Document:

<PAGE>

                                                                   Exhibit 10(j)

================================================================================

                               MERCK & CO., INC.

                         Plan for Deferred Payment of
                            Directors' Compensation

                 (Amended and Restated as of November 1, 2000)

================================================================================
<PAGE>

                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                                                               Page
<S>                                                                                                             <C>
Article I       Purpose                                                                                         1

Article II      Election of Deferral, Measurement Methods and Distribution Schedule                             1

Article III     Valuation of Deferred Amounts                                                                   2

Article IV      Redesignation Within a Deferral Account                                                         3

Article V       Redesignation of Deferred Amounts Measured by                                                   4
                Certain Measurement Methods on February 1, 2000

Article VI      Payment of Deferred Amounts                                                                     4

Article VII     Designation of Beneficiary                                                                      6

Article VIII    Plan Amendment or Termination                                                                   6

Schedule A      Measurement Methods                                                                             7
</TABLE>
                                      (i)
<PAGE>

                               MERCK & CO., INC.
                         PLAN FOR DEFERRED PAYMENT OF
                            DIRECTORS' COMPENSATION

I.   PURPOSE

     To provide an arrangement under which directors of Merck & Co., Inc. other
     than current employees may (i) elect to voluntarily defer payment of the
     annual retainer and meeting and committee fees until after termination of
     their service as a director, and (ii) value compensation mandatorily
     deferred on their behalf.

II.  ELECTION OF DEFERRAL, MEASUREMENT METHODS AND DISTRIBUTION SCHEDULE

     A.   Election of Voluntary Deferral Amount
          -------------------------------------

     1.   Prior to December 28 of each year, each director is entitled to make
          an irrevocable election to defer until termination of service as a
          director receipt of payment of (a) 50% or 100% of the retainer for the
          12 months beginning April 1 of the next calendar year, (b) 50% or 100%
          of the Committee Chairperson retainer beginning April 1 of the next
          calendar year, and (c) 50% or 100% of the meeting and committee fees
          for the 12 months beginning April 1 of the next calendar year.

     2.   Prior to commencement of duties as a director, a director newly
          elected or appointed to the Board during a calendar year must make the
          election under this paragraph for the portion of the Voluntary
          Deferral Amount applicable to such director's first year of service
          (or part thereof).

     3.   The Voluntary Deferral Amount shall be credited as follows:  (1)
          Meeting and committee fees that are deferred are credited as of the
          day the director's services are rendered; (2) if the Board retainer
          and/or Committee Chairperson retainer is deferred, a pro-rata share of
          the deferred retainer is credited on the last business day of each
          calendar quarter.  The dates the Voluntary Deferral Amount, or parts
          thereof, are credited to the director's deferred account are
          hereinafter referred to as the Voluntary Deferral Dates.

     B.   Mandatory Deferral Amount
          -------------------------

     1.   On the Friday following the Company's Annual Meeting of Stockholders
          (such Friday hereinafter referred to as the "Mandatory Deferral
          Date"), each director will be credited with an amount equivalent to
          one-third of the annual cash retainer for the 12 month period
          beginning on the April 1 preceding the Annual Meeting  (the "Mandatory
          Deferral Amount").  The Mandatory Deferral Amount will be measured by
          the Merck Common Stock account.

     2.   A director newly elected or appointed to the Board after the Mandatory
          Deferral Date will be credited with a pro rata portion of the
          Mandatory Deferral Amount applicable to such director's first year of
          service (or part thereof). Such pro rata portion shall be credited to
          the director's account on the first day of such director's service.

                                       1
<PAGE>

     C.   Election of Measurement Method
          ------------------------------

          Each such annual election referred to in Section A shall include an
          election as to the measurement method or methods by which the value of
          amounts deferred will be measured in accordance with Article III,
          below. The available measurement methods are set forth on Schedule A
          hereto.

     D.   Election of Distribution Schedule
          ---------------------------------

          Each annual election referred to in Section A above shall also include
          an election to receive payment following termination of service as a
          director of all Voluntary Deferral Amounts and Mandatory Deferral
          Amounts in a lump sum either immediately or one year after such
          termination, or in quarterly or annual installments over five, ten or
          fifteen years.

III. VALUATION OF DEFERRED AMOUNTS

     A.   Common Stock
          ------------

     1.   Initial Crediting. The annual Mandatory Deferral Amount shall be used
          to determine the number of full and partial shares of Merck Common
          Stock which such amount would purchase at the closing price of the
          Common Stock on the New York Stock Exchange on the Mandatory Deferral
          Date.

          That portion of the Voluntary Deferral Amount allocated to Merck
          Common Stock shall be used to determine the number of full and partial
          shares of Merck Common Stock which such amount would purchase at the
          closing price of the Common Stock on the New York Stock Exchange on
          the applicable Voluntary Deferral Date.

          However, should it be determined by the Committee on Directors of the
          Board of Directors that a measurement of Merck Common Stock on any
          Mandatory or Voluntary Deferral Date would not constitute fair market
          value, then the Committee shall decide on which date fair market value
          shall be determined using the valuation method set forth in this
          Article III, Section A.1.

          At no time during the deferral period will any shares of Merck Common
          Stock be purchased or earmarked for such deferred amounts nor will any
          rights of a shareholder exist with respect to such amounts.

     2.   Dividends.  Each director's account will be credited with the
          additional number of full and partial shares of Merck Common Stock
          which would have been purchasable with the dividends on shares
          previously credited to the account at the closing price of the Common
          Stock on the New York Stock Exchange on the date each dividend was
          paid.

     3.   Distributions. Distribution from the Merck Common Stock account will
          be valued at the closing price of Merck Common Stock on the New York
          Stock Exchange on the distribution date.

                                       2

<PAGE>

     B.   Mutual Funds
          ------------

     1.   Initial Crediting. The amount allocated to each Mutual Fund shall be
          used to determine the full and partial Mutual Fund shares which such
          amount would purchase at the closing net asset value of the Mutual
          Fund shares on the Mandatory or Voluntary Deferral Date, whichever is
          applicable. The director's account will be credited with the number of
          full and partial Mutual Fund shares so determined.

          At no time during the deferral period will any Mutual Fund shares be
          purchased or earmarked for such deferred amounts nor will any rights
          of a shareholder exist with respect to such amounts.

     2.   Dividends.  Each director's account will be credited with the
          additional number of full and partial Mutual Fund shares which would
          have been purchasable, at the closing net asset value of the Mutual
          Fund shares as of the date each dividend is paid on the Mutual Fund
          shares, with the dividends which would have been paid on the number of
          shares previously credited to such account (including pro rata
          dividends on any partial shares).

     3.   Distributions.  Mutual Fund distributions will be valued based on the
          closing net asset value of the Mutual Fund shares on the distribution
          date.

     C.   Adjustments
          -----------

          In the event of a reorganization, recapitalization, stock split, stock
          dividend, combination of shares, merger, consolidation, rights
          offering or any other change in the corporate structure or shares of
          the Company or a Mutual Fund, the number and kind of shares or units
          of such investment measurement method available under this Plan and
          credited to each director's account shall be adjusted accordingly.

IV.  REDESIGNATION WITHIN A DEFERRAL ACCOUNT

     A.   General
          -------

          A director may request a change in the measurement methods used to
          value all or a portion of his/her account other than Merck Common
          Stock. Amounts deferred using the Merck Common Stock method and any
          earnings attributable to such deferrals may not be redesignated.  The
          change will be effective on  (i) the day when the redesignation
          request is received pursuant to administrative guidelines established
          by the Human Resources Financial Services area of the Treasury
          department, provided the request is received prior to the close of the
          New York Stock Exchange on such day or (ii) the next following
          business day if the request is received when the New York Stock
          Exchange is closed.

     B.   When Redesignation May Occur
          ----------------------------

     1.   During Active Service. There is no limit on the number of times a
          director may redesignate the portion of his/her deferred account
          permitted to be redesignated. Each such request shall be irrevocable
          and can be designated in whole percentages or as a dollar amount.

                                       3
<PAGE>

     2.   After Death. Following the death of a director, the legal
          representative or beneficiary of such director may redesignate subject
          to the same rules as for active directors set forth in Article IV,
          Section B.1.

     C.   Valuation of Amounts to be Redesignated
          ----------------------------------------

          The portion of the director's account to be redesignated will be
          valued at its cash equivalent and such cash equivalent will be
          converted into shares or units of the other measurement method(s). For
          purposes of such redesignations, the cash equivalent of the value of
          the Mutual Fund shares shall be the closing net asset value of such
          Mutual Fund on (i) the day when the redesignation request is received
          pursuant to administrative guidelines established by the Human
          Resources Financial Services area of the Treasury department, provided
          the request is received prior to the close of the New York Stock
          Exchange on such day or (ii) the next following business day if the
          request is received when the New York Stock Exchange is closed.

V.   REDESIGNATION OF DEFERRED AMOUNTS MEASURED BY CERTAIN MEASUREMENT METHODS
     ON FEBRUARY 1, 2001

     Prior to February 1, 2001, each director who has any part of his/her
     deferred account measured by the ten investment funds listed in the chart
     below may elect the investments by which such part of the deferred account
     will be measured as of February 1, 2001.

     If a director fails to make an election regarding amounts measured by those
     ten funds before February 1, 2001, then the amount in each such fund shall
     automatically be redesignated as of February 1, 2001, to the investments
     specified in the chart below as the replacement investments. The value to
     be redesignated will be the closing value on January 31, 2001 as determined
     in accordance with Article III.
<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------
               Investment Fund to Be Replaced                 Replacement Investment Fund
<S>                                                           <C>
-------------------------------------------------------------------------------------------------------
PIMCO Global Bond Institutional                               PIMCO Foreign Bond Institutional
-------------------------------------------------------------------------------------------------------
Vanguard Wellington Fund                                      Vanguard Asset Allocation
-------------------------------------------------------------------------------------------------------
Fidelity Magellan Fund                                        T. Rowe Price Blue Chip Growth Fund
-------------------------------------------------------------------------------------------------------
Sequoia Fund                                                  Fidelity Destiny I
-------------------------------------------------------------------------------------------------------
Scudder Growth & Income                                       Fidelity Destiny I
-------------------------------------------------------------------------------------------------------
T. Rowe Price Small-Cap Value Fund                            Fidelity Low-Priced Stock Fund
-------------------------------------------------------------------------------------------------------
T. Rowe Price International Stock Fund                        Putnam International Voyager A
-------------------------------------------------------------------------------------------------------
Templeton Growth Fund, Inc.                                   Putnam Global Equity A
-------------------------------------------------------------------------------------------------------
Templeton Developing Markets A                                American Century Emerging Markets Fund
-------------------------------------------------------------------------------------------------------
Fidelity Retirement Government Money Market                   Fidelity Retirement Money Market
-------------------------------------------------------------------------------------------------------
</TABLE>

VI.    PAYMENT OF DEFERRED AMOUNTS

       A.     Payment
              -------

              All payments to directors of amounts deferred will be in cash in
              accordance with the distribution schedule elected by the director
              pursuant to Article II, Section D. Distributions shall be pro rata
              by measurement method. Distributions shall be valued on the
              fifteenth day of the distribution month (or, if such day is not a
              business day, the next business day) and paid as soon thereafter
              as possible.

                                       4
<PAGE>

       B.     Changes to Distribution Schedule Prior to Termination
              -----------------------------------------------------

              Upon the request of a director made at any time during the
              calendar year immediately preceding the calendar year in which
              service as a director is expected to terminate, the Committee on
              Directors of the Board of Directors ("Committee on Directors"), in
              its sole discretion, may authorize: (a) an extension of a payment
              period beyond that originally elected by the director not to
              exceed that otherwise allowable under Article II, Section D,
              and/or (b) a payment frequency different from that originally
              elected by the director. Such request may not be made with regard
              to amounts deferred after December 31, 1990 using the Merck Common
              Stock method and to any earnings attributable to such deferrals.
              Deferrals into Merck Common Stock made after December 31, 1990 and
              any earnings thereon may only be distributed in accordance with
              the schedule elected by the director under Article II, Section D
              or determined by the Committee on Directors under Article VII.

        C.    Post-Termination Changes to Distribution Schedule
              -------------------------------------------------

              Following termination of service as a director, each director may
              make one request for a further extension of the period for
              distribution of his/her deferred compensation. Such request must
              be received by the Committee on Directors prior to the first
              distribution to the participant under his/her previously elected
              distribution schedule. Any revised distribution schedule may not
              exceed the deferral period otherwise allowable under Article II,
              Section C. This request may be granted and a new payment schedule
              determined in the sole discretion of the Committee on Directors.
              Such request may not be made with regard to amounts deferred after
              December 31, 1990 using the Merck Common Stock Method and to any
              earnings attributable to such deferrals. Any retired director who
              is not subject to U.S. income tax may petition the Committee on
              Directors to change payment frequency, including a lump sum
              distribution, and the Committee on Directors may grant such
              petition if, in its discretion, it considers there to be
              reasonable justification therefor. Deferrals into Merck Common
              Stock made after December 30, 1990 and any earnings thereon may
              only be distributed in accordance with the schedule elected by the
              director under Article II, Section D or determined by the
              Committee on Directors under Article VII.

       D.     Forfeitures
              -----------

              A director's deferred amount attributable to the Mandatory
              Deferral Amount and earnings thereon shall be forfeited upon his
              or her removal as a director or upon a determination by the
              Committee on Directors in its sole discretion, that a director
              has:

              (i)   joined the Board of, managed, operated, participated in a
                    material way in, entered employment with, performed
                    consulting (or any other) services for, or otherwise been
                    connected in any material manner with a company,
                    corporation, enterprise, firm, limited partnership,
                    partnership, person, sole proprietorship or any other
                    business entity determined by the Committee on Directors in
                    its sole discretion to be competitive with the business of
                    the Company, its subsidiaries or its affiliates (a
                    "Competitor");

              (ii)  directly or indirectly acquired an equity interest of five
                    (5) percent or greater in a Competitor; or

                                       5
<PAGE>

              (iii) disclosed any material trade secrets or other material
                    confidential information, including customer lists, relating
                    to the Company or to the business of the Company to others,
                    including a Competitor.

VII.   DESIGNATION OF BENEFICIARY

       In the event of the death of a director, the deferred amount at the date
       of death shall be paid to the last named beneficiary or beneficiaries
       designated by the director, or, if no beneficiary has been designated, to
       the director's legal representative, in one or more installments as the
       Committee on Directors in its sole discretion may determine.

VIII.  PLAN AMENDMENT OR TERMINATION

       The Committee on Directors shall have the right to amend or terminate
       this Plan at any time for any reason.

                                       6
<PAGE>

                                   SCHEDULE A

                              MEASUREMENT METHODS
                  (Effective July 1, 1999 - January 31, 2001)

     Merck Common Stock

     Mutual Funds

          Acorn Fund
          Fidelity Destiny I
          Fidelity Equity Income Fund
          Fidelity Magellan Fund
          Fidelity Retirement Government Money Market
          Fidelity Spartan Government Income
          Fidelity Spartan U.S. Equity Index Fund
          PIMCO Long Term US Government Institutional
          PIMCO Total Return Institutional
          PIMCO Global Bond Institutional
          Scudder Growth & Income Fund
          Sequoia Fund
          T. Rowe Price Small-Cap Value Fund
          T. Rowe Price International Stock Fund
          Templeton Developing Markets A
          Templeton Growth Fund, Inc. I
          Vanguard Wellington Fund

                                       7
<PAGE>

                                   SCHEDULE A

                              MEASUREMENT METHODS

                               (February 1, 2001)

     Merck Common Stock

     Mutual Funds

          Acorn Fund
          American Century Emerging Markets Fund
          Europacific Growth Fund
          Fidelity Destiny I
          Fidelity Dividend Growth
          Fidelity Equity Income Fund
          Fidelity Low-Priced Stock Fund
          Fidelity Retirement Money Market
          Fidelity Spartan Government Income
          Fidelity Spartan U.S. Equity Index
          Franklin Small Cap Growth A
          Janus Enterprise
          Janus Growth & Income
          PIMCO Foreign Bond Institutional
          PIMCO Long Term US Government Institutional
          PIMCO Total Return Institutional
          Putnam Global Equity A
          Putnam International Voyager A
          Putnam Vista A
          T. Rowe Price Blue Chip Growth Fund
          Vanguard Asset Allocation
          Vanguard U.S. Growth Portfolio

                                       8<PAGE>

                                                                   Exhibit 10(o)

                                                                  Execution Copy

                       LIMITED LIABILITY COMPANY AGREEMENT

                                       OF

                           MERCK CAPITAL VENTURES, LLC

                          Dated as of November 27, 2000
                          -----------------------------
<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                      Page
<S>                                                                                   <C>
ARTICLE 1   DEFINITIONS................................................................1
            -----------

ARTICLE 2   FORMATION; TERM; FISCAL YEAR...............................................1
            ----------------------------
            2.1.     Formation.........................................................1
            2.2.     Term..............................................................2
            2.3.     Fiscal Year.......................................................2

ARTICLE 3   NAME AND PLACE OF BUSINESS.................................................2
            --------------------------
            3.1.     Name..............................................................2
            3.2.     Principal Place of Business.......................................2

ARTICLE 4   PURPOSE AND POWERS.........................................................2
            ------------------
            4.1.     Purpose...........................................................2
            4.2.     Powers............................................................2

ARTICLE 5   CAPITAL CONTRIBUTIONS; MEMBERSHIP INTERESTS................................3
            -------------------------------------------
            5.1.     Capital Contributions.............................................3
            5.2.     Notice and Funding of Capital Contributions.......................4
            5.4.     No Return of Capital Contributions................................5
            5.5.     Designated Additional Carry Members...............................5

ARTICLE 6   BOARD OF MANAGERS AND OFFICERS OF THE COMPANY..............................6
---------   ---------------------------------------------
            6.1.     Designation of Board of Managers..................................6
            6.2.     Election; Resignation; Removal....................................7
            6.3.     Board Action......................................................7
            6.4.     Meetings..........................................................7
            6.5.     Quorum............................................................8
            6.6.     Action By Consent.................................................8
            6.7.     Telephonic Meetings...............................................8
            6.8.     Managers as Agents................................................8
            6.9.     Powers of the Board...............................................8
            6.10.    Reimbursement.....................................................8
            6.11.    Non-Exclusive Engagement..........................................9
            6.12.    Officers..........................................................9
            6.13.    Certain Actions..................................................10
            6.14.    Reliance by Third Parties........................................12
            6.15.    No Right to Manage...............................................12

ARTICLE 7   RIGHTS AND OBLIGATIONS OF LOFBERG.........................................12
            ---------------------------------
            7.1.     Powers...........................................................12
</TABLE>

                                      -i-
<PAGE>

<TABLE>
<S>                                                                                   <C>
            7.2.     Consultation with Investment Committee...........................13

ARTICLE 8   OTHER AGREEMENTS..........................................................13
            ----------------
            8.1.     The Investment Committee and the Executive Committee.............13
            8.2.     Other Investments................................................14
            8.3.     Certain Other Fees...............................................16
            8.4.     MCV Budget.......................................................17
            8.5.     Administrative Staff.............................................18
            8.6.     Fees and Expenses; Carry Member Costs............................18

ARTICLE 9   ACCOUNTS AND ALLOCATIONS..................................................18
            ------------------------
            9.1.     Capital Accounts.................................................18
            9.2.     Allocations......................................................19
            9.3.     Tax Allocations..................................................20

ARTICLE 10  DISTRIBUTIONS.............................................................21
            -------------
            10.1.    Distributions....................................................21
            10.2.    Certain Other Distributions......................................22
            10.3     Distributions in Kind............................................24
            10.4.    Withholding Requirements.........................................25
            10.5.    Valuations.......................................................25

ARTICLE 11  TRANSFER OF MEMBERSHIP INTERESTS..........................................26
            --------------------------------
            11.1.    Transfers........................................................26
            11.2.    Ownership of Membership Interests................................27

ARTICLE 12  WITHDRAWAL; DISSOLUTION AND LIQUIDATION...................................27
            ---------------------------------------
            12.1.    Withdrawal of Members............................................27
            12.3.    Liquidation......................................................27
            12.4.    Return of Excess Distributions to Investor Members...............28

ARTICLE 13  TAX MATTERS; CERTAIN REPRESENTATIONS OF MEMBERS...........................29
            -----------------------------------------------
            13.1.    Designation of Tax Matters Member................................29
            13.2.    Tax Returns......................................................29
            13.3.    Taxable Year.....................................................29
            13.4.    Tax Elections....................................................29
            13.5.    Certain Representations of Members...............................29

ARTICLE 14  BOOKS OF ACCOUNT; REPORTS.................................................31
            -------------------------
            14.1.    Books of Account.................................................31
            14.2.    Reports to Members...............................................31
            14.3.    Final Accounting.................................................31
</TABLE>

                                     -ii-
<PAGE>

<TABLE>
<S>                                                                                   <C>
ARTICLE 15  LIMITATION ON LIABILITY; INDEMNIFICATION..................................32
            ----------------------------------------
            15.1.    Limitation on Members' Liability.................................32
            15.2.    Limitation on Protected Parties' Liability.......................32
            15.3.    Indemnification of the Protected Parties.........................32
            15.4.    No Liability for Acts of Agents..................................32
            15.5.    General..........................................................33
            15.6.    Survival.........................................................33

ARTICLE 16  MISCELLANEOUS.............................................................33
            -------------
            16.1.    Special Power of Attorney........................................33
            16.2.    Amendments.......................................................33
            16.3.    Binding Effects; Benefits........................................34
            16.4.    Headings.........................................................34
            16.5.    Counterparts.....................................................34
            16.6.    Grammatical Construction.........................................34
            16.7.    Separability.....................................................34
            16.8.    Waiver...........................................................34
            16.9.    Entire Agreement.................................................35
            16.10.  Notices...........................................................35
            16.11.   Insurance........................................................35
            16.12.   Disclosure of Investment.........................................36
            16.13.   Arbitration......................................................36
            16.14.  Appointment of Executive Agent....................................37
            16.15.   Payments on Business Days........................................37
            16.16.  Governing Law.....................................................38
</TABLE>

APPENDIX A        Definitions
<PAGE>

                       LIMITED LIABILITY COMPANY AGREEMENT

                                       OF

                           MERCK CAPITAL VENTURES, LLC

      LIMITED LIABILITY COMPANY AGREEMENT of Merck Capital Ventures, LLC (the
"Company"), dated as of November 27, 2000, by and among Merck-Medco Managed
  ------
Care, L.L.C. ("Merck"), the individuals listed on Part A of Schedule A hereto
               -----                              --------------------
(the "Other Investor Members" and together with Merck, the "Investor Members")
      ----------------------                                ----------------
and the individuals listed on Part B of Schedule A hereto (the "Carry Members"
                              --------------------              -------------
and together with the Investor Members, the "Members").
                                             -------

      WHEREAS, the Company was formed by the filing of a Certificate of
Formation with the Secretary of State of the State of Delaware; and

      WHEREAS, the Members desire to enter into this Limited Liability Company
Agreement (the "Agreement") in accordance with the provisions of the Delaware
                ---------
Limited Liability Company Act (the "LLC Act") in order to set forth the rights
                                    -------
and obligations of the Members.

      NOW, THEREFORE, the parties hereto hereby agree as follows:

                                    ARTICLE 1

                                   DEFINITIONS
                                   -----------

      Certain capitalized terms used herein are defined in Appendix A attached
                                                           ----------
hereto and made a part hereof.

                                    ARTICLE 2

                          FORMATION; TERM; FISCAL YEAR
                          ----------------------------

      2.1. Formation. The Members hereby acknowledge the formation of the
           ---------
Company as a limited liability company pursuant to the LLC Act by virtue of the
filing of a Certificate of Formation with the Secretary of State of the State of
Delaware, and confirm and agree to their status as Members of the Company. The
Members hereby execute this Agreement for the purpose of establishing the
rights, duties and relationship of the Members.

      2.2. Term. This Agreement shall continue until the Company is dissolved
           ----
and liquidated in accordance with the provisions of Article 12 hereof.

                                      -1-
<PAGE>

      2.3. Fiscal Year. Unless the Board of Managers at any time shall otherwise
           -----------
determine or with respect to the last fiscal year of the Company, the fiscal
year of the Company (the "Fiscal Year") shall end on December 31. The initial
                          -----------
Fiscal Year shall commence on the date hereof and end on December 31, 2000.

                                    ARTICLE 3

                           NAME AND PLACE OF BUSINESS
                           --------------------------

      3.1. Name. The name of the Company shall be, and the business of the
           ----
Company shall be conducted under the name, "Merck Capital Ventures, LLC";
                                            ---------------------------
provided that such name shall be subject to change, from time to time, by the
Board of Managers.

      3.2. Principal Place of Business. The principal place of business of the
           ---------------------------
Company shall be at such place as the Board of Managers shall determine from
time to time. The Board of Managers shall notify the Members of any change of
the principal place of business of the Company. The Company may maintain such
office or offices for the transaction of business at such other locations as the
Board of Managers may deem advisable.

                                    ARTICLE 4

                               PURPOSE AND POWERS
                               ------------------

      4.1. Purpose. The purpose of the Company is to purchase, invest or
           -------
otherwise acquire or engage in investments of no more than 20% (unless otherwise
approved by the Board of Managers) in the equity of (a) Clinical Development
Entities and (b) private internet and other private emerging businesses engaged
in the businesses of (i) improving the quality and/or reducing the cost of
commercialization, distribution and delivery of pharmaceuticals and healthcare
services related thereto, or (ii) exploiting data derived therefrom (together
with Clinical Development Entities, "E-Healthcare Companies") and such other
                                     ----------------------
investments in private companies as may be approved by the Board of Managers or
are made in accordance with Section 7.1(a) and to engage in any and all
activities that are reasonably related thereto, provided, however, that the
                                                --------  -------
Company may not invest in entities engaged in research based pharmaceutical,
vaccine or biotech businesses.

      4.2. Powers. The Company shall have and may exercise all the powers and
           ------
privileges to the fullest extent permitted by law as are necessary, appropriate
or incidental to the conduct, promotion or attainment of the purpose of the
Company, including, without limitation:

      (a) to purchase, sell, possess, transfer, or otherwise deal in, and to
exercise all rights, powers, privileges and other incidents of ownership or
possession with

                                      -2-
<PAGE>

respect to, the equity, assets and businesses of E-Healthcare Companies and
other investments or of any of their respective successors or assigns;

      (b) to have and maintain one or more offices and, in connection therewith,
to rent or acquire office space and furnishings, engage personnel and do such
other acts and things as may be necessary or advisable in connection with the
maintenance of such office or offices;

      (c) to open, maintain and close bank accounts and to draw checks or other
orders for the payment of moneys;

      (d) to enter into, perform and carry out contracts and agreements of every
kind necessary or incidental to the accomplishment of the Company's purpose, and
to take or omit to take such other or further action in connection with the
Company's business as may be necessary or desirable in the opinion of the Board
of Managers to further the purpose of the Company;

      (e) to invest such funds as are temporarily not required for Company
purposes in short-term high-grade investments selected by the Board of Managers,
including money market accounts, short-term investment funds, government
securities, certificates of deposit of commercial banks (domestic or foreign),
commercial paper, bankers' acceptances and other money market instruments; and

      (f) to carry on any other activities necessary to, in connection with, or
incidental to any of the foregoing.

                                    ARTICLE 5

                   CAPITAL CONTRIBUTIONS; MEMBERSHIP INTERESTS
                   -------------------------------------------

      5.1. Capital Contributions. (a) Merck agrees to contribute to the Company
           ---------------------
up to $100 million for investments in Portfolio Investments (the "Merck Base
                                                                  ----------
Commitment") as and when called by the Company in accordance with the terms of
----------
this Agreement, and to contribute additional amounts to pay certain Fees and
Expenses of the Company as set forth in Section 5.1(b), and each Other Investor
Member agrees to contribute to the Company in respect of each Portfolio
Investment in which Merck invests the Merck Base Commitment (including without
limitation any follow on Portfolio Investments in a Portfolio Company), an
amount calculated by multiplying the Ratable Contribution Percentage of such
Investor Member expressed as a decimal multiplied by the lesser of (i) 10% of
the Acquisition Cost of such Portfolio Investment (or follow on Portfolio
Investment as the case may be) or (ii) $1,000,000 (the "Other Investor Members
                                                        ----------------------
Base Commitment"), in accordance with the terms of this Agreement (collectively
---------------
with the Merck contributions, the "Capital Contributions"). Except as specified
                                   ---------------------
by this Agreement or as required by applicable law, (i) no Member shall at any
time be required

                                      -3-
<PAGE>

to make any additional contribution to the capital of the Company or any loans
to the Company, (ii) no Investor Member (other than Merck) shall be obligated to
make a Capital Contribution in respect of a Portfolio Investment made or
committed to be made before the Start Date of such Investor Member or after the
End Date of such Investor Member, and (iii) the Aggregate Capital Contributions
of the Other Investor Members shall not exceed $10 million.

      (b) Capital Contributions shall be called and used (i) during the
Investment Period, to fund Portfolio Investments (including follow on
investments) and (ii) during the Expenses Period (including both during and
after the Investment Period), to pay all reasonable Fees and Expenses of the
Company.

      (c) Notwithstanding the provisions of Sections 5.1(a) and (b), (i) each
Investor Member's obligation to fund its Capital Contributions (other than the
Capital Contributions set out in Section 5.1(b)(ii)) will expire at the end of
the Investment Period and (ii) Merck's obligation to fund Capital Contributions
in accordance with Section 5.1(b)(ii) will expire at the end of the Expenses
Period.

      5.2. Notice and Funding of Capital Contributions. (a) On each occasion
           -------------------------------------------
that the Company proposes to make an investment in a Portfolio Company in which
a Capital Contribution is required, the Company shall give to each Investor
Member who is eligible to participate in such Capital Contribution a written
notice at least 10 days prior to the date such Capital Contribution is required
(a "Funding Notice") which shall include (i) a brief description of the
    --------------
transaction (including a reasonable description of the form and structure
thereof) or purpose for which such Capital Contributions are required, (ii) the
aggregate amount of Capital Contributions required and the respective Investor
Member's share thereof, (iii) the date by which such Capital Contributions are
required to be funded, and (iv) if applicable, the account of the Portfolio
Company to which such Capital Contributions shall be made.

           (b) During the Expenses Period, Merck will contribute to the Company
as a Capital Contribution from time to time as may be reasonably required
amounts sufficient to pay all anticipated Fees and Expenses as provided in the
MCV Budget. In addition, from time to time during the Expenses Period, Merck
will contribute to the Company as a Capital Contribution an amount equal to any
Break-Up Expenses or other Fees and Expenses required to be contributed by Merck
to the Company in accordance with this Agreement.

           (c) Each Investor Member shall deposit its required Capital
Contributions, in immediately available funds, in the account of the Company or
of the Portfolio Company, as the case requires, within the time period specified
in the Funding Notice. If an Investor Member deposits its required Capital
Contribution later than the last day specified in the Funding Notice, and the
Company incurs any costs or expenses

                                      -4-
<PAGE>

(including, without limitation, interest expenses) as a result of such late
deposit, then such Investor Member shall pay to the Company an additional amount
equal to the amount of such costs and expenses (and such additional amount shall
not be considered Capital Contributions). If an Investor Member shall Default in
all or any portion of their contribution obligations as set forth in the Funding
Notice, the Company shall give to the other Investor Members ("Non-Defaulting
                                                               --------------
Investor Members") a further written notice, which shall include the amount of
----------------
the deficiency in the required Capital Contributions. The majority of the
Non-Defaulting Investor Members may either, (i) agree to pay the full amount of
the deficiency in the required Capital Contribution (in such proportion as is
agreed by such Non-Defaulting Investor Members) or (ii) agree that the Company
not proceed with the Portfolio Investment the subject of the Funding Notice in
which case, the Company will refund to the Investor Members the full amount of
all Capital Contributions made by the Investor Members in respect of such
Portfolio Investment.

      5.3. Voting Rights. (a) The Investor Members shall have Membership
           -------------
Interests in the Company in the amounts representing their respective Capital
Contributions. All such Membership Interests shall be of a single class for
purposes of the LLC Act's voting requirements.

      (b) The Carry Members shall be Members entitled to distributions in
accordance with this Agreement. However, except as provided in Sections 5.5(b)
and 16.2, the Membership Interests of the Carry Members shall not entitle them
to vote on any matter as a Member.

      5.4. No Return of Capital Contributions. Except as provided in Section
           ----------------------------------
12.4 hereof, no Member is entitled to a withdrawal or return of its Capital
Contributions to the Company, but each shall look solely to distributions from
the Company for such purpose.

      5.5. Designated Additional Carry Members. (a) At any time and from time to
           -----------------------------------
time, Merck or, for so long as Lofberg is Chief Executive Officer of the
Company, Lofberg may propose to the Board of Managers, and the Board of Managers
may designate in accordance with and subject to the provisions of Sections
5.5(c) and 6.13, an additional Person as a "Designated Additional Carry Member".
                                            ----------------------------------
Upon designation of a Designated Additional Carry Member, the Board of Managers
will in accordance with the provisions of Section 6.13 specify the Applicable
Carried Interest applicable to such Designated Additional Carry Member and such
Designated Additional Carry Member shall be admitted to the Company as a Carry
Member; provided, however, that the sum of the Maximum Amount of all Carry
        --------  -------
Members shall not exceed 20%. Each Designated Additional Carry Member shall be
deemed a Carry Member for the purposes of this Agreement, and his or her
interest in the LLC and right to distribution shall be subject to all
restrictions imposed upon a Carry Member hereunder.

                                      -5-
<PAGE>

      (b) Upon the designation of a Designated Additional Carry Member as a
Carry Member in accordance with Section 5.5(a), the Other Investor Members
shall, with the prior written consent of Merck, reallocate the Ratable
Contribution Percentages of each of the Other Investor Members, provided,
                                                                --------
however, that (i) for so long as Lofberg is the Chief Executive Officer of the
-------
Company, the aggregate of all Ratable Contribution Percentages will be 100%, and
(ii) if Lofberg ceases to be the Chief Executive Officer, the aggregate of all
Ratable Contribution Percentages shall not be less than the aggregate of the
Ratable Contribution Percentages of all of the Carry Members other than Lofberg
existing immediately prior to the time Lofberg ceases to be the Chief Executive
Officer. Upon the allocation of a Ratable Contribution Percentage in accordance
with and subject to the provisions of this Section 5.5(b) and Section 5.5(c) to
a Designated Additional Carry Member, such Designated Additional Carry Member
shall be admitted to the Company as an Investor Member.

      (c) Notwithstanding anything in this Agreement to the contrary, no
amendment of this Agreement or allocation or reallocation of Membership
Interests shall reduce the Carry Interest of any Carry Member or change the
Ratable Contribution Percentage of any Other Investor Member without the prior
written consent of the affected Member.

                                    ARTICLE 6
                                    ---------

                  BOARD OF MANAGERS AND OFFICERS OF THE COMPANY
                  ---------------------------------------------

      6.1. Designation of Board of Managers.
           --------------------------------

      (a) Except as otherwise provided in Section 7.1, the management of the
Company's business shall be vested in a Board of Managers (the "Board of
                                                                --------
Managers" or the "Board"). The Board shall consist of a number of Managers (the
--------          -----
"Managers") determined in accordance with this Section 6.1. A Manager need not
 --------
be a Member.

      (b) The Board shall consist of up to five Managers as determined by Merck,
the appointment of which shall be determined as follows:

           (i)  so long as Lofberg is the Chief Executive Officer of the
   Company, Lofberg shall be a Manager; and

           (ii) all other Managers shall be designated by Merck from time to
   time. The initial Managers designated by Merck shall be Judy Lewent, Ken
   Frazier, Richard Clark and David Anstice.

      (c)  The Managers serving on the Board shall not be entitled to receive
fees for serving on the Board.

                                      -6-
<PAGE>

      (d)  The Board shall elect one of the Managers to act as Chairman (the
"Chairman". The Initial Chairman of the Board of Managers shall be Judy Lewent.
 --------

      6.2. Election; Resignation; Removal.
           ------------------------------

      (a) Each Manager shall serve from the effective date of his or her
designation until the effective date of his or her resignation or removal.
Except as provided in Section 6.2(c) hereof, in the event any Manager ceases to
be a Manager of the Company, whether by resignation or removal as provided in
this Agreement or otherwise, a successor Manager shall be designated by the
parties that were entitled, pursuant to Section 6.1(b), to designate the former
Manager.

      (b) A Manager may resign from his or her position as a Manager at any time
upon not less than 10 days' prior written notice to each of the other Managers
and Merck.

      (c) A Manager may be removed only by the parties that designated such
Manager provided, however that Lofberg shall (unless otherwise determined by the
        --------
Board of Managers) be removed as a Manager immediately upon his ceasing to be
the Chief Executive Officer of the Company. The parties requiring the removal of
a Manager may specify an effective date for such removal; otherwise, all such
removals shall be effective immediately.

      6.3. Board Action. Unless otherwise specified in this Agreement, the Board
           ------------
shall act by majority vote of those Managers present at the meeting, with each
Manager on the Board having one vote.

      6.4. Meetings. The Board may hold regular meetings and in any event
           --------
quarterly without call or notice at such places and at such times as the Board
may from time to time determine, provided that reasonable notice of the first
regular meeting following any such determination is given to Managers absent at
the meeting fixing regular meetings. When called by the Chairman, Chief
Executive Officer or Managers holding a majority of the votes on the Board, the
Board may hold special meetings at such places and times as are designated in
the notice of such special meeting, upon at least seven days' notice given by
the Secretary or an Assistant Secretary, or by the Officer or Manager calling
the special meeting.

      6.5. Quorum. At any meeting of the Board, the presence of three Managers
           ------
including the Chief Executive Officer shall constitute a quorum. Any meeting may
be adjourned from time to time by a majority of votes, whether or not a quorum
is present, and the meeting may be held as adjourned upon reasonable notice.

      6.6. Action By Consent. Any action of the Board may be taken without a
           -----------------
meeting if (i) all of the Managers unanimously consent to the action in writing,
and (ii)

                                      -7-
<PAGE>

the written consent is filed with the records of the meetings of the Board.
Such actions by consent shall be treated for all purposes as actions taken at a
meeting.

      6.7. Telephonic Meetings. Managers may participate in a meeting of the
           -------------------
Board by means of a conference telephone or similar communications equipment,
provided that all Managers participating in the meeting can hear each other at
the same time. Participation by such means shall constitute presence in person
at a meeting.

      6.8. Managers as Agents. The Managers, to the extent of the powers set
           ------------------
forth herein, are agents of the Company for the purpose of the Company's
business, and the actions of the Managers taken in accordance with such powers
shall bind the Company.

      6.9. Powers of the Board.
           -------------------

           (a) The Board's powers on behalf and in respect of the Company,
subject to the provisions of this Agreement requiring the approval of the
Members and those powers delegated to Lofberg in accordance with Section 7 of
this Agreement, shall be all powers and privileges permitted to be exercised by
managers of a limited liability company under the LLC Act, including, without
limitation, (i) Section 18-402 of the LLC Act, (ii) the revocation or
suspension, at any time, of the powers granted to Lofberg or any other Officer
pursuant this Agreement or otherwise and (iii) the approval of the MCV Budget;
provided, however, that nothing herein shall supersede, limit or otherwise
--------  -------
invalidate any action, authorization or resolution of the Members set forth in
this Agreement.

           (b) The Board may delegate any of its powers to the Executive
Committee or, except as otherwise required by Section 6.13, the Investment
Committee. Any powers not delegated by the Board shall remain with the Board.

      6.10. Reimbursement. The Company shall reimburse each Manager and Officer
            -------------
for all reasonable and necessary out-of-pocket expenses incurred by such Manager
or Officer on behalf of the Company according to such terms, as shall be
approved by the Board. Such reimbursement shall be treated as an expense of the
Company that shall be deducted in computing Net Profits and shall not be deemed
to constitute a distributive share of Net Profits or a distribution or return of
capital to any Manager or Officer that is also a Member.

      6.11. Non-Exclusive Engagement. Subject to Section 7, the services of the
            ------------------------
Managers to the Company hereunder are not to be deemed exclusive and the
Managers shall be free to render similar or other services to others, so long as
such Managers' services hereunder are not impaired thereby, and to retain for
their own use and benefit fees or other moneys payable thereby. The Managers
shall not be deemed to be affected with notice of or to be under any duty to
disclose to the Company any fact or thing which

                                      -8-
<PAGE>

may come to the notice of the Managers in the course of the Managers rendering
similar services to others, or in the course of its business in any other
capacity, or in any manner whatsoever other than in the course of carrying out
its duties hereunder; provided, however, that the Managers shall give notice to
                      --------  -------
each of the Members of any matter that comes to their attention that would
reasonably be expected to have a material adverse effect on the Company or the
ability of the Board of Managers to perform its duties under this Agreement.

      6.12. Officers.
            --------

           (a) General. The Board may appoint agents and employees of the
               -------
Company who are designated as Officers of the Company. The Officers of the
Company shall include a President, one or more Vice Presidents, a Treasurer and
a Secretary with the duties and authority described below and such officers,
with such titles, duties and authority as may be approved by the Board from time
to time. The same person may hold any number of offices. Each of the Officers
shall be agents of the Company. The appointment of Officers shall not limit in
any respect the power and authority of the Managers to take any action on behalf
of the Company as provided in this Agreement.

           (b) Resignation; Removal. Each Officer shall hold office until his or
               --------------------
her successor shall have been duly elected and shall have qualified, or until
his or her death, or until he or she shall have resigned or have been removed,
as hereinafter provided. The Board may remove any Officer so appointed at any
time, with or without Cause, in its absolute discretion.

           (c) President. The President shall be the chief executive officer of
               ---------
the Company, and shall be responsible for the general and active management of
the business of the Company and shall see that all orders and resolutions of the
Board are carried into effect. Except to the extent otherwise provided in this
Agreement or in a resolution of the Board of Managers, the President shall have
such other duties and have such other powers as are similar to those of a
president and chief executive officer of a business corporation organized under
the LLC Act. Lofberg will be the initial President of the Company.

           (d) Vice President. Each Vice President shall perform all such duties
               --------------
as from time to time may be assigned to him by the Board or the President.

           (e) Treasurer. The Treasurer shall have the care and custody of the
               ---------
funds and valuable documents of the Company and shall have oversight and
administrative responsibility for raising and borrowing funds and establishing
banking and similar relationships and, in general, perform all duties incident
to the office of Treasurer and such other duties as from time to time may be
assigned to him or her by the Board. In the event that any Officer other than
the Treasurer shall be designated as the

                                      -9-
<PAGE>

Company's Chief Financial Officer, the Treasurer shall share the foregoing
powers and duties with such Chief Financial Officer, and all references herein
to the Treasurer shall be deemed to include such Chief Financial Officer of the
Company.

           (f) Secretary. The Secretary shall: (i) keep or cause to be kept in
               ---------
one or more books provided for the purpose, the minutes of all meetings and
consents of the Board; (ii) see that all notices are duly given in accordance
with the provisions of this Agreement and as required by law; (iii) be custodian
of the records of the Company; (iv) see that the books, reports, statements,
certificates and other documents and records required by law to be kept and
filed are properly kept and filed; and (v) in general, perform all duties
incident to the office of Secretary and such other duties as from time to time
may be assigned to him or her by the Board.

           (g) Subordinate Officers. The Board from time to time may delegate to
               ---------------------
any Officers the power to appoint subordinate officers or agents and to
prescribe their respective rights, terms of office, authorities and duties. Any
such Officer may remove any such subordinate officer or agent appointed by him
or her, for or without Cause.

           (h) Fiduciary Duties of Officers. Except as otherwise provided
               ----------------------------
herein, each Officer shall have fiduciary duties of loyalty and care similar to
those of officers of business corporations organized under the General
Corporation Law of the State of Delaware.

      6.13. Certain Actions. Without limiting the generality of Section 6.1(a),
            ---------------
none of the following actions may be taken by or on behalf of the Company
without prior approval of the Board or the Executive Committee, including, for
so long as Lofberg is the Chief Executive Officer of the Company, the
affirmative vote of Lofberg, in the case of any matter described in clauses (g),
(h) (i) and (j) and any matter described in clause (k) if the annual
compensation of such employee would exceed $150,000:

           (a) approval of the MCV Budget and expenditures or capital
commitments other than those authorized under Section 7.1 or otherwise contained
in the MCV Budget;

           (b) creating, incurring or assuming any indebtedness (including,
without limitation, any loans by the Members or any of their Affiliates to the
Company) or entering into any guarantees;

           (c) mortgaging or creating any liens on any assets;

           (d) entering into any employment agreement or amending or waiving any
provision of any employment agreement;

                                     -10-
<PAGE>

           (e) selling or disposing of any Portfolio Investment or other
material assets;

           (f) commencing or settling any legal actions;

           (g) investing in a Portfolio Investment in an amount exceeding $10
million or if all Portfolio Investments in the same Portfolio Company would
exceed $20 million in the aggregate;

           (h) investing in a Portfolio Investment of any entity that is a
Clinical Development Entity;

           (i) reviewing and approving or disapproving any changes in investment
strategy and scope;

           (j) reviewing and approving or disapproving the designation of any
Designated Additional Carry Member and the allocation and reallocation of all
Applicable Carried Interests and Ratable Contribution Percentages;

           (k) determining the compensation payable to any employee of the
Company, including without limitation, any Designated Additional Carry Members
and any employees of Merck or its Affiliates selected to provide services to the
Company in accordance with Section 8.5;

           (l) terminating the designation of any Carry Member or Designated
Additional Carry Member as a Carry Member of the Company (it being understood
that the employer of such Person retains the absolute authority to terminate
such Person's employment);

           (m) permitting the Other Investor Members to contribute, in respect
of an individual Portfolio Investment, an aggregate amount in excess of the
lesser of (A) 10% of the Acquisition Cost or (B) $1,000,000 of a Portfolio
Investment;

           (n) reviewing and approving or disapproving any potential conflicts
of interest of the Members;

           (o) reviewing and approving or disapproving any transaction involving
the Company and a Portfolio Company in which any Member, a Manager or their
respective Affiliates has or may have a material interest; or

           (p) reviewing and approving or disapproving any settlement of any
claim with respect to which any Manager, Officer, Members or any Affiliate of
any of them intends to seek indemnification pursuant to Section 15.

                                     -11-
<PAGE>

            Notwithstanding any other provision of the Agreement, so long as
Lofberg is a Member of the Company, if the Company shall take any of the actions
described in clauses (a), (b) or (c) of this Section 6.13 without Lofberg's
prior written consent, distributions to the Carry Members shall be calculated
without giving effect to such actions if the effect of such actions would
otherwise be to reduce a Carry Member's return in respect of any Portfolio
Investment.

      6.14. Reliance by Third Parties. Third parties dealing with the Company
            -------------------------
may rely conclusively upon any certificate of the Board of Managers or any
Officer to the effect that it is acting on behalf of the Company. The signature
of the Board of Managers or any Officer shall be sufficient to bind the Company
in every manner to any agreement or on any document.

      6.15. No Right to Manage. Except as otherwise expressly provided for in
            ------------------
this Agreement or with the consent of the Board of Managers, the Members shall
not have any right to take part in the management of the business, affairs or
properties of the Company or any right or authority to act for or bind the
Company and shall have only the rights and powers expressly granted to the
Members hereunder.

                                    ARTICLE 7

                        RIGHTS AND OBLIGATIONS OF LOFBERG
                        ---------------------------------

      7.1.  Powers. For so long as Lofberg is the Chief Executive Officer of the
            ------
Company and has not had his investment authority revoked or suspended by the
Board of Managers, Lofberg shall have the authority and power on behalf and in
respect of the Company, without the need for approval from the Board of
Managers, to:

      (a)   make Portfolio Investments in amounts not exceeding $10 million in
any one Portfolio Investment and, when aggregated with all other Portfolio
Investments in the same Portfolio Company, not exceeding $20 million; provided,
                                                                      --------
(i) Lofberg shall have consulted with the Board of Managers or the Executive
Committee regarding the timing and accounting implications to Merck of such
investment to the extent feasible and, in all cases, if the investment, together
with all other Portfolio Investments consummated by the Company in a Quarter
would exceed $15 million, (ii) such Portfolio Investment shall not result in the
Company acquiring in excess of 20% of the equity of a Portfolio Company, and
(iii) any Portfolio Investment in a Clinical Development Entity shall require
approval of the Board of Managers or Executive Committee following consultation
with Merck Research Laboratories.

                                     -12-
<PAGE>

      (b) incur reasonable Break-Up Expenses and such other Fees and Expenses as
are necessary to manage the Portfolio Investments in accordance with the MCV
Budget or as otherwise authorized by this Agreement.

      7.2. Consultation with Investment Committee. In the exercise of the powers
           --------------------------------------
conferred on him by Section 7.1, Lofberg will on a regular basis inform the
members of the Investment Committee of Portfolio Investments made and proposed
to be made and provide members of the Investment Committee with such information
within the Company's possession concerning each such Portfolio Investment or
proposed Portfolio Investment, as well as such other information within the
Company's possession as any member of the Investment Committee may request.

                                    ARTICLE 8

                                OTHER AGREEMENTS
                                ----------------

      8.1. The Investment Committee and the Executive Committee. (a) The Board
           ----------------------------------------------------
of Managers will from time to time appoint an Investment Committee which shall
consist of Lofberg, so long as he is Chief Executive Officer of the Company, and
other members of the Board of Managers, Officers of the Company and other
Persons, as determined by the Board of Managers. The initial members of the
Investment Committee will be Lofberg, Cooper, Jon Filderman, Richard Kender,
Paul Howes and one person designated by Merck. The Board of Managers may remove
any member of the Investment Committee at any time. The Investment Committee
shall meet as necessary. Members of the Investment Committee may participate in
meetings of the Investment Committee in person, by proxy, or by telephonic
conference call in which all participants can hear each other.

      (b) The functions of the Investment Committee will be to consult with and
provide investment advice on proposed investments to the Officers, Board of
Managers and the Members, including in regard to any proposed commercial
arrangements with Merck. To assist the Investment Committee, the Officers of the
Company will review all aspects of each proposed investment including
suitability of investment candidates, results of due diligence, terms of
proposed investments, expected synergies and analysis of competitive effects
and, following such review, will present such information and analysis to the
Investment Committee for its review.

      (c) Other than as expressly set forth in this Agreement, the
recommendations of the Investment Committee shall be advisory only and shall not
obligate the Members or the Board of Managers to act or refrain from acting in
accordance therewith. Neither the Investment Committee nor any member thereof,
in his or her capacity as such, may act on behalf of or may bind the Company in
any manner. The Company shall be responsible for all reasonable out-of-pocket
expenses incurred by

                                     -13-
<PAGE>

members of the Investment Committee in connection with fulfilling their
responsibilities to the Investment Committee.

      (d) The Board of Managers will from time to time appoint an executive
committee of not more than 3 Persons which shall consist of members of the Board
of Managers, Officers of the Company and other Persons, as determined by the
Board of Managers (the "Executive Committee"), provided, however that, for so
                        -------------------    --------  -------
long as Lofberg is Chief Executive Officer of the Company, he will be a member
of the Executive Committee. The initial members of the Executive Committee will
be Lofberg, Judy Lewent and Ken Frazier. Subject to the proviso in the first
sentence of this paragraph (d), the Board of Managers may remove any member of
the Executive Committee at any time. The Executive Committee shall meet as
necessary. Members of the Executive Committee may participate in meetings of the
Executive Committee in person, by proxy, or by telephonic conference call in
which all participants can hear each other.

      (e) The Executive Committee shall have the power and authority to take all
actions delegated to it by the Board of Managers.

      8.2. Other Investments. (a) Except as provided in Sections 8.2(b) and (c),
           -----------------
no Member may make directly or indirectly, and each Member shall cause its
Affiliates and Associates not to make, directly or indirectly, an investment in
any E-Healthcare Company, except through its interest in the Company in
accordance with the terms of this Agreement, unless and until (i) each Member
has contributed its respective Base Commitment to the Company, (ii) the
expiration of the Investment Period or (iii) Lofberg ceases to be the Chief
Executive Officer of the Company.

           (b) Notwithstanding anything to the contrary in this Agreement, if
Merck proposes an investment in an E-Healthcare Company to the Company
(including a follow-on investment in a Portfolio Company) and Lofberg rejects
such proposal or does not approve such proposal within 21 days of its submission
to the Investment Committee in the case of an initial investment and 10 Business
Days of its submission to the Investment Committee in the case of a follow-on
investment (such submission to include such information in the possession of
Merck that it reasonably believes is necessary to enable the Investment
Committee to make an informed investment decision), Merck or any of its
Affiliates or Associates (other than the Company) shall be permitted to make an
investment in such E-Healthcare Company on terms no more favorable than those
rejected by Lofberg.

           (c) Notwithstanding anything to the contrary in this Agreement, Merck
and any of its Affiliates and Associates may make any investment in an
E-Healthcare Company if such investment together with all previous investments
in such E-Healthcare Company, in the aggregate, would exceed $20 million or if
it would result in Merck, together with its Affiliates and Associates
beneficially owning in excess of 20%

                                     -14-
<PAGE>

of the outstanding equity of such E-Healthcare Company, provided, however, that,
                                                        --------  -------
except as provided by paragraph (b), this paragraph shall not permit Merck to
invest in an existing Portfolio Company other than through the Company, unless,
upon consummation of such investment, the Company, Merck and all Affiliates and
Associates of Merck would, in the aggregate, beneficially own equity interests
representing 50% or more of the voting equity interests of such Portfolio
Company.

           (d) If Merck or any of its Affiliates or Associates (other than the
Company) enters into a binding agreement to make a Control Acquisition (a
"Control Acquisition Agreement"), Merck shall, on its own behalf or on behalf of
 -----------------------------
its Affiliate or Associate that is a party to the Control Acquisition Agreement,
have the absolute right, for a period of 10 Business Days from the date of the
Control Acquisition Agreement (and, if applicable, so long as the majority of
the Other Investors has not previously delivered a Put Notice as defined in
paragraph (e) below), by giving written notice to the Carry Members (a "Call
                                                                        ----
Notice"), to buy all, but not less than all, of the Portfolio Investments in the
------
relevant Portfolio Company held by the Company (the "Control Acquisition
                                                     -------------------
Interest").
--------

           (e) If Merck or any of its Affiliates or Associates (other than the
Company) makes a Control Acquisition, the majority of the Other Investors shall
have an absolute right, for a period of 10 Business Days from the date of the
Control Acquisition and so long as Merck has not previously delivered a Call
Notice, by giving written notice to Merck (the "Put Notice"), to cause the
                                                ----------
Company to sell all, but not less than all, of the Control Acquisition Interest
to Merck or such Affiliate or Associate.

           (f) Upon delivery of a Call Notice pursuant to Section 8.2(d) or a
Put Notice pursuant to Section 8.2(e), Merck or its Affiliate or Associate will
be obligated to purchase from the Company, and the Company will be obligated to
sell to Merck or its Affiliate or Associate, all, but not less than all, of the
Control Acquisition Interest in exchange for payment of the Control Acquisition
Price.

           (g) The consummation of the purchase of the Control Acquisition
Interest pursuant to this section 8.2 will take place (i) in the case of a
purchase resulting from the delivery of a Call Notice, to the extent reasonably
practicable simultaneously with the closing of the relevant Control Acquisition,
and (ii) in the case of a purchase resulting from the delivery of a Put Notice,
on a date mutually agreeable to the parties but in any event not later than 30
Business Days following the date of the Put Notice (in each case, the "Purchase
                                                                       --------
Date"). On the Purchase Date, Merck or its Affiliate or Associate shall pay to
----
the Company the Control Acquisition Price against delivery to Merck or its
Affiliate or Associate of the Control Acquisition Interest, free and clear of
all encumbrances, but without representation or warranty by the Company other
than as to title. The consummation of the sale and purchase under this Section
8.2(g) will be a Sale of a Portfolio Investment for the purposes of this
Agreement.

                                     -15-
<PAGE>

           (h) Merck and its Affiliates or Associates shall be free to make any
and all investments not expressly required by this Agreement to be made in the
Company outside the Company; provided, however, that Merck and its Affiliates
and Associates (other than the Company) shall not, following termination of the
Investment Period, make a follow-on investment in which the Company has an
existing Portfolio Investment unless and until it shall have given each Other
Investor Member, by written notice to such Other Investor Member specifying the
Portfolio Company to which such follow-in investment relates and the terms and
conditions of such follow-on investment (a "Co-Investment Notice"), the right to
co-invest, on the same terms and conditions as Merck or its Affiliate or
Associate, an amount equal to (but not less than) the amount such Other Investor
Member would have been required to contribute to the Company in respect of the
acquisition of such follow-on investment, assuming (1) it were then being made
by the Company, (2) the Investment Period had not ended and (3) the $10 million
limit set forth in clause (iii) of the last sentence of Section 5.1 did not
apply (the "Co-investment Right"). The Co-investment Right of an Other
Investment Member in respect of a follow-up investment shall expire if such
Other Investment Member shall not, within 10 Business Days of the delivery of
the Co-Investment Notice to such Member, deliver to Merck written notice
irrevocably electing to exercise such Co-investment Right. The Other Investor
Members shall not have any Carry Interest in follow-on investments to which the
Co-Investment Right pertains.

      8.3 Certain Other Fees. (a) Each Carry Member covenants that if it or any
          ------------------
of its Affiliates or Associates provides any services to, or enters into any
transaction with, a Portfolio Company (or a Person in which the Company is
considering making a Portfolio Investment if such Person subsequently becomes a
Portfolio Company), in which such Carry Member (a "Benefiting Member") or its
Affiliates or Associates receives securities, transaction fees, financing fees,
director fees, or any other type of fees or any other thing of value
(collectively, "Other Fees"), from such Portfolio Company, all such Other Fees
will be deemed to be the property of the Company, will, except as provided in
paragraph (c), be promptly conveyed to the Company net of any taxes, if any,
assumed to be payable at the Applicable Tax Rate, for which such Benefiting
Member or its Affiliates or Associates are liable and, until so conveyed, will
be held in trust for the benefit of the Company.

      (b) Merck covenants that if it or any of its Affiliates or Associates
enters into a commercial arrangement with a Portfolio Company (or a Person in
which the Company is considering making a Portfolio Investment if such Person
subsequently becomes a Portfolio Company), in which Merck or its Affiliates or
Associates receives securities from such Portfolio Company as part of such
commercial arrangement and not for cash (and excluding Warrants Acquired for
Cash and securities acquired upon the cashless exercise of Warrants Acquired for
Cash) ("Other Securities"), all such Other Securities will be deemed to be the
        ----------------
property of the Company, will, except as provided in paragraph (c), be promptly
conveyed to the Company net of any taxes, if any, assumed

                                     -16-
<PAGE>

to be payable at the Applicable Tax Rate, for which Merck or its Affiliates or
Associates are liable and, until so conveyed, will be held in trust for the
benefit of the Company. The acquisition of Other Securities by Merck shall not
constitute a Control Acquisition for purposes of Section 8.2 even if after
giving effect thereto, the Company, Merck and Merck's Affiliates and Associates
would, in the aggregate, own more than 20% of the outstanding voting equity of a
Portfolio Company.

      (c) Each Benefiting Member or Merck, as the case may be, that is required
by this Section 8.3 to transfer Other Fees or Other Securities to the Company
(the "Transferring Member"), shall use commercially reasonable efforts (at the
      -------------------
Company's expense) to obtain all necessary consents and approvals that may be
required in connection with the transfer of such Other Fees and Other Securities
to the Company ("Required Consents"). If a Required Consent is denied or if the
                 -----------------
Transferring Member has not, for any other reason transferred any Other Fees or
Other Securities to the Company as required by this Section 8.3, then the
Benefiting Member or Merck, as applicable, shall pay to the Company in cash
immediately on receipt for distribution in accordance with Article 10 an amount
or amounts equal to all Net Sale Proceeds upon a Sale of such securities by such
Benefiting Member or Merck, as applicable, or their respective Affiliates or
Associates net of any taxes, assumed to be payable at the Applicable Tax Rate,
for which such Benefiting Member or Merck or Affiliates or Associates thereof,
as applicable, are liable.

      (d) Notwithstanding anything to the contrary contained in this Agreement,
any contributions made to the Company pursuant to this Section 8.3 will not be
deemed Capital Contributions of the Benefiting Member or increase the
Acquisition Cost or the Benefiting Member's share of the Acquisition Cost of the
related Portfolio Investment. Except as provided in the immediately preceding
sentence, all Other Fees and Other Securities shall be deemed to be part of the
related Portfolio Investments for all purposes of this Agreement and shall be
distributed to the Members to the extent contemplated by and in accordance with
Article 10, except that, until transferred to the Company as required by this
Section 8.3, Other Fees and Other Securities (and their acquisition and
disposition) shall not be subject to the provisions of Section 6.13 or 10.2(a),
(b) or (c).

      8.4. MCV Budget. (a) At least 30 days but not more than 90 days prior to
           ----------
the beginning of each Fiscal Year (other than with respect to the 2001 Fiscal
Year), the Company will prepare and submit to the Board of Managers for its
approval the proposed budget for the following Fiscal Year, showing on a monthly
basis anticipated Fees and Expenses for such Fiscal Year together with any other
information that the Board of Managers shall require) (the budget, as so
approved in accordance with Section 6.13 and this Section 8.4, the "MCV
                                                                    ---
Budget"). The MCV Budget in respect of the 2001 Fiscal Year shall be prepared
------
and submitted for approval as soon as reasonably practicable following the date
of this Agreement and in any event no later than December 11, 2000.

                                     -17-
<PAGE>

      8.5. Administrative Staff. Merck shall make available to the Company the
           --------------------
full-time services of (i) up to two employees of Merck or an Affiliate of Merck,
as necessary, to act as financial analysts for the Company, and (ii) up to two
employees of Merck or an Affiliate of Merck to support the Company as
administrative staff. So long as he is Chief Executive Officer of the Company,
Lofberg shall (i) with the consent of the employee and of the employee's
employer (the "Applicable Employer"), whose consent shall not be unreasonably
               -------------------
withheld or delayed, be entitled to select the employees seconded to the Company
pursuant to this Section 8.5, and (ii) be entitled to terminate the secondment
of any such employee. Notwithstanding anything in this Agreement to the
contrary, (a) the Applicable Employer retains the right to terminate for Cause
the employment of any employee seconded to the Company, and (b) any costs and
expenses incurred by the Applicable Employer in connection with the employment
of seconded employees during the period such person's services are used by the
Company shall be deemed to be Carry Member Costs for purposes of this Agreement
unless otherwise excluded from the definition of Carry Member Costs.

      8.6. Fees and Expenses; Carry Member Costs. The Company shall be
           -------------------------------------
responsible for all Fees and Expenses and Carry Member Costs from the end of the
Expenses Period and will reimburse Merck and its Affiliates for all such Carry
Member Costs incurred by Merck or any of its Affiliates upon receipt of an
invoice from Merck specifying the nature and amount of such Carry Member Costs.

                                    ARTICLE 9

                            ACCOUNTS AND ALLOCATIONS
                            ------------------------

      9.1. Capital Accounts.
           ----------------

      (a) A separate Capital Account shall be established and maintained for
each Member in accordance with Reg. ss.1.704-1(b)(2)(iv). The initial balance of
each Member's Capital Account shall be equal to the amount of cash and the Fair
Market Value of any property (net of any liability secured by such property that
the Company is considered to assume, or take subject to, under Section 752 of
the Code) contributed by such Member as a Capital Contribution to the Company.

      (b) The Capital Account of each Member shall be increased by any Net
Profits and gross income items allocated to such Member and any additional
Capital Contributions by such Member.

      (c) The Capital Account of each Member shall be reduced by (i) the amount
of any distribution of cash or the Fair Market Value of any property (net of any
liability secured by such property that the Member is considered to assume or
take subject to Section 752 of the Code) distributed to such Member pursuant to
Article 10 in respect of the Member's Capital Account (other than distributions
treated as guaranteed

                                     -18-
<PAGE>

payments within the meaning of Section 707(c) of the Code) when such
distribution is made, and (ii) the Net Losses and items of deduction or expense
allocated to such Member including, without limitation, any "partner nonrecourse
deductions" (as defined in Reg. ss. 1.704-2(i)) and any "nonrecourse deductions"
(as defined in Reg. ss. 1.704-2(b)) allocated to such Member.

      (d) Except as otherwise provided in this Agreement, whenever it is
necessary to determine the Capital Account of any Member, the Capital Account of
such Member shall be determined after giving effect to the allocations of Net
Profits, Net Losses and other items realized prior or concurrently to such time
(including, without limitation, any Net Profits and Net Losses attributable to
adjustments to Book Values with respect to any concurrent distribution), and all
contributions and distributions made prior or concurrently to the time as of
which such determination is to be made.

      (e) In the event that there is a negative balance in the Capital Account
of any Member, such Member shall not be obligated to make any additional Capital
Contributions or otherwise be liable to restore the negative balance to zero.

      9.2. Allocations.
           -----------

      (a) Allocation of Net Profits and Net Losses.
          ----------------------------------------

                (i)   Net Losses. After giving effect to the special allocations
                      ----------
      in clauses (b) through (e) hereof, Net Losses (and if necessary, items
      thereof) for any Fiscal Year (or period) shall be allocated among the
      Members so as to eliminate the differences between their respective
      Partially Adjusted Capital Account balances and Target Capital Account
      balances for such Fiscal Year (or other period).

                (ii)  Net Profits. After giving effect to the special
                      -----------
      allocations in clauses (b) through (e) hereof, Net Profits (and if
      necessary, items thereof) for any Fiscal Year (or period) shall be
      allocated among the Members so as to eliminate the differences between
      their respective Target Capital Accounts balances and Partially Adjusted
      Capital Account balances for such Fiscal Year (or other period).

                (iii) Limitation on Allocations. Notwithstanding anything to the
                      -------------------------
      contrary contained herein, Net Profits, Net Losses and items thereof
      arising with respect to a Portfolio Investment shall not be allocated to a
      Member who has not made a Capital Contribution with respect to such
      Portfolio Investment (unless such Member has a Carry Interest with respect
      to such Portfolio Investment).

                (iv) Schedule C illustrates the intent of Section 9.2(a) by way
      of a

                                     -19-
<PAGE>

      hypothetical example.

      (b) Notwithstanding any other provision of this Agreement, (i) "partner
nonrecourse deductions" (as defined in Reg. ss. 1.704-2(i)), if any, of the
Company shall be allocated to the Members that bear the economic risk of loss
within the meaning of Reg. ss. 1.704-2(i), and (ii) "nonrecourse deductions" (as
defined in Reg. ss. 1.704-2(b)), if any, of the Company with respect to each
period as it relates to a particular Portfolio Investment shall be allocated
among the Members in proportion to their share of the Net Acquisition Cost of
such Portfolio Investment made by such Members, and to the extent that such
nonrecourse deductions do not relate to any particular Portfolio Investment, to
the Members in accordance with the proportion of aggregate Capital Contributions
made by each Member.

      (c) This Agreement shall be deemed to include "qualified income offset,"
"minimum gain chargeback" and "partner nonrecourse debt minimum gain chargeback"
provisions within the meaning of Regulations under Section 704(b) of the Code.
Accordingly, notwithstanding any other provision of this Agreement, items of
income or gain shall be allocated to the Members on a priority basis to the
extent and in the manner required by such provisions.

      (d) Subject to Sections 9.2(b), (c) and (e), if any items of income,
expense or deduction are specially allocated pursuant to Section 9.2(b) or (c),
or the allocation of Net Loss or items of deduction or expense is limited by
Section 9.2(e), items of income, gain, deduction and expense, in subsequent
periods, shall be specially allocated so that the net cumulative amount of all
items allocated to each Member (taking into account any minimum gain or partner
nonrecourse debt minimum gain chargeback that would occur if the Company were to
liquidate) shall, to the extent possible, be equal to the amount that would have
been allocated to such Member without regard to Section 9.2(b), (c) or (e).

      (e) Notwithstanding any other provisions of this Agreement, no allocation
of Net Loss or items of deduction or expense shall be made to any Member to the
extent that the effect of such allocation would be to cause the Member to have a
negative balance in its Capital Account, after taking into account any
adjustments, allocations or distributions described in Reg. ss. 1.704-
1(b)(2)(ii)(d)(4), (5) or (6), in excess of the maximum amount of such negative
balance such Member would be obligated (or deemed obligated under the
Regulations) to contribute to the Company upon liquidation.

      9.3. Tax Allocations. (a) For tax purposes, all items of income, gain,
           ---------------
loss, or deduction shall be allocated to the Members in the same manner as they
are allocated for purposes of maintaining Capital Accounts; provided, however,
                                                            --------  -------
that (i) if the Fair Market Value of any property of the Company differs from
its adjusted basis for tax

                                      -20-
<PAGE>

purposes, then items of income, gain, loss, deduction for tax purposes shall be
allocated among the Members in a manner that takes account of both the amount
and character of the variation between the adjusted basis of the property for
tax purposes and its Fair Market Value in the manner provided for under Section
704(c) of the Code using any method or methods determined by the Board of
Managers after reasonable consultation with Lofberg and (ii) the Board of
Managers may make such adjustments as it deems appropriate, in its discretion
after reasonable consultation with Lofberg, to reflect the economic interests of
the Members in the Company.

      (b) Items of credit shall be allocated among the Members in the manner
provided in Reg.ss. 1.704-1(b)(4)(ii).

                                   ARTICLE 10

                                  DISTRIBUTIONS
                                  -------------

      10.1. Distributions. (a) Subject to the provisions of this Article 10,
            -------------
Available Cash shall be distributed from time to time as the Board of Managers
shall determine but not less often than annually; provided, that Available Cash
                                                  --------
arising by reason of the sale by the Company of a Portfolio Investment or by
reason of Section 8.3 shall be distributed within 30 days after receipt thereof
by the Company in accordance with Section 10.1(b). Pending distribution, all
Available Cash shall be invested in Short-Term Investments. Subject to this
Article 10, other Company property, less such amounts as the Board of Managers
deems necessary to meet current or future Company costs or obligations, shall be
distributed at such time or times as the Board of Managers deems appropriate,
subject to the restrictions described herein.

      (b) All Available Cash of the Company in respect of a Portfolio
Investment, less, if the Portfolio Investment was Sold, expenses attributable to
such Sale (the "Proceeds" of such Portfolio Investment) shall be distributed as
                --------
follows:

                (i)   first, 100% to Merck until it has received an amount equal
                      -----
      to all Attributable Carry Member Costs and Attributable Fees and Expenses
      of all Portfolio Investments that have been Sold;

                (ii)  second, 100% to the Contributing Members in proportion to
                      ------
      their share of the Acquisition Cost of that Portfolio Investment until
      they have received an amount equal to the Net Acquisition Cost of the
      Portfolio Investment; and

                (iii) thereafter, subject to Section 10.1(c), all remaining
                      ----------
      Proceeds to the Contributing Members in proportion to their share of the
      Acquisition

                                     -21-
<PAGE>

      Cost of such Portfolio Investment; provided, however, that
                                         --------  -------
      Merck's distribution pursuant to this Section 10.1(b)(iii) shall be
      reduced by an amount equal to each Carry Member's Applicable Carried
      Interest in respect of such Portfolio Investment of Merck's share of the
      Proceeds distributable pursuant to this Section 10.1(b)(iii) (before
      giving effect to this proviso) less the amount, if any, of such Carry
                                     ----
      Member's Negative Carry Balance and such amount, if any, will be
      distributed to such Carry Member.

      (c) Notwithstanding the foregoing, if a distribution in respect of a
Portfolio Investment is made and a Carry Member's Applicable Carried Interest in
respect of that Portfolio Investment later increases in accordance with the
definition of Applicable Carried Interest, the Company shall promptly make an
additional distribution to such Carry Member and/or Merck shall pay over to such
Carry Member an amount (or securities in the case of an in kind distribution)
equal to the difference between the distribution such Carry Member would have
been entitled to receive at the higher Applicable Carried Interest and the
distribution previously made. In connection with any distribution, the Company
shall be entitled to withhold and set aside such reserves as the Board of
Managers may determine may be required to fund such subsequent retroactive
adjustments.

      (d) At the time final distributions are made upon the dissolution of the
Company or upon a Carry Member ceasing to be a Carry Member in respect of all
Portfolio Investments, any amounts required to be contributed by such Member to
the Company pursuant to Section 12.4, may be off set by the Company against any
distributions required to be made by the Company to a Member pursuant to Section
10.1(b).

      (e) Notwithstanding the foregoing, if the aggregate distributions to a
Member during a Fiscal Year, and the three months following such Fiscal Year,
would not otherwise equal or exceed the Tax Liability Amount, then on or prior
to the Tax Payment Date, the Company shall distribute the amount of such
deficiency to such Member (the "Tax Distribution"). Tax Distributions shall be
                                ----------------
treated as advances on future distributions that would otherwise be made to such
Member, so that future amounts otherwise distributable to a Member shall be
reduced by the amount of any Tax Distribution. At the election of the Board of
Managers, in reasonable consultation with Lofberg, Tax Distributions may be made
in quarterly installments during the Fiscal Year.

      (f) Schedule C, illustrates the intent of Section 10.1(b) by way of a
hypothetical example.

      10.2. Certain Other Distributions.
            ---------------------------

      (a) If, at a time when Lofberg is Chief Executive Officer of the Company
or, thereafter, if Lofberg's employment with Merck or an Affiliate of Merck to

                                      -22-
<PAGE>

act as Chief Executive Officer of the Company is terminated (i) at any time
without Cause or (ii) for any reason after the second anniversary of this
Agreement, a Portfolio Company closes a Qualified IPO and Lofberg recommends to
the Board of Managers no later than 10 Business Days prior to the commencement
of the roadshow for such Qualified IPO selling 100% of the Company's interest in
such Portfolio Company in such Qualified IPO and the Board of Managers rejects
such recommendation, then the Company shall distribute 100% of the Portfolio
Investment in the Portfolio Company to the Members in accordance with Section
10.1(b), as soon as practicable following the date of such Qualified IPO (or if
requested by the underwriters of such Qualified IPO, following the date the
Company is no longer subject to any lock up restrictions), on the assumption
that such Portfolio Investments were sold for the issue price under the
Qualified IPO.

      (b) If, at a time when Lofberg is Chief Executive Officer of the Company
or, thereafter, if Lofberg's employment with Merck or an Affiliate of Merck to
act as Chief Executive Officer of the Company is terminated (i) at any time
without Cause or (ii) for any reason after the second anniversary of this
Agreement, Lofberg recommends selling 100% of the Company's Portfolio Investment
at the time when the entirety of such Portfolio Investment constitutes
Marketable Securities (a "Divestment Proposal") and the Board of Managers
                          ---------- --------
rejects such Divestment Proposal, then

                (A) if the Portfolio Company is a Qualifying Issuer, the Company
      shall distribute the securities of such Portfolio Company to the Members
      in accordance with Section 10.1(b) within 10 Business Days following the
      determination by the Board of Managers of the Fair Market Value of such
      Portfolio Investments as of the Applicable Valuation Date, on the
      assumption that such Portfolio Investment was sold for the Fair Market
      Value determined by the Board of Managers as of the Applicable Valuation
      Date; and

                (B) in all other cases, the Company shall promptly distribute to
      the Other Investor Members their pro rata share of the securities of such
      Portfolio Company (net of securities having a Fair Market Value equal to
      their share of Attributable Carry Member Costs and Attributable Fees and
      Expenses, assuming 100% of the Portfolio Investment was distributed in
      accordance with clause (A) above) and following such distribution the
      Other Investor Members shall have no further interest (other than as Carry
      Members) in the portion of the Portfolio Investment retained by the
      Company.

      (c) If, at a time when Lofberg is Chief Executive Officer of the Company,
Lofberg recommends to the Board of Managers approval of a Bona Fide Third Party
Offer setting forth the price and other material terms of such Bona Fide Third
Party

                                      -23-
<PAGE>

Offer and the Board of Managers rejects such Bona Fide Third Party Offer,
then, at the written request of Lofberg delivered to the Board of Managers
within 10 Business Days of such rejection, the Members shall be entitled to
receive distributions in respect of their Interests in accordance with Section
10.1(b), at the election of the Board of Managers, either in cash or by
distribution in kind within 30 Business Days following the demand by Lofberg, on
the assumption that such Portfolio Investment were sold for the price set forth
in the Bona Fide Third Party Offer. Notwithstanding anything to the contrary, if
a distribution is made pursuant to this Section 10.2(c), the Carry Members will
not, except to the extent provided in Section 10.1(c) be entitled to any further
distributions made by the Company pursuant to Section 10.1(b), or otherwise in
respect of such Portfolio Investment (other than as Investor Members) and their
Applicable Carried Interest in respect thereof after the application of this
Section 10.2(c) shall be deemed to be zero.

      (d) If a Portfolio Investment has not been liquidated or distributed prior
to the tenth anniversary of this Agreement, the Board of Managers shall either
(i) cause such Portfolio Investment to be liquidated within 90 days or (ii)
valued in accordance with Section 10.5 as of the Applicable Valuation Date. The
Members shall be entitled to receive distributions in respect of their Interests
(A) in accordance with Section 10.1(b) in cash upon the final liquidation of all
Portfolio Investments being liquidated in the case of clause (i), and (B) at the
election of the Board of Managers either in cash or by distribution in kind
within 10 Business Days following delivery by the Third Party Valuation Firm of
its report calculating the Fair Market Value of the remaining Portfolio
Investments, on the assumption in such case that each unliquidated Portfolio
Investment were sold for the Fair Market Value set forth in the valuation report
(the "Valuation Report") in the case of clause (ii). Notwithstanding anything to
      ----------------
the contrary, if a distribution is made pursuant to this Section 10.2(d), the
Carry Members will not be entitled to any further distributions made by the
Company pursuant to Section 10.1(b) or otherwise in respect of such Portfolio
Investment (other than as Investor Members) and their Applicable Carried
Interest in respect thereof after the application of this Section 10.2(d) shall
be deemed to be zero.

      10.3 Distributions in Kind. (a) The Board of Managers shall have
           ---------------------
authority, but, except as required by Section 10.2, shall not be required to
distribute in kind any non-cash assets held by the Company.

      (b) In the event of any distribution in kind, the value of the assets
distributed shall be determined as of the Applicable Valuation Date in
accordance with Section 10.5 hereof. If the Carry Members will be entitled to
receive a distribution in respect of their Applicable Carried Interests pursuant
to Section 10.2(d), the Fair Market Value of the assets to be distributed will
be calculated by a Third Party Valuation Firm in accordance with the methodology
set forth in Section 10.5. A "Third Party Valuation Firm" shall mean any
                              --------------------------
independent nationally recognized investment banking firm, accounting firm or
appraisal firm selected by the Board of Managers and approved by

                                      -24-
<PAGE>

Lofberg, such approval not to be unreasonably withheld or delayed. The Company
shall bear all of the expenses of the Third Party Valuation Firm retained by the
Company.

      (c) Except as required by Section 10.2, no determination by the Board of
Managers to obtain a valuation from a Third Party Valuation Firm in
contemplation of an in-kind distribution shall obligate the Company to make any
such in-kind distribution.

      (d) Investments distributed in kind pursuant to this Agreement shall be
distributed, to the extent reasonably practicable, pro rata to the Members
entitled thereto and shall be subject to such conditions and restrictions as are
required by applicable law or any contractual obligation or as were previously
imposed on the Company.

      10.4. Withholding Requirements. (a) Notwithstanding any other provision of
            ------------------------
this Agreement, the Board of Managers is authorized to take any action that it
determines to be necessary or appropriate to cause the Company to comply with
any withholding requirements imposed under Section 1446 or any other provision
of the Code or state, local or foreign law.

      (b) If the Code or any state, local or foreign law requires that the
Company remit to the Internal Revenue Service (the "IRS") or any other taxing
                                                    ---
authority any withholding tax with respect to, or for the account of, any Member
(in its capacity as a Member), the Board of Managers shall provide notice to
such Member of such obligation and such Member shall have the opportunity to
make such payment on its own behalf. If such Member fails, or is not otherwise
able, to make such payment on its own behalf, the Company shall so remit to the
IRS or other taxing authority the full required amount of such withholding tax.
Any amount so remitted shall be credited against any distributions that would
otherwise be made to such Member during such period or thereafter and any excess
of the amount so remitted over amounts so credited against distributions shall
be treated as a recourse demand loan from the Company to the Member. For so long
as the Company is not dissolved and the Member remains a Member, unless
otherwise paid, such loan shall be payable by credit against the first amounts
that would otherwise be distributed to such Member (with any such payment being
allocated first to accrued and unpaid interest through the date of such payment)
but may be prepaid in Cash by the Member, in whole or any part, at any time.

      10.5. Valuations. To the extent the assets of the Company, or any portion
            ----------
thereof, are required to be valued for any purpose, including without limitation
the calculation of distributions in respect of the Applicable Carried Interests,
such valuation shall be made by the Third Party Valuation Firm in the case of
Sections 10.2(d) and 12.3(c) and in all other cases by the Board of Managers in
accordance with the following:

      (a) In determining the Fair Market Value on a given date of
publicly-traded securities for which market quotations are readily available (i)
any securities traded on a national securities exchange shall be valued at the
average of the last trade

                                      -25-
<PAGE>

prices for the twenty Business Days prior to the valuation date on which trading
in such securities actually occurred on the exchange where they are primarily
traded or, if the securities are not traded on such valuation date, then for the
twenty Business Days prior to the immediately preceding date on which such
securities were traded on which trading in such securities actually occurred,
and (ii) any securities traded in the over-the-counter market shall be valued at
the average of the closing bid prices last quoted for the twenty Business Day
period prior to the valuation date by NASDAQ or, if not quoted by NASDAQ, at the
average last quote prices for the twenty Business Days prior to such valuation
date on which trading in such securities actually occurred as quoted in a
recognized list for over-the-counter securities or, if the securities are not
quoted on such valuation date (but are actively quoted in such recognized list),
then for the twenty Business Days prior to the immediately preceding date on
which such securities were quoted on which trading in such securities actually
occurred; provided, that in the case of any publicly-traded securities, the
          --------
determination of Fair Market Value shall be adjusted downward to the extent that
the Board of Managers or the Third Party Valuation Firm, as the case may be,
reasonably determines trading restrictions, block positions, thin trading or
other similar matters would materially adversely affect the realizable value of
such securities.

      (b) The Fair Market Value of all other securities or other assets of the
Company shall be reasonably determined by the Board of Managers or the Third
Party Valuation Firm, as the case may be, acting in good faith based on, among
other things, public market comparables, private market transactions,
independent appraisals and discounted cash flow analyses.

      (c) Liabilities shall be determined based upon GAAP by the Board of
Managers or the Third Party Valuation Firm, in consultation with the Board of
Managers and the Carry Members. The Board of Managers or the Third Party
Valuation Firm, in consultation with the Board of Managers, as the case may be,
may in its discretion provide reserves for estimated accrued expenses,
liabilities or contingencies, (including for the purpose specified in Section
10.1(c)) even if such reserves are not required by GAAP. If such reserves are
later reversed, the amounts released shall be distributed to the Member or
Members who would have been entitled to receive distributions of such amounts if
the reversed portion of the reserve had not been established.

                                   ARTICLE 11

                        TRANSFER OF MEMBERSHIP INTERESTS
                        --------------------------------

      11.1. Transfers. (a) Subject to Section 11.1(b) and (c), no Member may
            ---------
sell, transfer, assign, pledge, hypothecate or otherwise dispose of ("Transfer")
all or any part of its Membership Interests in the Company (including, without
limitation, its right to

                                      -26-
<PAGE>

receive a share of profits, losses and other allocations and distributions of
the Company). Any purported Transfer of any interest in the Company in violation
of this Article 11 shall be null and void.

      (b) Notwithstanding the provisions of Section 11.1(a), Merck shall be
permitted to Transfer its interests in the Company to any direct or indirect
wholly owned subsidiary of Merck & Co., Inc., provided that such transferee has
agreed in writing with the Company to be bound by the provisions of this
Agreement as a Member.

      (c) Notwithstanding the provisions of Section 11.1(a), each Other Investor
Member and Carry Member shall be permitted to grant participations in such
Member's Membership Interests to his or her heirs or to a Family Trust for
estate planning purposes, but no such participant shall have any rights as a
Member or any consent rights under this Agreement.

      11.2. Ownership of Membership Interests. The Company and the Board of
            ---------------------------------
Managers shall be entitled to treat the record owner of any Membership Interests
as the absolute owner thereof in all respects until such time as a written
instrument evidencing the Transfer of such Membership Interests has been
received by the Board of Managers and recorded on the books of the Company.

                                   ARTICLE 12

                     WITHDRAWAL; DISSOLUTION AND LIQUIDATION
                     ---------------------------------------

      12.1. Withdrawal of Members. (a) Except as expressly provided for in
            ---------------------
Article 11, no Member may withdraw from the Company.

      (b) A Member shall be deemed to have withdrawn from the Company upon an
Event of Bankruptcy of such Member or any dissolution or liquidation of such
Member.

      12.2. Events of Dissolution. The Company shall be dissolved upon the
            ---------------------
earliest to occur of the following: (a) an Event of Bankruptcy of the Company;
(b) at the election of Merck if Lofberg shall cease to be the Chief Executive
Officer of the Company or (c) the unanimous approval of the Investor Members to
dissolve the Company for any reason, including without limitation following the
disposition of all Portfolio Investments.

      12.3. Liquidation. If the Company is dissolved pursuant to Section 12.2,
            -----------
the Board of Managers (or any liquidating trustee appointed by the Board of
Managers or, in the event of a dissolution pursuant to Section 12.2(b), a
liquidating trustee appointed by Merck) shall (i) promptly file any notice,
publish any advertisement or take any other

                                      -27-
<PAGE>

action required under applicable law to effect such dissolution, (ii) commence
to wind up the affairs of the Company and liquidate the assets of the Company
and (iii) apply and distribute the proceeds of such liquidation and any
undistributed cash no later than the end of the Fiscal Year following the Fiscal
Year in which such liquidation occurs in accordance with the terms hereof and in
the following order of priority:

      (a) First, to pay and discharge, or make provisions or establish reserves
for, the claims of all creditors of the Company and to pay the expenses of
liquidation;

      (b) Second, to establish such reserves as the Board of Managers or
liquidating trustee deems reasonably necessary for any contingent or unforeseen
liabilities or obligations of the Company; such reserve may be paid over by the
Board of Managers or liquidating trustee to any attorney-at-law, or other party
acceptable to the Board of Managers or liquidating trustee, as escrow agent to
be held for disbursement in payment of any such liabilities or obligations and,
at the expiration of such period as shall be deemed advisable by the Board of
Managers or liquidating trustee, for distribution of the balance in the manner
hereinafter provided in this Section 12.3; and

      (c) Third, to make distributions to the Members in accordance with Section
10.1(b) (including, without limitation, applying the valuation methodology set
out in Section 10.5 in relation to distributions in kind, if any).

      12.4. Return of Excess Distributions to Investor Members. If, at the time
            --------------------------------------------------
final distributions are made upon the dissolution of the Company or upon a Carry
Member ceasing to have an Applicable Carried Interest in any outstanding
Portfolio Investments, after giving effect to all distributions to that Carry
Member calculated pursuant to Sections 10.1(b), 10.1(c) and 12.3, but before
giving effect to this Section 12.4, such Carry Member will have received an
Excess Carry Amount, such Carry Member shall contribute to the Company, without
interest, for distribution to Merck, an amount that equals the Excess Carry
Amount, reduced by the amount of federal, state, local and foreign tax
obligations borne by such Carry Member with respect to the Excess Carry Amount
as reasonably determined by such Carry Member (it being acknowledged and agreed
that in making such determination such Carry Member shall assume that such
amounts were earned by an individual paying income taxes at the Carry Member's
Applicable Tax Rate), and increased by the actual federal, state, local and
foreign tax benefits realized by such Carry Member or its beneficial owners with
respect to the repayment of any amount pursuant to this Section 12.4 as
reasonably determined by such Carry Member (it being acknowledged and agreed
that in making such determination such Carry Member shall (i) assume that such
amounts were paid by an individual paying income taxes at the Carry Member's
Applicable Tax Rate, (ii) shall include any tax benefits realized by such Carry
Member in connection with receiving a reduced distribution pursuant to Section
10.1(d)) and (iii) shall only be deemed actually used after all other applicable
tax benefits that could have been used by such Carry Member have

                                      -28-
<PAGE>

been deemed to be used; provided, however, that for the purposes of computing
such benefits, (a) any securities received by the Carry Member as a distribution
from the Company and held by such Carry Member shall be marked to market, and
(b) the gain or loss, as the case may be, with respect to such securities, shall
be taken into account in determining the tax benefits realized by such Carry
Member as if such securities had been sold in fully taxable transactions.

                                  ARTICLE 13

                TAX MATTERS; CERTAIN REPRESENTATIONS OF MEMBERS

          13.1. Designation of Tax Matters Member. Merck is hereby designated as
                ---------------------------------
the "tax matters partner" (in such capacity, the "Tax Matters Member") under
                                                  ------------------
Section 6231(a)(7) of the Code to manage, at the cost and expense of the
Company, administrative tax proceedings conducted at the Company level by the
IRS with respect to Company matters. The Members are specifically directed and
authorized to take whatever steps the Tax Matters Member, in its sole discretion
deems necessary or desirable to perfect such designation, including, without
limitation, filing any forms or documents with the IRS and taking such other
action as may from time to time be required under Regulations and cooperating
with the Tax Matters Member in connection with any tax audit, investigation or
litigation.

          13.2. Tax Returns. The Tax Matters Member shall cause to be prepared
                -----------
and filed, after reasonable consultation with Lofberg and at the cost and
expense of the Company, all necessary Company tax returns, and the Members (and
their Affiliates) shall prepare their tax returns consistently with such Company
tax returns.

          13.3. Taxable Year. The taxable year of the Company shall be the
                ------------
calendar year or such other year as may be reasonably determined by the Board of
Managers.

          13.4. Tax Elections. All tax elections required or permitted to be
                -------------
made under the Code and any applicable state, local or foreign tax law shall be
made in the discretion of the Tax Matters Member after reasonable consultation
with Lofberg, and any decision with respect to the treatment of Company
transactions on the Company's federal, state, local or foreign tax returns shall
be made in such manner as may be approved by the Tax Matters Member after
reasonable consultation with Lofberg. Each of the Carry Members shall file a
timely election in accordance with the rules set forth in Reg. (S)1.83-2,
with respect to his or her receipt of the Carry Interest.

          13.5. Certain Representations of Members. (a) Each Member, severally
                ----------------------------------
and not jointly, as to itself only, hereby represents, warrants and acknowledges
to the Company and the other Members as follows:

                                     -29-
<PAGE>

                    (i)   Such Member has full power and authority to execute
               and deliver this Agreement and to carry out its obligations
               hereunder in accordance with the terms and provisions hereof. The
               execution, delivery and performance of this Agreement and the
               consummation of the transactions contemplated hereby have been
               duly authorized by all requisite action, corporate or otherwise,
               on the part of such Member.

                    (ii)  Such Member is a "United States person" within the
               meaning of Section 7701(a)(30) of the Code.

                    (iii) Such Member is acquiring its Membership Interests
               solely for investment, for such Member's own account and not with
               a view to, or for resale in connection with, the distribution or
               other disposition thereof.

                    (iv)  Such Member has not pledged, hypothecated or
               encumbered his or her Membership Interest or entered into any
               agreement to do so.

               (b)  Each Member acknowledges that its Membership Interests may
be construed as "securities" for purposes of federal, state or local securities
laws or regulations. Each Member further acknowledges and represents that it has
been advised that the membership interests of the Company have not been
registered under the Securities Act of 1933, as amended.

               (c)  Each Member acknowledges and represents that it is
experienced in evaluating companies such as the Company, is able to fend for
itself in the transactions contemplated by this Agreement, has such knowledge
and experience in financial and business matters as to be capable of evaluating
the merits and risks of its investment, and has the ability to bear the economic
risks of its investment. Each Member further represents that it has had access,
during the course of the transactions and prior to its purchase of Membership
Interests, to all such information as it deemed necessary or appropriate (to the
extent the Company possessed such information or could acquire it without
unreasonable effort or expense) and that it has had, during the course of the
transactions and prior to its purchase of Membership Interests, the opportunity
to ask questions of, and receive answers from, the Company concerning the terms
and conditions of the offering and to obtain additional information (to the
extent the Company possessed such information or could acquire it without
unreasonable effort or expense) necessary to verify the accuracy of any
information furnished to it or to which it had access.

               (d)  Each Member acknowledges and represents that it understands
that the Membership Interests may not be sold, transferred or otherwise disposed
of without registration under the 1933 Act or an exemption therefrom, and that
in the absence of an effective registration statement covering the Membership
Interests or an available

                                     -30-
<PAGE>

exemption from registration under the 1933 Act, the Membership Interests must be
held indefinitely.

               (e)   Each Member acknowledges and represents that it understands
that no public market now exists for any of the securities issued by the Company
and that there is no assurance that a public market will ever exist for the
Membership Interests.

                                  ARTICLE 14

                           BOOKS OF ACCOUNT; REPORTS
                           -------------------------

               14.1. Books of Account. The Board of Managers shall keep, or
                     ----------------
cause to be kept, accurate and complete records and books of account of all
transactions of the Company. The Company books and records shall be maintained
at the principal place of business of the Company and shall be available for
inspection and examination, for a proper purpose and at reasonable times during
usual business hours, by Members or their respective duly authorized
representatives. Except as otherwise expressly provided in this Agreement, such
information shall not be disclosed to third parties and shall be used for
Company purposes only.

               14.2. Reports to Members. As promptly as practicable following
                     ------------------
the end of each Fiscal Year, the Board of Managers shall cause to be prepared
and mailed to each Member a report setting forth as of the end of such Fiscal
Year (i) the assets and liabilities of the Company, (ii) the Net Profit and Net
Loss of the Company and (iii) such Member's Capital Account balance and the
manner of calculation thereof. After the end of each Fiscal Year, the Board of
Managers shall cause to be prepared and delivered, as promptly as practicable, a
federal income tax form K-1 for each Member.

               14.3. Final Accounting. Following the date on which the Company
                     ----------------
is dissolved and liquidated pursuant to Article 12, an independent accounting
firm selected by the Board of Managers shall commence to take an account of the
affairs and financial transactions of the Company and shall prepare a statement
setting forth the financial position of the Company as of the close of business
on the date the dissolution and liquidation of the Company is completed pursuant
to Article 12 establishing reasonable reserves for contingencies, showing the
amount of each Member's share of the profits or losses of the Company through
such date and stating each Member's Capital Account balance on such date.

                                     -31-
<PAGE>

                                  ARTICLE 15

                   LIMITATION ON LIABILITY; INDEMNIFICATION
                   ----------------------------------------

               15.1. Limitation on Members' Liability. Except as otherwise
                     --------------------------------
required by the LLC Act, the debts, obligations and liabilities of the Company,
whether arising in contract, tort or otherwise, shall be solely the debts,
obligations and liabilities of the Company, and none of the Members or any
Managers or Officers appointed pursuant to Article 6 hereof (collectively, the
"Protected Parties") shall be obligated personally for any such debt, obligation
 -----------------
or liability of the Company solely by reason of being a Member, Manager or
Officer, or by reason of participating in the management of the Company. The
failure of the Company to observe any formalities or requirements relating to
the exercise of its powers or management of its business or affairs under the
LLC Act or this Agreement shall not be grounds for imposing personal liability
on the Members for liabilities of the Company.

               15.2. Limitation on Protected Parties' Liability. None of the
                     ------------------------------------------
Protected Parties shall have any liability to the Company or to any other Member
or to any shareholders, members, principals, officers, directors or employees of
any other Member for any Damages claimed by reason of any act or omission to act
on behalf of the Company or otherwise in connection with this Agreement,
provided that this release from liability shall not apply to the extent that
such action or failure to act has been found by a final judgment of a court of
competent jurisdiction to have constituted gross negligence or willful
misconduct.

               15.3. Indemnification of the Protected Parties. The Company shall
                     ----------------------------------------
indemnify and hold harmless the Protected Parties for any Damages incurred by
any of them by reason of any act or omission or alleged act or omission arising
out of the activities of the Protected Parties in connection with this
Agreement, any Portfolio Investment, or the Company provided that this
indemnification shall not apply to the extent that such action or failure to act
has been found by a final judgment of a court of competent jurisdiction to have
constituted gross negligence or willful misconduct of the applicable Protected
Parties, or with respect to which indemnification is not obtainable under the
securities laws of the United States or any other law. If the foregoing
indemnity is unavailable to any Protected Party, then the Company shall
contribute to the maximum extent permitted by law to the amount paid or payable
by the Protected Party.

               15.4. No Liability for Acts of Agents. None of the Protected
                     -------------------------------
Parties shall be liable for any act or omission of any third party with respect
to the Company as long as the same is retained by the Board of Managers in good
faith and with reasonable care and diligence.

                                     -32-
<PAGE>

     15.5.  General. (a) The termination of any proceeding by settlement shall
            -------
not, of itself, create a presumption that a Protected Party acted in a manner
which constituted gross negligence or willful misconduct. The right of any
Protected Party to the indemnification provided herein shall be cumulative with,
and in addition to, any and all rights to which such Protected Party may
otherwise be entitled by contract or as a matter of law or equity and shall
extend to its successors.

     (b)  All judgments against the Company and a Protected Party, with respect
to which a Protected Party is entitled to indemnification, shall first be
satisfied from Company assets to the extent available.

     (c)  To the extent that insurance from third parties has been obtained and
is available in respect of any Damages, the Board of Managers will use its best
efforts to have such Damages paid out of the proceeds of such insurance rather
than having the Company make any payments pursuant to the indemnification
obligations contained herein; provided, however, that if such proceeds are not
                              --------  -------
readily available, the Board of Managers shall cause the Company to pay such
Damages, in which event the Company will be entitled to reimbursement therefor
out of the proceeds of insurance when and if obtained.

     15.6.  Survival. The provisions of this Article 15 shall survive the
            --------
termination of this Agreement and the dissolution and liquidation of the
Company.

                                  ARTICLE 16

                                 MISCELLANEOUS
                                 -------------

     16.1.  Special Power of Attorney. Each Member hereby irrevocably makes,
            -------------------------
constitutes and appoints the Board of Managers, and such other Person or Persons
as the Board of Managers may designate, with full power of substitution, its
true and lawful representative and attorney-in-fact (acting in such capacity,
the "Attorney-in-Fact"), in the name, place and stead of such Member, with the
     ----------------
power from time to time to make, execute, sign, acknowledge, swear to, verify,
deliver, record, file and/or publish: (a) all certificates and other instruments
which the Board of Managers may deem appropriate, to form, qualify or continue
the Company as a limited liability company in the State of Delaware, and all
other jurisdictions in which the Company conducts or plans to conduct business
and to change the name of the Company; (b) all conveyances and other instruments
which the Board of Managers may deem appropriate to reflect the dissolution and
termination of the Company pursuant to the terms hereof, including any writing
required by the LLC Act to cancel the Company; and (c) a certificate of assumed
name and such other certificates and instruments as may be necessary under the
fictitious or assumed name statutes from time to time in effect in the State of
Delaware, and all other jurisdictions in which the Company conducts or plans to
conduct business.

                                     -33-
<PAGE>

This power-of-attorney is a special power-of-attorney and is coupled with an
interest in favor of the Attorney-in-Fact and as such (i) shall be irrevocable,
and (ii) may be exercised for such Member by a facsimile signature of the
Attorney-in-Fact.

     16.2.  Amendments. This Agreement may not be amended without the written
            ----------
consent of each of the following: (i) Merck, and (ii) the Executive Agent;
provided, however, that no amendment to this Agreement shall (A) reduce the
--------  -------
distributions to which a Member is entitled under this Agreement or extend the
time for making such distributions or the form or currency in which such
distributions are made or adversely affect the rights of such Member under
Section 5.5(c), 8.3 or 12.4, without the consent of each Member affected
thereby, or (B) adversely affect the rights of Lofberg under Article 7 or
Section 5.5, 6.1(b)(i), 6.4, 6.5, 6.13, 8.1(d), 8.5, 9.3(a), 10.2(a), (b) or
(c), 13.2, 13.4 or this Section 16.2 of the Agreement, without Lofberg's consent
or (C) adversely affect the rights of the Other Investor Members under Section
8.2(d) through (h) without the consent of the majority of the Other Members.

     16.3.  Binding Effects; Benefits. This Agreement shall be binding upon and
            -------------------------
inure to the benefit of the Members hereto and their legal representatives and
permitted successors, as applicable. No Person, other than the Members, shall be
entitled to any benefits under this Agreement, except as otherwise expressly
provided herein.

     16.4.  Headings. The article, section and other headings of this Agreement
            --------
are for reference purposes only and shall not affect the meaning or
interpretation of this Agreement.

     16.5.  Counterparts. This Agreement may be executed in any number of
            ------------
counterparts, each of which shall be deemed to be an original and all of which
together shall be deemed to be one and the same agreement.

     16.6.  Grammatical Construction. Whenever the context may require, any
            ------------------------
pronouns used herein shall include the corresponding masculine, feminine and/or
neuter forms, and the singular form of nouns and pronouns shall include the
plural and vice versa.

     16.7.  Separability. Any term or provision of this Agreement which is
            ------------
invalid or unenforceable in any jurisdiction shall, as to such jurisdiction, be
ineffective to the extent of such invalidity or unenforceability without
rendering invalid or unenforceable the remaining terms or provisions of this
Agreement or affecting the validity or enforceability of any of the terms or
provisions of this Agreement in any other jurisdiction.

     16.8.  Waiver. No waiver of any breach or condition of this Agreement shall
            ------
be deemed to be a waiver of any other subsequent breach or condition, whether of
like or different nature.

                                     -34-
<PAGE>

     16.9.  Entire Agreement. Other than the employment agreements of even date
            ----------------
herewith between Merck and Lofberg and Merck and Cooper and the Former
Agreements referred to therein, this Agreement constitutes the entire agreement
among the parties hereto and supersedes any prior agreements, understandings and
arrangements, oral or written, among the parties hereto.

     16.10. Notices. (a) Any notice or other communication in connection with
            -------
this Agreement may be made in writing delivered personally or by courier, or
sent by facsimile transmission (with confirmation slip showing receipt at
correct number) or by certified or registered mail and shall be addressed to the
intended recipient at its address or number initially specified as follows:

                  if to the Board of Managers:

                           Merck Capital Ventures, LLC
                           c/o Merck & Co. Inc.
                           1 Merck Drive
                           Whitehouse Station, NJ  08889
                           Fax  No.: (908) 735 1244
                           Attn:  Ken Frazier

                  if to the Members:
                  at the addresses set forth in Schedule A.

     (b)  The addresses specified above may be changed by either party at any
time in writing delivered to the other party in accordance with this Section
16.10. Any such notice is deemed to be given as follows: (i) if in writing and
delivered in person or by courier, on the date when it is delivered; (ii) if by
facsimile, when received at correct number (proof of which shall be an original
facsimile transmission confirmation slip or equivalent); or (iii) if sent by
certified or registered mail (airmail, if overseas) or the equivalent (return
receipt requested), on the date that mail is delivered or its delivery is
attempted, unless the date of that delivery (or attempted delivery) or that
receipt, as applicable, is not a working day in the recipient's city or that
communication is delivered (or attempted) or received, as applicable, after the
close of business on a working day in the recipient's city in which case that
communication shall be deemed given and effective on the first following day
that is a working day in the recipient's city.

     16.11.  Insurance. The Board of Managers may cause the Company to purchase
             ---------
and maintain, at the expense of the Company, insurance on behalf of the Company
or its Members or any Officer, Manager or agent of the Company against any
liability asserted against any of them or incurred by any of them in any such
capacity or

                                     -35-
<PAGE>

arising out of their status as such, whether or not the Company would have the
power to indemnify any of them against such liability under the provisions of
this Agreement.

     16.12.  Disclosure of Investment. The Company and each of the Members
             ------------------------
agree, and each Member and the Board of Managers will use reasonable best
efforts to procure that any Portfolio Company in which the Company is to make a
Portfolio Investment will agree, that, from the date hereof, no public release
or announcement concerning the transactions contemplated by this Agreement,
including without limitation, the formation of the Company and the consummation
of a Portfolio Investment in a Portfolio Company (or the contemplation thereof),
shall be issued by any party without the prior consent of Merck in its sole
discretion except (i) as such release or announcement may be required by
           ------
applicable securities law or the rules or regulations of the United States
Securities and Exchange Commission, (ii) if a Portfolio Company reasonably
considers that such a public release or announcement is in the best interests of
the Portfolio Company, in which case the party required or electing to make the
release or announcement shall make its reasonable best efforts to allow Merck
reasonable time to comment on such release or announcement in advance of such
issue or (iii) if such public release or announcement does not include a
reference to Merck or any of its Affiliates or to the Merck name.

     16.13.  Arbitration. (a) Except for determinations of whether Protected
             -----------
Parties are entitled to a release from liability or indemnification in
accordance with Sections 15.2 and 15.3, any controversy, dispute or claim
arising under this Agreement or any breach thereof shall be settled by
arbitration conducted in accordance with this Section 16.13 in the County of New
York, in accordance with the then existing rules of the American Arbitration
Association, and judgment upon any award rendered by the arbitrator may be
entered by any United States federal or state court having jurisdiction thereof,
provided that the foregoing shall not limit the Company's right to seek an
injunction or other equitable relief. Any such arbitration shall be conducted by
a single arbitrator, and, in the case of any dispute with respect to accounting
issues, the arbitrator (the "Arbitrator") shall be a partner of a "Big Five"
                             ----------
accounting firm other than the Company's accountants. If the parties are unable
to agree upon an arbitrator within 5 Business Days of any Member requesting the
appointment thereof, then an arbitrator shall be appointed in accordance with
the rules of the American Arbitration Association. The parties intend that this
agreement to arbitrate be valid, enforceable and irrevocable and that any
determination reach pursuant to the foregoing procedure shall be final and
binding on the parties absent fraud. Each party shall bear their own costs and
expenses of any such arbitration and all of the fees and expenses of the
arbitrator shall be paid as to 50% by Merck and 50% by the other parties to the
Arbitration in proportion to their respective Maximum Amounts.

     (b)  A party seeking to enforce its rights pursuant to this Section 16.13
shall submit to the Arbitrator, with a copy sent to all other Members to the
dispute, a

                                     -36-
<PAGE>

notice of the existence of the dispute and a brief description of the action
giving rise to the dispute (such submission, a "Dispute Notice").
                                                --------------

          (c)  No later than the close of business on the second Business Day
following submission of the Dispute Notice to the Arbitrator, representatives of
the relevant Members shall meet in person or by teleconference with the
Arbitrator and at such meeting the Arbitrator shall determine the process by
which the dispute (including scheduling presentations to him) shall be resolved
within 20 Business Days following submission of the Dispute Notice to him
(subject to extension for good cause). The relevant Members shall provide the
Arbitrator with all the information the Arbitrator deems necessary within the
time period specified by the Arbitrator.

          (d)  The Arbitrator shall deliver a written report to the relevant
Members and a copy to the Company of his determination as to the dispute by the
tenth Business Day following submission of the Dispute Notice to him (subject to
extension for good cause). Such report shall set forth the basis for such
determination and shall constitute an arbitral award that is final, binding and
unappealable under the Federal Arbitration Act, 9 U.S.C. (S)(S) 1 et seq. (the
"FAA").
 ---

     16.14.    Appointment of Executive Agent. Until his successor as Executive
               ------------------------------
Agent shall have been designated in the manner hereafter provided and, in any
event, for so long as he is the Chief Executive Officer of the Company, Lofberg
shall act as the sole agent (the "Executive Agent") for each Carry Member and
each Other Investor Member (collectively, the "Non-Merck Members") and shall,
                                               -----------------
except as provided in Sections 5.5(c), 16.2 and this Section 16.14 be authorized
to exercise all rights of the Non-Merck Members hereunder. Except as provided in
Sections 5.5(c), 16.2 and this Section 16.14, the Executive Agent will have sole
power and authority to take any action on behalf of the Non-Merck Members
pursuant to this Agreement, including delivering any notice or granting any
waiver or consent hereunder, and Merck shall be entitled to rely on any action
taken by the Executive Agent as being taken on behalf of any or all of the Non-
Merck Members as the case requires. Except as provided in Sections 5.5(c), 16.2
and this Section 16.14, the rights of the Non-Merck Members under this Agreement
shall be exercised only by the Executive Agent on behalf of such Non-Merck
Members and no such Non-Merck Member shall be separately authorized to exercise
any such rights. Any notice required to be delivered to any Non-Merck Member
shall be deemed delivered if delivered to the Executive Agent. If Lofberg ceases
to be Chief Executive Officer of the Company, a majority of the Carry Members
may from time to time, by written notice to the Company and Merck, appoint a
replacement Executive Agent, who shall serve as Executive Agent until replaced
as provided in this sentence.

     16.15.    Payments on Business Days. Any payment required to be made
               -------------------------
hereunder on a day which is not a Business Day shall be made on the next
succeeding Business Day.

                                     -37-
<PAGE>

     16.16.    Governing Law. This Agreement shall be governed by and construed
               -------------
both as to validity and enforceability in accordance with the laws of the State
of Delaware, without regard to the conflict of laws provisions thereof.

     [Remainder of Page is Intentionally Blank]

                                     -38-
<PAGE>

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

                              Merck-Medco Managed Care, L.L.C.

                              By:  ________________________________________
                                   Name:
                                   Title:

                                   ----------------------------------------
                                              Per G.H. Lofberg

                                    ---------------------------------------
                                                James Cooper

                                     -39-
<PAGE>

                                                                      APPENDIX A
                                                                      ----------

                                 DEFINITIONS
                                 -----------

                                      -1-
<PAGE>

          As used in the foregoing Agreement, the following terms shall have the
meanings set forth below:

          "Acquisition Cost" means the amount of Capital Contributions invested
           ----------------
in a Portfolio Investment, excluding any Fees and Expenses incurred in
connection therewith.

          "Affiliate" means, with respect to any Person, any other Person,
           ---------
directly or indirectly, through one or more intermediaries, controlling,
controlled by, or under common control with such Person. The term "control," as
used in the immediately preceding sentence means, with respect to any Person,
the possession, directly or indirectly, of the power to direct or cause the
direction of the management or policies of the controlled Person.

          "Agreement" shall have the meaning set forth in the Recitals.
           ---------

          "Applicable Carried Interest" means:
           ---------------------------

           (a)  with respect to Lofberg, (i) from the date of this Agreement to
the first anniversary of this Agreement, 0%, (ii) from and after the first
anniversary of this Agreement to the second anniversary of this Agreement, 6%,
and (iii) thereafter, 12%;

          (b)   with respect to Cooper, (i) from the date of this Agreement to
the first anniversary of this Agreement, 0%, (ii) from and after the first
anniversary of this Agreement to the second anniversary of this Agreement,
1.25%, and (iii) thereafter, 2.5%;

          (c)   with respect to any other Carry Member, as determined by the
Board of Managers and set forth in a resolution of the Board, provided, however,
that the Applicable Carried Interest of a Carry Member shall be 0% in respect of
any Portfolio Investment:

          (1)   made or committed to be made by the Company prior to the Start
                Date for such Carry Member; or

          (2)   made by the Company after the End Date for such Carry Member,
                and provided further, that:

          (A)   in the case of a Carry Member whose employment by Merck or any
                of its Affiliates is terminated without Cause, or as a result of
                such Carry Member's Death or Disability or, in the case of
                Lofberg, if Lofberg terminates his employment with the Company
                for Good Reason, the Applicable Carried Interest of such Carry
                Member in respect of any Portfolio Investment made on or after
                the Start Date and on or before the End Date for such Carry
                Member, shall be such

                                      -1-
<PAGE>

               Carry Member's Maximum Amount; and

          (B)  in the case of a Carry Member whose employment by Merck or any of
               its Affiliates is terminated for any reason other than the
               reasons set out in paragraph (A) of this definition, the
               Applicable Carried Interest of such Carry Member in respect of
               any Portfolio Investment made on or after the Start Date and on
               or before the End Date for such Carry Member, shall be the
               Applicable Carried Interest in effect at the End Date for such
               Carry Member.

          "Applicable Employer" shall have the meaning set forth in Section 8.5.
           -------------------

          "Applicable Portfolio Investment" is defined in the definition of
           -------------------------------
Negative Carry Balance.

          "Applicable Tax Rate" in respect of a Member, means that Member's
           -------------------
marginal tax rate for the applicable Fiscal Year, taking into account, where
applicable, the deductibility of state and local taxes paid for federal tax
purposes, such Member's eligibility for a lower rate on long-term capital gains,
and any preferential rate or exemption to which such Member is actually
entitled.

          "Applicable Valuation Date" means:
           -------------------------

          (a)  in the case of Section 10.2(b), the 20/th/ Business Day following
the date the Divestment Proposal is recommended to the Board of Managers by
Lofberg; and

          (b)  in the case of Section 10.2(d), a date mutually agreed to by the
Members, or if no valuation date is agreed upon, December 31, 2010.

          "Associate" has the meaning set forth in Rule 12b-2 under the
           ---------
Securities Exchange Act of 1934.

          "Attorney-in-Fact" shall have the meaning set forth in Section 16.1.
           ----------------

          "Attributable Carry Member Costs" shall mean, with respect to any
           -------------------------------
Portfolio Investment, an amount equal to the cumulative previously unrecovered
Carry Member Costs incurred during the Expenses Period multiplied by a fraction,
(x) the numerator of which is the Acquisition Cost of such Portfolio Investment
and (y) the Denominator of which is (i) the aggregate Acquisition Costs of all
Portfolio Investments less (ii) the aggregate Acquisition Costs of Portfolio
Investments that have been Sold other than such Portfolio Investment.

          "Attributable Fees and Expenses" shall mean, with respect to any
           ------------------------------
Portfolio Investment, an amount equal to the cumulative previously unrecovered
Fees and Expenses of the Company incurred during the Expenses Period which were
funded by a

                                      -2-
<PAGE>

Capital Contribution of Merck multiplied by a fraction, (x) the numerator of
which is the Acquisition Cost of such Portfolio Investment and (y) the
Denominator of which is (i) the aggregate Acquisition Costs of all Portfolio
Investments less (ii) the aggregate Acquisition Costs of Portfolio Investments
that have been Sold other than such Portfolio Investment.

          "Available Cash" means Cash which is available in the accounts of the
           --------------
Company and not reserved to make any payments due and owing by the Company or
otherwise reserved by the Board of Managers, in its reasonable discretion, for
Fees and Expenses, operations, or contingencies of the Company.

          "Base Commitment" shall mean, as to Merck, the Merck Base Commitment
           ---------------
and, as to each Other Investor Member, an amount equal to the Other Investor
Members Base Commitment multiplied by such Other Investor Member's Ratable
Contribution Percentage.

          "Benefiting Member" has the meaning set forth in Section 8.3(a).
           -----------------

          "Board of Managers" and "Board" shall have the meaning set forth in
           -----------------       -----
Section 6.1.

          "Bona Fide Third Party Offer" means a bona fide offer by a third party
           ---------------------------
that is not an Affiliate or Associate of the Company or any Member to acquire
the Company's entire interest in a Portfolio Company for cash, which offer:

          (a)  shall not be subject to financing, due diligence or other
contingencies that in the reasonable judgment of the Board of Managers create a
reasonable risk of delay or failure provided, however, that this paragraph (a)
shall not apply in respect of an offer that otherwise satisfies the definition
from an offeror who is bound by a customary confidentiality agreement with a
Portfolio Company if Merck unreasonably prevents such third party from
performing customary due diligence investigations;

          (b)  shall include evidence reasonably satisfactory to Board of the
offeror's ability to pay the purchase price;

          (c)  shall not include surviving representations and warranties or
indemnities (other than in respect of title); and

          (d)  shall not be subject to post-closing purchase price adjustments
or earn-outs.

          "Book Value" means:
           ----------

          (a)  with respect to any asset, the asset's adjusted basis for federal

                                      -3-
<PAGE>

income tax purposes, except that, in accordance with the rules set forth in
Reg. (S) 1.704-1(b)(iv)(f):

          (i)   The initial Book Value of the assets of the Company as of the
     date of the contribution or deemed contribution shall be their respective
     gross Fair Market Values at such time as reasonably determined by the Board
     of Managers;

          (ii)  The Book Value of any asset distributed or deemed distributed by
     the Company to any Member shall be adjusted immediately prior to such
     distribution to equal its gross Fair Market Value at such time as
     reasonably determined by the Board of Managers;

          (iii) The Book Values of all Company assets may be adjusted in the
     discretion of the Board of Managers to equal their respective gross Fair
     Market Values, as reasonably determined by the Board of Managers as of:

               (1)  The date of the acquisition of an additional interest in the
                    Company by any new or existing Member in exchange for a
                    Capital Contribution to the Company; or

               (2)  Any distribution in liquidation of the Company, or the
                    distribution by the Company to a retiring or continuing
                    Member of money or other assets of the Company in reduction
                    of such Member's Membership Interest in the Company;

          (iv)  Any adjustments to the adjusted basis of any asset of the
     Company pursuant to Sections 734 or 743 of the Code shall be taken into
     account in determining such asset's Book Value in a manner consistent with
     Reg. (S) 1.704-1(b)(2)(iv)(m); and

          (v)  If the Book Value of an asset has been determined pursuant to
     clauses (i) through (iv) above, to the extent permitted under the Income
     Tax Regulations, such Book Value shall thereafter be adjusted in the same
     manner as would the asset's adjusted tax basis for federal income tax
     purposes, except that depreciation and amortization deductions shall be
     computed based on the asset's Book Value as so determined, and not on the
     asset's adjusted tax basis in a manner consistent with Reg. (S) 1.704-
     1(b)(2)(iv)(g)(3) or 1.704-3(d)(2), as applicable; and

     (b)  with respect to any liability, at a given time, the amount of such
liability to the extent:

                                      -4-
<PAGE>

               (i)    reflected in the basis of any asset;

               (ii)   previously or currently deductible in computing Net
          Profit, Net Loss or items of income, deduction or expense for Capital
          Account maintenance purposes; or

               (iii)  otherwise previously taken into account for Capital
          Account maintenance purposes.

          "Break-Up Expenses" means all expenses incurred by the Company in
           -----------------
connection with any Portfolio Investment that is not consummated, provided (a) a
term sheet and letter of intent for such Portfolio Investment has been approved
by the Board of Managers or (b) such Portfolio Investment does not require
approval of the Board of Managers and has been approved by Lofberg.

          "Business Day" means any day excluding Saturday, Sunday and any day
           ------------
which shall be in the City of New York a legal holiday or a day on which banking
institutions are authorized by law or other government action to close.

          "Capital Account" means, with respect to any Member, the capital
           ---------------
account of such Member maintained pursuant to Section 9.1, including all
additions and subtractions thereto, pursuant to this Agreement.

          "Capital Contributions" shall have the meaning set forth in Section
           ---------------------
5.1(a).

          "Carry Distributions" shall mean all amounts distributed to the Carry
           -------------------
Members pursuant to the proviso in Section 10.1(b)(iii).

          "Carry Interest" shall mean the interest of the Carry Members in
           --------------
distributions made or to be made by the Company under this Agreement.

          "Carry Members" has the meaning set forth in the Preamble and includes
           -------------
any person who is designated as a Carry Member pursuant to Section 5.5.

          "Carry Member Costs" means all costs and expenses (excluding severance
           ------------------
costs of terminated employees (other than Carry Members) and the initial costs,
such as headhunter's fees and relocation expenses, of hiring new employees to
replace employees seconded to the Company) incurred by Merck or any of its
Affiliates (other than the Company) in connection with the employment of any
person who is seconded to the Company pursuant to this Agreement or is a Carry
Member or Designated Additional Carry Member, during the period that such person
is employed to provide such services or be such Carry Member or Designated
Additional Carry Member, including, without limitation, any base compensation,
any overtime compensation, any bonus and any compensation related expenses and
the amount of any other employee benefits (including

                                      -5-
<PAGE>

welfare and pension benefits) in the amount (equal to 36% of the base salary
plus overtime of such person) billed by Merck or its Affiliates to the relevant
business division of the entity that employs such employee.

          "Cash" when capitalized means money and cash equivalents.
           ----

          "Cause" shall have the meaning set forth in the applicable employment
           -----
agreement between the entity employing the Carry Member and the Carry Member or,
if there is no employment agreement, shall mean (i) the continued failure by the
Carry Member to substantially perform the Carry Member's duties with the Company
(other than any such failure resulting from the Carry Member's incapacity due to
physical or mental illness), (ii) the Carry Member's engaging in conduct which
is demonstrably and materially injurious to the Company or any of its
Affiliates, monetarily or otherwise, (iii) the conviction of the Carry Member
for the commission of (A) a felony or (B) any other crime involving moral
turpitude, (iv) the Carry Member's material violation of any employment policies
or applicable codes of conduct of the Company, Merck or an Affiliate of Merck ,
or (v) a material breach by the Carry Member of any employee covenants to which
such an Carry Member is subject.

          "Certificate of Formation" means the limited liability certificate of
           ------------------------
the Company and any amendments thereto.

          "Clinical Development Entity" means any private emerging entity
           ---------------------------
engaged in innovative ways to manage documentation and information processing,
physician and patient recruitment, information analysis, communications and site
management all with the goal of shortening pharmaceutical development time
frames and/or lowering pharmaceutical development costs. Nothing in this
definition shall restrict the Company's power to invest in entities otherwise
satisfying the definition of E-Healthcare Companies under clause (b) of the
definition of such term in Section 4.1.

          "Code" means the Internal Revenue Code of 1986, as in effect on the
           ----
date of this Agreement and as amended thereafter from time to time.

          "Company" shall have the meaning set forth in the Preamble.
           -------

          "Contributing Member" means, in respect of a Distributing Investment,
           -------------------
each Investor Member who contributed to the Acquisition Cost of such
Distributing Investment.

          "Control Acquisition" means any cash investment prior to termination
           -------------------
of the Investment Period (including by way of the cashless exercise of Warrants
Acquired for Cash) by Merck or any of its Affiliates or Associates (other than
the Company) in a Portfolio Company in which the Company has an existing
Portfolio Investment that (i) is rejected or not approved by Lofberg within the
period specified in Section 8.2(b) and

                                      -6-
<PAGE>

(ii) upon the consummation of which, the Company, Merck and Merck's Affiliates
and Associates would, in the aggregate, own more than 20% of the outstanding
voting equity of the Portfolio Company.

          "Control Acquisition Interest" shall have the meaning set forth in
           ----------------------------
Section 8.2(d).

          "Control Acquisition Price" of a Control Acquisition Interest means
           -------------------------
the same consideration per share (or equity equivalent) paid or to be paid by
Merck or the applicable Affiliate or Associate under the related Control
Acquisition Agreement.

          "Cooper" means James Cooper.
           ------

          "Damages" means any and all losses, damages, expenses and liabilities
           -------
whether joint or several, including, without limitation, those losses, damages,
expenses and liabilities (including reasonable attorneys' fees) arising under or
connected with the securities laws of the United States, or any other provision
of statutory law, common law, or other applicable law of any jurisdiction.

          "Death" shall mean the death of the Carry Member.
           -----

          "Designated Additional Carry Member" shall have the meaning set forth
           ----------------------------------
in Section 5.5(a).

          "Disability" shall have the meaning set forth in the applicable
           ----------
employment agreement between the entity employing the Carry Member and the Carry
Member, or if there is no employment agreement, a Carry Member shall be
considered to be disabled after he or she has been unable fully to perform his
or her duties as an employee of the Company (as determined in good faith by the
Board of Managers), with reasonable accommodation as required by law, by reason
of physical or mental illness for 180 days during any 360 day period.

          "Distributing Investment" means, in respect of each distribution under
           -----------------------
Section 10.1(b), the Portfolio Investment whose Sale gives rise to such
distribution.

          "E-Healthcare Companies" shall have the meaning given to it in Section
           ----------------------
4.1 of the Agreement.

          "employee of the Company" or "employees" means any employee of Company
           -----------------------
or Merck or an Affiliate of Merck who provides services to the Company under the
terms of this Agreement.

          "End Date" means the earlier of (i) the date the applicable Carry
           --------
Member's employment with Merck or an Affiliate of Merck is terminated and (ii)
date the applicable Carry Member's designation as a Carry Member is terminated
by the Board of

                                      -7-
<PAGE>

Managers pursuant to Section 6.13(l), in each case for any reason, except that
the End Date shall be the 90/th/ day following such termination date in respect
of a Portfolio Investment initiated prior to such termination date and
consummated on or before such 90th day if the applicable Carry Member's
employment or designation as a Carry Member is terminated without Cause or by
reason of the Carry Member's Death or Disability.

          "Event of Bankruptcy" means, with respect to any Person, (i) the
           -------------------
filing of a voluntary petition seeking liquidation, reorganization, arrangement
or readjustment, in any form, of its debts under Title 11 of the United States
Code or any other federal or state insolvency law, or the filing of an answer
consenting to or acquiescing in any such petition; (ii) the making of any
general assignment for the benefit of its creditors, or the admission in writing
of its inability to pay debts as they become due; (iii) the expiration of 30
days after the filing of an involuntary petition under Title 11 of the United
States Code, an application for the appointment of a receiver for the assets of
such Person, or an involuntary petition seeking liquidation, reorganization,
arrangement or readjustment of its debts under any other federal, state or
foreign insolvency law, provided that the same shall not have been vacated, set
aside or stayed within such 30-day period; (iv) the appointment of a receiver,
liquidator, assignee, custodian, trustee, sequestrator, or other similar agent
for the Person or for any substantial part of the Person's assets or property;
and (v) the ordering of the winding up or liquidation of the Person's affairs.

          "Excess Carry Amount" means, with respect to each Carry Member, an
           -------------------
amount, determined on an aggregate basis for all Portfolio Investments in which
such Carry Member has or had a Carry Interest, equal to such amount, if any, by
which its Carry Distributions exceed the product of (i) the highest Applicable
Carried Interest of such Carry Member in respect of any Portfolio Investment,
and (ii) the Net Profit Amount of all Portfolio Investments in which such Carry
Member has or had a Carry Interest.

          "Exchange" means (i) a United States national, regional, or local
           --------
securities exchange (ii) a foreign securities exchange or (iii) an interdealer
quotation system that regularly disseminates firm buy or sell quotations by
identified brokers or dealers (including, without limitation, NASDAQ).

          "Executive Agent" shall have the meaning set forth in section 16.14.
           ---------------

          "Executive Committee" shall have the meaning set forth in Section
           -------------------
8.1(d).

          "Expenses" shall mean, collectively, the Organizational Expenses and
           --------
the Operating Expenses.

          "Expenses Period" means the period commencing on the date of this
           ---------------
Agreement and ending on the third anniversary thereof.

                                      -8-
<PAGE>

          "Fair Market Value" shall mean, as to any non-cash property of the
           -----------------
Company, the fair market value thereof as determined pursuant to Section 10.5 of
the Agreement.

          "Family Trust" in respect of any Person means any trust, partnership,
           ------------
limited liability company or other entity, the beneficiaries, partners, members
or other equity owners of which (as the case may be), comprise solely members of
that Person's family, by blood or marriage.

          "Fees and Expenses" shall mean, collectively, the Break-Up Expenses,
           -----------------
the Organizational Expenses and the Operating Expenses.

          "Fiscal Year" shall have the meaning set forth in Section 2.3.
           -----------

          "Funding Notice" shall have the meaning set forth in Section 5.2(a).
           --------------

          "Good Reason" shall mean the termination by Lofberg of his employment
           -----------
as Chief Executive Officer of the Company following the revocation or suspension
of any of the powers granted to Lofberg pursuant to Section 7 of this Agreement
(other than in connection with the termination of Lofberg for Cause).

          "GAAP" means the United States generally accepted accounting
           ----
principles.

          "Investment Committee" shall mean a committee appointed by the Board
           --------------------
of Managers in accordance with Section 8.1 of the Agreement.

          "Investment Period" shall mean the period beginning on the date of
           -----------------
this Agreement and ending on the earlier of (i) the date that all of the Merck
Base Commitment has been invested or committed for investment in Portfolio
Investments and Merck has advised the Executive Agent in writing that it does
not intend to make any further investments, (ii) the second anniversary of the
date of this Agreement or (iii) the termination thereof pursuant to Section 12.2

          "Investor Members" shall have the meaning set forth in the Preamble
           ----------------
and includes any person who is designated as an Investor Member pursuant to
Section 5.5.

          "LLC Act" shall have the meaning set forth in the Recitals.
           -------

          "Lofberg" means Per G. H. Lofberg.
           -------

          "MCV Budget" has the meaning set forth in Section 8.4.
           ----------

          "majority of the Carry Members" means Carry Members  holding a
           -----------------------------
majority of the Carry Interests in respect of a Portfolio  Investment,  assuming
such Portfolio

                                      -9-
<PAGE>

Investment were incurred on the date of determination and all unvested Carry
Interests were then vested.

          "majority of the Non-Defaulting Investor Members" means Non-Defaulting
           -----------------------------------------------
Investor Members providing a majority by monetary value of the Capital
Contributions in respect of a Portfolio Investment.

          "majority of the Other Members" means Other Investor Members having a
           -----------------------------
majority of the Other Investor Interests in the applicable Portfolio Investment.

          "Marketable Securities" means securities that (i) are listed and
           ---------------------
traded on a national securities exchange or listed for quotation on the National
Association of Securities Dealers, Inc. Automated Quotation System National
Market System, or registered or otherwise transferable under Rule 144 under the
Securities Act of 1933, as amended without any waiting period or volume
restrictions applicable to the Members, (ii) are not subject to any "lock-up" or
other contractual restrictions on transfer and (iii) either (A) are not subject
to any limitations on sale or transfer under the Securities Act of 1933, as
amended or relevant state blue sky or similar foreign laws or (B) are covered by
a registration rights agreement pursuant to which (1) the Company has presently
exercisable registration rights covering 100% of the securities held by the
Company in the applicable Portfolio Investment, (2) Lofberg has recommended in
writing to the Board of Managers that such registration rights be exercised, and
(3) the Board of Managers shall have failed to request registration of such
registrable securities within 30 days of Lofberg's recommendation unless the
failure to request such registration was based upon the Board's determination,
after due inquiry of the Portfolio Company, that there was a reasonable
likelihood the Portfolio Company would exercise deferral or blackout rights if
the Company were to exercise such registration rights.

          "Maximum Amount" means the maximum Applicable Carried Interest of a
           --------------
Carry Member which is, (a) in respect of Lofberg, 12%, (b) in respect of Cooper,
2.5% and (c) in respect of any other Carry Member, the maximum Applicable
Carried Interest of such Carry Member as specified in the determination of the
Board of Managers and set forth in the applicable resolution of the Board.

          "Members" shall have the meaning set forth in the Preamble.
           -------

          "Membership Interest" means the interests of the Members in the
           -------------------
Company.

          "Merck Base Commitment" shall have the meaning set forth in Section
           ---------------------
5.1(a).

          "Negative Carry Balance" means, with respect to a Carry Member, such
           ----------------------
Carry Member's Applicable Carried Interest of the amount, if any (without
duplication of Portfolio Investments sold concurrently for a gain), by which (i)
the sum of Merck's share

                                     -10-
<PAGE>

of the Acquisition Costs of all Portfolio Investments in which the Carry Member
had a Carry Interest and that have been previously Sold, or are being Sold
concurrently with the Sale for which the Negative Carry Balance is to be
calculated, since the last Sale of a Portfolio Investment in which such Carry
Member received a distribution of Carry Interest pursuant to Section
10.1(b)(iii) (the "Applicable Portfolio Investments") exceeds (ii) all amounts
                   --------------------------------
distributable to Merck pursuant to Section 10.1(b)(ii) or (iii) with respect to
the Applicable Portfolio Investments before reducing such amounts by the amounts
distributed as Carry Distributions to the Carry Members pursuant to Section
10.1(b)(iii). For purposes of this definition, if a Carry Member's Carry
Interest increases in accordance with the definition of Applicable Carried
Interest, the Negative Carry Balance of such Carry Member shall be recomputed
using the new higher percentage.

          "Net Acquisition Cost" shall mean, with respect to any Portfolio
           --------------------
Investment, the Acquisition Cost of such Portfolio Investment reduced by the
cumulative amount of distributions under Section 10.1(b)(ii) with respect to
such Portfolio Investment.

          "Net Profit" and "Net Loss" mean, respectively, for any period the
           ----------       --------
taxable income and taxable loss of the Company for the period as determined for
federal income tax purposes, provided that for purposes of determining Net
Profit and Net Loss and items of gross income, deductions and expenses and not
for income tax purposes: (i) there shall be taken into account any tax exempt
income of the Company; (ii) any expenditures of the Company which are described
in Section 705(a)(2)(B) of the Code or which are deemed to be described in
Section 705(a)(2)(B) of the Code pursuant to Regulations under Section 704(b) of
the Code shall be treated as deductible expenses; (iii) if any Company asset has
a Book Value which differs from its adjusted tax basis as determined for federal
income tax purposes, income, gain, loss and deduction with respect to such asset
shall be computed based upon the asset's Book Value rather than its adjusted tax
basis in such manner as provided in the Regulations; (iv) items of gross income
or deduction allocated pursuant to Section 9.2(b)-(d) shall be excluded from the
computation of Net Profit and Net Loss; (v) there shall be taken into account
any separately stated items computed under Section 703(a) of the Code; and (vi)
if the Book Value of any Company asset is adjusted pursuant to clauses (ii) -
(iv) of the definition thereof, the amount of such adjustment shall be taken
into account in the taxable year of adjustment as gain or loss from the
disposition of such asset for purposes of computing Net Profit and Net Loss.

          "Net Profit Amount" shall mean in respect of a Carry Member an amount
           -----------------
equal to the excess of (i) the aggregate amount of all distributions made to
Merck pursuant to Sections 10.1(b)(ii) and (iii) and the Carry Members pursuant
to the proviso in Section 10.1(b)(iii) in respect of all Portfolio Investments
in which such Carry Member has or had a Carry Interest, provided, however, that
                                                        --------  -------
in relation to those Portfolio Investments for which a deemed distribution under
Section 10.2(c) has occurred, the price

                                     -11-
<PAGE>

set forth in the Bona Fide Third Party Offer will be deemed to be the amount of
the distribution in respect of that Portfolio Investment for the purposes of
sentence (i) of this definition, over (ii) the aggregate amount of Acquisition
Costs contributed by Merck with respect to such Portfolio Investments.

          "Net Sales Proceeds" means Cash payments (including any Cash received
           ------------------
by way of deferred payment pursuant to, or by amortization of, a note receivable
or otherwise, as and when so received) received upon the Sale of Other Fees or
Other Securities, net of any bona fide direct costs incurred in connection with
such sale, including, without limitation, brokers' fees, legal fees and expenses
and investment banking fees (but excluding any income taxes) reasonably
estimated to be payable as a result of any gain recognized in connection
therewith.

          "Non-Merck Members" shall have the meaning set forth in Section 16.14.
           -----------------

          "Officers" shall have the meaning set forth in Section 6.12.
           --------

          "Operating Expenses" shall mean all costs and expenses relating to the
           ------------------
Company's activities, investments and business (to the extent not borne or
reimbursed by a Portfolio Company), including, without limitation, (i) all costs
and expenses attributable to acquiring, holding and disposing of the Company's
investments (including, without limitation, interest on money borrowed by the
Company or on behalf of the Company, legal fees and expenses, travel expenses,
registration expenses and brokerage, finders', custodial and other fees), (ii)
legal, accounting, auditing, consulting and other costs and expenses directly
relating to the ongoing activities of the Company (including, without
limitation, travel expenses, expenses associated with the preparation of
financial statements, valuation reports, tax returns and forms K-1), (iii)
expenses of the Board of Managers and Investment Committee that the Company is
required to pay, (iv) costs, expenses and liabilities of the Company (including,
without limitation, litigation and indemnification costs and expenses, judgments
and settlements), (v) the payment of the salaries of all of the employees of the
Company (if any), (vi) rental and other office expenses of the Company and (vii)
all out-of-pocket fees and expenses incurred by the Company or its members,
officers and employees (without duplication) whether prior to or after the date
hereof directly relating to investment and disposition opportunities for the
Company not consummated (including, without limitation, legal, travel,
accounting, auditing, engineering, consulting and other fees and expenses of
advisors and experts, financing commitment and investment banking fees, and
printing).

          "Organizational Expenses" shall mean all costs actually incurred in
           -----------------------
organizing the Company, including, without limitation, all fees, costs and
expenses in connection with the planning, negotiation, execution and delivery of
this Agreement and the organization and offering of interests in the Company
(including, without limitation, travel, planning, printing and attorneys' and
accountants' fees and expenses).

                                     -12-
<PAGE>

          "Other Fees" shall have the meaning set forth in Section 8.3(a).
           ----------

          "Other Investor Members Base Commitment" shall have the meaning set
           --------------------------------------
forth in Section 5.1

          "Other Securities" shall have the meaning set forth in Section 8.3(b).
           ----------------

          "Partially Adjusted Capital Account" means, with respect to any Member
           ----------------------------------
and any Fiscal Year (or period), the Capital Account of such Member at the
beginning of such Fiscal Year (or period), adjusted for all contributions and
distributions during such year (or period) and all special allocations pursuant
to Sections 9.2(b), (c), (d) and (e) with respect to such Fiscal Year (or
period), but before giving effect to any allocations of Net Profit or Net Loss
with respect to such Fiscal Year (or period).

          "Person" means any natural person, corporation, membership, trust,
           ------
partnership, limited liability company, association or other entity.

          "Portfolio Company" shall mean any Person that is the issuer of a
           -----------------
Portfolio Investment (other than a Short-Term Investment).

          "Portfolio Investment" shall mean an investment made by the Company,
           --------------------
directly or by or through an entity created for the purpose of making such
investment, in a Portfolio Company, including, without limitation, through the
acquisition of assets, capital stock, partnership interests, equity securities,
equity related securities, joint venture interests, undivided interests, leasing
interests, limited liability company interests or convertible or other
investment interests, or any combination thereof, or securities or interests
convertible into or exchangeable for any of the foregoing, including, without
limitation, any business transaction in which the Company or an entity created
for the purpose of making such investment acquires a Portfolio Company or
interest therein by tender offer, takeover bid, merger, leveraged buyout, open
market purchase, private placement or otherwise and including any of the
foregoing received in exchange for or upon conversion of a Portfolio Investment
in connection with the merger or consolidation or other business combination of
a Portfolio Company with or into another Person.

          "Proceeds" shall have the meaning set forth in Section 10.1(b).
           --------

          "Public Float" means the aggregate Fair Market Value of the common
           ------------
stock of an issuer held by Persons who are not Affiliates of such issuer.

          "Purchase Date" shall have the meaning set forth in Section 8.2(g).
           -------------

          "Qualified IPO" means a bona fide underwritten public offering,
           -------------
pursuant to an effective registration statement under the Securities Act of
1933, of the common stock of a Portfolio Company in which the underwriters
represent in writing that they are

                                     -13-
<PAGE>

prepared to include in such public offering the Company's entire interest in
such Portfolio Company.

          "Qualifying Issuer" means any Portfolio Company whose common stock is
           -----------------
traded on a national securities exchange or on the Nasdaq Stock Market having
(i) a Public Float of at least $500 million or (ii) an average daily trading
volume for the 20 Business Days prior to the date Lofberg presents a Divestment
Proposal to the Board of Managers of at least 25% of the Company's interest in
such Portfolio Company.

          "Quarter" means any consecutive three month period.
           -------

          "Ratable Contribution Percentage" means the proportion of the total
           -------------------------------
obligation of the Other Investor Members to make Capital Contributions
attributable to each Other Investor Member expressed as a percentage which shall
initially be the percentages set out in Schedule B of this Agreement but which
may be amended from time to time in accordance with Section 5.5.

          "Reg.(S)" shall mean a section of the Regulations.
           -------

          "Regulations" shall mean the Treasury regulations from time to time
           -----------
issued pursuant to, and in effect under, the Code.

          "Required Consents" shall have the meaning set forth in Section
           -----------------
8.3(c).

          "Sale" or "Sold" means the sale, liquidation or other disposition of a
           ----      ----
Portfolio Investment for cash or the distribution in kind of a Portfolio
Investment; provided that (i) if a Portfolio Investment is partially sold or
distributed in kind, only the portion so sold or distributed shall be treated as
a "Sold" Portfolio Investment and (ii) if a Portfolio Investment is exchanged
for securities, the Portfolio Investment shall not be treated as a "Sold"
Portfolio Investment.

          "Section 705(a)(2)(B) Expenditure" shall mean an expenditure described
           --------------------------------
in Section 705(a)(2)(B) of the Code which is neither deductible in computing
taxable income nor properly chargeable to capital accounts and any expenditure
considered to be an expenditure described in Section 705(a)(2)(B) of the Code
pursuant to Regulations under Section 704(b) of the Code.

          "Short-Term Investments" shall mean: (i) negotiable instruments or
           ----------------------
securities (whether certificated or uncertificated) which evidence (A)
obligations of or fully guaranteed by the United States of America, (B) time
deposits in, or bankers' acceptances or certificates of deposit issued by, any
depository institution or trust company organized under the laws of the United
States of America or any state thereof, subject to supervision and examination
by United States or state banking or depository institution authorities and
having, to the knowledge of the Carry Members at the time

                                     -14-
<PAGE>

such investment is made or committed, reported capital and surplus in excess of
$250,000,000, and (c) commercial paper having a maturity of less than 180 days
and having, at the time of the investment or commitment to invest therein, a
rating from Moody's Investors Service, Inc. or Standard & Poor's Corporation of
P-1 or A-1, respectively; and (ii) demand deposits in any depository institution
or trust company referred to in (i)(B) above.

          "Start Date" means, in respect of Lofberg and Cooper, the date of this
           ----------
Agreement, and in respect of any Designated Applicable Carry Member, the date
such Designated Applicable Carry Member is designated pursuant to section 5.5 or
such other date after such designation as may be specified by the Board of
Managers in a resolution of the Board.

          "Target Capital Account" means, with respect to any Member and any
           ----------------------
Fiscal Year (or period), an amount (which may be either a positive or a deficit
balance) equal to the hypothetical distribution such Member would receive
pursuant to clause (i) below, minus the hypothetical contribution such Member
would be required to make pursuant to clause (ii), and minus the Member's share
of the Company's partnership minimum gain, and minus the Member's share of the
Company's partner nonrecourse debt minimum gain, all computed immediately prior
to the hypothetical sale described in clause (i) below.

               (i)   The hypothetical distribution to a Member at any time is
                     equal to the amount that would be received by such Member
                     if all of the Company's assets were sold for an amount of
                     cash equal to their Book Values, all Company liabilities
                     were satisfied to the extent required by their terms
                     (limited, with respect to each nonrecourse liability or
                     "partner nonrecourse debt" (as defined in Reg.(S) 1.704-
                     2(b)(4)) to the Book Value of the Company assets securing
                     each such liability), and the net assets of the Company,
                     including any amount returned to the Company pursuant to
                     Section 12.4, were distributed in full to the Members
                     pursuant to Section 12.3(c) hereof upon liquidation of the
                     Company.

               (ii)  The hypothetical contribution by a Member is equal to the
                     amount that such Member would be obligated to contribute
                     pursuant to Section 12.4 upon the hypothetical sale
                     described in clause (i) above in liquidation of the
                     Company.

          "Tax Distribution" shall have the meaning set forth in Section
           ----------------
10.1(e).

                                     -15-
<PAGE>

          "Tax Liability Amount" with respect to a Member for a Fiscal Year,
           --------------------
shall equal the product of (i) the Applicable Tax Rate, times (ii) the amount of
the Company's taxable income allocated to such Member with respect to such
Fiscal Year.

          "Tax Matters Member" shall have the meaning set forth in Section 13.1.
           ------------------

          "Tax Payment Date" with respect to a Fiscal Year shall mean March 31st
           ----------------
of the year following such Fiscal Year.

          "Transfer" shall have the meaning set forth in Section 11.1(a).
           --------

          "Transferring Member" shall have the meaning set forth in Section
           -------------------
8.3(c).

          "Warrants Acquired for Cash" means warrants or options acquired for
           --------------------------
cash consideration if such warrants, after giving effect to the cash purchase
price and no other consideration, were not in-the-money at the date of
acquisition. Warrants acquired in connection with a cash investment in other
securities (a "Unit Investment") shall be deemed Warrants Acquired for Cash if
               ---------------
such Unit Investment is a financing transaction for a cash purchase price made
on arm's length terms.

                                     -16-
<PAGE>

                                  Schedule A
                                  ----------

Part A - Investor Members:

1.   Merck-Medco Managed Care, L.L.C.
     c/o Merck & Co. Inc.
     1 Merck Drive
     Whitehouse Station, NJ 08889
     Fax No.: (908) 735-1244
     Attention: Ken Frazier

2.   Per G. H. Lofberg
     63 East 92/nd/ Street
     New York, NY 10128
     Fax No.: (212) 423-3034

3.   James Cooper
     8 Lambert Lane
     Upper Saddle River, NJ 07458
     Fax No.: (201) 327-2671

Part B - Carry Members:

1.   Per G. H. Lofberg
     63 East 92/nd/ Street
     New York, NY 10128
     Fax No.: (212) 423-3043

2.   James Cooper
     8 Lambert Lane
     Upper Saddle River, NJ 07458
     Fax No.: (201) 327-2671

                                      -1-
<PAGE>

                                  Schedule B
                                  ----------

                             Contribution Schedule

          ----------------------------------------------------
           Lofberg                         82.75%
          ----------------------------------------------------
           Cooper                          17.25%
          ----------------------------------------------------

                                      -1-
<PAGE>

                                  Schedule C
                                  ----------

    Illustration of Distributions and Allocation of Net Profits and Losses

                      [See attached Distribution Example]

                                      -2-

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