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                                                                   Exhibit 10.3

                              ASSIGNMENT AGREEMENT

This Assignment Agreement (hereinafter referred to as "Agreement") is made
and effective as of the 25th day of August, 1999, by and between
SEPRACOR INC. (hereinafter referred to as "SEPRACOR") with a principal place
of business located at 111 Locke Drive, Marlborough, Massachusetts 01752, and
GEORGETOWN UNIVERSITY (hereinafter referred to as "UNIVERSITY") having a
principal place of business at 37th and O Streets NW, Washington, DC 20057

                                   WITNESSETH:

WHEREAS, SEPRACOR and UNIVERSITY have executed two Statements of Agreement,
one effective as of 1 October 1990 (Exhibit A), and one effective as of 1
January 1993 (Exhibit B), as amended by the Amendment to Agreement effective
as of 16 January 1998 (Exhibit C)(collectively, the "Statements of
Agreement");

WHEREAS, under the Statements of Agreement UNIVERSITY has granted to SEPRACOR
certain exclusive rights under University Intellectual Property and Joint
Intellectual Property, as such terms are defined in the Statements of
Agreement, but has retained its share of ownership of such intellectual
property; and

WHEREAS, SEPRACOR wishes to own the entire right, title, and interest in
University Intellectual Property and Joint Intellectual Property, and,
pursuant to the terms hereof, UNIVERSITY is willing to assign such to
SEPRACOR.

NOW, THEREFORE, in consideration of the promises and mutual covenants
contained herein, the parties agree to as follows:

ARTICLE I - Definitions

1.1      All terms appearing herein and not otherwise defined herein and defined
         in the Statements of Agreement shall have the meaning set forth in the
         Statement of Agreement effective 1 January 1993, as amended by the
         Amendment to Agreement effective 16 January 1998, except that such
         terms when used herein are understood to refer to the cumulative
         subject matter of the Statements of Agreement.


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ARTICLE II- Grant

2.1      Effective as of the Closing Date (as hereinafter defined), UNIVERISITY
         hereby assigns to SEPRACOR all of UNIVERSITY's right, title, and
         interest in Joint Intellectual Property and University Intellectual
         Property, including but not limited to Invention(s), Licensed
         Patent(s), and Joint Licensed Patent(s). UNIVERSITY shall cooperate
         fully at SEPRACOR's expense in executing any and all documents
         necessary to effectuate such assignment to SEPRACOR and in prosecution
         of Licensed Patents and Joint Licensed Patents. The Licensed Patent(s)
         and Joint Licensed Patent(s) presently existing and assigned to
         SEPRACOR pursuant to this Agreement are listed in Exhibit D.

2.2      From and after the Closing Date, UNIVERSITY, its directors, officers,
         employees, consultants, and agents, shall cooperate fully with and
         provide assistance to SEPRACOR and its nominees with regard to
         prosecution, maintenance, enforcement, or defense relating to Joint
         Intellectual Property and University Intellectual Property, including
         but not limited to Invention(s), Licensed Patent(s), or Joint Licensed
         Patent(s), and shall execute any and all documents SEPRACOR or its
         nominees deem necessary to the prosecution, maintenance, enforcement,
         or defense of such Joint Intellectual Property and University
         Intellectual Property, all at SEPRACOR's expense.

ARTICLE III - Consideration

3.1      Common Stock.  In partial consideration for the assignment and other
         obligations set forth in Article II, SEPRACOR shall issue to
         UNIVERSITY on the Closing Date, one  hundred thousand (100,000)
         shares of SEPRACOR common stock ($0.10 par value per
         share)(hereinafter the "Shares").  Effective upon issuance of the
         Shares to UNIVERSITY, SEPRACOR grants to UNIVERSITY the registration
         rights with respect to the Shares set forth in Exhibit E, which is
         incorporated herein by reference and made a part hereof.  In
         connection with issuance of the Shares on the Closing Date,
         UNIVERSITY shall execute and deliver to SEPRACOR an Investment
         Letter in a form substantially as shown in Exhibit F.

3.2      Cash. In partial consideration for the assignment and other obligations
         set forth in Article II, on the Closing Date SEPRACOR shall pay to
         UNIVERSITY by wire transfer of immediately available funds (or such

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         other method of funds transfer as may be mutually agreed upon by
         SEPRACOR and UNIVERSITY) Ten Million Dollars ($10,000,000).

3.3      The closing of the transactions contemplated hereby (the "Closing")
         shall occur no later than ten (10) days after the effective date as
         first above written (the "Closing Date"). The Closing shall take place
         at the offices of Covington & Burling, 1201 Pennsylvania Avenue, NW,
         Washington, DC, at 10:00 AM on the Closing Date, or at such other
         location or such other time as may be mutually agreed upon by SEPRACOR
         and the UNIVERSITY. At the Closing, SEPRACOR shall (a) pay to the
         UNIVERSITY the cash portion of the consideration as provided in Section
         3.2 and (b) deliver to the UNIVERSITY a duly executed stock
         certificate(s) evidencing the Shares issued in the name of the
         UNIVERSITY.

3.4      REGISTRATION RIGHTS. From and after the Closing Date, UNIVERSITY shall
         have, and SEPRACOR shall be bound by, the Registration Rights attached
         hereto as Exhibit E and incorporated herein by reference (the
         "Registration Rights"). The Registration Rights shall survive the
         Closing Date and the expiration or termination of this Agreement.


ARTICLE IV  - Termination of Statements of Agreement, Retained Rights or
Obligations

Effective as of the Closing Date, the Statements of Agreement are hereby
terminated, except that Article 7 Publicity, Article 8 - Publications, and
Article 16 - Indemnification of each statement of Agreement shall survive
termination and remain in full force and effect. Except as stated in the
preceding sentence, from and after the Closing Date, UNIVERSITY shall retain
no rights under Joint Intellectual Property or University Intellectual
Property, and SEPRACOR shall have no remaining obligations to UNIVERSITY. By
way of non-limiting example, the Payments made by Sepracor hereunder shall be
in full satisfaction of any and all of SEPRACOR's payment obligations to
UNIVERSITY arising out of this Agreement or the Statements of Agreement;
SEPRACOR shall have no obligation to UNIVERSITY in respect of use, non-use,
licensing, enforcement, prosecution, abandonment, maintenance, or any other
matter relating to Joint Intellectual Property or University Intellectual
Property; SEPRACOR shall have no reporting obligations and no obligation to
make any further payments to UNIVERSITY relating to University Intellectual
Property, Joint Intellectual Property, or Licensed Product, including but not
limited to any portion of Net Sales or royalty payments, lump sum payments,
or Equity received by SEPRACOR.

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ARTICLE V  - Sepracor Representations and Warranties

5.1      ORGANIZATION. SEPRACOR is (a) a corporation duly organized, validly
         existing and in good standing under the laws of the State of Delaware
         and (b) duly qualified and in good standing as a foreign corporation in
         each jurisdiction where the properties owned, leased or operated, or
         the business conducted, by it requires such qualification, except where
         a failure so to qualify either singly or in the aggregate would not
         have a material adverse effect on the financial condition, assets,
         business, prospects or results of operations of SEPRACOR.

5.2      POWER. SEPRACOR has all requisite power and authority to (a) execute,
         deliver and perform this Agreement and (b) own, lease and operate its
         properties and assets and to carry on its business as presently
         conducted.

5.3      DUE EXECUTION. This Agreement has been duly authorized, executed and
         delivered by SEPRACOR and is the legal, valid and binding obligation of
         SEPRACOR, enforceable against SEPRACOR in accordance with its terms.

5.4      NON-CONTRAVENTION. The execution, delivery and performance of this
         Agreement and the consummation of the transactions contemplated hereby
         will not (a) violate in any material respect any federal, state or
         local law, statute, ordinance, rule or regulation which is or may be
         applicable to SEPRACOR; (b) violate in any material respect any
         agreement, indenture, instrument, note, mortgage, lease, license,
         franchise, permit or other authorization, right, restriction or
         obligation to which SEPRACOR is a party or may be bound; (c) violate in
         any material respect any order, injunction, judgment or decree of any
         court or other governmental authority or arbitrator by which SEPRACOR
         is or may be bound; (d) constitute an act of bankruptcy, preferences,
         insolvency or fraudulent conveyance under any bankruptcy act or other
         law for the protection of debtors or creditors; or (e) conflict with or
         result in any material breach or violation of the terms, conditions or
         provisions of the Certificate of Incorporation or Bylaws of SEPRACOR.

5.5      SHARES. All of the Shares to be issued in connection with the
         transactions contemplated hereby, on the Closing Date, will be (a) duly
         authorized, validly issued, fully paid and nonassessable and (b)
         offered and sold pursuant to a valid exemption from the registration
         requirements under the Securities Act of 1933, as amended (the
         "Securities Act").

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5.6      CAPITAL STOCK OF SEPRACOR. The authorized capital stock of SEPRACOR
         consists of 80,000,000 shares of common stock, par value $0.10 per
         share, of which 32,793,644 are issued and outstanding as of April 7,
         1999, and 1,000,000 shares of preferred stock, par value $0.10 per
         share, none of which are outstanding as of the date hereof. All of the
         issued and outstanding shares of capital stock of SEPRACOR are validly
         issued and outstanding, fully paid and nonassessable, and none of such
         shares has been issued in violation of any preemptive or other rights
         of any person, the Securities Act or, to the best knowledge of
         SEPRACOR, any state securities or blue sky law.

5.7      SEC FILINGS. SEPRACOR has heretofore delivered or made available to
         UNIVERSITY true and complete copies of its Annual Report on Form 10-K
         for the year ended December 31, 1998, as filed with the SEC (the "SEC
         Filing"). SEPRACOR has made all filings required under the Securities
         Exchange Act of 1934, as amended (the "Exchange Act"). As of its date,
         of the SEC Filing did not contain any untrue statement of a material
         fact or omit to state a material fact required to be stated therein or
         necessary to make the statements therein, in the light of the
         circumstances under which they were made, not misleading.

5.8      MATERIAL ADVERSE CHANGE. All material adverse changes in the financial
         condition, assets, liabilities (contingent or otherwise), business or
         results of operations of SEPRACOR since December 31, 1998, have been
         publicly announced by SEPRACOR.

ARTICLE VI  - University Representations and Warranties

6.1      POWER.   UNIVERSITY has all requisite power and authority to
         execute, deliver and perform this Agreement.

6.2      DUE EXECUTION. This Agreement has been duly authorized, executed and
         delivered by UNIVERSITY and is the legal, valid and binding obligation
         of UNIVERSITY, enforceable against UNIVERSITY in accordance with its
         terms.

6.3      NON-CONTRAVENTION. The execution, delivery and performance of this
         Agreement and the consummation of the transactions contemplated hereby
         will not (a) violate in any material respect any federal, state or
         local law, statute, ordinance, rule or regulation which is or may be
         applicable to

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         UNIVERSITY; (b) violate in any material respect any agreement,
         indenture, instrument, note, mortgage, lease, license, franchise,
         permit or other authorization, right, restriction or obligation to
         which UNIVERSITY is a party or may be bound; (c) violate in any
         material respect any order, injunction, judgment or decree of any
         court or other governmental authority or arbitrator by which
         UNIVERSITY is or may be bound; (d) constitute an act of bankruptcy,
         preferences, insolvency or fraudulent conveyance under any
         bankruptcy act or other law for the protection of debtors or
         creditors; or (e) conflict with or result in any material breach or
         violation of the terms, conditions or provisions of the Bylaws of
         UNIVERSITY.

ARTICLE VII - Entire Agreement

7.1      This Agreement, together with the attached Exhibits, is the entire
         agreement between the parties and constitutes all the terms,
         conditions, and covenants of this agreement.


IN WITNESS WHEREOF, the parties have caused this Assignment Agreement to be
executed in their names by their properly and duly authorized officers or
representatives in duplicate and under seal as of the day and year first
written above.

SEPRACOR INC.                               GEORGETOWN UNIVERSITY


By: /s/ Douglas E. Reedich                  By: /s/Nicole F. Mandeville
   ---------------------------                 ----------------------------

Date: August 25, 1999                       Date: August 24, 1999
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