is required to be delivered under the 1933
Act, upon discovery that, or upon the happening of any event as a result of
which, the Prospectus included in a Registration Statement, as then in effect,
includes an untrue statement of a material fact or omits to state any material
fact required to be stated therein or necessary to make the statements therein
not misleading in light of the circumstances then existing, and at the request
of any such holder, promptly prepare and furnish to such holder a reasonable
number of copies of a supplement to or an amendment of such Prospectus as may be
necessary so that, as thereafter delivered to the Purchasers of such Registrable
Securities, such Prospectus shall not include an untrue statement of a material
fact or omit to state a material fact required to be stated therein or necessary
to make the statements therein not misleading in light of the circumstances then
existing; and

     (k)  otherwise use commercially reasonable efforts to comply with all
applicable rules and regulations of the SEC under the 1933 Act and the 1934 Act,
take such other actions as may be reasonably necessary to facilitate the
registration of the Registrable Securities hereunder; and make available to its
security holders, as soon as reasonably practicable, but not later than the
Availability Date (as defined below), an earnings statement covering a period of
at least twelve (12) months, beginning after the effective date of each
Registration Statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the 1933 Act (for the purpose of this Subsection 3(k),
"Availability Date" means the 45th day following the end of the fourth fiscal
quarter that includes the effective date of such Registration Statement, except
that, if such fourth fiscal quarter is the last quarter of the Company's fiscal
year, "Availability Date" means the 90th day after the end of such fourth fiscal
quarter).

4.   Due Diligence Review; Information. The Company shall make available, during
normal business hours, for inspection and review by the Purchasers, advisors to
and representatives of the Purchasers (who may or may not be affiliated with the
Purchasers and who are reasonably acceptable to the Company), any underwriter
participating in any disposition of shares of Common Stock on behalf of the
Purchasers pursuant to a Registration Statement or amendments or supplements
thereto or any blue sky, NASD or other filing, all financial and other records,
all SEC Filings (as defined in the Purchase Agreement) and other filings with
the SEC, and all other corporate documents and properties of the Company as may
be reasonably necessary for the purpose of such review, and cause the Company's
officers, directors and employees, within a reasonable time period, to supply
all such information reasonably requested by the Purchasers or any such
representative, advisor or underwriter in connection with such Registration
Statement (including, without limitation, in response to all questions and other
inquiries reasonably made or submitted by any of them), prior to and from time
to time after the filing and effectiveness of the Registration Statement for the
sole purpose of enabling the Purchasers and such representatives, advisors and
underwriters and their respective accountants and attorneys to conduct initial
and ongoing due diligence with respect to the Company and the accuracy of such
Registration Statement.

                                       -6-
<Page>

     The Company shall not disclose material nonpublic information to the
Purchasers, or to advisors to or representatives of the Purchasers, unless prior
to disclosure of such information the Company identifies such information as
being material nonpublic information and provides the Purchasers, such advisors
and representatives with the opportunity to accept or refuse to accept such
material nonpublic information for review.

5.   Obligations of the Purchasers.

     (a)  Each Purchaser shall furnish in writing to the Company such
information regarding itself, the Registrable Securities held by it and the
intended method of disposition of the Registrable Securities held by it, as
shall be reasonably required to effect the registration of such Registrable
Securities and shall execute such documents in connection with such registration
as the Company may reasonably request. At least five (5) Business Days prior to
the first anticipated filing date of any Registration Statement, the Company
shall notify each Purchaser of the information the Company requires from such
Purchaser if such Purchaser elects to have any of the Registrable Securities
included in the Registration Statement. A Purchaser shall provide such
information to the Company at least two (2) Business Days prior to the first
anticipated filing date of such Registration Statement if such Purchaser elects
to have any of the Registrable Securities included in the Registration
Statement.

     (b)  Each Purchaser, by its acceptance of the Registrable Securities
agrees to cooperate with the Company as reasonably requested by the Company in
connection with the preparation and filing of a Registration Statement
hereunder, unless such Purchaser has notified the Company in writing of its
election to exclude all of its Registrable Securities from such Registration
Statement.

     (c)  In the event the Company, at the request of the Purchasers, determines
to engage the services of an underwriter, such Purchaser agrees to enter into
and perform its obligations under an underwriting agreement, in usual and
customary form, including, without limitation, customary indemnification and
contribution obligations, with the managing underwriter of such offering and
take such other actions as are reasonably required in order to expedite or
facilitate the dispositions of the Registrable Securities.

     (d)  Each Purchaser agrees that, upon receipt of any notice from the
Company of either (A) the commencement of an Allowed Delay pursuant to Section
2(c)(ii) or (B) the happening of an event pursuant to Section 3(j) hereof, such
Purchaser will immediately discontinue disposition of Registrable Securities
pursuant to the Registration Statement covering such Registrable Securities,
until the Purchaser's receipt of the copies of the supplemented or amended
prospectus filed with the SEC and declared effective and, if so directed by the
Company, the Purchaser shall deliver to the Company (at the expense of the
Company) or destroy (and deliver to the Company a certificate of destruction)
all copies in the Purchaser's possession of the Prospectus covering the
Registrable Securities current at the time of receipt of such notice.

                                       -7-
<Page>

     (e)  No Purchaser may participate in any third party underwritten
registration hereunder unless it (i) agrees to sell the Registrable Securities
on the basis provided in any underwriting arrangements in usual and customary
form entered into by the Company, (ii) completes and executes all
questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents reasonably required under the terms of such underwriting
arrangements, and (iii) agrees to pay its pro rata share of all underwriting
discounts and commissions. Notwithstanding the foregoing, no Purchaser shall be
required to make any representations to such underwriter, other than those with
respect to itself and the Registrable Securities owned by it, including its
right to sell the Registrable Securities, and any indemnification in favor of
the underwriter by the Purchasers shall be several and not joint and limited in
the case of any Purchaser, to the proceeds received by such Purchaser from the
sale of its Registrable Securities. The scope of any such indemnification in
favor of an underwriter shall be limited to the same extent as the indemnity
provided in Section 6(b) hereof.

6.   Indemnification.

     (a)  Indemnification by the Company. The Company will indemnify and hold
harmless each Purchaser and its officers, directors, members, employees and
agents, successors and assigns, and each other person, if any, who controls such
Purchaser within the meaning of the 1933 Act, against any losses, claims,
damages or liabilities, joint or several, to which such Purchaser, officer,
director, member, or controlling person may become subject under the 1933 Act or
otherwise, insofar as such losses, claims, damages or liabilities (or actions in
respect thereof) arise out of or are based upon: (i) any untrue statement or
alleged untrue statement of any material fact contained in any Registration
Statement, any preliminary prospectus or final prospectus contained therein, or
any amendment or supplement thereof; (ii) any blue sky application or other
document executed by the Company specifically for that purpose or based upon
written information furnished by the Company filed in any state or other
jurisdiction in order to qualify any or all of the Registrable Securities under
the securities laws thereof (any such application, document or information
herein called a "Blue Sky Application"); (iii) the omission or alleged omission
to state therein a material fact required to be stated therein or necessary to
make the statements therein not misleading; (iv) any violation by the Company or
its agents of any rule or regulation promulgated under the 1933 Act applicable
to the Company or its agents and relating to action or inaction required of the
Company in connection with such registration; or (v) any failure to register or
qualify the Registrable Securities included in any such Registration in any
state where the Company or its agents has affirmatively undertaken or agreed in
writing that the Company will undertake such registration or qualification on a
Purchaser's behalf (the undertaking of any underwriter chosen by the Company
being attributed to the Company) and will reimburse such Purchaser, and each
such officer, director or member and each such controlling person for any legal
or other expenses reasonably incurred by them in connection with investigating
or defending any such loss, claim, damage, liability or action; provided,
however, that the Company will not be liable in any such case if and to the
extent that any such loss, claim, damage or liability arises out of or is based
upon an untrue statement or alleged untrue statement or omission or alleged
omission so made in conformity with information furnished by such Purchaser or
any such controlling person in writing specifically for use in such Registration
Statement or Prospectus.

                                       -8-
<Page>

     (b)  Indemnification by the Purchasers. In connection with any registration
pursuant to the terms of this Agreement, each Purchaser will furnish to the
Company in writing such information as the Company reasonably requests
concerning the holders of Registrable Securities or the proposed manner of
distribution for use in connection with any Registration Statement or Prospectus
and agrees, severally but not jointly, to indemnify and hold harmless, to the
fullest extent permitted by law, the Company, its directors, officers,
employees, stockholders and each person who controls the Company (within the
meaning of the 1933 Act) against any losses, claims, damages, liabilities and
expense (including reasonable attorney fees) resulting from any untrue statement
of a material fact or any omission of a material fact required to be stated in
the Registration Statement or Prospectus or preliminary prospectus or amendment
or supplement thereto or necessary to make the statements therein not
misleading, to the extent, but only to the extent that such untrue statement or
omission is contained in any information furnished in writing by such Purchaser
to the Company specifically for inclusion in such Registration Statement or
Prospectus or amendment or supplement thereto. In no event shall the liability
of a Purchaser be greater in amount than the dollar amount of the proceeds (net
of all expense paid by such Purchaser and the amount of any damages such holder
has otherwise been required to pay by reason of such untrue statement or
omission) received by such Purchaser upon the sale of the Registrable Securities
included in the Registration Statement giving rise to such indemnification
obligation.

     (c)  Conduct of Indemnification Proceedings. Any person entitled to
indemnification hereunder shall (i) give prompt notice to the indemnifying party
of any claim with respect to which it seeks indemnification and (ii) permit such
indemnifying party to assume the defense of such claim with counsel reasonably
satisfactory to the indemnified party; provided that any person entitled to
indemnification hereunder shall have the right to employ separate counsel and to
participate in the defense of such claim, but the fees and expenses of such
separate counsel shall be at the expense of such person unless (a) the
indemnifying party has agreed to pay such fees or expenses, or (b) the
indemnifying party shall have failed to assume the defense of such claim and
employ counsel reasonably satisfactory to such person or (c) in the reasonable
judgment of any such person, based upon written advice of its counsel, a
conflict of interest exists between such person and the indemnifying party with
respect to such claims (in which case, if the person notifies the indemnifying
party in writing that such person elects to employ separate counsel at the
expense of the indemnifying party, the indemnifying party shall not have the
right to assume the defense of such claim on behalf of such person); and
provided, further, that the failure of any indemnified party to give notice as
provided herein shall not relieve the indemnifying party of its obligations
hereunder, except to the extent that such failure to give notice shall
materially adversely affect the indemnifying party in the defense of any such
claim or litigation. It is understood that the indemnifying party shall not, in
connection with any proceeding in the same jurisdiction, be liable for fees or
expenses of more than one separate firm of attorneys at any time for all such
indemnified parties. No indemnifying party will, except with the consent of the
indemnified party, consent to entry of any judgment or enter into any settlement
that does not include as an unconditional term thereof the giving by the
claimant or plaintiff to such indemnified party of a release from all liability
in respect of such claim or litigation.

                                       -9-
<Page>

     (d)  Contribution. If for any reason the indemnification provided for in
the preceding paragraphs (a) and (b) is unavailable to an indemnified party or
insufficient to hold it harmless, other than as expressly specified therein,
then the indemnifying party shall contribute to the amount paid or payable by
the indemnified party as a result of such loss, claim, damage or liability in
such proportion as is appropriate to reflect the relative fault of the
indemnified party and the indemnifying party, as well as any other relevant
equitable considerations. No person guilty of fraudulent misrepresentation
within the meaning of Section 11(f) of the 1933 Act shall be entitled to
contribution from any person not guilty of such fraudulent misrepresentation. In
no event shall the contribution obligation of a holder of Registrable Securities
be greater in amount than the dollar amount of the proceeds (net of all expenses
paid by such holder and the amount of any damages such holder has otherwise been
required to pay by reason of such untrue or alleged untrue statement or omission
or alleged omission) received by it upon the sale of the Registrable Securities
giving rise to such contribution obligation.

7.   Miscellaneous.

     (a)  Amendments and Waivers. This Agreement may be amended only by a
writing signed by the parties hereto. The Company may take any action herein
prohibited, or omit to perform any act herein required to be performed by it,
only if the Company shall have obtained the written consent to such amendment,
action or omission to act, of Purchaser.

     (b)  Notices. All notices and other communications provided for or
permitted hereunder shall be made as set forth in the Purchase Agreement.

     (c)  Assignments and Transfers by Purchasers. The provisions of this
Agreement shall be binding upon and inure to the benefit of the Purchasers and
their respective successors and assigns. A Purchaser may transfer or assign, in
whole or from time to time in part, to one or more persons its rights hereunder
in connection with the transfer of Registrable Securities by such Purchaser to
such person, provided that such Purchaser complies with all laws applicable
thereto and provides written notice of assignment to the Company promptly after
such assignment is effected.

     (d)  Assignments and Transfers by the Company. This Agreement may not be
assigned by the Company (whether by operation of law or otherwise) without the
prior written consent of each Purchaser, provided, however, that the Company may
assign its rights and delegate its duties hereunder to any surviving or
successor corporation in connection with a merger or consolidation of the
Company with another corporation, or a sale, transfer or other disposition of
all or substantially all of the Company's assets to another corporation, without
the prior written consent of the Purchasers, after notice duly given by the
Company to each Purchaser.

     (e)  Benefits of the Agreement. The terms and conditions of this Agreement
shall inure to the benefit of and be binding upon the respective permitted
successors and assigns of the parties. Nothing in this Agreement, express or
implied, is intended to confer upon any party other than the parties hereto or
their respective successors and assigns any rights, remedies,

                                      -10-
<Page>

obligations, or liabilities under or by reason of this Agreement, except as
expressly provided in this Agreement.

     (f)  Counterparts; Faxes. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument. This Agreement may also
be executed via facsimile, which shall be deemed an original.

     (g)  Titles and Subtitles. The titles and subtitles used in this Agreement
are used for convenience only and are not to be considered in construing or
interpreting this Agreement.

     (h)  Severability. Any provision of this Agreement that is prohibited or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the extent of such prohibition or unenforceability without invalidating the
remaining provisions hereof but shall be interpreted as if it were written so as
to be enforceable to the maximum extent permitted by applicable law, and any
such prohibition or unenforceability in any jurisdiction shall not invalidate or
render unenforceable such provision in any other jurisdiction. To the extent
permitted by applicable law, the parties hereby waive any provision of law which
renders any provisions hereof prohibited or unenforceable in any respect.

     (i)  Further Assurances. The parties hereto shall execute and deliver all
such further instruments and documents and take all such other actions as may
reasonably be required to carry out the transactions contemplated hereby and to
evidence the fulfillment of the agreements herein contained.

     (j)  Entire Agreement. This Agreement and the Purchase Agreement (and the
Exhibits and Schedules annexed thereto) are intended by the parties hereto as a
final expression of their agreement and intended to be a complete and exclusive
statement of the agreement and understanding of the parties hereto in respect of
the subject matter contained herein and therein. This Agreement and the Purchase
Agreement (and the Exhibits and Schedules annexed thereto) supersede all prior
agreements and understandings between the parties with respect to such subject
matter.

     (k)  Governing Law; Consent to Jurisdiction. This Agreement shall be
governed by, and construed in accordance with, the internal laws of the State of
Delaware without regard to the choice of law principles thereof. Each of the
parties hereto irrevocably submits to the exclusive jurisdiction of the courts
located in Boston, Massachusetts for the purpose of any suit, action, proceeding
or judgment relating to or arising out of this Agreement and the transactions
contemplated hereby. Service of process in connection with any such suit, action
or proceeding may be served on each party hereto anywhere in the world by the
same methods as are specified for the giving of notices under this Agreement.
Each of the parties hereto irrevocably consents to the jurisdiction of any such
court in any such suit, action or proceeding and to the laying of venue in such
court. Each party hereto irrevocably waives any objection to the laying of venue
of any such suit, action or proceeding brought in such courts and irrevocably
waives any claim that any such suit, action or proceeding brought in any such
court has been brought in an inconvenient forum.

                                      -11-
<Page>

                            [signature page follows]

                                      -12-
<Page>

     IN WITNESS WHEREOF, the parties have executed this Agreement or caused
their duly authorized officers to execute this Agreement as of the date first
above written.

                                The Company:

                                PHOTOGEN TECHNOLOGIES, INC.


                                By:
                                    --------------------------------------
                                Name:
                                Title:


                                The Purchasers:

                                MI3 L.P.

                                    By: MI3 Services L.L.C., its General Partner

                                    By:
                                        ----------------------------------------
                                    William D. McPhee, President

                                OXFORD BIOSCIENCE PARTNERS IV L.P.

                                    By: OBP Management IV L.P.

                                    By:
                                        ----------------------------------------
                                    Jonathan J. Fleming - General Partner

                                MRNA Fund II L.P.

                                    By: OBP Management IV L.P.

                                    By:
                                        ----------------------------------------
                                    Jonathan J. Fleming - General Partner

                                NEW ENGLAND PARTNERS CAPITAL, L.P.

                                    By: NEP Capital LLC, its General Partner

                                    By:
                                        ----------------------------------------
                                    John Rousseau, President

                                      -13-
<Page>

                                TANNEBAUM LLC

                                By:
                                    --------------------------------------------
                                Name:
                                Title:

                                      -14-




<Page>

                 EXHIBIT I to the Common Stock Purchase Agreement
                                  (SECTION 1.1)
                                     SHARES

<Table>
<Caption>

PURCHASER                          INVESTMENT AMOUNT
---------                          -----------------
<S>                                <C>
Mi3                                  $    750,0000

Oxford BioScience Partners           $  12,000,000

New England Venture Fund             $   1,500,000

Tannebaum LLC                        $   2,000,000
</Table>

<Page>


            DISCLOSURE SCHEDULE to the Common Stock Purchase Agreement

SECTION 3.1:  ORGANIZATION; AMENDED ARTICLES
No exceptions.

SECTION 3.2:  CORPORATE POWER
No exceptions, except as disclosed in Schedule 3.6 below.

SECTION 3.3:  AUTHORIZATION

Under NASD rules, the issuance of the Common Stock contemplated by the Common
Stock Purchase Agreement must be approved by the Company's stockholders.

SECTION 3.4:  CAPITALIZATION

See attached Capitalization Table.

In addition to the information presented in the Capitalization Table:

(i) Subscription, warrant, option, convertible security or other right
(contingent or otherwise) to purchase or acquire any shares of capital stock of
the Company.

     1. The following warrants have been granted by the Company and remain
        outstanding to date:

<Table>
<Caption>
NAME                             WARRANTS*           GRANT DATE           EXPIRATION         EXERCISE
                                                                                             PRICE
-----------------------------------------------------------------------------------------------------
<S>                              <C>                 <C>                  <C>                <C>
Farcap Group, LLC                1,000,000**         Aug. 9, 1999         Aug. 9, 2004       $   9.45
-----------------------------------------------------------------------------------------------------
Elan Pharmaceutical
 Investments II, Ltd.              100,000           Oct. 20, 1999        Oct. 20, 2004      $  21.17
-----------------------------------------------------------------------------------------------------
Al Snyder                           15,000           Jan. 24, 2000        Jan. 24, 2010      $ 15.625
-----------------------------------------------------------------------------------------------------
Gilford Securities Incorporated     32,724           Feb. 11, 2000        Feb. 11, 2005      $  16.88
-----------------------------------------------------------------------------------------------------
Aqua Partners, Inc.                  2,000           Nov. 30, 1999        Nov. 30, 2004      $  16.62
-----------------------------------------------------------------------------------------------------
</Table>

     *The total amount of warrants granted is 1,149,724; concurrent with the
     Closing, the total warrants outstanding will be 349,724 reflecting the
     substitution of a revised Farcap Group warrant.

<Page>


     **As of the Closing, the Farcap Group, LLC warrant shall be canceled and
     substituted by a warrant to purchase 200,000 shares (presuming a 1 for 4
     reverse split of the Company's common stock) exercisable at the per share
     purchase price of the Common Stock Purchase Agreement with an expiration
     date of August 9, 2004.

<Page>

     2. The following stock option awards have been granted by the Company under
        its various plans and are currently outstanding:

<Table>
<Caption>
      NAME               SHARES           GRANT DATE       EXERCISE           TERM            VESTING*          PLAN**
                                                            PRICE
-----------------------------------------------------------------------------------------------------------------------
<S>                    <C>              <C>               <C>               <C>             <C>               <C>
Lester McKeever           20,000        Aug. 6, 1998      $    13.25        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Daniel Tosteson           10,000        Aug. 6, 1998      $    13.25        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Jay Harkins               10,000        Sept. 4, 1998     $   11.125        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Mark Peterson             20,000        Sept. 4, 1998     $   11.125        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Dan Hamilton              18,000        Sept. 4, 1998     $   11.125        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Harry Morrison            10,000        Nov. 6, 1998      $  15.0625        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Merrill Biel              10,000        Feb. 4, 1999      $    12.75        10 years        5 years           1998
-----------------------------------------------------------------------------------------------------------------------
Taffy Williams         3,000,000        May 17, 2000      $    15.00        10 years        3 years           Executive
-----------------------------------------------------------------------------------------------------------------------
Brooks Boveroux        1,000,000        Aug. 1, 2000      $     8.25        10 years        3 years           Executive
-----------------------------------------------------------------------------------------------------------------------
Josh Fisher                8,000        Sept. 11, 2000    $    6.875        10 years        Immediate         1998
-----------------------------------------------------------------------------------------------------------------------
Dan Hamilton               5,000        Sept. 11, 2000    $    6.875        10 years        Immediate         1998
-----------------------------------------------------------------------------------------------------------------------
Jay Harkins                3,000        Sept. 11, 2000    $    6.875        10 years        Immediate         1998
-----------------------------------------------------------------------------------------------------------------------
Heather Long               2,000        Sept. 11, 2000    $    6.875        10 years        Immediate         1998
-----------------------------------------------------------------------------------------------------------------------
Brooks Boveroux          250,000        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Josh Fisher                3,000        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Gene Golub                30,000        Dec. 1, 2000      $     2.75        10 years        Immediate         1998
-----------------------------------------------------------------------------------------------------------------------
Dan Hamilton               2,500        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Jay Harkins                1,500        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Heather Long               1,000        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Lester McKeever           30,000        Dec. 1, 2000      $     2.75        10 years        Immediate         1998
-----------------------------------------------------------------------------------------------------------------------
Al Snyder                 10,000        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Taffy Williams         1,200,000        Dec. 1, 2000      $     2.75        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Reinhard Koenig          400,000        Jan. 8, 2001      $     2.13        10 years        4 years           2000
-----------------------------------------------------------------------------------------------------------------------
Joanne Blake              50,000        Feb. 16, 2001     $   5.3125        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Ken Sylvester            200,000        Mar. 22, 2001     $   1.9062        10 years        4 years           1998
-----------------------------------------------------------------------------------------------------------------------
Nicholas Lowe, M.D.       30,000        Aug. 9, 2001      $     1.70        10 years        100% at           1998
                                                                                            first
                                                                                            anniversary
                                                                                            (Aug. 9,
                                                                                            2002)
-----------------------------------------------------------------------------------------------------------------------
Joanne Blake              50,000        Dec. 5, 2001      $     1.14        10 years        4 years           2000
-----------------------------------------------------------------------------------------------------------------------
Dan Hamilton              60,000        Dec. 5, 2001      $     1.14        10 years        4 years           2000
-----------------------------------------------------------------------------------------------------------------------
Jay Harkins               20,000        Dec. 5, 2001      $     1.14        10 years        4 years           2000
-----------------------------------------------------------------------------------------------------------------------
Heather Long               5,000        Dec. 5, 2001      $     1.14        10 years        4 years           2000
-----------------------------------------------------------------------------------------------------------------------
Lester McKeever           30,000        Dec. 5, 2001      $     1.14        10 years        100% at           1998
                                                                                            first
                                                                                            anniversary
                                                                                            (Dec 5, 2002)
-----------------------------------------------------------------------------------------------------------------------
Gene Golub                30,000        Dec. 5, 2001      $     1.14        10 years        100% at           1998
                                                                                            first
                                                                                            anniversary
                                                                                            (Dec 5, 2002)
-----------------------------------------------------------------------------------------------------------------------
</Table>

<Page>


The total amount of stock option awards outstanding is 6,519,000.

*All options vest immediately upon a change of control which will occur upon
consummation of the transactions in the Common Stock Purchase Agreement. As
scheduled in the original grant, however, "3 years" means that 33% of each
option grant vests on each anniversary of years 1-3; "4 years" means 25% of each
option grant vests on each anniversary of years 1-4; and "5 years means 20% of
each option grant vests on each anniversary of years 1-5.

** The stock option awards were granted pursuant to the 1998 Long Term Incentive
Compensation Plan ("1998"), the 2000 Long Term Incentive Compensation Plan
("2000"), and the Senior Executive Long Term Incentive Compensation Plan
("Executive").

        3.  Pursuant to that certain Settlement Agreement and Mutual Release of
            Claims (the "Settlement Agreement"), dated as of June 13, 2002, by
            and among Photogen Technologies, Inc., Photogen, Inc., The General
            Hospital Corporation, d/b/a Massachusetts General Hospital and
            Gerald L. Wolf, Ph.D., M.D., Dr. Wolf received the following
            options: (i) an option to purchase up to $300,000 worth of shares of
            Company common stock determined in accordance with a formula set
            forth in the Settlement Agreement at an exercise price of twenty
            cents ($0.20) per share; and (ii) an option to purchase up to
            150,000 shares of Company common stock at an exercise price per
            share equal to the average closing price for the shares over the
            thirty day trading period immediately preceding the date of the
            Settlement Agreement.

(ii) Commitment or offer of the Company to issue any subscription, warrant,
option, convertible security or other such right or to issue or distribute to
holders of any shares of its capital stock any evidences of indebtedness or
assets of the Company.

        1.  See (i) of this Schedule 3.4.

(iii) Obligation of the Company (contingent or otherwise) to purchase, redeem or
otherwise acquire any shares of its capital stock or any interest therein or to
pay any dividend or make any other distribution in respect thereof.

        1.  Series A and B Preferred in-kind dividends pursuant to respective
            Certificates of Designations, Preferences and Rights, as amended,
            and as supplemented by agreements to adjust conversion prices
            disclosed in the Capital Structure table below.

        2.  The Company expects to enter into a Separation Agreement by and
            among Craig Dees, Ph.D. and Dees Family Foundation, Eric A. Wachter,
            Ph.D. and Eric A. Wachter 1998 Charitable Remainder Unitrust,
            Timothy D. Scott,

<Page>


            Ph.D. and Scott Family Limited Partnership, Walter Fisher, Ph.D.,
            Fisher Family Investment Limited Partnership, and Walt Fisher 1998
            Charitable Remainder Unitrust, and John A. Smolik and Smolik Family
            LLP, Photogen Technologies, Inc., Photogen, Inc., Robert J.
            Weinstein, M.D., Stuart P. Levine and Tannebaum, LLC, whereby the
            Company shall redeem 20,548,435 shares of the Company held by Drs.
            Dees, Wachter, Scott, Fisher and Smolik as the record and beneficial
            owners in exchange for all of the shares of the Company's wholly
            owned subsidiary, Photogen, Inc.

        3.  The Company is subject to a contingent liability in the amount of
            $650,000 relating to shares issued to Ballsbridge Ltd. pursuant to
            the Company's Form S-3. See Schedule 3.6 below. This is also
            relevant to the sixth sentence of Section 3.4.

(iv) Restrictions on the transfer of the Company's capital stock other than
those arising from securities laws or contemplated by this Agreement and the
other Financing Documents.

        1.  None, except for that certain Agreement entered into as of May 9,
            2001 by and among Photogen Technologies, Inc., Photogen, Inc. and
            the following individuals: Timothy Scott, John Smolik, Eric Wachter,
            Craig Dees, Walter Fisher, Theodore Tannebaum and Robert Weinstein,
            M.D. (the "Lockup Agreement").

Voting trusts or agreements, stockholders' agreements, pledge agreements,
buy-sell agreements, rights of first refusal, preemptive rights or proxies
relating to any securities of the Company, whether or not the Company is a party
thereto (other than the Voting, Drag-Along and Right of First Refusal
Agreement).

        1.  The Lockup Agreement set forth in (iv) of this Schedule 3.4.

        2.  Amended and Restated Voting Agreement entered into as of the 4th day
            of September, 2001, by and among Eric A. Wachter, Ph.D.
            (individually and as sole Trustee of the Eric A. Wachter 1998
            Charitable Remainder Trust), Craig Dees, Ph.D. (individually and as
            Director of the Dees Family Foundation), Walter G. Fisher, Ph.D.
            (individually, as General Partner of the Fisher Family Investment
            Limited Partnership, and as Sole Trustee of the Walt Fisher 1998
            Charitable Remainder Unitrust), Tim Scott, Ph.D. (individually and
            as General Partner of Scott Family Investment Limited Partnership,
            John Smolik (individually and as General Partner of the Smolik
            Family, L.P.), Robert J. Weinstein, M.D. (individually and as a
            General Partner of W.F. Investments Enterprises, Limited
            Partnership, as Director of the Robert and Lois Weinstein Family
            Foundation, Inc. and as Trustee of the Robert and Lois Weinstein
            Joint Revocable Trust), and Theodore Tannebaum (individually and as
            Trustee of the Theodore Tannebaum Trust), and joined into by
            Photogen Technologies, Inc. as stockholder of Photogen, Inc.

<Page>


        3.  Amended and Restated Certificate of Designations, Preferences and
            Rights of Series A Preferred Stock (filed as Exhibit 3.5 to the
            Company's Quarterly Report on Form 10-QSB for the quarter ended
            September 30, 1999).

        4.  Certificate of Designations, Preferences and Rights of Series B
            Convertible Preferred Stock (filed as Exhibit 3 to the Company's
            Current Report on Form 8-K dated February 18, 2000).

<Page>


                                CAPITAL STRUCTURE
                               AS AT JUNE 30, 2002

<Table>
<Caption>
                                                               ACTUAL                                  PRO FORMA
                                          AMOUNT OR         COMMON STOCK          FULLY DILUTED      COMMON STOCK     FULLY DILUTED
                                          SHARES (1)      & EQUIVALENTS (2)          PERCENT       & EQUIVALENTS (3)     PERCENT
                                         -----------      -----------------       -------------    -----------------  -------------
<S>                                      <C>                      <C>                      <C>            <C>                  <C>
LONG TERM DEBT
Elan                                     $ 3,043,775                169,098                 0.3%

SERIES A PREFERRED STOCK
Elan                                       14,464.28                683,244                 1.3%           4,821,427            4.8%

SERIES B PREFERRED STOCK
Series B Stockholders                     389,130.82                563,084                 1.1%

STOCK OPTIONS (SHARES RESERVED)
    1998 Plan                                                     1,995,500                                1,995,500
    2000 Plan                                                     2,000,000                                2,000,000
    2000 Senior Plan                                              5,000,000                                5,000,000
    Additional options - financing                                        0                               11,173,500
                                                          -----------------                        -----------------
TOTAL OPTION POOL (4)                                             8,995,500                17.7%          20,169,000           20.0%

STOCK WARRANTS AND OPTIONS(5)                                     1,466,391                 2.9%           1,466,391            1.5%

COMMON STOCK
FOUNDERS (6)
Craig Dees                                                        4,021,667                 7.9%                   0            0.0%
Walter Fisher                                                     3,994,167                 7.9%                   0            0.0%
Timothy Scott                                                     4,007,667                 7.9%                   0            0.0%
Eric Wachter                                                      4,524,667                 8.9%                   0            0.0%
John Smolik                                                       4,000,267                 7.9%                   0            0.0%

DIRECTORS & OFFICERS
Tannebaum LLC                                                     4,116,921                 8.1%           4,116,921            4.1%
Robert J. Weinstein                                               3,449,421                 6.8%           3,449,421            3.4%
Eugene Golub                                                         32,000                 0.1%              32,000            0.0%
Lester McKeever                                                      32,000                 0.1%              32,000            0.0%
Taffy J. Williams                                                    17,000                 0.0%              17,000            0.0%
Reinhard Koenig                                                       6,000                 0.0%               6,000            0.0%

CORPORATE INVESTMENTS
Alliance Pharmaceutical Corp. (7)                                    42,328                 0.1%              42,328            0.0%
Elan                                                              1,224,964                 2.4%           1,224,964            1.2%

INSTITUTIONS
Isosceles Fund Limited                                              196,978                 0.4%             196,978            0.2%
Ballsbridge Finance Limited (8)                                     498,508                 1.0%             498,508            0.5%

OTHER GREATER THAN 5% SHAREHOLDERS
Stuart Levine                                                     3,289,621                 6.5%           3,289,621            3.3%
</Table>

<Page>


<Table>
<S>                                                              <C>                      <C>            <C>                  <C>
OTHER SHAREHOLDERS                                                5,388,122                10.6%           5,388,122            5.3%

SHARES FROM LONG TERM DEBT CONVERSION                                                                        507,293            0.5%

SHARES FROM SERIES B PREFERRED STOCK CONVERSION                                                            1,653,806            1.6%

INSTITUTIONAL FINANCING (9)                                                                 0.0%          54,166,667           53.6%
                                                          -----------------       -------------    -----------------  -------------

TOTAL COMMON STOCK OUTSTANDING                                   38,842,298                               74,621,628
                                                          =================                        =================

TOTAL FULLY DILUTED COMMON STOCK & EQUIVALENTS                   50,719,614               100.0%         101,078,446          100.0%
                                                          =================       =============    =================  =============
</Table>

1.  Balances, including accrued interest and dividends, at June 30, 2002
2.  Common stock equivalents based
on conversion of:

    Elan debt at $18.00 per share

    Series A Preferred at $21.17 per share

    Series B Preferred at 1.44703 conversion factor

3.  Common stock equivalents based on conversion of:

    Elan debt at $6.00 per share

    Series A Preferred at $3.00 per share

    Series B Preferred at 4.25 conversion factor

4.  6,519,000 options outstanding at June 30, 2002

5.  Stock warrants:
    Include net options granted to Dr. Wolf pursuant to Settlement Agreement
    Reflect exchange of warrant to Farcap Group from 1,000,000 to 200,000
    shares

6.  Founders shares are locked up through May, 2004

7.  In August 2001, Alliance filed a Form 144 to sell shares owned by them

8.  Ballsbridge is a sister company to Isosceles; these shares are subject to
    recission

9. Pro-forma for $16.25 MM new capital @$0.30 per share

<Page>


SECTION 3.5: SUBSIDIARIES

        1.  Photogen, Inc. is a wholly-owned subsidiary of the Company. Upon the
            closing of that certain Separation Agreement expected to be
            completed contemporaneously with the closing of the Common Stock
            Purchase Agreement, the Company will no longer hold an equity
            interest in Photogen, Inc. and Photogen, Inc. will no longer be a
            subsidiary of the Company.

        2.  Sentigen, Ltd. is an 80.1% owned subsidiary of the Company and the
            vehicle for a joint venture with units of Elan Corporation plc.

SECTION 3.6: SEC FILINGS; BUSINESS

        1.  Letter, dated June 5, 2002, from Company's counsel (Grippo & Elden)
            to the Securities and Exchange Commission regarding the Company's
            sales of securities under the Form S-3 Registration Statement (File
            No. 333-46394).

        2.  Letter, dated June 27, 2002, from the Securities and Exchange
            Commission to Company's counsel (Grippo & Elden) regarding the
            Company's sales of securities under the Form S-3 Registration
            Statement (File No. 333-46394).

        3.  Letter, dated July 3, 2002, from Company's counsel (Grippo & Elden)
            to the Securities and Exchange Commission describing the Company's
            compliance with the tasks set forth in the June 27, 2002 letter
            (item 2 above).

        4.  On or about July 11, 2002, Company's counsel received verbal
            approval from the SEC to proceed with the matters in item number 3.
            The Company intends to make comparable revisions to its Form 110-Q
            for the quarter ended March 31, 2002.

        5.  In connection with the SEC's investigation of Elan, the Company
            received a subpoena from the SEC for documents relating to the joint
            venture with Elan in connection with inquiries the SEC was making
            about Elan. The Company responded to the subpoena and has heard
            nothing further from the SEC concerning this matter.

        6.  On July 25, 2002, the Company filed a post-effective amendment to
            its Form S-3 registration de-registering all unsold shares
            thereunder.

        7.  See also Schedule 3.22 regarding AmeriCal Securities, Inc.

SECTION 3.7: NO MATERIAL ADVERSE CHANGE

(a) The Company is currently operating at a loss and such losses are funded by a
$2.5 million secured line of credit from Tannebaum LLC.

<Page>


Pursuant to that certain Settlement Agreement and Mutual Release of Claims (the
"Settlement Agreement"), dated as of June 13, 2002 by and among Photogen
Technologies, Inc., Photogen, Inc., The General Hospital Corporation, d/b/a
Massachusetts General Hospital and Gerald L. Wolf, Ph.D., M.D., the Company paid
$150,000 in cash and granted various stock options to Dr. Wolf.

(b) Contemporaneous with the closing of the Common Stock Purchase Agreement, the
Company expects to have completed the split off of its therapeutic business to
five founders in exchange for 100% (20,548,435 shares) of the shares of Common
Stock of the Company owned or controlled by such founders.

Contemporaneous with the closing of the Common Stock Purchase Agreement, the
Company will have completed the conversion of its Series B Preferred Stock into
shares of its Common Stock at a conversion ratio of 4.25 shares of Common Stock
for each share of Series B Preferred..

Contemporaneous with the closing of the Common Stock Purchase Agreement, the
Company will have completed the conversion of borrowings under the Convertible
Promissory Note to Elan into shares of its Common Stock at $6.00 per share; and
the Series A Preferred conversion price will be reduced to $3.00 per share and
the liquidation reference eliminated..

Pursuant to the Settlement Agreement (as defined in item (a) above), Dr. Wolf
received the following options: (i) an option to purchase up to the number of
shares of Company common stock determined in accordance with a formula set forth
in the Settlement Agreement at an exercise price of twenty cents ($0.20) per
share; and (ii) an option to purchase up to 150,000 shares of Company common
stock at an exercise price per share equal to the average closing price for the
shares over the thirty day trading period immediately preceding the date of the
Settlement Agreement.

Pursuant to the Certificate of Designations for the Company's Series A Preferred
Stock, the Company has and expects to continue to declare a mandatory
semi-annual in-kind dividend (payable April 20 and October 20) equal to 7.0% of
the outstanding shares of the Series A Preferred Stock.

(c) None.

(d) None.

(e) Contemporaneous with the closing of the Common Stock Purchase Agreement,
Elan Pharma International Ltd. ("Elan") will convert the outstanding principal
and interest of its line of credit to the Company in exchange for shares of
Common Stock of the Company.

As contemplated by the closing of the Common Stock Purchase Agreement, the
outstanding borrowings (including principal up to two million dollars
($2,000,000) and

<Page>


accrued interest) under the Company's secured line of credit
from Tannebaum LLC will be converted into Common Stock of the Company and the
note will have been canceled.

See items (a) and (b) of this Schedule 3.7 for disclosures regarding the
Settlement Agreement.

(f) Changes to the Company's Series A Preferred Stock as described in the
attached letter agreement between an Elan affiliate and the Company.

Termination of the following agreements: (i) Letter Agreement between the
Company and AmeriCal Securities, Inc., dated March 25, 2002, regarding business
development; and (ii) Letter Agreement between the Company and AmeriCal
Securities, Inc., dated March 25, 2002, regarding raising of capital. See
Schedule 3.22 below.

(g) None.

(h) See items (a) and (b) of this Schedule 3.7 for disclosures regarding the
Settlement Agreement and Separation Agreement.

(i) None (other than pursuant to the Separation Agreement).

(j) None.

(k) None.

<Page>


SECTION 3.8: FINANCIAL STATEMENTS

        1.  Litigation was resolved pursuant to that certain Settlement
            Agreement and Mutual Release of Claims (the "Settlement Agreement"),
            dated as of June 13, 2002, by and among Photogen Technologies, Inc.,
            Photogen, Inc., The General Hospital Corporation, d/b/a
            Massachusetts General Hospital and Gerald L. Wolf, Ph.D., M.D.
            Subject to the valuation of certain stock options granted to Dr.
            Wolf under the Settlement Agreement, (the impact of which is
            expected to require a non-cash increment to the financial provision
            the Company has established regarding this litigation), the Company
            has made disclosure and financial provision in its SEC Filings for
            the expected cost of this settlement.

        2.  Contingent liability regarding certain sales of Common Stock of the
            Company to Ballsbridge Finance Limited. See Schedule 3.6

SECTION 3.9: CONTRACTS AND COMMITMENTS

(i)   The Company has entered into the following agreements.

        1.  UCC-1 Financing Statement No. 2002015141-1 filed by Tannebaum, LLC,
            as secured party, with the Secretary of State of Nevada on June 11,
            2002 against the assets of Photogen Technologies, Inc. and Photogen,
            Inc., as debtors, in connection with the line of credit.

        2.  The Company expects to enter into a Separation Agreement (the
            "Separation Agreement") by and among the following: Craig Dees,
            Ph.D. and Dees Family Foundation, Eric A. Wachter, Ph.D. and Eric A.
            Wachter 1998 Charitable Remainder Unitrust, Timothy D. Scott, Ph.D.
            and Scott Family Investment Limited Partnership, Walter Fisher,
            Ph.D., Fisher Family Investment Limited Partnership, and Walt Fisher
            1998 Charitable Remainder Unitrust, and John A. Smolik and Smolik
            Family LLP, Photogen Technologies, Inc. ("Technologies"), Photogen,
            Inc. ("Photogen"), Robert J. Weinstein, M.D., Stuart P. Levine and
            Tannebaum, LLC (note that pursuant to the Separation Agreement
            non-competition agreements shall be executed to effect the
            following: (i) Photogen and Drs. Dees, Wachter, Scott, Fisher and
            Mr. Smolik shall not develop or sublicense technologies that are a
            part of the therapeutic business of Technologies for diagnostic
            x-ray purposes or adversely affect the development of N1177 or
            PH-50; and (ii) Technologies shall not develop or sublicense
            non-nanoparticulate PH-10 or adversely affect the development of
            PH-10).

(ii)  See item (i) of this Schedule 3.9.

(iii) No exceptions.

SECTION 3.10: PROPRIETARY RIGHTS, EMPLOYEE RESTRICTIONS

<Page>


1.  The Company's Intellectual Property Rights are listed in Schedules A and B
    of the Separation Agreement.

2.  The Company expects to enter into a License Agreement and a
    Noncompetition Agreement, each between Photogen, Inc. and the Company in
    connection with the anticipated separation transaction. Forms of these
    agreements are attached as exhibits to the Separation Agreement.

3.  License Agreement dated as of September 30, 1999 between The General
    Hospital Corporation d/b/a Massachusetts General Hospital and Photogen, Inc.
    (recently assigned to Photogen Technologies, Inc.).

4.  License Agreement dated October 20, 1999 between Photogen Technologies, Inc,
    Photogen Newco Ltd. (n/k/a Sentigen Ltd.) and Elan Pharma International
    Limited. (Filed as Exhibit 10.13 to the Company's Quarterly Report on Form
    10-QSB for the quarter ended September 30, 1999).

SECTION 3.11: LITIGATION; COMPLIANCE WITH LAW
No exceptions, except for the matters disclosed in Schedule 3.6 above.

<Page>


SECTION 3.12: LEASEHOLD INTERESTS
No exceptions.

SECTION 3.13: INSURANCE
No exceptions.

SECTION 3.14:  LOANS AND ADVANCES

        1.  Loan and Security Agreement between Photogen Technologies, Inc.,
            Photogen, Inc. and Tannebaum, LLC, dated April 8, 2002.

        2.  Revolving Promissory Note (Secured) between Photogen Technologies,
            Inc., Photogen, Inc. and Tannebaum, LLC, dated April 8, 2002.

        3.  Advance of $60,000 to the founding stockholders by the Company to be
            repaid as part of the split off transaction.


SECTION 3.15: ASSUMPTIONS, GUARANTIES, ETC. OF INDEBTEDNESS OF OTHER PERSONS

The Company is a guarantor of an Equipment Lease between Picker Financial Group,
L.L.C. ("Picker") and Photogen, Inc., dated October 25, 1999, with aggregate
remaining lease payments of $622,710 due thereunder. The Company has $230,500 on
deposit with Picker to partially cover this obligation. Pursuant to the
Separation Agreement, the Company assumes all liability under this lease.

SECTION 3.16: GOVERNMENTAL APPROVALS

The Company must comply with the comments of the Securities and Exchange
Commission ("SEC"), if any, with regard to the Company's preliminary proxy
statement.

SECTION 3.17:  TAX MATTERS

See Section 6.2 of the Separation Agreement which provides that the Company
shall receive written advice from BDO Seidman that, if the corporate separation
is not tax free to the Company under Section 355 of the Internal Revenue Code of
1986, as amended, that the resulting tax would not exceed the amount of the
Company's current net operating losses which would be eligible to offset such
tax.

<Page>


SECTION 3.18: TITLE TO PROPERTIES

UCC-1 Financing Statement No. 2002015141-1 filed by Tannebaum, LLC, as secured
party, with the Secretary of State of Nevada on June 11, 2002 against the assets
of Photogen Technologies, Inc. and Photogen, Inc., as debtors, in connection
with the line of credit, which shall be terminated immediately prior to or
contemporaneous with the closing of the Common Stock Purchase Agreement.

SECTION 3.19: LABOR DISPUTES
No exceptions.

SECTION 3.20: ENVIRONMENTAL MATTERS
No exceptions.

SECTION 3.21: COMPLIANCE WITH NASDAQ CONTINUED LISTING REQUIREMENTS

Although the price of the Company's Common Stock has recently traded below $1.00
on various occasions, it has not done so for any period of thirty consecutive
days. The Company has not received any notice of delisting of its Common Stock
and believes that it complies with all continued listing requirements of the
Nasdaq SmallCap Market.

SECTION 3.22: BROKERS

AmeriCal Securities, Inc. agreements:

   1. Letter Agreement between the Company and AmeriCal Securities, Inc., dated
      March 25, 2002, regarding business development.

   2. Letter Agreement between the Company and AmeriCal Securities, Inc., dated
      March 25, 2002, regarding raising of capital.

   3. Letter, dated April 17, 2002, from the Company to AmeriCal Securities,
      Inc. terminating the Letter Agreements referenced in Items 1 and 2 of this
      Schedule 3.22.

   4. Letter from AmeriCal Securities, Inc. responding to April 17, 2002 letter.

SECTION 3.23:  NO DIRECTED SELLING EFFORTS OR GENERAL SOLICITATION
No exceptions.

<Page>


SECTION 3.24:  NO INTEGRATED OFFERING
No exceptions; however, in the course of filing its preliminary proxy materials,
the Company plans to raise with the SEC the issue of integration between the
private placement to the Purchasers and the shareholder offering to confirm that
the Staff would not view the two offerings as integrated.

SECTION 3.25: TRANSACTIONS WITH AFFILIATES

1.  Stuart P. Levine is the direct beneficial holder of 3,289,621 shares of
    Common Stock (approximately 8.8% of the outstanding Common Stock) and, along
    with Dr. Weinstein, may be deemed to control 4,116,921 shares held by
    Tannebaum, LLC. As disclosed in the SEC Filings, the Company has entered
    into a secured line of credit with Tannebaum LLC.

2.  The Company expects to enter into a Separation Agreement (the "Separation
    Agreement") by and among the following: Craig Dees, Ph.D. and Dees Family
    Foundation, Eric A. Wachter, Ph.D. and Eric A. Wachter 1998 Charitable
    Remainder Unitrust, Timothy D. Scott, Ph.D. and Scott Family Investment
    Limited Partnership, Walter Fisher, Ph.D., Fisher Family Investment Limited
    Partnership, and Walt Fisher 1998 Charitable Remainder Unitrust, and John A.
    Smolik and Smolik Family LLP, Photogen Technologies, Inc. ("Technologies"),
    Photogen, Inc. ("Photogen"), Robert J. Weinstein, M.D., Stuart P. Levine and
    Tannebaum, LLC (note that pursuant to the Separation Agreement
    non-competition agreements shall be executed to effect the following: (i)
    Photogen and Drs. Dees, Wachter, Scott, Fisher and Mr. Smolik shall not
    develop or sublicense technologies that are a part of the therapeutic
    business of Technologies for diagnostic x-ray purposes or adversely affect
    the development of N1177 or PH-50; and (ii) Technologies shall not develop
    or sublicense non-nanoparticulate PH-10 or adversely affect the development
    of PH-10).

SECTION 3.26: QUESTIONABLE PAYMENTS
No exceptions.

SECTION 3.27:  INFORMATION SUPPLIED TO PURCHASERS
No exceptions.