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                                                                   EXHIBIT 10.25

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                           SECOND AMENDED AND RESTATED

                           REVOLVING CREDIT AGREEMENT

                                      AMONG

                              FLEET NATIONAL BANK,

                                  SEPRACOR INC.

                                       AND

                             BIOSPHERE MEDICAL, INC.

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

                          Dated as of December 22, 1999

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                               TABLE OF CONTENTS
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<S>           <C>                                                                                          <C>
SECTION 1         DEFINITIONS................................................................................1

     1.1      Definitions....................................................................................1

     1.2      Accounting Terms...............................................................................9

     1.3      Multiple Borrowers.............................................................................9

SECTION 2             DESCRIPTION OF CREDIT.................................................................10

     2.1      The Revolving Loans...........................................................................10

     2.2      Fees..........................................................................................11

     2.3      Reduction of Revolving Commitment Amount/Biosphere Sublimit...................................11

     2.4      The Notes.....................................................................................11

     2.5      Letters of Credit.............................................................................12

     2.6      Capital Requirements..........................................................................12

     2.7      Payments and Prepayments of the Revolving Loans...............................................12

     2.8      Method of Payment.............................................................................13

     2.9      Overdue Payments..............................................................................13

     2.10     Holidays......................................................................................13

     2.11     Interest......................................................................................13

     2.12     Certain LIBOR Provisions......................................................................14

     2.13     Conditions for Basing Interest on the LIBOR Rate..............................................16

     2.14     Indemnification for Funding and Other Losses..................................................16

     2.15     Change in Applicable Laws, Regulations, etc...................................................16

     2.16     Taxes.........................................................................................17

SECTION 3         CONDITIONS OF LOANS.......................................................................17

     3.1      Conditions Precedent to Initial Revolving Loan................................................17

     3.2      Conditions Precedent to all Revolving Loans...................................................19

SECTION 4         REPRESENTATIONS AND WARRANTIES............................................................19

     4.1      Organization and Qualification................................................................20

     4.2      Corporate Authority...........................................................................20

     4.3      Valid Obligations.............................................................................20

     4.4      Consents or Approvals.........................................................................20

     4.5      Title to Properties; Absence of Encumbrances..................................................20

     4.6      Financial Statements..........................................................................20
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<S>           <C>                                                                                           <C>
     4.7      Changes.......................................................................................21

     4.8      Defaults......................................................................................21

     4.9      Taxes.........................................................................................21

     4.10     Material Agreements...........................................................................21

     4.11     Material Licenses.............................................................................21

     4.12     Litigation....................................................................................21

     4.13     Use of Proceeds...............................................................................21

     4.14     Existing Indebtedness.........................................................................22

     4.15     Existing Investments..........................................................................22

     4.16     Subsidiaries..................................................................................22

     4.17     Investment Company Act........................................................................22

     4.18     Compliance with ERISA.........................................................................22

     4.19     FDA Compliance, Etc...........................................................................22

     4.20     Environmental Matters.........................................................................22

SECTION 5         AFFIRMATIVE COVENANTS.....................................................................24

     5.1      Financial Statements and other Reporting Requirements.........................................24

     5.2      Conduct of Business...........................................................................25

     5.3      Maintenance and Insurance.....................................................................26

     5.4      Taxes.........................................................................................26

     5.5      Inspection by the Bank........................................................................26

     5.6      Maintenance of Books and Records..............................................................27

     5.7      Maintenance of Accounts.......................................................................27

     5.8      [Reserved]....................................................................................27

     5.9      Minimum Liquidity Ratio.......................................................................27

     5.10     Minimum Tangible Capital Base.................................................................27

     5.11     Minimum Cash or Equivalents/Fixed Charge Coverage Ratio.......................................27

     5.12     Further Assurances............................................................................27

SECTION 6             NEGATIVE COVENANTS....................................................................27

     6.1      Indebtedness..................................................................................27

     6.2      Contingent Liabilities........................................................................28

     6.3      Sale and Leaseback............................................................................28

     6.4      Encumbrances..................................................................................28
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<S>           <C>                                                                                           <C>
     6.5      Lines of Business.............................................................................29

     6.6      Merger; Consolidation; Sale or Lease of Assets................................................29

     6.7      Additional Stock Issuance.....................................................................30

     6.8      Restricted Payments...........................................................................30

     6.9      Transactions with Affiliates..................................................................30

     6.10     Investments...................................................................................31

     6.11     ERISA.........................................................................................31

     6.12     Observance of Subordination Provisions, etc...................................................31

     6.13     Restrictive Agreements........................................................................31

SECTION 7         DEFAULTS..................................................................................31

     7.1      Events of Default.............................................................................31

     7.2      Remedies......................................................................................33

SECTION 8         MISCELLANEOUS.............................................................................34

     8.1      Notices.......................................................................................34

     8.2      Expenses......................................................................................35

     8.3      Set-Off.......................................................................................35

     8.4      Term of Agreement.............................................................................36

     8.5      No Waivers....................................................................................36

     8.6      Governing Law; Jurisdiction...................................................................36

     8.7      Amendments....................................................................................36

     8.8      Binding Effect of Agreement; Assignments; Participations......................................36

     8.9      Currency Conversion...........................................................................37

     8.10     Counterparts..................................................................................37

     8.11     Partial Invalidity............................................................................38

     8.12     Captions......................................................................................38

     8.13     WAIVER OF JURY TRIAL..........................................................................38

     8.14     Entire Agreement..............................................................................38
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                                TABLE OF CONTENTS

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                             EXHIBITS AND SCHEDULES

<S>                        <C>
     Exhibit A-1           Sepracor Promissory Note
     Exhibit A-2           Biosphere Promissory Note
     Exhibit B             Compliance Certificate
     Exhibit C             Guaranty Agreement

     Schedule 4.10         Material Agreements
     Schedule 4.11         Material Licenses
     Schedule 4.12         Litigation
     Schedule 4.15         Investments
     Schedule 4.16         Subsidiaries
     Schedule 6.1          Indebtedness
     Schedule 6.2          Guaranties
     Schedule 6.4          Encumbrances
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                           SECOND AMENDED AND RESTATED
                           REVOLVING CREDIT AGREEMENT

                          Dated as of December 22, 1999

     THIS SECOND AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT is made as of
December 22, 1999, by and among SEPRACOR INC., a Delaware corporation having its
chief executive office at 111 Locke Drive, Marlborough, Massachusetts 01752 (the
"BORROWER"), BIOSPHERE MEDICAL, INC., a Delaware corporation having its chief
executive office at 111 Locke Drive, Marlborough, Massachusetts 01752
("BIOSPHERE, collectively with the Borrower, the "CREDIT PARTIES") and FLEET
NATIONAL BANK (the "BANK"), having its office at One Federal Street, Boston,
Massachusetts 02110.

     This Agreement amends, restates and supersedes the Amended and Restated
Revolving Credit Agreement dated as of December 31, 1996 as amended to date (the
"PRIOR CREDIT AGREEMENT") by and among the Borrower, Sepracor Securities
Corporation and Fleet National Bank, pursuant to which the Bank agreed to
establish a Revolving Line of Credit and make Revolving Credit Loans (the "PRIOR
LOANS") to the Borrower.

     NOW, THEREFORE, the parties hereby agree as follows:

                                    SECTION 1

                                   DEFINITIONS

     1.1  DEFINITIONS

     All capitalized terms used in this Agreement or in the Notes or in any
certificate, report or other document made or delivered pursuant to this
Agreement (unless otherwise defined therein) shall have the meanings assigned to
them below:

     ACCOUNT AND ACCOUNT RECEIVABLE. Include all rights to payment for goods
sold or leased or for services rendered, all sums of money or other proceeds due
or becoming due thereon, all instruments pertaining thereto, all guaranties and
security therefor, and all goods giving rise thereto and the rights pertaining
to such goods, including the right of stoppage in transit, and all related
insurance.

     AFFILIATE. As applied to any Person, a spouse or relative of such Person,
any member, director or officer of such Person, any corporation, association,
firm or other entity of which such Person is a member, director or officer, and
any other Person directly or indirectly controlling, controlled by or under
direct or indirect common control with such Person.

     AGREEMENT. This Second Amended and Restated Revolving Credit Agreement, as
the same may be supplemented, amended or restated from time to time.

     ALTERNATIVE CURRENCY. The lawful currency of a foreign country which may be
established as an alternate currency by mutual agreement entered into between
the Bank and the

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Credit Parties hereafter as confirmed in writing, so long as any such currency
is freely transferable, convertible into Dollars and traded on the inter-bank
currency deposits market in which the Bank customarily funds foreign currency
loans.

         ALTERNATIVE CURRENCY COMMITMENT. A commitment, to the extent mutually
agreed by the Bank and the Credit Parties, for (i) the exchange, for future
delivery, of an Alternative Currency into Dollars or Dollars into an Alternative
Currency or (ii) the purchase, for future delivery, of an Alternative Currency
with Dollars or Dollars with an Alternative Currency, in accordance with the
Bank's prevailing customs and practices.

     ALTERNATIVE CURRENCY EQUIVALENT. The amount in Alternative Currency of
Dollars at the quoted spot rate at which the Bank's principal office in the
United States offers to exchange such Alternative Currency for Dollars at 11:00
a.m. (Boston time) two (2) Business Days prior to the date on which such
equivalent is determined.

     AUTHORIZED OFFICER. The president, chief financial officer or senior vice
president finance and administration of the Borrower.

     AVAILABLE AGGREGATE REVOLVING COMMITMENT. The excess, if any, of (1) the
Revolving Commitment Amount MINUS (2) the LC Exposure.

     BANK. See Preamble.

     BIOSPHERE. See Preamble.

     BIOSPHERE LOAN SUBLIMIT A sublimit of the Revolving Commitment Amount equal
to $2,000,000, as such amount may be reduced from time to time pursuant to
Section 2.3.

     BIOSPHERE LOANS. Revolving Loans made by the Bank to Biosphere.

     BIOSPHERE NOTE. The Promissory Note dated the date hereof made by Biosphere
payable to the order of the Bank in the original principal amount of $2,000,000.

     BORROWER. See Preamble.

     BUSINESS DAY. Any day other than a Saturday, Sunday or legal holiday on
which banks in Boston, Massachusetts are open for the conduct of a substantial
part of their commercial banking business.

     CANADIAN INDEBTEDNESS. The indebtedness of the Borrower's wholly-owned
Canadian subsidiary, Sepracor Canada Limited, to certain Canadian investors in
the maximum principal amount of 4,891,000 Canadian Dollars which is guaranteed
by the Borrower.

     CAPITAL EXPENDITURE. Any payment made directly or indirectly for the
purpose of acquiring or constructing fixed assets, real property or equipment
which in accordance with GAAP would be added as a debit to the fixed asset
account of the Person making such expenditure, including, without limitation,
amounts paid or payable under any conditional sale or other title retention
agreement or under any lease or other periodic payment arrangement which

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is of a nature that payment obligations of the lessee or obligor thereunder
would be required by GAAP to be capitalized and shown as liabilities on the
balance sheet of such lessee or obligor.

     CAPITAL LEASE. Any lease of property (real, personal or mixed) which, in
accordance with GAAP, should be capitalized on the lessee's balance sheet or for
which the amount of the asset and liability thereunder as if so capitalized
should be disclosed in a note to such balance sheet.

     CASH EQUIVALENT AMOUNT. The sum of the following, without duplication, none
of which may be subject to any Encumbrances except for Encumbrances in favor of
the Bank or any of its Affiliates: (1) cash held by the Borrower in the United
States and at the Bank, PLUS (2) Qualified Investments of the Borrower held in
the United States and Canada, PLUS (3) Net Outstanding Amount of Accounts of the
Borrower.

     CLOSING DATE. December 22, 1999

     CODE. The Internal Revenue Code of 1986 and the rules and regulations
thereunder, collectively, as the same may from time to time be supplemented or
amended and remain in effect.

     CONTROLLED GROUP. All trades or businesses (whether or not incorporated)
under common control that, together with the Credit Parties, are treated as a
single employer under Section 414(b) or 414(c) of the Code or Section 4001 of
ERISA.

     CORPORATE AFFILIATE. As applied to any Person, any corporation,
association, firm or other entity directly or indirectly controlling, controlled
by or under direct or indirect common control with such Person.

     CORPORATE SERVICES AGREEMENT. The Corporate Services Agreement between the
Borrower and each of its Subsidiaries, each as originally executed and delivered
to the Bank.

     CREDIT PARTIES. See Preamble.

     DEFAULT. Any event or condition that, with the giving of notice or lapse of
time, or both, would constitute an Event of Default.

     DOLLARS or $. The lawful currency of the United States of America.

     DOLLAR EQUIVALENT. The amount in Dollars of any Alternative Currency at the
quoted spot rate at which the Bank's principal office in the United States
offers to exchange Dollars for such Alternative Currency at 11:00 a.m. (Boston
time) two (2) Business Days prior to the date on which such equivalent is to be
determined.

     EBITDA. For any period, operating income for the Borrower and its
Subsidiaries (determined on a consolidated basis without duplication in
accordance with GAAP) for such period (calculated before taxes, Interest
Expense, depreciation, amortization, other non-cash income (other than
receivables arising in the ordinary course of business) or charges accrued for
such period) and (except to the extent received or paid in cash by the Borrower)
income or loss attributable to equity in Affiliates for such period, excluding
(i) any extraordinary and unusual

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gains or losses during such period, and (ii) the proceeds of insurance and asset
sales received by the Borrower or any of its Subsidiaries during such period.

     ENCUMBRANCES. See Section 6.4.

     ENVIRONMENTAL LAWS. Any and all applicable foreign, federal, state and
local environmental, health or safety statutes, laws, regulations, rules,
ordinances, policies and rules or common law (whether now existing or hereafter
enacted or promulgated), of all governmental agencies, bureaus or departments
which may now or hereafter have jurisdiction over the Borrower or any of its
Subsidiaries and all applicable judicial and administrative and regulatory
decrees, judgments and orders, including common law rulings and determinations,
relating to injury to, or the protection of, real or personal property or human
health or the environment, including, without limitation, all requirements
pertaining to reporting, licensing, permitting, investigation, remediation and
removal of emissions, discharges, releases or threatened releases of Hazardous
Materials, chemical substances, pollutants or contaminants whether solid, liquid
or gaseous in nature, into the environment or relating to the manufacture,
processing, distribution, use, treatment, storage, disposal, transport or
handling of such Hazardous Materials, chemical substances, pollutants or
contaminants.

     ERISA. The Employee Retirement Income Security Act of 1974 and the rules
and regulations thereunder, collectively, as the same may from time to time be
supplemented or amended and remain in effect.

     EVENT OF DEFAULT. Any event described in Section 8.1.

     FDA. See Section 4.19.

     FIXED CHARGE COVERAGE RATIO. As at any date, the ratio of (a) EBITDA for
the period of four fiscal quarters ending on or most recently ended prior to
such date to (b) the sum, for the Borrower and its Subsidiaries (determined on a
consolidated basis without duplication in accordance with GAAP) of (i) all
regularly scheduled payments of principal of any Indebtedness (including the
principal component of any payments in respect of Capital Leases) for such
period plus, (ii) all Interest Expense for such period, plus (iii) the aggregate
amount of all Non-Financed Capital Expenditures made during such period
(excluding payment of Capital Leases to the extent included in principal
payments or Interest Expense for such period).

     GAAP. Generally accepted accounting principles as defined by the United
States Financial Accounting Standards Board, as from time to time in effect.

     GUARANTIES. As applied to the Credit Parties and their Subsidiaries, all
guarantees, endorsements or other contingent or surety obligations with respect
to obligations of others whether or not reflected on the consolidated balance
sheet of the Credit Parties and their Subsidiaries, including any obligation to
furnish funds, directly or indirectly (whether by virtue of partnership
arrangements, by agreement to keep-well or otherwise), through the purchase of
goods, supplies or services, or by way of stock purchase, capital contribution,
advance or loan, or to enter into a contract for any of the foregoing, for the
purpose of payment of obligations of any other Person or entity.

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     GUARANTY AGREEMENT. The Guaranty Agreement executed and delivered by the
Borrower on the date hereof in favor of the Bank guarantying the Biosphere
Loans.

     HAZARDOUS MATERIAL. Any substance (i) the presence of which requires or may
hereafter require notification, investigation or remediation under any
Environmental Law; (ii) which is or becomes defined as a "hazardous waste",
"hazardous material" or "hazardous substance" or "controlled industrial waste"
or "pollutant" or "contaminant" under any present or future Environmental Law or
amendments thereto including, without limitation, the Comprehensive
Environmental Response, Compensation and Liability Act (42 U.S.C. Section 9601
ET SEQ.) and any applicable local statutes and the regulations promulgated
thereunder; (iii) which is toxic, explosive, corrosive, flammable, infectious,
radioactive, carcinogenic, mutagenic or otherwise hazardous and is or becomes
regulated by any governmental authority, agency, department, commission, board,
agency or instrumentality of any foreign country, the United States, any state
of the United States, or any political subdivision thereof to the extent any of
the foregoing has or had jurisdiction over the Borrower; or (iv) without
limitation, which contains gasoline, diesel fuel or other petroleum products,
asbestos or polychlorinated biphenyls ("PCB's").

     INDEBTEDNESS. As applied to the Credit Parties and their Subsidiaries, (i)
any and all obligations for borrowed money or other extensions of credit whether
or not secured or unsecured, absolute or contingent, including, without
limitation, Capital Leases, unmatured reimbursement obligations with respect to
letters of credit or guarantees issued for the account of or on behalf of the
Credit Parties and their Subsidiaries and all obligations representing the
deferred purchase price of property, other than accounts payable arising in the
ordinary course of business, (ii) all obligations evidenced by bonds, notes,
debentures or other similar instruments, (iii) all obligations secured by any
mortgage, pledge, security interest or other lien on property owned or acquired
by the Credit Parties or any Subsidiary of a Credit Party whether or not the
obligations secured thereby shall have been assumed, (iv) that portion of all
obligations arising under Capital Leases that is required to be capitalized on
the consolidated balance sheet of the Credit Parties and their Subsidiaries, (v)
all Guaranties, and (vi) all obligations that are immediately due and payable
out of the proceeds of or production from property now or hereafter owned or
acquired by the Credit Parties or any Subsidiary of a Credit Party.

     INTEREST EXPENSE. For any period, the sum for the Borrower and its
Subsidiaries (determined on a consolidated basis without duplication in
accordance with GAAP), of the following: (a) all interest paid or payable during
such period by the Borrower and its Subsidiaries in respect of Indebtedness for
borrowed money plus (b) all fees, including Letter of Credit fees and expenses,
incurred hereunder during such period.

     INVESTMENT. As applied to the Borrower and its Subsidiaries, the purchase
or acquisition of any share of capital stock, partnership interest, evidence of
indebtedness or other equity security of any other Person or entity, any loan,
advance or extension of credit to, or contribution to the capital of, any other
Person or entity, any real estate held for sale or investment, any commodities
futures contracts held other than in connection with bona fide hedging
transactions, any other investment in any other Person or entity, and the making
of any commitment or acquisition of any option to make an Investment.

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     LC EXPOSURE. At any time, the sum of (a) the aggregate undrawn amount of
all outstanding Letters of Credit at such time PLUS (b) the aggregate amount of
all payments made by the Bank pursuant to Letters of Credit which have not yet
been reimbursed by or on behalf of the Credit Parties.

     LETTERS OF CREDIT. Letters of credit previously and hereafter issued by the
Bank for the account of a Credit Party in accordance with the provisions of
Section 2.5 hereof, or drafts accepted under any agreement for banker's
acceptances entered into by a Credit Party with the Bank.

     LOAN ACCOUNT. The account on the books of the Bank in which will be
recorded Revolving Loans made by the Bank to the Credit Parties pursuant to this
Agreement, payments made on such Revolving Loans and other appropriate debits
and credits as provided by this Agreement.

     LOAN DOCUMENTS. See Section 7.2.

     MATERIAL LICENSES. See Section 4.11.

     MONEY MARKETS. See Section 8.10.

     NET OUTSTANDING AMOUNT OF ACCOUNTS. As of any date, the net amount of
Accounts Receivable of the Borrower outstanding on such date after (a)
eliminating from the aggregate amount of outstanding Accounts (i) such Accounts
past due under the original terms of sale more than sixty (60) days, (ii) any
Account owed by any account debtor whose principal place of business or chief
executive office is not within the United States or the District of Columbia
("FOREIGN ACCOUNT DEBTORS"), (iii) such Accounts due from Affiliates or
Subsidiaries of the Borrower, (iv) such Accounts for services not yet rendered
or goods not yet delivered, and (v) such Accounts representing obligations in
respect of any joint venture interest owned by the Borrower and in respect of
royalties and license fees payable to the Borrower by any such joint venture or
any joint venture therein, and (b) deducting from the aggregate face amount of
the remaining Accounts Receivable of the Borrower (i) net offsets from accounts
owing from account debtors, other than foreign account debtors, which maintain
both receivable and payable balances with the Borrower, (ii) the aggregate
amount of outstanding claims asserted by account debtors, other than foreign
account debtors, against the Borrower and (iii) all payments, adjustments, and
credits applicable thereto and all amounts due thereon considered by the Bank to
be difficult to collect or uncollectible by reason of return, rejection,
repossession, loss or damage of or to the merchandise giving rise thereto, a
merchandise or other dispute, insolvency of the account debtor or any other
reason, all as determined by the Bank in its sole and reasonable discretion,
which determination shall be final and binding upon the Borrower.

     NON-FINANCED CAPITAL EXPENDITURES. For any period, all Capital Expenditures
made by the Borrower and its Subsidiaries during such period that have not been
funded, directly or indirectly, with the proceeds of purchase money financing
(including, without limitations, Capital Leases) other than the proceeds of
Revolving Loans.

     NOTES. Collectively, the Sepracor Note and the Biosphere Note.

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     NOTICE OF BORROWING. See Section 2.1(b).

     OBLIGATIONS. Any and all obligations of the Credit Parties to the Bank of
every kind and description (i) hereunder and under the Notes and (ii) under
Alternative Currency Commitments and under any and all documents pertaining
thereto whether direct or indirect, absolute or contingent, primary or
secondary, due or to become due, now existing or hereafter arising, regardless
of how they arise or by what agreement or instrument, if any, and including
obligations to perform acts and refrain from taking action as well as
obligations to pay money.

     ORIGINAL CURRENCY. See Section 8.10.

     PBGC. The Pension Benefit Guaranty Corporation or any entity succeeding to
any or all of its functions under ERISA.

     PERMITTED ENCUMBRANCES. See Section 6.4.

     PERSON. A corporation, an association, a partnership, a limited liability
company or partnership, a joint venture, an organization, a business, an
individual, a government or political subdivision thereof or a governmental
agency.

     PLAN. At any time, an employee pension or other benefit plan that is
subject to Title IV of ERISA or subject to the minimum funding standards under
Section 412 of the Code and is either (i) maintained by the Credit Parties or
any member of the Controlled Group for employees of the Credit Parties or any
member of the Controlled Group or (ii) if such Plan is established, maintained
pursuant to a collective bargaining agreement or any other arrangement under
which more than one employer makes contributions and to which the Credit Parties
or any member of the Controlled Group is then making or accruing an obligation
to make contributions or has within the preceding five Plan years made
contributions.

     PRIME RATE. The rate of interest announced from time to time by the Bank at
its office in Boston, Massachusetts as its prime rate.

     PRIOR CREDIT AGREEMENT. See Preamble.

     PRIOR LOANS. See Preamble.

     QUALIFIED INVESTMENTS. As applied to the Borrower, Investments in (i)
notes, bonds or other obligations of the United States of America or any agency
thereof that as to principal and interest constitute direct obligations of or
are guaranteed by the United States of America; (ii) certificates of deposit or
other deposit instruments or accounts of banks or trust companies organized
under the laws of the United States or any state thereof that have capital and
surplus of at least $100,000,000, (iii) commercial paper issued by companies
organized under the laws of the United States or any state thereof and that is
rated not less than prime-two or A-2 or their equivalents by Moody's Investors
Service, Inc. or Standard & Poor's Corporation, respectively, or their
successors, (iv) mutual or closed end funds that invest solely in Investments
described in clauses (i) through (iii) of this definition and (v) any repurchase
agreement secured by any one or more of the foregoing.

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     RESTRICTED PAYMENTS. (a) Any dividend or other distribution, direct or
indirect, on or on account of any shares of any class of stock of any Credit
Party now or hereafter outstanding and (b) any redemption, purchase or other
acquisition, direct or indirect, of any shares of any class of stock of Credit
Party now or hereafter outstanding or of any warrants or rights to purchase any
such stock (including without limitation the repurchase of any such stock or
warrant or any refund of the purchase price thereof in connection with the
exercise by the holder thereof of any right of rescission or similar remedies
with respect thereto) and (c) any payment of principal of, premium, if any, or
interest on, or otherwise in respect of any Subordinated Indebtedness.

     REVOLVING COMMITMENT AMOUNT. Twenty-five Million Dollars ($25,000,000) or
any lesser amount, including zero, resulting from a termination or reduction of
such amount in accordance with Section 2.3 or Section 7.2.

     REVOLVING CREDIT PERIOD. The period beginning on the date hereof and
extending through and including the Revolving Credit Termination Date.

     REVOLVING CREDIT TERMINATION DATE. December 31, 2001 or such earlier date
on which the commitment to make Revolving Loans is terminated or the Revolving
Commitment Amount is reduced to zero in accordance with the terms of this
Agreement.

     REVOLVING LOANS. Loans made pursuant to Section 2.1(a) that utilize the
Revolving Commitment Amount including, without limitation, all Biosphere Loans.

     SECOND CURRENCY. See Section 8.10.

     SEPRACOR NOTE. The Promissory Note dated the date hereof made by the
Borrower payable to the order of the Bank in the original principal amount of
$25,000,000.

     SUBORDINATED INDEBTEDNESS. (a) the existing Indebtedness of the Credit
Parties which is designated as "Subordinated Indebtedness" in SCHEDULE 6.1
attached hereto, and (b) any other Indebtedness of the Credit Parties consented
to in writing by the Bank which matures in its entirety later than the Notes and
by its terms (or by the terms of the instrument under which it is outstanding
and to which appropriate reference is made in the instrument evidencing such
Subordinated Indebtedness) is made subordinate and junior in right of payment to
the Notes and to the Credit Parties' other obligations to the Bank hereunder by
provisions reasonably satisfactory in form and substance to the Bank and its
counsel.

     SUBORDINATED NOTES. The Borrower's (i) $165,000,000 6 1/4% Convertible
Subordinated Debentures due 2005 issued by the Borrower pursuant to an Indenture
dated February 5, 1998 from the Borrower to Chase Manhattan Bank, and (ii)
$300,000,000 7.00% Convertible Subordinated Debentures due 2005 issued pursuant
to an Indenture dated December 15, 1998 by the Borrower to Chase Manhattan Bank.

     SUBSIDIARY. Any corporation, association, limited liability company, joint
stock company, business trust or other similar organization of which 50% or more
of the ordinary voting power for the election of a majority of the members of
the board of directors or other governing body of such entity is held or
controlled by any Credit Party or their Subsidiaries; or any other such
organization the management of which is directly or indirectly controlled by any

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Credit Party or a Subsidiary of any Credit Party through the exercise of voting
power or otherwise; or any joint venture, whether incorporated or not, in which
any Credit Party has, at least, a 50% ownership interest.

     TANGIBLE CAPITAL BASE. At any date as of which the amount thereof shall be
determined, the stockholders' equity of the Borrower and its Subsidiaries
determined on a consolidated basis in accordance with GAAP PLUS the outstanding
principal amount of any Subordinated Indebtedness MINUS the sum of any amounts
attributable to (a) goodwill, (b) intangible items such as unamortized debt
discount and expense, patents, trade and service marks and names, copyrights and
research and development expenses except prepaid expenses, (c) all reserves not
already deducted from assets, (d) any write-up in the book value of assets
resulting from any revaluation thereof subsequent to the date of the financial
statements referred to in Section 4.6 and (e) any and all items included as
assets on the consolidated balance sheet of the Borrower and its Subsidiaries if
and to the extent such items consist of the equity in Subsidiaries or other
joint ventures holdings or similar Investments.

     TECHNOLOGY TRANSFER AGREEMENTS. The Technology Transfer and License
Agreements dated as of January 1, 1994 between the Borrower and each of its
Subsidiaries each as originally executed and delivered to the Bank.

     TOTAL LIABILITIES. Any and all liabilities of the Credit Parties and their
Subsidiaries on a consolidated basis determined in accordance with GAAP.

     U.S. SUBSIDIARY. With respect to any Person, each of such Person's
Subsidiaries organized, and having a principal place of business located in the
United States.

     VERSICOR. Versicor Inc., a Delaware corporation, a Subsidiary of the
Borrower and an Affiliate of Biosphere.

     1.2  ACCOUNTING TERMS. All terms of an accounting character shall have the
meanings assigned thereto by GAAP applied on a basis consistent with the
financial statements referred to in Section 4.6 of this Agreement, modified to
the extent, but only to the extent, that such meanings are specifically modified
herein.

     1.3  MULTIPLE BORROWERS. All Obligations are several (and not joint)
between the Borrower and Biosphere except that the Borrower is guarantying the
Biosphere Loans. All representations and covenants shall apply and be applied to
the Borrower (and not Biosphere). The Credit Parties hereby designate the
Borrower to act on behalf of the Credit Parties for all purposes under this
Agreement, including, without limitation, reduction of the Revolving Commitment
Amount and the Biosphere Sublimit. Notice when given to the Borrower shall be
sufficient notice to the Credit Parties. Any document delivered to the Borrower
shall be considered delivered to each of the Borrower and Biosphere. Any Event
of Default by the Borrower shall be an Event of Default by the Credit Parties.

                                       -9-
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                                    SECTION 2

                              DESCRIPTION OF CREDIT

     2.1  THE REVOLVING LOANS.

          (a)  Upon the terms and subject to the conditions of this Agreement,
and in reliance upon the representations, warranties and covenants of the Credit
Parties made herein, the Bank agrees to make Revolving Loans to the Borrower and
Biosphere Loans to Biosphere, in each case in Dollars, pursuant to Notices of
Borrowing as delivered by the Credit Parties to the Bank from time to time, from
and after the Closing Date and during the Revolving Credit Period; PROVIDED,
that (1) the aggregate principal amount of Revolving Loans outstanding at any
time shall not exceed the Available Aggregate Revolving Commitment at such time,
(2) the sum of the aggregate principal amount of Biosphere Loans outstanding at
such time PLUS Biosphere LC Exposure shall not exceed the Biosphere Sublimit at
such time and (3) at the time a Credit Party requests a Revolving Loan or a
Letter of Credit and after giving effect to the making thereof there has not
occurred and is not continuing any Default or Event of Default. The Credit
Parties agree that it shall be an Event of Default if at any time the debit
balance of the Loan Account shall exceed the Available Aggregate Revolving
Commitment or the aggregate principal amount of Biosphere Loans plus Biosphere
LC Exposure exceeds the Biosphere Sublimit unless, in each case, the Credit
Parties shall, upon demand by the Bank, pay, within two (2) Business Days, cash
to the Bank to be credited to the Loan Account in such amount as shall be
necessary to eliminate any such the excess.

          (b)  Prior to 12:00 noon (Boston time) on the Revolving Loan request
date, (1) with respect to all Revolving Loans (except for Biosphere Loans), an
Authorized Officer and (2) with respect to Biosphere Loans, the Chief Financial
Officer of Biosphere and the Senior Vice President, Finance and Administration
of the Borrower, shall, subject to the notice requirements for LIBOR Loans as
set forth in Section 2.3(a), notify the Bank in writing or by telephone
confirmed by (i) telex, (ii) telecopy or (iii) other facsimile transmission, on
the same day as the telephonic request (the "NOTICE OF BORROWING"), of the
proposed date of borrowing and the principal amount requested. No Notice of
Borrowing shall be revocable by any Credit Party. No Notice of Borrowing for a
Biosphere Loan shall be effective unless the Bank shall have received, on or
prior to the date of such Notice of Borrowing, a certificate of the secretary of
Biosphere with respect to resolutions of the Board of Directors authorizing such
Biosphere Loan or granting authority to certain officers of Biosphere to request
Biosphere Loans pursuant to the terms hereof.

          (c)  The Bank shall enter the Revolving Loans as debits in the Loan
Account. The Bank shall also record in the Loan Account all payments made by the
Credit Parties on account of the Revolving Loans, and may also record therein,
in accordance with customary accounting practices, other debits and credits, and
all interest, fees, charges and expenses chargeable to the Credit Parties under
this Agreement. The debit balance of the Loan Account shall reflect the amount
of the Credit Parties' Obligations to the Bank from time to time by reason of
the Revolving Loans (including Biosphere Loans) and other appropriate charges
hereunder. Periodically, the Bank shall render a statement of account showing as
of its date the debit balance of the Loan Account which, unless within thirty
(30) days of such date notice to the

                                      -10-
<Page>

contrary is received by the Bank from the Credit Parties, absent manifest error,
shall be considered correct and accepted by each of the Credit Parties and
conclusively binding upon both Credit Parties.

          (d)  Subject to the terms and conditions of this Agreement, the Bank
shall make each Revolving Loan on the effective date specified therefor by
crediting the amount of such Revolving Loan to the applicable Credit Party's
demand deposit account with the Bank.

     2.2  FEES. The Borrower shall pay to the Bank during the Revolving Credit
Period a commitment fee computed at the rate of one quarter of one percent
(0.25%) per annum on the average daily amount of the unborrowed portion of the
Revolving Commitment Amount during each quarter or portion thereof; provided,
that LC Exposure shall be deemed borrowed. Commitment fees shall be payable
quarterly in arrears, on the first day of January, April, July and October of
each year beginning on April 1, 2000, and on the last day of the Revolving
Credit Period.

     2.3  REDUCTION OF REVOLVING COMMITMENT AMOUNT/BIOSPHERE SUBLIMIT. The
Borrower may from time to time by written notice delivered to the Bank by the
Borrower at least five Business Days prior to the date of the requested
reduction or termination, reduce by integral multiples of Five Hundred Thousand
Dollars ($500,000) any unborrowed portion of the Revolving Commitment Amount by
integral multiples of One Hundred Thousand Dollars ($100,000) any unborrowed
portion of the Biosphere Sublimit or, subject to the prior payment in full of
any Biosphere Loans, together with all interest and fees accrued thereon,
terminate the Biosphere Sublimit; provided that if the Borrower shall cease to
own directly at least 51% of the outstanding capital stock of Biosphere, then
the Biosphere Sublimit shall be terminated automatically, and all Biosphere
Loans, together with all interest and fees accrued thereon, shall be immediately
due and payable in full. No reduction of the Revolving Commitment Amount or the
Biosphere Sublimit shall be subject to reinstatement.

     2.4  THE NOTES.

          (a)  The Revolving Loans (except the Biosphere Loans) shall be
evidenced by the Sepracor Note substantially in the form of EXHIBIT A-1 hereto
and the Biosphere Loans shall be evidenced by the Biosphere Note, substantially
in the form of EXHIBIT A-2 hereto, each of which is payable to the order of the
Bank and with a final maturity on the Revolving Credit Termination Date. The
Notes shall be dated on or before the date of the first Revolving Loan and shall
have the blanks therein appropriately completed.

          (b)  The Bank shall, and is hereby irrevocably authorized (but not
required) by the Credit Parties to, enter on the schedule forming a part of each
Note or otherwise in its records appropriate notations evidencing the date and
the amount of each Revolving Loan, the interest rate applicable thereto and the
date and amount of each payment of principal made by the applicable Credit Party
with respect thereto; and in the absence of manifest error, such notations shall
constitute conclusive evidence thereof. The Bank is hereby irrevocably
authorized by the Credit Parties to attach to and make a part of each Note a
continuation of any such schedule as and when required. No failure on the part
of the Bank to make any notation as provided in this

                                      -11-
<Page>

subsection (b) shall in any way affect any Revolving Loan or Biosphere Loan or
the rights or obligations of the Bank or any Credit Party with respect thereto.

     2.5  LETTERS OF CREDIT. Upon the request of a Credit Party (and if
Biosphere, subject to the requirements of Section 2.1(b)(2)), the Bank shall
issue such Letters of Credit as such Credit Party may request, PROVIDED that
such Letters of Credit shall not be issued unless and until such Credit Party
has completed and executed such application as the Bank may require from time to
time and such other agreements evidencing Letters of Credit as the Bank shall
request from time to time (consistent with the Bank's usual practice), and
PROVIDED FURTHER that, each Letter of Credit shall be subject to customary fees
relating to issuance, negotiation, settlement, amendment and other similar fees
and charges as agreed by the Bank and such Credit Party. All Letters of Credit
shall expire no later than five (5) Business Days prior to the Revolving Credit
Termination Date. Letters of Credit issued hereunder shall constitute
utilization of the Revolving Commitment Amount and the Biosphere Sublimit, as
applicable.

     2.6  CAPITAL REQUIREMENTS. If after the date hereof, the Bank shall have
determined that the adoption or implementation of any applicable law, rule or
regulation regarding capital requirements for banks or bank holding companies,
or any change therein (including, without limitation, any change according to a
prescribed schedule of increasing requirements, whether or not known on the date
hereof), or any change in the interpretation or administration thereof by any
governmental authority, central bank or comparable agency charged with the
interpretation or administration thereof, or compliance by the Bank with any
request or directive of such entity regarding capital adequacy (whether or not
having the force of law) has the effect of reducing the return on the Bank's
capital to a level below that which the Bank could have achieved (taking into
consideration the Bank's policies with respect to capital adequacy immediately
before such adoption, implementation, change or compliance and assuming that the
Bank's capital was fully utilized prior to such adoption, implementation, change
or compliance) but for such adoption, implementation, change or compliance as a
consequence of its Commitment to make Revolving Loans hereunder by any amount
deemed by the Bank to be material, the Credit Parties shall pay to the Bank as
an additional fee from time to time on demand such amount as the Bank shall have
determined to be necessary to compensate it for such reduction. The
determination by the Bank of such amount, if done on the basis of any reasonable
averaging and attribution methods, shall in the absence of manifest error be
conclusive, and at the Borrower's request, the Bank shall demonstrate the basis
of such determination.

     2.7  PAYMENTS AND PREPAYMENTS OF THE REVOLVING LOANS. On at least two (2)
Banking Days prior written notice to the Bank with respect to Revolving Loans
subject to an exercised LIBOR Option and on at least one (1) Banking Day prior
written notice to the Bank with respect to all other Revolving Loans, the Credit
Parties may, at their option, prepay the Notes in whole at any time or in part
from time to time without penalty or premium; PROVIDED, that any prepayment of
any LIBOR Portion shall be made together with the applicable LIBOR Premium. Any
interest accrued on the amounts so prepaid to the date of such payment must be
paid at the time of any such payment. No prepayment of the Revolving Loans shall
affect the Revolving Commitment Amount or the Biosphere Sublimit or impair any
Credit Party's right to borrow as set forth in Section 2.1. On the Revolving
Credit Termination Date, the Borrower shall repay all outstanding Revolving
Loans and the Sepracor Note, and Biosphere shall repay all outstanding

                                      -12-
<Page>

Biosphere Loans and the Biosphere Note together with all unpaid interest thereon
and all fees and other amounts due hereunder with respect to the Revolving
Loans.

     2.8  METHOD OF PAYMENT. All payments and prepayments of principal and all
payments of interest shall be made by the Credit Parties to the Bank at One
Federal Street, Boston, Massachusetts 02110 in immediately available funds, on
or before 11:00 a.m. on the due date thereof, free and clear of, and without any
deduction or withholding for, any taxes or other payments. The Bank may, and
each Credit Party hereby authorizes the Bank to, debit the amount of any payment
not made by such time to the demand deposit account of such Credit Party with
the Bank.

     2.9  OVERDUE PAYMENTS.

          (a)  Upon the occurrence and during the continuance of an Event of
Default, interest on the outstanding principal amount of the Notes and (to the
extent permitted by law) on accrued but unpaid interest shall thereafter be
payable on demand at a rate per annum equal to two percent (2%) above the
interest rate otherwise in effect with respect to such Revolving Loans. Upon the
cure of an Event of Default and the payment of interest at the default rate
through the date of such cure, the interest rate shall revert to that provided
for in Section 2.10.

          (b)  If a payment of principal or interest hereunder is not made in
full within 10 days of date when due, the applicable Credit Party will pay to
the Bank a late fee equal to three percent (3%) of the amount of such payment.
Nothing in the preceding sentence shall affect the Bank's right to exercise any
of its rights or remedies, including those provided in Section 7.2, if an Event
of Default has occurred.

     2.10 HOLIDAYS. If any payment required by this Agreement becomes due on a
day that is not a Business Day such payment may be made on the next succeeding
Business Day, and such extension shall be included in computing interest in
connection with such payment.

     2.11 INTEREST. Each Note shall bear interest on the unpaid principal amount
thereof until paid in full at the rate or rates per annum determined (on the
basis of the actual number of days elapsed over a 360-day year) and payable as
follows:

          (a)  The rate of interest for any portion of the outstanding principal
amount of the Revolving Loans which is not then subject to an exercised LIBOR
Option under Section 2.12 of this Agreement shall be computed at the Prime Rate.

          (b)  The rate for any LIBOR Portion of the Revolving Loans shall be
computed at a rate equal to three-quarters percent (0.75%) above the applicable
LIBOR Rate.

          (c) Interest on each Note shall be payable monthly in arrears on the
first Business Day of each month, commencing on January 1, 2000 and, in
addition, interest on any LIBOR Portion of the Revolving Loans in respect of any
LIBOR Period shall also be payable on the last day of such LIBOR Period and on
the last day of the third month for each LIBOR Portion with a 180-day LIBOR
Period and at maturity (whether by acceleration or otherwise). The rate of
interest payable on any portion of the outstanding principal balance of any
Revolving

                                      -13-
<Page>

Loan which is not then subject to a LIBOR Option shall take effect
simultaneously with the corresponding change in the Prime Rate.

     2.12 CERTAIN LIBOR PROVISIONS.

          (a)  LIBOR OPTION. Subject to the provisions of this Section 2, each
Credit Party shall have the right to have the interest on all or any portion of
the principal amount of any Revolving Loan based on a LIBOR Rate.

          (b)  CERTAIN DEFINITIONS. As used herein, the following terms have the
following respective meanings:

     BANKING DAY. (i) When used with respect to the LIBOR Option, a day on which
transactions may be effected in deposits of U.S. dollars in the London interbank
foreign currency deposits market and on which banks may conduct business in
London, England and Boston, Massachusetts and (ii) when used with respect to the
other provisions of this Agreement, any day excluding Saturday and Sunday and
excluding any other day which shall be in Boston, Massachusetts, a legal holiday
or a day on which banking institutions are authorized by law to close.

     BOARD. The Board of Governors of the Federal Reserve System of the United
States.

     LEGAL REQUIREMENT. Any requirement imposed upon the Bank by any law of the
United States of America or the United Kingdom or by any regulation, order,
interpretation, ruling or official directive (whether or not having the force of
law) of the Board, the Bank of England or any other board, central bank or
governmental or administrative agency, institution or authority of the United
States of America, the United Kingdom or any political subdivision of either
thereof.

     LIBOR OPTION. The option granted pursuant to this Section 2 to have the
interest on all or a portion of the principal amount of the Revolving Loans
based on a LIBOR Rate.

     LIBOR PERIOD. Any period, as provided below in this Section 2.12, of 30,
60, 90 or 180 days, commencing on any Banking Day; PROVIDED, however, that no
LIBOR Period with respect to any LIBOR Portion of any Revolving Loan shall
extend beyond the maturity date of the Notes. If any LIBOR Period so selected
would otherwise end on a date which is not a Banking Day, such LIBOR Period
shall instead end on the next preceding or succeeding Banking Day as determined
by the Bank in accordance with the then current banking practice in London. Each
determination by the Bank of any LIBOR Period shall, in the absence of manifest
error, be conclusive, and at any Credit Party's request the Bank shall
demonstrate the basis for such determination.

     LIBOR PORTION. That portion of the Revolving Loans specified in a LIBOR
Request, (i) which is not less than Five Hundred Thousand Dollars ($500,000),
(ii) which is an integral multiple of Ten Thousand Dollars ($10,000), (iii)
which does not exceed the outstanding balance of the Revolving Loan not already
subject to an exercised LIBOR Option, (iv) which, as of the date of the LIBOR
Request specifying such LIBOR Portion, has met the conditions for basing

                                      -14-
<Page>

interest on the LIBOR Rate in Section 2.13 of this Agreement and (v) the LIBOR
Period of which has commenced and not terminated.

     LIBOR PREMIUM. With respect to the prepayment of any LIBOR Portion of any
Revolving Loan, whether voluntary or as a result of acceleration, an amount
equal to the product of (i) the excess, if any, of the rate of interest on the
principal amount so prepaid over the rate of interest on debt securities issued
by the Treasury of the United States of America on a date approximating the date
of payment of such principal amount and having a maturity date approximating the
last Banking Day of the applicable LIBOR Period, multiplied by (ii) the
principal amount so prepaid, multiplied by (iii) a fraction, the numerator of
which is the number of days remaining in the related LIBOR Period and the
denominator of which is 360.

     LIBOR RATE. With respect to any LIBOR Portion for the related LIBOR Period,
an interest rate per annum (rounded upwards, if necessary, to the next higher
1/8 of 1%) equal to the product of (a) the Base LIBOR Rate (as hereinafter
defined) and (b) Statutory Reserves. For purposes of this definition, the term
"BASE LIBOR RATE" shall mean the rate (rounded to the nearest 1/8 of 1% or, if
there is no nearest 1/8 of 1%, the next higher 1/8 of 1%) at which deposits of
U.S. dollars approximately equal in principal amount to the LIBOR Portion and
for a maturity equal to the applicable LIBOR Period are offered to the Bank in
the London interbank foreign currency deposits market at approximately 11:00
a.m., London time, two (2) Banking Days prior to the commencement of such LIBOR
Period, for delivery on the first day of such LIBOR Period. Each determination
by the Bank of any LIBOR Rate shall, in the absence of manifest error, be
conclusive, and at any Credit Party's request, the Bank shall demonstrate the
basis for such determination.

     LIBOR REQUEST. Notice in writing (or by telephonic communications confirmed
by telex, telecopy or other facsimile transmission on the same day as the
telephone request) from Biosphere with respect to Biosphere Loans or from the
Borrower with respect to all other Revolving Loans, to the Bank requesting that
interest on a LIBOR Portion be based on the LIBOR Rate, specifying: (i) the
first day of the LIBOR Period, (ii) the length of the LIBOR Period consistent
with the definition of that term and (iii) a dollar amount of the LIBOR Portion
consistent with the definition of that term.

     STATUTORY RESERVES. A fraction, the numerator of which is the number one
and the denominator of which is the number one minus the aggregate of the
maximum reserve percentages (including, without limitation, any marginal,
special, emergency or supplemental reserves), expressed as a decimal,
established by the Board and any other banking authority to which the Bank is
subject for Eurocurrency Liabilities (as defined in Regulation D of the Board).
Such reserve percentages shall include, without limitation, those imposed under
such Regulation D. LIBOR Portions of the Revolving Loans shall be deemed to
constitute Eurocurrency Liabilities and as such shall be deemed to be subject to
such reserve requirements without benefit of or credit for proration, exceptions
or offsets which may be available from time to time to the Bank under such
Regulation D. Statutory Reserves shall be adjusted automatically on and as of
the effective date of any change in any reserve percentage.

     TAX. In relation to any LIBOR Portion and the applicable LIBOR Rate, any
tax, levy, impost, duty, deduction, withholding or other charges of whatever
nature required by any Legal

                                      -15-
<Page>

Requirement (i) to be paid by the Bank and/or (ii) to be withheld or deducted
from any payment otherwise required hereby to be made by any Credit Party to the
Bank, PROVIDED that the term "Tax" shall not include any taxes imposed upon the
net income of the Bank by the United States of America or any political
subdivision thereof (including state and local governmental authorities).

     2.13 CONDITIONS FOR BASING INTEREST ON THE LIBOR RATE. Upon the condition
that:

          (a)  The Bank shall have received a LIBOR Request from the Borrower or
Biosphere, as applicable, prior to noon at least two (2) Banking Days prior to
the first day of the LIBOR Period requested;

          (b)  There shall have occurred no change in applicable law which would
make it unlawful for the Bank to obtain deposits of U.S. dollars in the London
interbank foreign currency deposits market;

          (c)  As of the date of the LIBOR Request and the first day of the
LIBOR Period, there shall exist no Event of Default, nor any Default, which has
not been waived by the Bank;

          (d)  The Bank shall not have determined in good faith that it is
unable to determine the LIBOR Rate in respect of the requested LIBOR Period or
that it is unable to obtain deposits of U.S. dollars in the London interbank
foreign currency deposits market in the applicable amounts and for the requested
LIBOR Period; and

          (e)  As of the first date of the LIBOR Period specified in such LIBOR
Request, and after having given effect thereto, there shall be no more than an
aggregate of four (4) LIBOR Portions outstanding;

then interest on the LIBOR Portion requested during the LIBOR Period requested
will be at the applicable LIBOR Rate.

     2.14 INDEMNIFICATION FOR FUNDING AND OTHER LOSSES. Each LIBOR Request shall
be irrevocable and binding on the applicable Credit Party. Without limiting the
generality of Section 2.15, the Credit Parties shall indemnify the Bank against
any loss or expense incurred by the Bank as a result of any failure on the part
of any Credit Party to fulfill, on or before the date specified in any LIBOR
Request, the applicable conditions set forth in this Agreement, including,
without limitation, any loss (including loss of anticipated profits) or expense
incurred by reason of the liquidation or redeployment of deposits or other funds
acquired by the Bank to fund or maintain the requested LIBOR Portion when
interest on such LIBOR Portion, as a result of such failure on the part of the
Credit Parties, is not based on the applicable LIBOR for the requested LIBOR
Period. The Bank shall determine the amount of such loss or expense incurred by
it, and absent manifest error such determination shall be conclusive, and at any
Credit Party's request the Bank shall demonstrate the basis for such
determination.

     2.15 CHANGE IN APPLICABLE LAWS, REGULATIONS, ETC. If any Legal Requirement
shall make it unlawful for the Bank to fund through the purchase of U.S. dollar
deposits any LIBOR Portion, or otherwise to give effect to its obligations as
contemplated hereby, or shall impose on

                                      -16-
<Page>

the Bank any costs based on or measured by the excess above a specified level of
the amount of a category of deposits or other liabilities of the Bank, which
includes deposits by reference to which the LIBOR Rate is determined as provided
herein or a category of extensions of credit or other assets of the Bank which
includes any LIBOR Portion, or shall impose on the Bank any restrictions on the
amount of such a category of liabilities or assets which the Bank may hold, (a)
the Bank may by notice thereof to the Credit Parties terminate the LIBOR Option,
(b) any LIBOR Portion subject thereto shall immediately bear interest thereafter
at the rate provided for in Section 2.10.(a), and (c) the Credit Parties shall
indemnify the Bank against any loss, penalty or expense incurred by the Bank by
reason of the liquidation or redeployment of deposits or other funds acquired by
the Bank to fund or maintain such LIBOR Portion, as provided in Section 2.14.

     2.16 TAXES. It is the understanding of the Credit Parties and the Bank that
the Bank shall receive payments of amounts of principal of and interest on the
Revolving Loans with respect to the LIBOR Portions from time to time subject to
a LIBOR Option free and clear of, and without deduction for, any Taxes. If (a)
the Bank shall be subject to any such Tax in respect of any such LIBOR Portion
or part thereof or (b) the Credit Parties shall be required to withhold or
deduct any such Tax from any such amount, and (c) such Tax shall not have
existed as of the date of the applicable LIBOR Request, the LIBOR applicable to
such LIBOR Portion shall be adjusted by the Bank to reflect all additional costs
incurred by the Bank in connection with the payment by the Bank or the
withholding by the Credit Parties of such Tax and the Credit Parties shall
provide the Bank with a statement detailing the amount of any such Tax actually
paid by the Credit Parties. Determination by the Bank of the amount of such
costs shall, in the absence of manifest error, be conclusive, and at any Credit
Party's request, the Bank shall demonstrate the basis of such determination. If
after any such adjustment, any part of any Tax paid by any Bank is subsequently
recovered by the Bank, the Bank shall reimburse the Credit Parties to the extent
of the amount so recovered. A certificate of an officer of the Bank setting
forth the amount of such recovery and the basis therefor shall, in the absence
of manifest error, be conclusive.

                                    SECTION 3

                               CONDITIONS OF LOANS

     3.1  CONDITIONS PRECEDENT TO INITIAL REVOLVING LOAN. The obligation of the
Bank to make its initial Revolving Loans, to issue Letters of Credit is subject
to the condition precedent that the Bank shall have received, in form and
substance satisfactory to the Bank and its counsel, the following:

          (a)  this Agreement, duly executed by the Credit Parties;

          (b)  the Sepracor Note, duly executed by the Borrower;

          (c)  the Biosphere Note, duly executed by Biosphere;

          (d)  the Guaranty Agreement duly executed by the Borrower;

                                      -17-
<Page>

          (e)  a certificate of the Secretary or an Assistant Secretary of the
Borrower with respect to resolutions of its Board of Directors authorizing the
execution and delivery of this Agreement, the Notes, and identifying the
officer(s) authorized to execute, deliver and take all other actions required
under this Agreement, and providing specimen signatures of such officers;

          (f)  a certificate signed by an Authorized Officer, certifying that
the conditions of Section 3.2.(b) have been fulfilled;

          (g)  the certificate of incorporation of the Borrower and all
amendments and supplements thereto, filed in the office of the Secretary of
State of the State of Delaware, each certified by said Secretary of State as
being a true and correct copy thereof;

          (h)  the bylaws of the Borrower and all amendments and supplements
thereto, certified by the Secretary or an Assistant Secretary as being a true
and correct copy thereof;

          (i)  a certificate of the Secretary of State of the State of Delaware,
as to legal existence and good corporate standing of the Borrower in such state
and listing all documents on file in the office of said Secretary of State;

          (j)  a certificate of the Secretary or an Assistant Secretary of
Biosphere with respect to resolutions of the Board of Directors authorizing the
execution and delivery of this Agreement, the Biosphere Note, and identifying
the officer(s) authorized to execute, deliver and take all other actions
required under this Agreement, and providing specimen signatures of such
officers;

          (k)  a certificate signed by a principal officer of Biosphere,
certifying that the conditions of Section 3.2.(b) have been fulfilled;

          (l)  the certificate of incorporation of Biosphere and all amendments
and supplements thereto, filed in the office of the Secretary of State of the
State of Delaware, each certified by said Secretary of State as being a true and
correct copy thereof;

          (m)  the bylaws of Biosphere and all amendments and supplements
thereto, certified by the Secretary or an Assistant Secretary as being a true
and correct copy thereof;

          (n)  a certificate of the Secretary of State of the State of Delaware,
as to legal existence and good corporate standing of Biosphere in such state and
listing all documents on file in the office of said Secretary of State;

          (o)  Lien searches against each Credit Party in all appropriate state
filing offices and in the United States Patent and Trademark Office and the
United States Copyright Office;

          (p)  if necessary, UCC-3 Termination Statements and other appropriate
lien discharge documentation terminating all liens except those consisting of
Permitted Encumbrances.

                                      -18-
<Page>

          (q)  a certificate signed by an Authorized Officer, certifying that
there has been no material adverse change in the condition (financial or
otherwise), operations, properties, assets, liabilities or earnings of the
Credit Parties since the date of its most recent financial statement;

          (r)  an opinion addressed to it from Hale and Dorr LLP, counsel to the
Credit Parties, in form and substance satisfactory to the Bank and its counsel;
and

          (s)  such other documents, and completion of such other matters, as
counsel for the Bank may deem reasonably necessary or appropriate.

     Notwithstanding the foregoing, the obligations of the Bank to make
Revolving Loans or Biosphere Loans or issue Letters of Credit hereunder shall
not become effective unless each of the foregoing conditions is satisfied (or
waived) at or prior to 12:00 p.m. on January 7, 2000 (and in the event such
conditions are not so satisfied or waived, the Revolving Commitment Amount (and
the Biosphere Sublimit) shall terminate).

     3.2  CONDITIONS PRECEDENT TO ALL REVOLVING LOANS. The obligation of the
Bank to make each Revolving Loan, including the initial Revolving Loan, or
continue or convert the Revolving Loans to loans of another type, is further
subject to the following conditions:

          (a)  timely receipt by the Bank of a Notice of Borrowing as provided
in Section 2.1;

          (b)  the representations and warranties contained in Section 4 shall
be true and accurate in all material respects on and as of the date of such
Notice of Borrowing and on the effective date of the making, continuation or
conversion of each Revolving Loan as though made at and as of each such date
(except to the extent that such representations and warranties expressly relate
to an earlier date), and no Default or Event of Default shall have occurred and
be continuing, or would result from such Revolving Loan;

          (c)  the resolutions referred to in Sections 3.1.(d) and 3.1(i) shall
remain in full force and effect; and

          (d)  no change shall have occurred in any law or regulation or
interpretation thereof that, in the opinion of counsel for the Bank, would make
it illegal or against the policy of any governmental agency or authority for the
Bank to make Revolving Loans hereunder.

     The making of each Revolving Loan shall be deemed to be a representation
and warranty by the Credit Parties on the date of the making, continuation or
conversion of such Revolving Loan as to the accuracy of the facts referred to in
subsection (b) of this Section 3.2.

                                    SECTION 4

                         REPRESENTATIONS AND WARRANTIES

     In order to induce the Bank to enter into this Agreement and to make the
Revolving Loans hereunder, issue Letters of Credit, the Borrower represents and
warrants to the Bank that:

                                      -19-
<Page>

     4.1  ORGANIZATION AND QUALIFICATION. Each of the Credit Parties and their
Subsidiaries (a) is a corporation duly organized, validly existing and in good
standing under the laws of its jurisdiction of incorporation, (b) has all
requisite corporate power to own its property and conduct its business as now
conducted and as presently contemplated and (c) is duly qualified and in good
standing as a foreign corporation and is duly authorized to do business in each
jurisdiction where the nature of its properties or business requires such
qualification, except where the failure to be so qualified would not have a
material adverse effect on the financial condition, operations, properties or
business.

     4.2  CORPORATE AUTHORITY. The execution, delivery and performance of this
Agreement, the Notes, and the transactions contemplated hereby are within the
corporate power and authority of the Credit Parties, as applicable, and the
execution, delivery and performance of the Notes are within the corporate power
and authority of the Credit Parties, as applicable, and have been authorized by
all necessary corporate proceedings, and do not and will not (a) require any
consent or approval of the stockholders of the Credit Parties, (b) contravene
any provision of the charter documents or by-laws of the Credit Parties or any
law, rule or regulation applicable to any Credit Party, (c) contravene any
provision of, or constitute an event of default or event that, but for the
requirement that time elapse or notice be given, or both, would constitute an
event of default under, any other agreement, instrument, order or undertaking
binding on any Credit Party, or (d) result in or require the imposition of any
Encumbrance on any of the properties, assets or rights of any Credit Party.

     4.3  VALID OBLIGATIONS. This Agreement, the Notes, and all of their
respective terms and provisions are the legal, valid and binding obligations of
the Credit Parties, as applicable, each enforceable in accordance with their
respective terms except as limited by bankruptcy, insolvency, reorganization,
moratorium or other laws affecting the enforcement of creditors' rights
generally, and except as the remedy of specific performance or of injunctive
relief is subject to the discretion of the court before which any proceeding
therefor may be brought.

     4.4  CONSENTS OR APPROVALS. The execution, delivery and performance of this
Agreement, the Notes, and the transactions contemplated herein do not require
any approval or consent of, or filing or registration with, any governmental or
other agency or authority, or any other party.

     4.5  TITLE TO PROPERTIES; ABSENCE OF ENCUMBRANCES. Each of the Credit
Parties and their Subsidiaries has good and marketable title to all of the
properties, assets and rights of every name and nature now purported to be owned
by it, including, without limitation, such properties, assets and rights as are
reflected in the financial statements referred to in Section 4.6 (except such
properties, assets or rights as have been disposed of in the ordinary course of
business since the date thereof), free from all Encumbrances except Permitted
Encumbrances hereto, and, except as so disclosed, free from all defects of title
that might materially adversely affect such properties, assets or rights, taken
as a whole.

     4.6  FINANCIAL STATEMENTS. The Borrower has furnished the Bank the
consolidated and consolidating balance sheets of the Borrower and its
Subsidiaries as of December 31, 1998, and the related consolidated and
consolidating statements of income, changes in stockholders' equity and cash
flow for the fiscal year then ended, and related footnotes, audited and
certified by

                                      -20-
<Page>

PriceWaterhouseCoopers. The Borrower has also furnished the foregoing unaudited
financial statements to the Bank for the nine-month period ending September 30,
1999 and financial projections for the 1999 fiscal year prepared by the
Borrower. All such financial statements, except for such projections, were
prepared in accordance with GAAP applied on a consistent basis throughout the
periods specified and present fairly the financial position of the Borrower and
its Subsidiaries as of such date and the results of the operations of the
Borrower and its Subsidiaries for such period. The projections were prepared in
good faith and based on assumptions which were reasonable when made. There are
no liabilities, contingent or otherwise, not disclosed in such financial
statements that involve a material amount.

     4.7  CHANGES. Since the date of the financial statements for the
three-month period ending September 30, 1999 referred to in Section 4.6, there
have been no changes in the assets, liabilities, financial condition, business
or prospects of the Borrower or any of its Subsidiaries other than changes in
the ordinary course of business, the effect of which has not, in the aggregate,
been materially adverse.

     4.8  DEFAULTS. As of the date hereof, no Default or Event of Default
exists.

     4.9  TAXES. The Borrower and each Subsidiary has filed all federal, state
and other tax returns required to be filed, and all taxes, assessments and other
governmental charges due from the Borrower and each Subsidiary have been fully
paid. The Borrower and each Subsidiary have established on their books reserves
adequate for the payment of all federal, state and other tax liabilities.

     4.10 MATERIAL AGREEMENTS. As of the Closing Date, SCHEDULE 4.10 hereto
accurately and completely lists all material leases, management, stockholder,
partnership, joint venture, stock redemption or retirement, employment
(including severance), non-competition and related agreements, if any, which are
presently in effect in connection with the conduct of business of the Borrower
and its Subsidiaries.

     4.11 MATERIAL LICENSES. As of the Closing Date, SCHEDULE 4.11 hereto
accurately and completely lists all material licenses and related agreements, if
any, which are presently in effect in connection with the conduct of business of
the Borrower and its Subsidiaries (the "MATERIAL LICENSES"), and all such
Material Licenses are in full force and effect.

     4.12 LITIGATION. Except as set forth in SCHEDULE 4.12 hereto, there is no
litigation, arbitration, proceeding or investigation pending, or, to the
knowledge of any Credit Party's or any Credit Party's Subsidiary's officers,
threatened, against any Credit Party or any such Subsidiary that, if adversely
determined, could result in a material judgment not fully covered by insurance,
could result in a forfeiture of all or any substantial part of the property of
the Credit Parties or their Subsidiaries, or could otherwise have a material
adverse effect on the assets, business or prospects of the Credit Parties or any
Subsidiary.

     4.13 USE OF PROCEEDS.

          (a)  The Credit Parties will not, directly or indirectly, use any part
of the proceeds of any of the Revolving Loans (i) for the purpose of making any
Restricted Payment which is prohibited by Section 6.8 hereof, (ii) for the
purpose of purchasing or carrying any

                                      -21-
<Page>

margin stock within the meaning of Regulations U and X (12 C.F.R. Part 221 and
224) of the Board, or (iii) for any other purpose which would violate any
provision of any other applicable statute, regulation, order or restriction.

          (b)  The proceeds of the Revolving Loans shall be used exclusively for
the working capital purposes of the Credit Parties and for acquisitions
permitted hereunder.

     4.14 EXISTING INDEBTEDNESS. SCHEDULE 6.1 hereto accurately and completely
lists all existing Indebtedness of the Credit Parties and their Subsidiaries as
of the date hereof.

     4.15 EXISTING INVESTMENTS. SCHEDULE 4.15 hereto accurately and completely
lists the record owner, location and any relevant account numbers of all
depository and operating accounts and marketable securities owned by the Credit
Parties and their Subsidiaries as of the date hereof.

     4.16 SUBSIDIARIES. As of the date hereof, all the Subsidiaries of the
Credit Parties are listed in SCHEDULE 4.16 hereto. The Borrower or a Subsidiary
of the Borrower is the owner, free and clear of all liens and encumbrances,
except as expressly provided in such schedule, of all of the issued and
outstanding stock of each Subsidiary. All shares of such stock have been validly
issued and are fully paid and nonassessable, and no rights to subscribe to any
additional shares have been granted, and no options, warrants or similar rights
are outstanding.

     4.17 INVESTMENT COMPANY ACT. Neither Credit Party nor any of its
Subsidiaries is subject to regulation under the InvestmentCompany Act of 1940,
as amended.

     4.18 COMPLIANCE WITH ERISA. The Credit Parties and each member of the
Controlled Group have fulfilled their obligations under the minimum funding
standards of ERISA and the Code with respect to each Plan and are in compliance
in all material respects with the applicable provisions of ERISA and the Code,
and have not incurred any liability to the PBGC or a Plan under Title IV of
ERISA; and no "prohibited transaction" or "reportable event" (as such terms are
defined in ERISA) has occurred with respect to any Plan.

     4.19 FDA COMPLIANCE, ETC. Without limiting the scope of Section 4.2, the
Credit Parties and their Subsidiaries are in compliance in all material respects
with all applicable foreign and federal and state laws and regulations,
including all material rules, regulations and administrative orders of the
United States Food and Drug Administration (the "FDA") and of foreign
authorities with jurisdiction over the Credit Parties and their Subsidiaries.
The Credit Parties and their Subsidiaries are in compliance in all material
respects with all of the applicable provisions of the Food, Drug and Cosmetic
Act, as amended.

     4.20 ENVIRONMENTAL MATTERS.

          (a)  The Credit Parties and their Subsidiaries have obtained all
permits, licenses and other authorizations which are required under all
Environmental Laws, except to the extent failure to have any such permit,
license or authorization would not have a material adverse effect on the
business, financial condition or operations of the Credit Parties and their
Subsidiaries. The Credit Parties and their Subsidiaries are in compliance with
the terms and conditions of all such permits, licenses and authorizations, and
are also in compliance with all

                                      -22-
<Page>

other limitations, restrictions, conditions,standards, prohibitions,
requirements, obligations, schedules and timetables contained in any applicable
Environmental Law or in any regulation, code, plan, order, decree, judgment,
injunction, notice or demand letter issued, entered, promulgated or approved
thereunder, except to the extent failure to comply would not have a material
adverse effect on the business, financial condition or operations of the Credit
Parties and their Subsidiaries.

          (b)  No notice, notification, demand, request for information,
citation, summons or order has been issued, no complaint has been filed, no
penalty has been assessed and no investigation or review is pending or
threatened by any governmental or other entity with respect to any alleged
failure by the Credit Parties or any of its Subsidiaries, which could materially
adversely affect the properties, business, prospects, operating results or
condition (financial or otherwise) of the Credit Parties, to have any permit,
license or authorization required in connection with the conduct of its business
or with respect to any Environmental Laws, including, without limitation,
Environmental Laws relating to the generation, treatment, storage, recycling,
transportation, disposal or release of any Hazardous Materials.

          (c)  To the best of each Credit Party's knowledge no oral or written
notification of a release of a Hazardous Material, which could materially
adversely affect the properties, business, prospects, operating results or
condition (financial or otherwise) of any Credit Party, has been filed by or on
behalf of any Credit Party or any Subsidiary of a Credit Party and no property
now or previously owned, leased or used by any Credit Party or any Subsidiary of
a Credit Party is listed or proposed for listing on the National Priorities List
under the Comprehensive Environmental Response, Compensation and Liability Act
of 1980, as amended, or on any similar state list of sites requiring
investigation or clean-up.

          (d)  There are no liens or encumbrances arising under or pursuant to
any Environmental Laws on any of the real property or properties owned, leased
or used by any Credit Party or any Subsidiary of a Credit Party and no
governmental actions have been taken or are in process which could subject any
of such properties to such liens or encumbrances or, as a result of which any
Credit Party or any Subsidiary of a Credit Party would be required to place any
notice or restriction relating to the presence of Hazardous Materials at any
property owned by it in any deed to such property.

          (e)  Neither any Credit Party nor any Subsidiary of a Credit Party
nor, to the best knowledge of any Credit Party, any previous owner, tenant,
occupant or user of any property owned, leased or used by any Credit Party or
any Subsidiary of a Credit Party (i) engaged in or permitted any operations or
activities upon or any use or occupancy of such property, or any portion
thereof, for the purpose of or in any way involving the handling, manufacture,
treatment, storage, use, generation, release, discharge, refining, dumping or
disposal (whether legal or illegal, accidental or intentional) of any Hazardous
Materials on, under, in or about such property, except to the extent commonly
used in day-to-day operations of such property and in such case only in
compliance with all Environmental Laws, or (ii) transported any Hazardous
Materials to, from or across such property except to the extent commonly used in
day-to-day operations of such property and, in such case, in compliance with,
all Environmental Laws, except, in the case of both clause (i) and clause (ii)
above, where so doing would not have a material adverse affect on the business,
prospects, operating results or condition (financial or

                                      -23-
<Page>

otherwise) of any Credit Party; nor to the best knowledge of any Credit Party
have any Hazardous Materials migrated from other properties upon, about or
beneath such property, nor, to the best knowledge of any Credit Party, are any
Hazardous Materials presently constructed, deposited, stored or otherwise
located on, under, in or about such property except to the extent commonly used
in day-to-day operations of such property and, in such case, in compliance with,
all Environmental Laws.

                                   SECTION 5

                              AFFIRMATIVE COVENANTS

     So long as the Bank has any commitment to lend hereunder, issue Letters of
Credit or any Revolving Loan or other Obligation hereunder remains outstanding,
the Borrower covenants as follows:

     5.1  Financial Statements and other Reporting Requirements. The Credit
Parties shall furnish to the Bank:

          (a)  as soon as available to each Credit Party and its Subsidiaries,
but in any event within 90 days after the end of each of fiscal year, the
consolidated and consolidating balance sheet of each Credit Party and its
Subsidiaries as of the end of, and the related consolidated and consolidating
statement of income, changes in stockholders' equity and cash flow for, such
year, audited and certified by PriceWaterhouseCoopers (or other independent
nationally recognized certified public accountants reasonably acceptable to the
Bank) in the case of such consolidated statements, and certified by an
Authorized Officer in the case of such consolidating statements; and,
concurrently with such financial statements, a copy of said certified public
accountants' management report and a written statement by such accountants that,
in the making of the audit necessary for their report and opinion upon such
financial statements they have obtained no knowledge of any Default or Event of
Default or, if in the opinion of such accountants any such Default or Event of
Default exists, they shall disclose in such written statement the nature and
status thereof;

          (b)  as soon as available to the Borrower, but in any event within 45
days after the end of each fiscal quarter, the consolidated and consolidating
balance sheets of the Borrower and its Subsidiaries as of the end of, and the
related consolidated and consolidating statements of income for, the period then
ended, certified by an Authorized Officer but subject, however, to normal,
recurring year-end adjustments;

          (c)  as soon as available to the Borrower, but in any event
concurrently with the delivery of each financial statement of the Borrower
pursuant to subsection 5.1.(a), a copy of each so-called management letter
submitted to the Borrower or any of its Subsidiaries by independent certified
public accountants in connection with each annual audit of the books of the
Borrower and its Subsidiaries by such accountants or in connection with any
interim audit thereof pertaining to any phase of the business of the Borrower or
any such Subsidiary;

          (d)  concurrently with the delivery of each financial statement of the
Borrower pursuant to subsections 5.1.(a) and 5.1.(b) and at any time reasonably
requested by the Bank, a

                                      -24-
<Page>

completed compliance certificate substantially in the form of EXHIBIT C hereto
signed on behalf of the Borrower by an Authorized Officer;

          (e)  as soon as available to the Borrower and its Subsidiaries, but in
any event within 90 days after the end of each fiscal year, projections for the
Borrower and its consolidated Subsidiaries on a consolidating and consolidated
basis for the current fiscal year, including projected balance sheets, income
statements, cash flow statements and such other statements as the Bank may
reasonably request and in form and substance satisfactory to the Bank, all
prepared in good faith and based on assumptions which were reasonable when made;

          (f)  if and when the Borrower gives or is required to give notice to
the PBGC of any "Reportable Event" (as defined in Section 4043 of ERISA) with
respect to any Plan that might constitute grounds for a termination of such Plan
under Title IV of ERISA, or knows that any member of the Controlled Group or the
plan administrator of any Plan has given or is required to give notice of any
such Reportable Event, a copy of the notice of such Reportable Event given or
required to be given to the PBGC;

          (g)  immediately upon becoming aware of the existence of any condition
or event that constitutes a Default or Event of Default, written notice thereof
specifying the nature and duration thereof and the action being or proposed to
be taken with respect thereto;

          (h)  promptly upon becoming aware of any litigation or of any
investigative proceedings by a governmental agency or authority commenced or
threatened against the Borrower or any of its Subsidiaries of which it has
notice, the outcome of which would or might have a materially adverse effect on
the assets, business or prospects of the Borrower or the Borrower and its
Subsidiaries on a consolidated basis, written notice thereof and the action
being or proposed to be taken with respect thereto;

          (i)  promptly upon becoming aware of any investigative proceedings
by a governmental agency or authority commenced or threatened against the
Borrower or any of its Subsidiaries regarding any potential violation of
Environmental Laws or any spill, release, discharge or disposal of any Hazardous
Material, written notice thereof and the action being or proposed to be taken
with respect thereto; and

          (j)  promptly after the same become available, (i) copies of all proxy
statements and annual, quarterly and interim reports (excluding reports in
respect of the beneficial ownership of officers, directors and certain other
shareholders on Forms 3, 4 and 5 promulgated under the Securities Exchange Act
of 1934, as amended) as the Borrower shall send to shareholders or as the
Borrower may file with the Securities and Exchange Commission or any
governmental authority at any time having jurisdiction over the Borrower and
(ii) with respect to Biosphere, copies of all annual reports as Biosphere shall
send to shareholders; and

          (k)  from time to time, such other financial data and information
about the Borrower or its Subsidiaries including, without limitation, a current
aging of Accounts, as the Bank may reasonably request.

     5.2  CONDUCT OF BUSINESS. Each of the Borrower and its Subsidiaries shall:

                                      -25-
<Page>

          (a)  duly observe and comply in all material respects with all
applicable laws and valid requirements of any governmental authorities relative
to its corporate existence, rights and franchises, to the conduct of its
business and to its property and assets (including, without limitation, the
Food, Drug and Cosmetic Act, and all regulations promulgated by the FDA, all
Environmental Laws and ERISA), and shall maintain and keep in full force and
effect all licenses and permits necessary in any material respect to the proper
conduct of its business;

          (b)  maintain its corporate existence; and

          (c)  with respect to the Borrower, maintain its business in developing
and commercializing improved chemical entities and related products and services
and transacting related business; and with respect to Biosphere, maintain its
business in developing and commercializing its business related to
intracorporeal and "on-line" extracorporeal therapies.

     5.3  MAINTENANCE AND INSURANCE. Each of the Credit Parties and their
Subsidiaries shall maintain and keep its properties in good repair, working
order and condition, and from time to time make all needful improvements thereto
so that its business may be properly and advantageously conducted at all times.
The Credit Parties will maintain or cause to be maintained on all insurable
properties now or hereafter owned by the Credit Parties insurance against loss
or damage by fire or other casualty to the extent customary with respect to like
properties of companies conducting similar businesses and will maintain or cause
to be maintained, products liability, public liability and workmen's
compensation insurance insuring the Credit Parties to the extent customary with
respect to companies conducting similar businesses and, upon request, will
furnish to the Bank satisfactory evidence of the same.

     5.4  TAXES. The Credit Parties shall pay or cause to be paid all taxes,
assessments or governmental charges on or against it or any Subsidiary of a
Credit Party or their properties on or prior to the time when they become due;
PROVIDED that this covenant shall not apply to any tax, assessment or charge
that is being contested in good faith by appropriate proceedings and with
respect to which adequate reserves have been established and are being
maintained in accordance with GAAP.

     5.5  INSPECTION BY THE BANK. Each Credit Party shall permit the Bank or its
designees, at any reasonable time, and upon reasonable notice (or if a Default
or Event of Default shall have occurred and is continuing, at any time and
without prior notice), to (i) visit and inspect the properties of each Credit
Party and its Subsidiaries, (ii) examine and make copies of and take abstracts
from the books and records of each Credit Party and its Subsidiaries and (iii)
discuss the affairs, finances and accounts of each Credit Party and its
Subsidiaries with their appropriate officers, employees and accountants. In
handling such information the Bank shall exercise the same degree of care that
it exercises with respect to its own proprietary information of the same types
to maintain the confidentiality of any non-public information thereby received
or received pursuant to Section 5 except that disclosure of such information may
be made (i) to the subsidiaries or affiliates of the Bank in connection with
their present or prospective business relations with any Credit Party and its
Subsidiaries if such subsidiaries agree in advance to be bound by the same
confidentiality provisions of the Bank as set forth in this Section 5.5, (ii) to
prospective transferees or purchasers of an interest in the Revolving Loans if
they agree in advance to be bound by the same confidentiality obligations of the
Bank as set forth in this

                                      -26-
<Page>

Section 5.5, (iii) as required by law, regulation, rule or order, subpoena,
judicial order or similar order and (iv) as may be required in connection with
the examination, audit or similar investigation of the Bank.

     5.6  MAINTENANCE OF BOOKS AND RECORDS. Each Credit Party and its
Subsidiaries shall keep adequate books and records of account, in which true and
complete entries will be made reflecting all of its business and financial
transactions, and such entries will be made in accordance with GAAP consistently
applied and applicable law.

     5.7  MAINTENANCE OF ACCOUNTS. The Credit Parties and each of their U.S.
Subsidiaries will maintain its principal depository and operating accounts with
the Bank at all times (except for Versicor which may maintain its principal
depository and operating accounts in California so long as its principal place
of business is located in California) and shall maintain in such accounts
sufficient funds to make all principal and interest payments when due.

     5.8  [RESERVED].

     5.9  MINIMUM LIQUIDITY RATIO. At the end of each fiscal quarter, the Cash
Equivalent Amount of the Borrower shall be equal to or greater than 150% of its
Total Liabilities.

     5.10 MINIMUM TANGIBLE CAPITAL BASE. The Borrower shall maintain at all
times a Tangible Capital Base of not less than $50,000,000.

     5.11 MINIMUM CASH OR EQUIVALENTS/FIXED CHARGE COVERAGE RATIO. The Borrower
shall maintain at all times (a) a Cash Equivalent Amount of not less than
$50,000,000 or (b) a Fixed Charge Coverage Ratio of not less than 1.50 to 1.00.

     5.12 FURTHER ASSURANCES. At any time and from time to time the Credit
Parties shall, and shall cause each of their Subsidiaries to, execute and
deliver such further instruments and take such further action as may reasonably
be requested by the Bank to effect the purposes of this Agreement and the Note.

                                   SECTION 6

                               NEGATIVE COVENANTS

     So long as the Bank has any commitment to lend hereunder, issue Letters of
Credit or any Revolving Loan or other Obligation hereunder remains outstanding,
the Borrower covenants as follows:

     6.1  INDEBTEDNESS. Neither the Borrower nor any of its Subsidiaries shall
create, incur, assume, guarantee or be or remain liable with respect to any
Indebtedness other than the following:

          (a)  Indebtedness of the Borrower or any of its Subsidiaries
(including Biosphere) to the Bank or any of its Affiliates;

                                      -27-
<Page>

          (b)  Indebtedness existing as of the date hereof and disclosed in
SCHEDULE 6.1 hereto and Guaranties disclosed on SCHEDULE 6.2 hereto and any
refinancing of such Indebtedness in amounts not exceeding the principal amount
thereof and on terms (including without limitation any subordination terms
applicable thereto) which are substantially the same as the terms of the
refinanced Indebtedness;

          (c)  Indebtedness of the Borrower to or from its Subsidiaries in the
aggregate principal amount outstanding at any time not in excess of $20,000,000;
PROVIDED that no Default shall exist and be continuing or caused thereby at the
time of incurrence of such Indebtedness;

          (d)  Indebtedness secured by Permitted Encumbrances under Section
6.2(c);

          (e)  Indebtedness not in excess of 4,891,000 Canadian Dollars in
respect of Sepracor Canada Limited's obligation with respect to the Canadian
Indebtedness and the Borrower's guaranty of the Canadian Indebtedness and any
refinancing of such Indebtedness in amounts not exceeding the principal amount
thereof and on terms which are substantially the same terms as the terms of the
refinanced indebtedness;

          (f)  Indebtedness in respect of Capital Leases and purchase money
financing for tangible property used in the Borrower's business in the aggregate
principal amount outstanding at any time not in excess of $15,000,000 LESS, with
respect to Biosphere, any indebtedness in respect of Capital Leases and purchase
money financing for tangible property used in their businesses; and

     6.2  CONTINGENT LIABILITIES. Neither the Borrower nor any of its
Subsidiaries shall create, incur, assume or remain liable with respect to any
Guaranties other than the following:

          (a)  Guaranties in favor of the Bank or any of its Affiliates; and

          (b)  Guaranties disclosed in SCHEDULE 6.2 hereto or in the financial
statements referred to in Section 4.6.

     6.3  SALE AND LEASEBACK. Neither the Borrower nor any of its Subsidiaries
shall enter into any arrangement, directly or indirectly, whereby it shall sell
or transfer any property owned by it in order to lease such property or lease
other property that the Borrower or any such Subsidiary intends to use for
substantially the same purpose as the property being sold or transferred.

     6.4  ENCUMBRANCES. Neither the Borrower nor any of its Subsidiaries shall
create, incur, assume or suffer to exist any mortgage, pledge, security
interest, lien or other charge or encumbrance, including the lien or retained
security title of a conditional vendor upon or with respect to any of its
property or assets ("ENCUMBRANCES"), or assign or otherwise convey any right to
receive income, including the sale or discount of accounts receivable with or
without recourse, except the following ("PERMITTED ENCUMBRANCES"):

          (a)  Encumbrances in favor of the Bank or any of its Affiliates;

                                      -28-
<Page>

          (b)  Encumbrances existing as of the date hereof and disclosed in
SCHEDULE 6.4 hereto and securing any refinancing of Indebtedness PROVIDED that
such refinancing is permitted pursuant to Section 6.1(b);

          (c)  Encumbrances for purchase money obligations or Capital Leases
permitted pursuant to Section 6.1(d); PROVIDED that such Encumbrances shall not
attach to property and assets of the Borrower or any Subsidiary not purchased
with the proceeds of such purchase money obligations;

          (d)  liens for taxes, fees, assessments and other governmental charges
to the extent that payment of the same may be postponed or is not required in
accordance with the provisions of Section 5.4; and

          (e)  landlords' and lessors' liens in respect of rent not in default
or liens in respect of pledges or deposits under workmen's compensation,
unemployment insurance, social security laws, or similar legislation (other than
ERISA) or in connection with appeal and similar bonds incidental to litigation;
mechanics', laborers' and materialmen's and similar liens, if the obligations
secured by such liens are not then delinquent; liens securing the performance of
bids, tenders, contracts (other than for the payment of money); and statutory
obligations incidental to the conduct of its business and that do not in the
aggregate materially detract from the value of its property or materially impair
the use thereof in the operation of its business.

     6.5  LINES OF BUSINESS. Neither the Borrower nor any Subsidiary will engage
in any line of business if as a result thereof the business of the Borrower and
its Subsidiaries taken as a whole would be materially different from what it was
on the date hereof.

     6.6  MERGER; CONSOLIDATION; SALE OR LEASE OF ASSETS. Neither the Borrower
nor any of its Subsidiaries shall, without the prior written consent of the
Bank, sell, lease or otherwise dispose of assets or properties, other than sales
or leases of inventory in the ordinary course of business; or liquidate, merge
or consolidate into or with any other Person or entity, PROVIDED that any
Subsidiary of a Credit Party may merge or consolidate into or with (i) the
Borrower if no Default or Event of Default has occurred and is continuing or
would result from such merger and if the Borrower is the surviving company or
(ii) any other wholly-owned Subsidiary of the Borrower.

     Notwithstanding the foregoing provisions of this section, the Borrower or
any Subsidiary may acquire (whether by way of purchase of assets or stock, by
merger or consolidation or otherwise) all or substantially all of the assets
located in or capital stock of any Person engaged primarily in the same line of
business as the Borrower or any Subsidiaries; PROVIDED that (a) no Default shall
exist at the time of such acquisition or shall be caused thereby in the
foreseeable future and (b) after giving effect to such acquisition the Borrower
shall be in compliance with all the provisions of Sections 5.9 through 5.11 and
the Borrower shall have delivered to the Bank a Compliance Certificate
demonstrating such compliance on a pro forma basis.

     Notwithstanding any provision of this Agreement to the contrary, the Credit
Parties may license and exploit any rights to their intellectual property,
including, without limitation, all

                                      -29-
<Page>

patents, patent applications, trademarks, service marks, and tradenames, in
arms-length transactions for fair market value, without the consent of the Bank.

     6.7  ADDITIONAL STOCK ISSUANCE. The Borrower shall not permit any of its
Subsidiaries to issue any additional shares of such Subsidiary's capital stock
or other equity securities, any options therefor or any securities convertible
thereto other than to the Borrower; PROVIDED, that such Subsidiaries may issue
additional shares of its capital stock if after any such issuance the Borrower
or such Subsidiary has 50% or more of the ordinary voting power for the election
of a majority of the members of the board of directors or other governing body
of such entity or the Borrower or such Subsidiary has, at least, a 50% ownership
interest.

     6.8  RESTRICTED PAYMENTS. Neither the Borrower nor its Subsidiaries will
directly or indirectly declare, order, pay or make any Restricted Payment or set
aside any sum or property therefore if at the time of such proposed action or
immediately after giving effect thereto, any condition or event shall exist
which constitutes a Default or an Event of Default and unless such Restricted
Payment is expressly permitted by this Section 6.8; provided that nothing herein
shall be deemed to prohibit the making of any dividend or distribution by any
Subsidiary to a Credit Party.

     Subject to the foregoing, the Borrower may (a) make any scheduled payment
of principal or interest on Subordinated Notes issued and outstanding on the
date of this Agreement in accordance with the subordination provisions for such
subordinated notes, (b) make payments under any Corporate Services Agreement,
(c) make distributions of shares of its capital stock as stock splits or stock
dividends, and (d) make any other Restricted Payment in addition to those
referred to in the previous clause; PROVIDED, that in the last event the
Borrower shall have received the prior written consent of the Bank to such
proposed Restricted Payment.

     The amount involved in any Restricted Payment declared, ordered, paid, made
or set apart in property shall be deemed to be the greater of the fair market
value thereof at the time of such distribution or payment (or the date of such
transaction, as the case may be), as determined in good faith by the Borrower,
or the net book value thereof on the books of the Borrower as at such time.

     6.9  TRANSACTIONS WITH AFFILIATES. Except for the Borrower's Subsidiaries
on the date hereof so long as they remain Subsidiaries of the Borrower, the
Credit Parties will not, and will not permit any Corporate Affiliate to,
directly or indirectly, enter into any lease or other transaction with any
shareholder or with any Affiliate of the Borrower or such shareholder, on terms
that are less favorable to the Borrower or such Subsidiary than those which
might be obtained at the time from Persons who are not a shareholder or an
Affiliate. Notwithstanding the preceding sentence, the Borrower may (1) sublease
its facilities to Biosphere, Versicor and Hemasure; (2) enter into and perform
the Corporate Services Agreements, the Technology Transfer Agreements and the
Cross License Agreement, (3) enter into an amended and restated cross license
agreement replacing the Cross License Agreement if such amended and restated
agreement is in form and substance acceptable to the Bank and its counsel and
(4) engage in transactions expressly permitted by Sections 6.1, 6.6 and 6.7.

                                      -30-
<Page>

     6.10 INVESTMENTS. Neither the Credit Parties nor any of their Subsidiaries
shall make or maintain any Investments other than (i) existing and additional
Investments in Subsidiaries on the date hereof so long as they remain
Subsidiaries of Sepracor, (ii) Qualified Investments and (iii) acquisitions
permitted under Section 6.6 and (iv) Investments consisting of foreign deposit
accounts used for ordinary course working capital purposes of the Credit Parties
or their Subsidiaries; PROVIDED, that the aggregate balance of foreign deposit
accounts of the Borrower and its Subsidiaries shall not at any time exceed
$10,000,000.

     6.11 ERISA. Neither the Credit Parties nor any member of the Controlled
Group shall permit any Plan maintained by it to (i) engage in any "prohibited
transaction" (as defined in Section 4975 of the Code, (ii) incur any
"accumulated funding deficiency" (as defined in Section 302 of ERISA) whether or
not waived, or (iii) terminate any Plan in a manner that could result in the
imposition of a lien or encumbrance on the assets of the Credit Parties or any
of their Subsidiaries pursuant to Section 4068 of ERISA.

     6.12 OBSERVANCE OF SUBORDINATION PROVISIONS, ETC. The Credit Parties will
not make, or cause or permit to be made, any payments in respect of any
Subordinated Indebtedness in contravention of the subordination and other
payment provisions contained in the evidence of such Subordinated Indebtedness
or in contravention of any written agreement pertaining thereto, nor will the
Credit Parties (a) amend, modify or change in any manner any of such
subordination or other payment provisions without the prior written consent of
the Bank or (b) amend, modify or change in any manner adverse to the interests
of the Bank any of the other provisions set forth in the agreements under which
such Subordinated Indebtedness is outstanding or contained in the evidence of
such Subordinated or other Indebtedness.

     6.13 RESTRICTIVE AGREEMENTS. No Credit Party will directly or indirectly,
enter into, incur or permit to exist any agreement or other arrangement that
prohibits, restricts or imposes any condition upon the ability of any Credit
Party to create, incur or permit to exist any Lien upon any of its property or
assets; PROVIDED that (i) the foregoing shall not apply to restrictions and
conditions imposed by law or by this Agreement, (ii) the foregoing shall not
apply to restrictions or conditions imposed by any agreement relating to secured
Indebtedness permitted by this Agreement if such restrictions or conditions
apply only to the property or assets securing such Indebtedness and (iii) the
foregoing shall not apply to customary provisions in leases and other contracts
restricting the assignment thereof.

                                   SECTION 7

                                    DEFAULTS

     7.1  EVENTS OF DEFAULT. There shall be an Event of Default hereunder if any
of the following events occurs:

          (a)  the Credit Parties shall fail to pay when due (i) any amount of
principal of any Revolving Loans, or (ii) any amount of interest thereon; or

          (b)  the Credit Parties shall fail to pay within three (3) days after
receipt of notice from the Bank any fees or expenses payable hereunder or under
any Note; or

                                      -31-
<Page>

          (c)  the Credit Parties shall fail to perform any term, covenant or
agreement contained in Sections 5 (except Section 5.3) or 6; or

          (d)  the Credit Parties shall fail to perform any term, covenant or
agreement (other than those referred to above in this Section 7.1) contained in
this Agreement and such default shall continue for twenty (20) days; or

          (e)  any representation or warranty of any Credit Party made in this
Agreement or in the Notes, or any Credit Parties in any other documents or
agreements executed in connection with the transactions contemplated by this
Agreement or in any certificate delivered hereunder shall prove to have been
false in any material respect upon the date when made or deemed to have been
made; or

          (f)  the failure to pay at maturity, or within any applicable period
of grace, any obligations of the Borrower in excess of One Million Dollars
($1,000,000) in the aggregate for borrowed monies or advances, or for the use of
real or personal property, or fail to observe or perform any term, covenant or
agreement evidencing or securing such obligations, the result of which failure
is to permit the holder or holders of such indebtedness to cause such
indebtedness to become due prior to its stated maturity upon delivery of
required notice, if any; or

          (g)  the Borrower shall default in any payment due on any Indebtedness
in respect of borrowed money, any Capital Lease or the deferred purchase price
of property with an outstanding principal amount in excess of One Million
Dollars ($1,000,000) and such default shall continue for more than the period of
grace, if any, specified therein and shall not have been waived pursuant
thereto; or

          (h)  the Borrower or any Subsidiary of the Borrower shall (i) apply
for or consent to the appointment of, or the taking of possession by, a
receiver, custodian, trustee, liquidator or similar official of itself or of all
or a substantial part of its property, (ii) be generally not paying its debts as
such debts become due, (iii) make a general assignment for the benefit of its
creditors, (iv) commence a voluntary case under the Federal Bankruptcy Code (as
now or hereafter in effect), (v) take any action or commence any case or
proceeding, as debtor, under any law relating to bankruptcy, insolvency,
reorganization, winding-up or composition or adjustment of debts, or any other
law providing for the relief of debtors, (vi) fail to contest in a timely or
appropriate manner, or acquiesce in writing to, any petition filed against it in
an involuntary case under the Federal Bankruptcy Code or other law, (vii) take
any action under the laws of its jurisdiction of incorporation or organization
similar to any of the foregoing, or (viii) take any corporate action for the
purpose of effecting any of the foregoing; or

          (i)  a proceeding or case shall be commenced, without the application
or consent of the Borrower or any Subsidiary of the Borrower in any court of
competent jurisdiction, seeking (i) the liquidation, reorganization,
dissolution, winding up, or composition or readjustment of its debts, (ii) the
appointment of a trustee, receiver, custodian, liquidator or the like of it or
of all or any substantial part of its assets, or (iii) similar relief in respect
of it, under any law relating to bankruptcy, insolvency, reorganization,
winding-up or composition or adjustment of debts or any other law providing for
the relief of debtors, and such proceeding or case shall continue undismissed,
or unstayed and in effect, for a period of 60 days; or an order

                                      -32-
<Page>

for relief shall be entered in an involuntary case under the Federal Bankruptcy
Code, against the Borrower or any Subsidiary of the Borrower; or action under
the laws of the jurisdiction of incorporation or organization of the Borrower or
any Subsidiary of the Borrower similar to any of the foregoing shall be taken
with respect to the Borrower or any Subsidiary of the Borrower and shall
continue unstayed and in effect for any period of 60 days; or

          (j)  a judgment or order for the payment of money shall be entered
against the Borrower by any court, or a warrant of attachment or execution or
similar process shall be issued or levied against property of the Borrower, that
in the aggregate exceeds One Million Dollars ($1,000,000) in value and such
judgment, order, warrant or process shall continue undischarged or unstayed for
45 days; or

          (k)  the Borrower or any member of the Controlled Group shall fail to
pay when due an amount or amounts aggregating in excess of One Hundred Thousand
Dollars ($100,000) that it shall have become liable to pay to the PBGC or to a
Plan under Title IV of ERISA; or notice of intent to terminate a Plan or Plans
shall be filed under Title IV of ERISA by the Borrower, any member of the
Controlled Group, any plan administrator or any combination of the foregoing; or
the PBGC shall institute proceedings under Title IV of ERISA to terminate or to
cause a trustee to be appointed to administer any such Plan or Plans or a
proceeding shall be instituted by a fiduciary of any such Plan or Plans against
the Borrower and such proceedings shall not have been dismissed within 30 days
thereafter; or a condition shall exist by reason of which the PBGC would be
entitled to obtain a decree adjudicating that any such Plan or Plans must be
terminated; or

          (l)  any Person or "group" (within the meaning of Section 13(d) and
14(d)(2) of the Securities and Exchange Act of 1934, as amended) shall
beneficially own or control in excess of 50% of the issued and outstanding
shares of the capital stock of the Borrower having ordinary voting power to
elect a majority of the board of directors of the Borrower; or

          (m)  the termination, expiration or non-renewal of any license or
other Material Agreement which termination, expiration or non-renewal has a
material adverse effect on the existing business or prospects of the Borrower.

     7.2  REMEDIES. Upon the occurrence of an Event of Default described in
Sections 7.1.(h) and 7.1.(i), immediately and automatically, and upon the
occurrence of any other Event of Default, at any time thereafter while such
Event of Default is continuing, at the Bank's option and upon the Bank's
declaration:

          (a)  the Bank's commitment to make any further Revolving Loans
hereunder or to issue Letters of Credit, generally, shall terminate;

          (b)  the unpaid principal amount of the Revolving Loans together with
accrued interest and all other Obligations hereunder shall become immediately
due and payable, including the unpaid principal amount of any Revolving Loan
subject to an exercised LIBOR Option together with accrued interest thereon and
the related LIBOR Premium in the same manner as though the Credit Parties had
exercised their right to prepayment pursuant to Section

                                      -33-
<Page>

2.7 of this Agreement, without presentment, demand, protest or further notice of
any kind, all of which are hereby expressly waived; and

          (c)  the Bank may exercise any and all rights it has under this
Agreement, the Notes or any other documents or agreements executed in connection
herewith, or at law or in equity, and proceed to protect and enforce the Bank's
rights by any action at law, in equity or other appropriate proceeding.

          (d)  Upon the occurrence of any Event of Default and at any time
thereafter (unless such Event of Default shall theretofore have been remedied),
at the Bank's option: (i) the Bank shall thereupon be relieved of all of its
obligations to make any Revolving Loans hereunder; (ii) the unpaid principal
amount of the Notes together with accrued interest thereon and all other
Obligations shall become immediately due and payable without presentment,
demand, protest or notice of any kind, all of which are hereby expressly waived;
and (iii) the Bank may exercise any and all rights it has under this Agreement,
the Notes, or any other documents or agreements executed in connection with the
transactions contemplated by this Agreement (the "LOAN DOCUMENTS"), or by law or
equity, and proceed to protect and enforce the Bank's rights by any action at
law, suit in equity or other appropriate proceeding, whether for specific
performance or for an injunction against a violation of any covenant contained
herein or in any Loan Document or in aid of the exercise of any power granted
hereby or thereby or by law.

                                   SECTION 8

                                  MISCELLANEOUS

     8.1  NOTICES. Unless otherwise specified herein, all notices hereunder to
any party hereto shall be in writing and shall be deemed to have been given when
delivered by hand, or three (3) days after being properly deposited in the mails
certified, return receipt requested, or when sent by electronic facsimile
transmission, or when delivered to the telegraph company or overnight courier,
the next business day following addressed to such party at its address indicated
below:

                                      -34-
<Page>

     If to the Credit Parties, at

          Sepracor Inc.
          111 Locke Drive
          Marlborough, Massachusetts 01752
          Attention: Robert F. Scumaci
          Senior Vice President Finance and Administration
          Tel. No.: 508-481-6700
          Fax No.: 508-357-7494

     If to the Bank, at

          Fleet National Bank
          100 Federal Street
          Boston, Massachusetts 02110
          Attention: Kimberly A. Martone
          Senior Vice President
          Tel. No.: 617-434-5316
          Fax No.: 617-434-2473

or at any other address specified by such party in writing.

     8.2  EXPENSES. The Credit Parties will pay on demand all expenses of the
Bank in connection with the preparation, waiver or amendment of this Agreement,
the Notes, or other documents executed in connection therewith, or the
administration, default or collection of the Revolving Loans or other
Obligations or in connection with the Bank's exercise, preservation or
enforcement of any of its rights, remedies or options thereunder, including,
without limitation, reasonable fees and disbursements of outside legal counsel
or accounting, consulting, brokerage or other similar professional fees or
expenses, and any fees or expenses associated with any travel or other costs
relating to any appraisals or examinations conducted in connection with the
Obligations and the amount of all such expenses shall, until paid, bear interest
at the rate applicable to principal hereunder for Revolving Loans not subject to
a LIBOR Option (including any default rate).

     8.3  SET-OFF. Regardless of other means of obtaining repayment of the
Obligations, any deposits, balances or other sums credited by or due from the
head office of the Bank or any of its branch offices to the Credit Parties may,
at any time and from time to time after the occurrence of an Event of Default
hereunder, without notice to the Credit Parties or compliance with any other
condition precedent now or hereafter imposed by statute, rule of law, or
otherwise (all of which are hereby expressly waived) be set off, appropriated,
and applied by the Bank against any and all Obligations of the Credit Parties to
the Bank or any of its affiliates in such manner as the head office of the Bank
or any of its branch offices in their sole discretion may determine, and the
Credit Parties each hereby grant the Bank a continuing security interest in such
deposits, balances or other sums for the payment and performance of all such
obligations.

                                      -35-
<Page>

     8.4  TERM OF AGREEMENT. This Agreement shall continue in force and effect
so long as the Bank has any commitment to make Revolving Loans hereunder or any
Revolving Loan or any Obligation hereunder shall be outstanding.

     8.5  NO WAIVERS. No failure or delay by the Bank in exercising any right,
power or privilege hereunder or under the Note or under any other documents or
agreements executed in connection herewith shall operate as a waiver thereof;
nor shall any single or partial exercise thereof preclude any other or further
exercise thereof or the exercise of any other right, power or privilege. The
rights and remedies herein and in the Notes provided are cumulative and not
exclusive of any rights or remedies otherwise provided by agreement or law.

     8.6  GOVERNING LAW; JURISDICTION. This Agreement and the Notes shall be
deemed to be contracts made under seal and shall be construed in accordance with
and governed by the laws of Massachusetts (without giving effect to any
conflicts of laws provisions contained therein). The Credit Parties, to the
extent that they may lawfully do so, hereby consent to the jurisdiction of the
courts of the Commonwealth of Massachusetts and the United States District Court
for the District of Massachusetts, as well as to the jurisdiction of all courts
to which an appeal may be taken from such courts, for the purpose of any suit,
action or other proceeding arising out of any of its obligations hereunder or
with respect to the transactions contemplated hereby, and expressly waives any
and all objections it may have as to venue in any such courts. The Credit
Parties further agree that a summons and complaint commencing an action or
proceeding in any of such courts shall be properly served and shall confer
personal jurisdiction if served personally or by certified mail to it at its
address provided in Section 8.1 of this Agreement or as otherwise provided under
the laws of the Commonwealth of Massachusetts.

     8.7  AMENDMENTS. Neither this Agreement nor the Notes nor any provision of
this Agreement or thereof may be amended, waived, discharged or terminated
except by a written instrument signed by the Bank and, in the case of
amendments, by the Credit Parties.

     8.8  BINDING EFFECT OF AGREEMENT; ASSIGNMENTS; PARTICIPATIONS.

          (a)  This Agreement shall be binding upon and inure to the benefit of
the Credit Parties and the Bank and their respective successors and assigns;
PROVIDED that the Credit Parties may not assign or transfer their rights or
obligations hereunder.

          (b)  ASSIGNMENTS BY THE BANK. From and after the date hereof, the Bank
may at any time assign all, or a proportionate part of all, of its rights,
interests and duties with respect to the Revolving Commitment Amount and the
Notes (1) to any one or more of its Affiliates without the consent or approval
of the Credit Parties or (2) to one or more banks or other financial
institutions with the consent of the Credit Parties which consent shall not be
unreasonably withheld (each assignee under clauses (1) and (2), an "Assignee"),
in each case on such terms, as between the Bank and each of its Assignees, as
the Bank may think fit, and such Assignee shall assume such rights, interests
and duties pursuant to an instrument executed by such Assignee and the Bank, and
for this purpose the Bank may make available to each of its potential Assignees
such information relating to the Credit Parties, this Agreement and the
transactions contemplated hereby as the Bank may think necessary or desirable,
which information shall be held by each potential Assignee strictly in
confidence. Upon execution and

                                      -36-
<Page>

delivery of such an instrument and payment by such Assignee to the Bank of an
amount equal to the purchase price agreed between the Bank and such Assignee,
such Assignee shall be a Bank party to this Agreement and shall have all the
rights, interests and duties of a Bank with a Revolving Commitment Amount and
Revolving Loan as set forth in such instrument of assumption, and the Bank shall
be released from its obligations hereunder to a corresponding extent, and no
further consent or action by any party shall be required. Upon the consummation
of any assignment pursuant to this paragraph (b), the Bank and the Credit
Parties shall make appropriate arrangements so that, if required, a new Note or
Notes are issued to the Assignee.

          (c)  PARTICIPATIONS BY THE BANK. From and after the date hereof, the
Bank shall be at liberty to offer the participations in the Revolving Commitment
Amount and the Notes to one or more banks or other financial institutions on
such terms as the Bank may think fit, and for this purpose the Bank may make
available to each of its potential participants such information relating to the
Credit Parties, this Agreement and the transactions contemplated hereby as the
Bank may think necessary or desirable, which information shall be held by each
potential participant strictly in confidence; PROVIDED, that the Bank shall not
offer any participations to foreign banks or financial institutions without the
prior written consent of the Credit Parties; PROVIDED FURTHER, that the Bank
shall retain the sole right to consent to amendments to, or waivers of, the
provisions of this Agreement and the Notes and the sole right and responsibility
to enforce the obligations of the Credit Parties hereunder and under the Notes;
PROVIDED FURTHER, that the Bank may agree with each of its participants that the
Bank will not agree, without the consent of the participant, to any amendment or
waiver of any provision of this Agreement which would increase or otherwise
change such Revolving Commitment Amount or reduce the principal of or rate of
interest on the Revolving Loans subject to such participation, or postpone the
date fixed for any payment of principal or of interest on any Revolving Loans.

     8.9  CURRENCY CONVERSION. If, for the purpose of obtaining or enforcing
judgment in any court or for any other purpose hereunder it is necessary to
convert an amount due hereunder in the currency in which it is due (the
"ORIGINAL CURRENCY") into another currency (the "SECOND CURRENCY") the rate of
exchange applied shall be that at which, in accordance with normal banking
procedures, the Bank could purchase, in the United States money market or the
United States foreign exchange market (the "MONEY MARKETS"), as the case may be,
the Original Currency with the Second Currency on the Business Day on which
judgment is given or the amount is due. The Borrower agrees that its obligations
in respect of any amounts due from it to the Bank, in the Original Currency
hereunder shall, notwithstanding any judgment expressed or payment made in the
Second Currency, be discharged only to the extent that on the Business Day
following receipt of any sums so paid or adjudged to be due hereunder in the
Second Currency, the Bank may, in accordance with normal banking procedure
purchase, in the appropriate Money Market, the Original Currency with the amount
of the Second Currency so paid or so adjudged to be due; and if the amount of
the Original Currency so purchased is less than the amount originally due in the
Original Currency, the Borrower agrees as a separate obligation, and
notwithstanding any such payment or judgment to indemnify the Bank.

     8.10 COUNTERPARTS. This Agreement may be signed in any number of
counterparts with the same effect as if the signatures hereto and thereto were
upon the same instrument.

                                      -37-
<Page>

     8.11 PARTIAL INVALIDITY. The invalidity or unenforceability of any one or
more phrases, clauses or sections of this Agreement shall not affect the
validity or enforceability of the remaining portions of it.

     8.12 CAPTIONS. The captions and headings of the various sections and
subsections of this Agreement are provided for convenience only and shall not be
construed to modify the meaning of such sections or subsections.

     8.13 WAIVER OF JURY TRIAL. THE BANK AND THE CREDIT PARTIES AGREE THAT
NEITHER OF THEM NOR ANY ASSIGNEE OR SUCCESSOR SHALL (A) SEEK A JURY TRIAL IN ANY
LAWSUIT, PROCEEDING, COUNTERCLAIM OR ANY OTHER ACTION BASED UPON, OR ARISING OUT
OF, THIS AGREEMENT, ANY RELATED INSTRUMENTS, OR THE DEALINGS OR THE RELATIONSHIP
BETWEEN OR AMONG ANY OF THEM, OR (B) SEEK TO CONSOLIDATE ANY SUCH ACTION WITH
ANY OTHER ACTION IN WHICH A JURY TRIAL CANNOT BE OR HAS NOT BEEN WAIVED. THE
PROVISIONS OF THIS PARAGRAPH HAVE BEEN FULLY DISCUSSED BY THE BANK AND THE
CREDIT PARTIES, AND THESE PROVISIONS SHALL BE SUBJECT TO NO EXCEPTIONS. NEITHER
THE BANK NOR THE CREDIT PARTIES HAVE AGREED WITH OR REPRESENTED TO THE OTHER
THAT THE PROVISIONS OF THIS PARAGRAPH WILL NOT BE FULLY ENFORCED IN ALL
INSTANCES.

     8.14 ENTIRE AGREEMENT. This Agreement, the Notes and the documents and
agreements executed in connection herewith constitute the final agreement of the
parties hereto and supersede any prior agreement or understanding, written or
oral, with respect to the matters contained herein and therein.

                                      -38-
<Page>

     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
by their duly authorized officers as of the day and year first above written.

                                   SEPRACOR INC.

                                   By: /s/ Robert F. Scumaci
                                       ---------------------
                                       Name:  Robert F. Scumaci
                                       Title: Senior Vice President Finance and
                                       Administration

                                   BIOSPHERE MEDICAL, INC.

                                   By: /s/ Robert M. Palladino
                                       -----------------------
                                       Name:  Robert M. Palladino
                                       Title: Vice President and Chief Financial
                                       Officer

                                   FLEET NATIONAL BANK

                                   By: /s/ Kimberly A. Martone
                                       -----------------------
                                       Name:  Kimberly A. Martone
                                       Title: Senior Vice President

                                      -39-
<Page>

                                                                     EXHIBIT A-1

                                     FORM OF

                                  SEPRACOR INC.
                                 PROMISSORY NOTE

                                                               December 22, 1999
$25,000,000                                                Boston, Massachusetts

     For value received, the undersigned hereby promises to pay to FLEET
NATIONAL BANK (the "BANK"), or order, at the head office of the Bank at One
Federal Street, Boston, Massachusetts 02110, the principal amount of TWENTY-FIVE
MILLION DOLLARS ($25,000,000) or such lesser amount as shall equal the principal
amount outstanding hereunder on December 31, 2001 or such earlier date as
provided in the Agreement (as defined below) in lawful money of the United
States of America and in immediately available funds, and to pay interest on the
unpaid principal balance hereof from time to time outstanding, at said office
and in like money and funds, for the period commencing on the date hereof until
paid in full, at the rates per annum and on the dates provided in the Agreement.

     Upon the occurrence and during the continuance of an Event of Default,
interest on the unpaid principal amount hereof and (to the extent permitted by
law) on unpaid interest shall thereafter be payable on demand at a rate per
annum equal to two percent (2%) above the interest rate otherwise in effect with
respect to such Revolving Loans. Upon the cure of an Event of Default and the
payment of interest at the default rate through the date of such cure, the
interest rate shall revert to that provided for in the Agreement.

     If the entire amount of any required principal and/or interest is not paid
in full within ten (10) days after the same is due, the undersigned shall pay to
the Bank a late fee equal to three percent (3%) of the required payment. Nothing
in the preceding sentence shall affect the Bank's rights to exercise any of its
rights and remedies provided in the Agreement (as defined below) if an Event of
Default (as defined in the Agreement) has occurred.

     This Note is issued pursuant to, and entitled to the benefits of, and is
subject to, the provisions of a certain Second Amended and Restated Revolving
Credit Agreement dated as of December 22, 1999, by and among the undersigned,
Biosphere Medical, Inc. and the Bank (herein, as the same may from time to time
be amended or extended, referred to as the "AGREEMENT"), but neither this
reference to the Agreement nor any provision thereof shall affect or impair the
absolute and unconditional obligation of the undersigned makers of this Note to
pay the principal of and interest on this Note as herein provided.

     In case an Event of Default (as defined in the Agreement) shall occur, the
aggregate unpaid principal of and accrued interest on this Note shall become or
may be declared to be due and payable in the manner and with the effect provided
in the Agreement.

     The undersigned may at its option prepay all or any part of the principal
of this Note before maturity upon the terms provided in the Agreement, and this
Note is subject to mandatory

<Page>

prepayment in certain circumstances, which repayment shall in certain cases
require the payment of a premium and in certain cases not require the payment of
a premium.

     The undersigned makers hereby waive presentment, demand, notice of
dishonor, protest and all other demands and notices in connection with the
delivery, acceptance, performance and enforcement of this Note.

     This instrument shall have the effect of an instrument executed under seal
and shall be governed by and construed in accordance with the laws of the
Commonwealth of Massachusetts (without giving effect to any conflicts of laws
provisions contained therein).

                                   SEPRACOR INC.

                                   By:
                                       ----------------------------------------
                                       Name:  Robert F. Scumaci
                                       Title: Senior Vice President Finance and
                                       Administration

                                       -2-
<Page>

                         SCHEDULE I TO PROMISSORY NOTE
<Table>
<Caption>
                    AMOUNT OF
                    REVOLVING       INTEREST          AMOUNT        NOTATION
     DATE             LOAN            RATE             PAID          MADE BY
<S>                 <C>             <C>               <C>           <C>

</Table>

                                       -3-
<Page>

                                                                     EXHIBIT A-2

                                    FORM OF

                             BIOSPHERE MEDICAL, INC.
                                 PROMISSORY NOTE

                                                               December 22, 1999
$2,000,000                                                 Boston, Massachusetts

     For value received, the undersigned hereby promises to pay to FLEET
NATIONAL BANK (the "BANK"), or order, at the head office of the Bank at One
Federal Street, Boston, Massachusetts 02110, the principal amount of TWO MILLION
DOLLARS ($2,000,000) or such lesser amount as shall equal the principal amount
outstanding hereunder on December 31, 2001 or such earlier date as provided in
the Agreement (as defined below) in lawful money of the United States of America
and in immediately available funds, and to pay interest on the unpaid principal
balance hereof from time to time outstanding, at said office and in like money
and funds, for the period commencing on the date hereof until paid in full, at
the rates per annum and on the dates provided in the Agreement.

     Upon the occurrence and during the continuance of an Event of Default,
interest on the unpaid principal amount hereof and (to the extent permitted by
law) on unpaid interest shall thereafter be payable on demand at a rate per
annum equal to two percent (2%) above the interest rate otherwise in effect with
respect to such Revolving Loans. Upon the cure of an Event of Default and the
payment of interest at the default rate through the date of such cure, the
interest rate shall revert to that provided for in the Agreement.

     If the entire amount of any required principal and/or interest is not paid
in full within ten (10) days after the same is due, the undersigned shall pay to
the Bank a late fee equal to three percent (3%) of the required payment. Nothing
in the preceding sentence shall affect the Bank's rights to exercise any of its
rights and remedies provided in the Agreement (as defined below) if an Event of
Default (as defined in the Agreement) has occurred.

     This Note is issued pursuant to, and entitled to the benefits of, and is
subject to, the provisions of a certain Second Amended and Restated Revolving
Credit Agreement dated as of December 22, 1999, by and among Sepracor, the
undersigned and the Bank (herein, as the same may from time to time be amended
or extended, referred to as the "AGREEMENT"), but neither this reference to the
Agreement nor any provision thereof shall affect or impair the absolute and
unconditional obligation of the undersigned makers of this Note to pay the
principal of and interest on this Note as herein provided.

     In case an Event of Default (as defined in the Agreement) shall occur, the
aggregate unpaid principal of and accrued interest on this Note shall become or
may be declared to be due and payable in the manner and with the effect provided
in the Agreement.

     The undersigned may at its option prepay all or any part of the principal
of this Note before maturity upon the terms provided in the Agreement, and this
Note is subject to mandatory

<Page>

prepayment in certain circumstances, which repayment shall in certain cases
require the payment of a premium and in certain cases not require the payment of
a premium.

     The undersigned makers hereby waive presentment, demand, notice of
dishonor, protest and all other demands and notices in connection with the
delivery, acceptance, performance and enforcement of this Note.

     This instrument shall have the effect of an instrument executed under seal
and shall be governed by and construed in accordance with the laws of the
Commonwealth of Massachusetts (without giving effect to any conflicts of laws
provisions contained therein).

                                   BIOSPHERE MEDICAL, INC.

                                   By:
                                       -----------------------------------------
                                       Name:  Robert M. Palladino
                                       Title: Vice President and Chief Financial
                                       Officer

                                       -2-
<Page>

                          SCHEDULE I TO PROMISSORY NOTE

<Table>
<Caption>
                    AMOUNT OF
                    REVOLVING       INTEREST          AMOUNT        NOTATION
     DATE             LOAN            RATE             PAID          MADE BY
<S>                 <C>             <C>               <C>           <C>

</Table>

                                       -3-
<Page>

                                                                       EXHIBIT B

                             COMPLIANCE CERTIFICATE

Fleet National Bank
100 Federal Street
Boston, Massachusetts 02110

Attention:    Kimberly A. Martone
              Senior Vice President

Re:  Sepracor Inc. Obligations under Second Amended and Restated Revolving
     Credit Agreement dated as of December 22, 1999

Ladies and Gentlemen:

     As required by Section 5.1(c) of the Second Amended and Restated Revolving
Credit Agreement dated as of December 22, 1999 (the "CREDIT AGREEMENT") by and
among Sepracor Inc. and Biosphere Medical, Inc. (collectively, the "CREDIT
PARTIES") and Fleet National Bank (the "BANK"), a review of the activities of
the Borrower for the fiscal year and/or fiscal quarter ending ___________, _____
(the "FISCAL PERIOD") has been made under my supervision to determine whether
the Credit Parties have performed and/or maintained all of their respective
obligations under the Credit Agreement. Based upon such review, I hereby certify
to you, as an Authorized Officer of the Borrower, that the Credit Parties have
performed and maintained all such obligations under the Credit Agreement, the
Notes and the Loan Documents for the Fiscal Period and, to the best of my
knowledge, no event has occurred that constitutes a Default or an Even of
Default as defined in the Credit Agreement. Other capitalized terms used herein
without definition have the same meanings as in the Credit Agreement.

     As required by Section [5.1(a)][5.1(b)] of the Credit Agreement financial
statements of the Credit Parties (the "FINANCIAL STATEMENTS") for the Fiscal
Period and other information required by such sections accompany this
certificate. The Financial Statements present fairly the financial position of
the Credit Parties as of the date thereof and the statements of operation of the
Credit Parties for the Fiscal Period covered thereby.

     I further certify to you, as an Authorized Officer of the Borrower, that
the figures set forth below accurately represent amounts required to be
calculated under the various provisions or covenants of the Credit Agreement
indicated, each as of the last day of the Fiscal Period unless otherwise
indicated.

Dated:
       ----------------------------    -----------------------------------------
                                       Title:

<Page>

<Table>
<S>                                                                          <C>
I.       SECTION 5.9 - MINIMUM LIQUIDITY RATIO

         A.    TOTAL LIABILITIES

                  (1) Total Liabilities                                      $

B.       MINIMUM CASH OR EQUIVALENTS

         QUALIFIED INVESTMENTS HELD IN THE U.S.
                  (2) Obligations of the United States of America held in    $
                        the U.S.

                  (3) Certificates of deposit, other deposit instruments,    $
                        bank accounts held in the U.S.

                  (4) Commercial Paper held in the U.S. (see definition of   $
                        Qualified Investments)

                  (5) Mutual/closed end funds that invest only in            $
                        investments set forth in clauses (2) through (4)

                  (6) Repurchase agreements secured by any one or more of    $
                        the foregoing held in the U.S.

                  (7) Qualified Investments: (sum of 2 through 6)            $

         NET OUTSTANDING AMOUNT OF BASE ACCOUNTS

                  (8) Base Accounts                                          $

                  (9) Ineligible as of ________________(1)

                       (i)   over 60 days from invoice date                  $

                       (ii)  Accounts outside of US                          $

                       (iii) Accounts due from Affiliates                    $
</Table>

----------
(1) Ineligible calculated monthly

                                       -2-
<Page>

<Table>
<S>                                                                          <C>
                       (iv)  Prepayments                                     $

                       (v)   Uninvoiced Accounts                             $

                       (vi)  Joint venture accounts                          $

                  (10) Ineligible Accounts (sum of 16(i) through (v))        $

                  (11) Contra Account offsets                                $

                  (12) Net Outstanding Amount of Base Accounts (8 - 10 - 11) $

                  (13) CASH EQUIVALENT AMOUNT

                  (14) Unencumbered Cash held in the United States           $

                  (15) Qualified Investments (from (14))                     $

                  (16) Net Outstanding Amount of Base Accounts (from (19))   $

                  (17) Actual Cash Equivalent Amount (13 + 14 + 15)          $

         C.         LIQUIDITY RATIO

                    (14) Actual Liability Ratio (13 DIVIDED BY 1)                              %

         Required Minimum Liquidity Ratio:                                                  150%

II.      SECTION 5.10 - MINIMUM TANGIBLE CAPITAL BASE

                  (1) Stockholders' equity                                   $

                  (2) Subordinated Indebtedness                              $

                  (3) Goodwill                                               $

                  (4) Intangible items                                       $

                  (5) Reserves not already deducted from assets              $

                  (6) Write-ups from revaluations                            $

</Table>

                                       -3-
<Page>

<Table>
<S>                                                                         <C>
                  (7) Equity in Subsidiaries or joint ventures               $

                  (8) Actual Tangible Capital Base                           $
                      (1 + 2) - (sum of 3 through 7)

Required Minimum Tangible Capital Base:                                      $   50,000,000

III.     A.       MINIMUM CASH OR EQUIVALENT (from I.B)                      $

                  Required Minimum Cash Equivalent                           $   50,000,000

         B.       FIXED CHANGE COVERAGE RATIO

                  EBITDA

                  (1)      Operating Income                                  $

                  (2)      Add Backs

                           (i)      Taxes                                    $

                           (ii)     Interest Expense                         $

                           (iii)    Depreciation/Amortization                $

                           (iv)     Non-Cash Income                          $

                           (v)      Losses from Equity in                    $
                                    Affiliates

                           (vi)     Extraordinary and Unusual                $
                                    Losses

                           (vii)    Total                                    $

                  (3)      Exclusions                                        $

                           (i)      Income from Equity in                    $
                                    Affiliates

                           (ii)     Extraordinary and Unusual                $
                                    Gains

                           (iii)    Proceeds of Insurance and                $
                                    asset sales

                           (iv)     Total
</Table>

                                       -4-
<Page>

<Table>
<S>                                                                          <C>
                  (4)      EBITDA ((1) + (2) - (3))                          $

                           FIXED CHARGES

                           (i)      Interest Expense                         $

                           (ii)     Non-Financed Capital                     $
                                    Expenditures

                  (5)      Total Fixed Charges ((i) + (ii))                  $

                  (6)      Actual Fixed Charge Coverage                          ____:1
                           Ratio (4 DIVIDED BY 5)

                  Required Fixed Charge Coverage Ratio                           1.5 to 1
</Table>

Dated:
      ------------------------,------         ---------------------------------
                                              Title:

<Page>

                                                                       EXHIBIT C

                               GUARANTY AGREEMENT

     THIS AGREEMENT, dated as of December __, 1999, by SEPRACOR, INC., a
Delaware corporation (the "Guarantor"), to FLEET NATIONAL BANK (the "Secured
Party").

                               W I T N E S S E T H

     WHEREAS, Biosphere Medical, Inc., a Delaware corporation (the "Company"),
the Guarantor and the Secured Party have entered into a Second Amended and
Restated Revolving Credit Agreement dated as of the date hereof (as amended from
time to time, the "Credit Agreement") pursuant to which the Secured Party has
agreed, subject to the terms and conditions set forth therein, to make certain
revolving loans to the Company (collectively, the "Biosphere Loans"), such
Biosphere Loans to be evidenced by the Company's Promissory note in the original
principal amount of $2,000,000 payable to the order of the Secured Party (as
amended or supplemented from time to time, the "Note"); and

     WHERES, the Guarantor owns a majority of the outstanding capital stock of
the Company and the making of the Biosphere Loans will therefore be beneficial
to the Guarantor; and

     WHEREAS, the obligation of the Secured Party to make the Biosphere Loans is
subject to the condition, among others, that the Guarantor shall execute and
deliver this Guaranty Agreement;

     NOW, THEREFORE, in consideration of the willingness of the Secured Party to
make the Biosphere Loans to the Company, and for other good and valuable
consideration, receipt of which is hereby acknowledged by the Guarantor, the
Guarantor hereby agrees as follows:

     1.     GUARANTEED OBLIGATIONS. The Guarantor does hereby irrevocably and
unconditionally guarantee the due and punctual payment and performance by the
Company of the following obligations to the Secured Party (individually, a
"Guaranteed Obligation" and collectively the "Guaranteed Obligations"):

     (a)    Principal of and premium, if any, and interest on the Note; and

     (b)    Any and all other obligations of the Company to the Secured Party
under the Credit Agreement or under any agreement or instrument relating
thereto, all as amended from time to time.

     2.     DEMAND BY SECURED PARTY. Upon failure by the Company punctually to
pay or perform any Guaranteed Obligation when due, after the expiration of any
applicable grace period, the Secured Period may make demand upon the Guarantor
for the payment or performance of such Guaranteed Obligation and the Guarantor
binds and obliges itself to make such payment or performance forthwith upon such
demand.

     3.     Waiver of Demands, Notices, Diligence, etc. The Guarantor hereby
assents to all of the terms and conditions of the Guaranteed Obligations and
waives: (a) demand for the

<Page>

payment of the principal of any Guaranteed Obligation or of any claim for
interest or any part of any thereof (other than the demand provided for in
Section 2 hereof); (b) notice of the occurrence of a default or an event of
default under any Guaranteed Obligation; (c) protest of the nonpayment of the
principal of any Guaranteed Obligation or of any claim for interest or any part
thereof: (d) notice of presentment, demand and protest; (e) notice of acceptance
of any guaranty herein provided for or of the terms and provisions thereof or
hereof by the Secured Party; (f) notice of any indulgences or extensions granted
to the Company or any successor to the Company or any person or party which
shall have assumed the obligations of the Company; (g) any requirement of
diligence or promptness on the part of the Secured Party in the enforcement of
any of its rights under the provisions of any Guaranteed Obligation or this
Guaranty Agreement; (h) any enforcement of any Guaranteed Obligation; (i) any
right which the Guarantor might have to require the Secured Party to proceed
against any other guarantor of the Guaranteed Obligations or to realize on any
collateral security therefor; and (j) any and all notices of every kind and
description which may be required to be given by an statute or rule of law in
any jurisdiction. The waivers set forth in this Section 3 shall be effective
notwithstanding the fact that the Company ceases to exist by reason of its
liquidation, merger, consolidation or otherwise.

     4.     Obligations of Guarantor Unconditional. The obligations of the
Guarantor under this Guaranty Agreement shall be unconditional, irrespective of
the validity, regularity or enforceability of any Guaranteed Obligation, and
shall not be affected by any action taken under any Guaranteed Obligation in the
exercise of any right or remedy therein conferred, or by any failure or omission
on the part of the Secured Party to enforce any right given thereunder or
hereunder or any remedy conferred thereby or hereby, or by any waiver of any
term, covenant, agreement or condition of any Guaranteed Obligation or this
Guaranty Agreement, or by any release of any security or any other guaranty at
any time existing for the benefit of any Guaranteed Obligation, or by the merger
or consolidation of the Company, or by sale, lease or transfer by the Company to
any person of any or all of its properties, or by any action of the Secured
Party granting indulgence or extension to, or waiving or acquiescing in any
default, the Company or any successor to the Company or any person or party
which shall have assumed its obligations, or by reason of any disability or
other defense of the Company or any successor to the Company, or by any
modification, alteration, or by any circumstance whatsoever (with or without
notice to or knowledge of the Guarantor) which may or might in any manner or to
any extent vary the risk of the Guarantor hereunder, it being the purpose and
intent of the Guarantor that the obligations of the Guarantor hereunder shall be
absolute and unconditional under any and all circumstances and shall not be
discharged except by payment or performance as herein provided, and then only to
the extent of such payment or performance.

     5.     Subordination of Claims of Guarantor. Any claims against the Company
to which the Guarantor may be or become entitled (including, without limitation,
claims by subrogation or otherwise by reason of any payment or performance by
the Guarantor in satisfaction and discharge, in whole or in part, of its
obligations under this Guaranty Agreement) shall be and hereby are made subject
and subordinate to the prior payment or performance in full of the Guaranteed
Obligations.

     6.     Reinstatement. This Agreement shall continue to be effective, or be
reinstated, as the case may be, if at any time any amount received by the
Secured Party in respect of the

                                       -2-
<Page>

Guaranteed Obligations is rescinded or must otherwise be restored by the Secured
Party upon the insolvency, bankruptcy, dissolution, liquidation or
reorganization of the Company or the Guarantor or upon the appointment of an
intervenor or conservator of, or trustee or similar official for, the Company or
the Guarantor or any substantial part of any of their respective properties, or
otherwise, all as though said payments had not been made.

     7.     Notices. Except as otherwise provided herein, all notices to the
Guarantor or the Secured Party shall be in writing and shall be deemed to have
been sufficiently given or served for all purposes hereof if personally
delivered or mailed by certified mail, return receipt requested, as follows:

     (a)    if to the Guarantor:

            Sepracor Inc.
            111 Locke Drive
            Marlborough, Massachusetts 01752
            Attention:      Robert F. Scumaci
                            Senior Vice President

            with a copy to:

            John D. Sigel, Esquire
            Hale & Dorr
            60 State Street
            Boston, Massachusetts 02109

     (b)    if to the Secured Party:

            Fleet National Bank
            100 Federal Street
            Mail Stop: MA BOS 01-08-06
            Boston, Massachusetts 02110
            Attention:      Kimberly A. Martone
                            Senior Vice President

            with a copy to:
            George Ticknor, Esquire
            Palmer & Dodge LLP
            One Beacon Street
            Boston, Massachusetts 02108

or at such other address as the party to whom such notice or demand is directed
may have designated in writing to the other party hereto. A notice shall be
deemed to have been given upon the earlier to occur of (i) three (3) days after
the date on which it is deposited in the U.S. mails or (ii) receipt by the party
to whom such notice is directed.

     8.     MISCELLANEOUS. This Guaranty Agreement shall inure to the benefit of
and be binding upon the Secured Party and the Guarantor and their respective
successors and assigns,

                                       -3-
<Page>

and the term "Secured Party" shall be deemed to include any other holder or
holders of any of the Guaranteed Obligations. In case any provision in this
Guaranty Agreement shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby. This Guaranty Agreement may be executed in any
number of counterparts and by the different parties hereto on separate
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument. The Guarantor agrees, as principal obligor and
not as guarantor, to pay to the Secured Party, all reasonable costs and expenses
(including court costs and reasonable attorneys' fees and disbursements)
incurred or expended by the Secured Party in connection with the enforcement of
this Guaranty Agreement.

     9.     GOVERNING LAW; JURISDICTION; WAIVER OF JURY TRIAL. This Guaranty
Agreement, including the validity hereof and the rights and obligations of the
parties hereunder, shall be construed in accordance with and governed by the
laws of the Commonwealth of Massachusetts. The Guarantor, to the extent that it
may lawfully do so, hereby consents to the jurisdiction of the courts of the
Commonwealth of Massachusetts and the United States District Court for the
District of Massachusetts, as well as to the jurisdiction of all courts to which
an appeal may be taken from such courts, for the purpose of any suit, action or
other proceeding arising out of any of its obligations hereunder or with respect
to the transactions contemplated hereby, and expressly waives any and all
objections it may have as to venue in any such courts. The Guarantor further
agrees that a summons and complaint commencing an action or proceeding in any of
such courts shall be properly served and shall confer personal jurisdiction if
served personally or by certified mail to it at its address provided in
Section 7 of this Guaranty Agreement or as otherwise provided under the law of
the Commonwealth of Massachusetts. The Guarantor irrevocably waives all right to
a trial by jury in any suit, action or other proceeding instituted by or against
it in respect of its obligations hereunder or the transactions contemplated
hereby.

     IN WITNESS WHEREOF, the parties have executed this Guaranty Agreement as a
sealed instrument as of the date first above written.

                                   SEPRACOR INC.
                                   By
                                      -------------------------------
                                         Name:  Robert F. Scumaci
                                         Title:  Senior Vice President

                                         The foregoing Guaranty Agreement
                                         is hereby accepted:

                                         FLEET NATIONAL BANK

                                       -4-
<Page>

                                   By
                                      --------------------------------
                                         Name:  Kimberly A. Martone
                                         Title:  Senior Vice President

                                       -5-
<Page>

                                                               February 14, 2000

Sepracor Inc. (the "Company")
111 Locke Drive
Marlborough, Massachusetts  19752

     Re:    $400,000,000 5.00% Convertible Subordinated Debentures due 2007
            (including up to an additional $60,000,000 of 5.00% Convertible
            Subordinated Debentures due 2007 which may be issued at the option
            of the initial purchaser thereof, the "Debentures") issued pursuant
            to a certain Indenture dated as of February 11, 2000 (the
            ("Indenture") by and between the Company and The Chase Manhattan
            Ban, as trustee (the "Trustee")

                           AMENDMENT NO. 1 AND CONSENT

Ladies and Gentlemen:

     Reference is made to that certain Second Amended and Restated Revolving
Credit and Security Agreement dated as of December 22, 1999 (the "Credit
Agreement") among Fleet National Bank (the "Bank"), Sepracor Inc. (the
"Company") and BioSphere Medical, Inc. ("BioSphere").

     The Company plans to issue the Debentures on or after February 14, 2000,
which Debentures shall be subordinated in right of payment to the amounts
payable pursuant to the Credit Agreement and the promissory note issued
thereunder and any other Obligations and to the obligations of the Company to
the Bank under (a) the Guaranty Agreement dated as of September 15, 1998 with
respect to certain loans to Hemasure Inc., (b) the Guaranty Agreement dated as
of December 22, 1999 with respect to certain loans to BioSphere (collectively
with the Guaranty Agreement described in clause (a), the "Guaranty Agreements")
by and between the Company and the Bank. Without the Bank's waiver pursuant to
this Consent and Amendment, Section 6.1 of the Credit Agreement would prohibit
the issuance by the Company of the Debentures and Section 6.8 would prohibit the
payment of principal or interest on the Debentures.

     The Company hereby covenants to the Bank that true and correct copies of
(i) the Confidential Offering Memorandum describing the issuance of the
Debentures and delivered to the purchasers thereof and (ii) the Indenture will
be promptly delivered to the Bank in the final and effective form.

     In reliance upon such representations and warranties and the subordination
provisions contained in the Indenture, and contingent thereon and upon receipt
by the Bank of a copy of this letter executed by the Company:

     (i)   the Bank, notwithstanding the provisions of Section 6.1 of the Credit
Agreement, the other Loan Documents, the Guaranty Agreements and the Put
Agreement, hereby consents to the issuance of the Debentures by the Company; and

<Page>

     (ii)  the Bank and the Company agree that the Credit Agreement is amended
as follows:

           (a)  the definition of "Subordinated Notes" set forth in Section 1.1
     of the Credit Agreement is hereby deleted and replaced by the following:

                  SUBORDINATED NOTES. The Borrower's (i) $93,048,000 6 1/4%
            Convertible Subordinated Debentures due 2005 issued by the Borrower
            pursuant to an Indenture dated February 5, 1998 from the Borrower to
            The Chase Manhattan Bank, (ii) $300.000,000 7.00% Convertible
            Subordinated Debentures due 2005 issued pursuant to an Indenture
            dated December 15, 1998 by the Borrower to The Chase Manhattan Bank
            and (iii) $400,000,000 5,00% Convertible Subordinated Debentures due
            2007 issued pursuant to an Indenture dated February 11, 2000 by the
            Borrower to The Chase Manhattan Bank (plus up to an additional
            $60,000,000 of such 5.00% Convertible Subordinated Debentures which
            may be issued at the Option of the initial purchaser thereof).

           (b)  The second paragraph of Section 6.8 of the Credit Agreement is
     amended by deleting the following phrase on the second line, "issued and
     outstanding on the date of this Agreement".

     The Company hereby confirms that: (a) the representations and warranties of
the Company contained in Section 4 of the Credit Agreement are true on and as of
the date hereof as if made on such date (except to the extent that such
representations and warranties expressly relate to an earlier date); (b) the
Company is in compliance in all material respects with all of the terms and
provisions set forth in the Credit Agreement on its part to be observed or
performed thereunder; and (c) after giving effect to this Consent and Amendment,
no Event of Default specified in Section 8 of the Credit Agreement, nor any
event which with the giving of notice or expiration of any applicable grace
period or both would constitute such an Event of Default, shall have occurred
and be continuing.

     Except as expressly stated herein, this letter (i) does not amend or modify
either of the Credit Agreement, any Loan Documents, the Guaranty Agreements or
the Put Agreement and (ii) does not constitute a consent to any other actions or
the issuance of any Indebtedness except for the Debentures. All provisions of
the Credit Agreement (as amended hereby), the Loan Documents, the Guaranty
Agreement and the Put Agreement shall remain in full force and effect and,
except as expressly stated herein, nothing herein shall constitute a waiver of
any such provision.

                                       -2-
<Page>

     Capitalized terms used herein which are defined in the Credit Agreement
have the same meanings herein as therein.

                                   Sincerely,

                                   FLEET NATIONAL BANK

                                   By: /s/ Thomas W. Davies
                                       -----------------------
                                       Name:  Thomas W. Davies
                                       Title: Senior Vice President

The foregoing is hereby
agreed to and accepted.

SEPRACOR INC.

By: /s/ Robert F. Scumaci
   -------------------------
   Name:  Robert F. Scumaci
   Title: Senior Vice President, Finance
          and Administration

                                       -3-
<Page>

                                                                November 8, 2001

Sepracor Inc.
111 Locke Drive
Marlborough, Massachusetts  01752

     Re:    $400,000,000 5.75% Convertible Subordinated Notes with
            Auto-Conversion Provision due 2006 (SNAPs(SM)) (including up to an
            additional $100,000,000 of 5.75% Convertible Subordinated Notes with
            Auto-Conversion Provision due 2006 which may be issued at the option
            of the initial purchaser thereof,) (the "Notes") issued pursuant to
            a certain Indenture dated as of November 14, 2001 (the "Indenture")
            by and between the Company and The Chase Manhattan Bank, as trustee
            (the "Trustee")

                           AMENDMENT NO. 2 AND CONSENT

Ladies and Gentlemen:

     Reference is made to that certain Second Amended and Restated Revolving
Credit Agreement dated as of December 22, 1999, as amended on February 14, 2000
(the "Credit Agreement") among Fleet National Bank (the "Bank"), Sepracor Inc.
(the "Company") and BioSphere Medical, Inc. ("BioSphere").

     The Company plans to issue the Notes on or after November 14, 2001, which
Notes shall be subordinated in right of payment to the amounts payable pursuant
to the Credit Agreement and the promissory note issued thereunder and any other
Obligations. Without the Bank's waiver pursuant to this Consent and Amendment,
Section 6.1 of the Credit Agreement would prohibit the issuance by the Company
of the Notes and Section 6.8 would prohibit the payment of principal or interest
on the Notes.

     The Company hereby covenants to the Bank that true and correct copies of
(i) the Confidential Offering Circular describing the issuance of the Notes will
be delivered to the purchasers thereof and (ii) the Indenture will be promptly
delivered to the Bank in the final and effective form.

     In reliance upon such representations and warranties and the
subordination provisions contained in the Indenture, and contingent thereon
and upon receipt by the Bank of a copy of this letter executed by the Company:

     (i)   the Bank, notwithstanding the provisions of Section 6.1 of the Credit
Agreement, and the other Loan Documents, hereby consents to the issuance of the
Notes by the Company and waives any Event of Default which may occur under the
Credit Agreement as a result of such issuance by the Company;

     (ii)  the Bank, notwithstanding the provisions of Section 6.8 of the Credit
Agreement and the other Loan Documents, hereby consents to any payment by the
Company of principal of,

<Page>

premium, if any, or interest on, or otherwise in respect of, the Notes, all as
pursuant to the provisions of the Indenture; and

     (iii) the Bank and the Company agree that the Credit Agreement is amended
as follows:

           (a)  the definition of "Subordinated Notes" set forth in Section 1.1
     of the Credit Agreement is hereby deleted in its entirety and replaced by
     the following:

                  SUBORDINATED NOTES. The Borrower's (i) $300,000,000 7.00%
            Convertible Subordinated Debentures due 2005 issued pursuant to an
            Indenture dated December 15, 1998 between the Borrower and The Chase
            Manhattan Bank, (ii) $460,000,000 5.00% Convertible Subordinated
            Debentures due 2007 issued pursuant to an Indenture dated February
            14, 2000 between the Borrower and The Chase Manhattan Bank and (iii)
            $400,000,000 5.75% Convertible Subordinated Notes with
            Auto-Conversion Provision due 2006 (SNAPs(SM)) issued pursuant to an
            Indenture dated November 14, 2001 between the Borrower and the Chase
            Manhattan Bank (plus up to an additional $100,000,000 of such 5.75%
            Convertible Subordinated Notes with Auto-Conversion Provision which
            may be issued at the option of the initial purchaser thereof).

     The Company hereby represents to the Bank that the Company owns
approximately 25% of the outstanding capital stock of BioSphere. Each of the
Company and BioSphere hereby acknowledge and agree that at such time when the
Company no longer owned at least 51% of the outstanding capital stock of
BioSphere (i) pursuant to Section 2.3 of the Credit Agreement the BioSphere
Sublimit was automatically terminated and all BioSphere Loans were required to
be paid in full and (ii) the Bank has no obligation under the Credit Agreement
or otherwise to make any BioSphere Loans or any other advances to BioSphere.
Based on the above representation and provided that BioSphere is not on the date
hereof and will not be at any time in the future be a Subsidiary (as such term
is defined in the Credit Agreement) of the Company, the Bank agrees that the
provisions of Section 6.7 of the Credit Agreement would not apply to BioSphere.

     The Company hereby confirms that: (a) the representations and warranties of
the Company contained in Section 4 of the Credit Agreement are true on and as of
the date hereof as if made on such date (except to the extent that such
representations and warranties expressly relate to an earlier date); (b) the
Company is in compliance in all material respects with all of the terms and
provisions set forth in the Credit Agreement on its part to be observed or
performed thereunder; and (c) after giving effect to this Consent and Amendment,
no Event of Default specified in Section 8 of the Credit Agreement, nor any
event which with the giving of notice or expiration of any applicable grace
period or both would constitute such an Event of Default, shall have occurred
and be continuing.

     Except as expressly stated herein, this letter (i) does not amend or modify
any of the Credit Agreement or any Loan Documents and (ii) does not constitute a
consent to any other actions or the issuance of any Indebtedness except for the
Notes. All provisions of the Credit

                                       -2-
<Page>

Agreement (as amended hereby) and the Loan Documents shall remain in full force
and effect and, except as expressly stated herein, nothing herein shall
constitute a waiver of any such provision.

     Capitalized terms used but not defined herein which are defined in the
Credit Agreement have the same meanings herein as therein.

                                   Sincerely,

                                   FLEET NATIONAL BANK

                                   By: /s/ David A. Meagher
                                       ---------------------------------
                                       Name: David A. Meagher
                                       Title: Senior Associate

The foregoing is hereby
agreed to and accepted.

SEPRACOR INC.

By: /s/ Robert F. Scumaci
   -------------------------
   Name:  Robert F. Scumaci
   Title: Executive Vice President, Finance
          and Administration

BIOSPHERE MEDICAL, INC.

By: /s/ Robert M. Palladino
   -------------------------
   Name:  Robert M. Palladino
   Title: Vice President and Chief Financial
          Officer
                                       -3-
<Page>

                                  AMENDMENT TO
                           SECOND AMENDED AND RESTATED
                        REVOLVING CREDIT AGREEMENT AMONG
                              FLEET NATIONAL BANK,
                                  SEPRACOR INC.
                                       AND
                             BIOSPHERE MEDICAL, INC.

     This Amendment (the "Amendment") to the Second Amended and Restated
Revolving Credit Agreement, dated as of December 22, 1999 (as amended, the
"Revolving Credit Agreement'), among Fleet National Bank ("Fleet"), Sepracor
Inc. ("Sepracor") and BioSphere Medical, Inc. ("BioSphere") is dated as of
November 13, 2001 and effective as of December 22, 1999.

     WHEREAS, Fleet, Sepracor and BioSphere are parties to the Revolving Credit
Agreement.

     WHEREAS, Fleet, Sepracor and BioSphere wish to amend the Revolving Credit
Agreement on the terms set forth herein.

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

1.   Capitalized terms used herein and not otherwise defined will have the
     meaning set forth in the Revolving Credit Agreement.

2.   Section 1.1 of the Revolving Credit Agreement is hereby amended by adding
     a new definition of "Total Senior Liabilities" to read in its entirety as
     follows:

          "Total Senior Liabilities. Total Liabilities minus, without
     duplication, the aggregate of Subordinated Indebtedness and Subordinated
     Notes."

3.   Section 5.9 of the Revolving Credit Agreement is hereby amended by deleting
     Section 5.9 in its entirety and inserting in lieu thereof the following:

          "5.9 Minimum Liquidity Ratio. At the end of each fiscal quarter, the
     Cash Equivalent Amount of the Borrower shall be equal to or greater than
     150% of its Total Senior Liabilities."

4.   In all other respects, the Revolving Credit Agreement will be in full
     force and effect.

5.   This Amendment will be deemed to be a contract made under seal and shall
     be construed in accordance with and governed by the laws of the
     Commonwealth of Massachusetts (without giving effect to any conflicts of
     laws provisions contained therein).

<Page>

6.   This Amendment may not be amended, waived, discharged or terminated
     except by a written instrument signed by the Bank and, in the case of
     amendment, by the Credit Parties. This Amendment shall be binding upon and
     inure to the benefit of the Credit Parties and Fleet and their respective
     successors and assigns; provided that the Credit Parties may not assign or
     transfer their rights or obligations hereunder. This Amendment may be
     signed in any number of counterparts with the same effect as if the
     signatures hereto and thereto were upon the same instrument.

                                       -2-
<Page>

     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
by their duly authorized officers and effective as of the day and year first
above written.

                                 SEPRACOR INC.

                                 By: /s/ Robert F. Scumaci
                                     -------------------------------------------
                                       Name:  Robert F. Scumaci
                                       Title: Executive Vice President, Finance
                                              and Administration

                                 BIOSPHERE MEDICAL, INC.

                                 By: /s/ Robert M. Palladino
                                     -------------------------------------------
                                       Name:  Robert M. Palladino
                                       Title: Vice President and Chief Financial
                                              Officer

                                 FLEET NATIONAL BANK

                                 By: /s/ Kimberly A. Martone
                                     -------------------------------------------
                                       Name:  Kimberly A. Martone
                                       Title: Managing Director

                                       -3-

<Page>

                    FOURTH AMENDMENT TO THE CREDIT AGREEMENT

       This FOURTH AMENDMENT (this "AMENDMENT") dated as of December 28, 2001 to
the Credit Agreement is among SEPRACOR INC. (the "BORROWER"), BIOSPHERE MEDICAL,
INC. ("BIOSPHERE", collectively with the Borrower, the "CREDIT PARTIES") and
FLEET NATIONAL BANK (the "BANK").

       WHEREAS, the Credit Parties and the Bank wish to amend the Revolving
Credit Agreement, the parties hereby agree as follows:

       NOW, THEREFORE, in consideration of the foregoing and the agreements
contained herein, the parties hereby agree as follows:

       1. REFERENCE TO REVOLVING CREDIT AGREEMENT.

       Reference is made to the Second Amended and Restated Revolving Credit
Agreement dated as of December 22, 1999, among the Credit Parties and the Bank
as amended by Amendment No. 1 and Consent dated February 14, 2001, Amendment No.
2 and Consent dated November 8, 2001, and the Amendment dated as of November 13,
2001 (as so amended and as the same may be further amended and restated from
time to time, the "REVOLVING CREDIT AGREEMENT"). Capitalized terms used herein
which are defined in the Revolving Credit Agreement have the same meanings
herein as therein, except to the extent that such meanings are amended hereby.

       2. AMENDMENTS AND TERMINATIONS. The Credit Parties and the Bank agree
that the Credit Agreement is hereby amended, effective as of the date hereof, as
follows:

       (a) Section 1.1 of the Credit Agreement is amended by deleting the
definition of REVOLVING CREDIT TERMINATION DATE and replacing it with the
following: "REVOLVING CREDIT TERMINATION DATE. March 31, 2002 or such earlier
date on which the commitment to make Revolving Loans is terminated or the
Revolving Commitment Amount is reduced to zero in accordance with the terms of
this Agreement."

       (b) As the Credit Parties and the Bank have agreed that the BioSphere
Sublimit has been terminated and no amounts are outstanding thereunder,
BioSphere shall no longer be deemed to be a party to the Revolving Credit
Agreement. All duties, rights, and obligations of Biosphere contained in the
Revolving Credit Agreement are hereby terminated. All references in the
Revolving Credit Agreement to the "Credit Parties" shall refer only to the
Borrower.

       (c) The Guaranty Agreement be and hereby is terminated in its entirety
and shall have no further force or effect.

       (d) The BioSphere Medical Inc. Promissory Note dated December 22, 1999,
in aggregate principal amount of $2,000,000 made in favor of the Bank by
BioSphere is cancelled and terminated and of no further force and effect, and
BioSphere has no further obligations under the Note.

<Page>

       3. NO DEFAULT; REPRESENTATIONS AND WARRANTIES, ETC.

       (a) The Borrower hereby confirms that: (i) the representations and
warranties of the Borrower contained in Article 4 of the Revolving Credit
Agreement are true on and as of the date hereof as if made on such date (except
to the extent that such representations and warranties expressly relate to an
earlier date); (ii) the Borrower is in compliance with all of the terms and
provisions set forth in the Credit Agreement on their part to be observed or
performed thereunder; and (iii) after giving effect to this Amendment, no Event
of Default, nor any event which with the giving of notice or expiration of any
applicable grace period or both would constitute such an Event of Default, shall
have occurred and be continuing.

       4. CONDITIONS TO THIS AMENDMENT.

       Concurrently herewith (and as conditions to the Bank's consent to this
Amendment), the Credit Parties will furnish the Bank with the following:

       (a) Appropriate corporate resolutions, if necessary, and such other
certificates, instruments and documents as the Bank may reasonably request for
the purpose of implementing or effectuating the provisions of the Credit
Agreement, as hereby amended, or this Amendment.

       (b) Such other documents and instruments as the Bank may reasonably
require in order to put this Amendment into full force and effect.

       (c) The Borrower shall have paid all reasonable expenses, including legal
fees and disbursements incurred by the Bank in connection with this Amendment
and the transactions contemplated hereby.

       5. MISCELLANEOUS.

       (a) Except to the extent specifically amended or terminated hereby, the
Revolving Credit Agreement, the Loan Documents and all related documents shall
remain in full force and effect. Whenever the terms or sections amended hereby
shall be referred to in the Credit Agreement, Loan Documents or such other
documents (whether directly or by incorporation into other defined terms), such
defined terms shall be deemed to refer to those terms or sections as amended by
this Amendment.

       (b) This Amendment may be executed in any number of counterparts, each of
which, when executed and delivered, shall be an original, but all counterparts
shall together constitute one instrument.

       (c) This Amendment shall be governed by the laws of the Commonwealth of
Massachusetts and shall be binding upon and inure to the benefit of the parties
hereto and their respective successors and assigns.

                                       2

<PAGE>

       IN WITNESS WHEREOF, the parties hereto have executed this Amendment which
shall be deemed to be a sealed instrument as of the date first above written.

                                       BORROWER

                                       SEPRACOR INC.,
                                       a Delaware corporation

                                       By: /s/ ROBERT F. SCUMACI
                                          ------------------------
                                          Name:  Robert F. Scumaci
                                          Title: Executive Vice President,
                                                 Finance and Administration

                                       3

<PAGE>

                                       BIOSPHERE MEDICAL, INC.,
                                       a Delaware corporation

                                       By: /s/ JOHN CARNUCCIO
                                          ------------------------
                                          Name:  John Carnuccio
                                          Title: President and CEO

                                       4

<PAGE>

                                       BANK

                                       FLEET NATIONAL BANK

                                       By: /s/ KIMBERLY MARTONE
                                          ------------------------
                                          Name: Kimberly Martone
                                          Title:  Managing Director

                                       5

<Page>

                                   ALLONGE TO
               $25,000,000 PROMISSORY NOTE DATED DECEMBER 22, 1999
                                    ISSUED BY
                                  SEPRACOR INC.
                           AND PAYABLE TO THE ORDER OF
                               FLEET NATIONAL BANK

                                                           Boston, Massachusetts
                                                               December 28, 2001

     This Allonge shall be affixed to that certain $25,000,000 Promissory Note
dated December 22, 1999 (the "NOTE") made by Sepracor Inc. (the "BORROWER") and
made payable to the order of FLEET NATIONAL BANK (the "BANK") and shall become a
permanent part thereof and shall amend the Note as provided herein.

     By their execution of this Allonge in the spaces provided below, each of
the Bank and the Borrower hereby agrees that the fifth line of the Note is
amended by deleting "December 31, 2001" and replacing it with "March 31, 2002."

     Except as specifically amended hereby, the Note shall remain in full force
and effect. The undersigned hereby authorizes the Bank to affix this Allonge to
the Note and it shall for all purposes henceforth be part of the Note.

                                   SEPRACOR INC.

                                   By: /s/ Robert F. Scumaci
                                      ---------------------------------------
                                       Name:  Robert F. Scumaci
                                       Title: Executive Vice President,
                                              Finance and Administration

AGREED AND ACCEPTED:

FLEET NATIONAL BANK

By: /s/ Kimberly A. Martone
   -------------------------
      Name:  Kimberly A. Martone
      Title: Managing Director<Page>

                                                                   EXHIBIT 10.42

                              [SEPRACOR LETTERHEAD]

                                   **REVISED**

VIA FAX & FEDERAL EXPRESS

September 10, 1999

Mr. James O'Shea
4005 Springfield Lane
Greenville, DE 19807

Dear Jim:

It is my pleasure to offer you the position of President and Chief Operating
Officer of Sepracor. This position will report to the Chairman and Chief
Executive Officer of the Company.

In this role, you will be responsible for all commercial operations of Sepracor,
including sales and marketing, business development, distribution, and
production. You will b responsible for the development and execution of the
Annual Operating Plan and will work together with the CEO to develop and
maintain a five-year strategic plan, and play an integral role in all major
strategic initiatives, such as acquisition.

In addition, you will play a major role in directing the Company's investments
in R&D through the establishment of a process of portfolio analysis and
planning.

We are pleased to offer you a salary of $350,000, paid bi-weekly. You will also
receive a yearly bonus of $200,000 paid annually upon achievement of mutually
acceptable goals which we will establish together.

In addition, you will also receive a stock option grant, contingent upon Board
of Directors' approval, for 500,000 shares at a strike price equivalent to the
price of Sepracor common stock at the close of the market on the day of the next
Board of Directors' meeting. 300,000 shares will vest over five years at a rate
of 20% per year, starting on the first anniversary of the option grant. 100,000
shares will begin to vest and will vest over four years at a of 25% per year,
when Sepracor common stock has traded at greater than $150/share for twenty
consecutive trading days. 100,000 shares will begin to vest and will vest over
three years at a rate of 33% per year, when Sepracor common stock has traded at
greater than $200/share for twenty consecutive trading days.

In the event involuntary termination occurs, continuance of your base salary and
benefits will be provided for you for one year from the date of your
termination.

<Page>

In the event of a change of control in the ownership of the Company as defined
by greater than 50% ownership of the common shares outstanding, your unvested
stock options would vest on the date of change of control, as per the Company's
Stock Option Plan.

The Company will reimburse you for all reasonable relocation expenses, including
realty and closing costs on the sale and purchase of your current and new house,
respectively, and for moving of household goods.

Jim, I am delighted at the prospect of your joining Sepracor. I look forward to
working together to create an unusually successful company, and to having great
fun at the same time.

Please sign below to indicate your acceptance of this offer.

Very truly yours,

/s/  Timothy J. Barberich

Timothy J. Barberich
Chairman & Chief Executive Officer

ACCEPTED AND AGREED TO HEREIN:

/s/  James O'Shea                                        9/21/99
------------------------------                ----------------------------
James O'Shea                                  Date

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