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                                                                    EXHIBIT 10.1

          Confidential Materials omitted and filed separately with the
         Securities and Exchange Commission. Asterisks denote omissions.

                    FIRST AMENDMENT TO CO-PROMOTION AGREEMENT

     This First Amendment to Co-Promotion Agreement (hereinafter "Amendment") is
made and effective this 19 day of January, 2000, by and between Sepracor Inc.,
having its principal offices at 111 Locke Drive, Marlborough, Massachusetts
01752 ("Sepracor"), and Abbott Laboratories Inc., through its Ross Products
Division, having its principal offices at 625 Cleveland Avenue, Columbus, Ohio
43215 ("Abbott").

     WHEREAS, Sepracor and Abbott executed a Co-Promotion Agreement effective as
of November 18, 1999 (hereinafter referred to as "Agreement').

     NOW, THEREFORE, Sepracor and Abbott hereby agree to amend the Agreement as
follows:

 1.  All terms in this Amendment, unless otherwise defined herein, shall have
     the same meaning as set forth in the Agreement.

 2.  Section 9.1 of the Agreement is deleted in its entirety, and a new
     Section 9.1 is added in lieu thereof which reads in its entirety as
     follows:

     9.1  PRODUCT RIGHTS EX-U.S. In the event Sepracor desires to have an entity
          other than Sepracor, or a Sepracor Affiliate market, sell, distribute,
          or promote the Product to the Pediatric Market in any country outside
          the Territory except Italy, Vatican City and San Marino, Sepracor
          shall give Abbott first notice of the opportunity to have Abbott
          market, sell, distribute, promote, co-promote or co-market the Product
          to the Pediatric Market in such country through a right of first
          negotiation for not more than thirty (30) calendar days after
          Sepracor's notice to Abbott hereunder. If during the Term of this
          Agreement, the rights relating to sale and distribution of Product in
          Italy, Vatican City and San Marino granted to a Third Party under an
          existing agreement, revert to Sepracor, such countries shall
          automatically be subject to the terms of the preceding sentence,
          beginning at the time such rights revert to Sepracor.

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 3.  Section 9.2 of the Agreement is deleted in its entirety, and a new Section
     9.2 is added in lieu thereof which reads in its entirety as follows:

     9.2  PRODUCT RIGHTS TO GERIATRIC MARKET. In the event Sepracor desires to
          have an entity other than Sepracor or a Sepracor Affiliate market,
          sell, distribute, or promote the Product specifically for use by the
          Geriatric Market in the Territory (and, if Abbott and Sepracor enter
          into any agreement with respect to the Geriatric Market in the
          Territory, in any country outside the Territory except, Italy, Vatican
          City and San Marino), Sepracor shall give Abbott first notice of the
          opportunity to have Abbott market, sell, distribute, promote,
          co-promote or co-market the Product for use by Geriatric Market in the
          Territory (and, if Abbott and Sepracor enter into any agreement with
          respect to the Geriatric Market in the Territory, in any country
          outside the Territory except Italy, Vatican City and San Marino)
          through a right of first negotiation for not more than thirty (30)
          calendar days after Sepracor's notice to Abbott hereunder. If during
          the Term of this Agreement, the rights relating to sale and
          distribution of Product in Italy, Vatican City and San Marino granted
          to a Third Party under an existing agreement, revert to Sepracor, such
          countries shall automatically be subject to the terms of the preceding
          sentence, beginning at the time such rights revert to Sepracor.

 4.  Schedule 10.4.6 of the Agreement is deleted in its entirety, and a new
     Schedule 10.4.6, which reads in its entirety as set forth in Attachment A
     hereto, is added in lieu thereof.

 5.  Except as expressly amended hereby, the Agreement shall be and remain in
     full force and effect in accordance with its terms.

     IN WITNESS WHEREOF, the parties hereto have caused this two (2) page
Amendment, with Attachment A, to be executed in duplicate by their duly
authorized representatives and entered into and effective as of the day and year
first set forth above.

SEPRACOR INC.                               ABBOTT LABORATORIES INC.


By:/s/ William James O'Shea                 By:/s/ Joy Amundson
   ------------------------                    -------------------------
   William James O'Shea                        Joy Amundson
   President and Chief Operating Officer       President, Ross Products Division

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                                  ATTACHMENT A

                             AMENDED SCHEDULE 10.4.6

                       OTHER AGREEMENTS REGARDING PRODUCT

1.   Sales Force Services Agreement between Innovex Inc. and Sepracor Inc.,
effective August 1, 1999.

2.   Development, Supply and License Agreement between Valeas SpA, and Sepracor
Inc., effective June 1, 1998.

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                   SECOND AMENDMENT TO CO-PROMOTION AGREEMENT

     This Second Amendment to Co-Promotion Agreement (hereinafter "Amendment")
is made and effective as of January 1, 2001, by and between Sepracor Inc.,
having its principal offices at 111 Locke Drive, Marlborough, Massachusetts
01752 ("Sepracor"), and Abbott Laboratories Inc., through its Ross Products
Division, having its principal offices at 625 Cleveland Avenue, Columbus, Ohio
43215 ("Abbott").

     WHEREAS, Sepracor and Abbott executed a Co-Promotion Agreement effective as
of November 18, 1999 (hereinafter referred to as "Agreement");

     WHEREAS, prior to January 1, 2001, total sales of Product have been such
that payment of Commission to Abbott has not required reference to the
definitions of Pediatric Market (Section 1.31) or Pediatric Sales (Section 1.32)
in the Agreement; and

     WHEREAS, the parties expect that sales of Product will reach the level
where reference to such definitions will be required in order for the Commission
payments to be properly calculated; and

     WHEREAS, the parties have agreed to lists of physicians that shall
constitute a basis for Commission payments to Abbott, such lists not directly
corresponding to those called for in the Agreement as originally written;

     NOW, THEREFORE, Sepracor and Abbott hereby agree to amend the Agreement as
follows:

     1.   All terms in this Amendment, unless otherwise defined herein, shall
          have the same meaning as set forth in the Agreement.

     2.   Section 1.31 of the Agreement is deleted in its entirety, and a new
          Section 1.31 is added in lieu thereof which reads in its entirety as
          follows:

          1.31 "PEDIATRIC MARKET" means pediatricians identified by Medical
          Education number (a list of such pediatricians, a "Pediatrician List",
          to be agreed to by the Marketing Committee and amended from time to
          time, as appropriate), primary care physicians with high birth
          practices identified by Medical Education number (a list of such
          physicians, a "PCP List", to be agreed to by the Marketing Committee
          and amended from time to time, as appropriate), primary care
          physicians with high birth practices identified by Medical Education
          number and called upon by both Abbott and Sepracor (a list of such
          physicians, a "Common PCP List", to be agreed to by the Marketing
          Committee and amended from time to time, as appropriate), and Abbott
          Targeted Hospitals, and clinics, mail-order and staff model health
          maintenance organizations for the purpose of pediatric care; PROVIDED,
          HOWEVER, that all pediatric allergists and pediatric pulmonologists
          are excluded from the Pediatric Market; FURTHER, PROVIDED, HOWEVER,
          that Abbott

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          shall have a right of first refusal to add pediatric allergists,
          pediatric pulmonologists, or both, to the Pediatric Market in the
          event that during the Term, Sepracor decides that it would like sales
          personnel other than Sepracor Representatives to promote Product to
          pediatric allergists, pediatric pulmonologists, or both, as
          appropriate, and in such case, expansion of the Pediatric Market to
          include one or both of pediatric allergists and pediatric
          pulmonologists shall be discussed by the Marketing Committee.

     3.   Section 1.32 of the Agreement is deleted in its entirety, and a new
          Section 1.32 is added in lieu thereof which reads in its entirety as
          follows:

          1.32 "PEDIATRIC SALES" means sales of Product by Sepracor and its
          Affiliates, as calculated by adding (a) the product determined by
          multiplying the Average Net Selling Price/Dose Vial or Average Net
          Selling Price/Dose Bottle during an applicable period by the sum of:

          the number of unit dose vials or multidose bottles of Product, as
          appropriate, sold during such period through pediatricians identified
          on the Pediatrician List,

          the number of unit dose vials or multidose bottles of Product, as
          appropriate, sold during such period through those primary care
          physicians with high birth practices identified on the PCP List, and

          one half of the number of unit dose vials or multidose bottles of
          Product, as appropriate, sold during such period through primary care
          physicians with high birth practices identified on Common PCP List,
          that are dispensed by retail drug stores (independent, chains, food
          and mass merchandise stores), clinics, and mail-order and staff model
          health maintenance organizations {[determined by multiplying the
          number of prescriptions generated by such identified primary care
          physicians and so dispensed (using Xponent data) by the average number
          of unit dose vials per pediatric script [which is equal to the unit
          dose ratio (the numerator of which is the total milliliter volume of
          the Product dispensed in unit dose vials to fill pediatric
          prescriptions, and the denominator of which is dose size in
          milliliters) divided by the number of unit dose vial prescriptions
          written by pediatricians] or by the average number of multidose
          bottles per pediatric script [which is equal to the multidose ratio
          (the numerator of which is the total milliliter volume of the Product
          dispensed in multidose bottles to fill pediatric prescriptions, and
          the denominator of which is the bottle volume in milliliters) divided
          by the number of multidose bottle prescriptions written by
          pediatricians], as appropriate, (using the National Prescription
          Audit)}, and (b) pediatric purchases of Product by hospitals, which
          shall be calculated by multiplying the number of unit dose vials or
          multidose bottles of Product, as appropriate, sold to Abbott Targeted
          Hospitals during an applicable period as reported by Drug Distribution
          Data by the Average Net Selling Price/Dose Vial or Average Net Selling
          Price/Dose Bottle, as appropriate, during such period and by the
          fraction equal to the number of unit dose vials or multidose bottles,
          as appropriate,

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          prescribed by pediatricians in the retail segment (as reported by the
          National Prescription Audit) divided by the number of all unit dose
          vials or multidose bottles, as appropriate, prescribed in the retail
          segment (as reported by the National Prescription Audit) during such
          period. For example purposes only, a mock sample calculation of
          Pediatric Sales is set forth in Schedule 1.32 hereto.

     4.   The Pediatrician List, the PCP List, and the Common PCP List are set
          forth in the file identified as "fff_49523_ross05_29_01.xls,
          transmitted to Abbott by Sean Daugherty on May 29, 2001, which is
          incorporated herein by reference.

     5.   The lists referred to in the letter of November 18, 1999 from Mr.
          William J. O'Shea to Ms. Joy Amundson shall be disregarded.

     6.   Except as expressly amended hereby, the Agreement shall be and remain
          in full force and effect in accordance with its terms.

     IN WITNESS WHEREOF, the parties hereto have caused this three (3) page
Amendment, incorporating by reference the file referenced in paragraph 4 above,
to be executed in duplicate by their duly authorized representatives and entered
into and effective as of the day and year first set forth above.

SEPRACOR INC.                               ABBOTT LABORATORIES INC.


By:/s/William James O'Shea                  By:/s/Joy Amundson
   --------------------------------------      ---------------------------------
   William James O'Shea                        Joy Amundson
   President and Chief Operating Officer       President, Ross Products Division

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                    THIRD AMENDMENT TO CO-PROMOTION AGREEMENT

THIS THIRD AMENDMENT to Co-Promotion Agreement (hereinafter "Third Amendment")
is made and effective as of March 19, 2004, by and between Sepracor Inc., having
its principal offices at 84 Waterford Drive, Marlborough, MA 01752 ("Sepracor")
and Abbott Laboratories, Inc., through its Ross Products Division, having its
principal offices at 625 Cleveland Avenue, Columbus, OH 43215 ("Abbott").

WHEREAS, Sepracor and Abbott executed a Co-Promotion Agreement effective as of
November 18, 1999, as subsequently amended by that certain January 19, 2000
First Amendment to Co-Promotion Agreement ("First Amendment") and that certain
January 1, 2001 Second Amendment to Co-Promotion Agreement ("Second Amendment")
(said Co-Promotion Agreement, First Amendment and Second Amendment shall
hereinafter be collectively referred to as the "Agreement");

WHEREAS, the parties desire to terminate the Agreement effective December 31,
2004 and adjust the subsequent residual payments

NOW, THEREFORE, Sepracor and Abbott hereby agree to further amend the Agreement
as follows:

     1.   All terms in this Third Amendment, unless otherwise defined herein,
          shall have the same meaning as set forth in the Agreement.

     2.   By execution of this Third Amendment Sepracor hereby withdraws, waives
          and releases Abbott from all claims set forth in the October 9, 2003
          correspondence from Mark J. Wanda of Sepracor to the attention of Mr.
          Gary Flynn of Abbott (the "Notice of Dispute"). In addition, by
          execution of this Third Amendment each Party hereby withdraws, waives
          and releases the other from all claims that could have been brought by
          either Party and related to the other Party's co-promotion efforts
          under the Agreement through the effective date of this Third
          Amendment, whether known or unknown.

     3.   Section 3.1.1.1, PROMOTION TO PEDIATRICIANS, is hereby amended by
          deleting the reference to "Product and one other pharmaceutical
          product will be part of such calling pattern and will be detailed
          before any other products" in lines 7-9 of the section.

     4.   Section 3.4 of the Agreement, ABBOTT REPRESENTATIVES' INCENTIVE
          COMPENSATION, is hereby amended by adding the following language to
          the end of the section:

               The other provisions in this Section notwithstanding, for the
               last two (2) trimesters of the 2004 Sales Year (May 1, 2004
               through December 31, 2004), Abbott shall set the incentive
               weighting bonus for the Product for all Abbott Representatives at
               [**] percent ([**]%). Abbott shall take commercially reasonable
               steps to communicate this incentive weighting

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               bonus percentage for the Product to the Abbott Representatives
               prior to the start of the second trimester of the 2004 Sales
               Year.

     5.   Section 12.1, INITIAL TERM, is hereby deleted from the Agreement in
          its entirety and replaced with the following:

               12.1 TERM. This Agreement shall commence as of the Effective Date
               and shall remain in full force and effect through December 31,
               2004 (the "Term").

     6.   Section 13.5, RESIDUAL PAYMENTS, is hereby deleted in its entirety and
          replaced with the following:

               13.5 RESIDUAL PAYMENTS. The Parties acknowledge and agree that in
                    the Territory, through the Abbott Promotion Efforts, Abbott
                    has enhanced the value of and goodwill associated with the
                    Product, Trademarks and other property of Sepracor.
                    Therefore, upon execution of this Third Amendment, Sepracor
                    agrees to pay Abbott as follows:

                    13.5.1 Thirty Million and 00/100 U.S. Dollars or
                           $30,000,000.00 on or before December 31, 2005. The
                           Parties agree that one-half of this payment or $15
                           million, shall not be subject to any contingencies
                           whatsoever. The Parties agree that with respect to
                           the other half of this payment or $15 million, $3.75
                           million shall be earned and shall accrue each
                           quarter of calendar year 2005 in which Sepracor
                           achieves Pediatric Sales for the Product of at least
                           $[**]; and

                    13.5.2 Three Million and 00/100 US Dollars or $3,000,000.00
                           on or before December 31, 2006. The Parties agree
                           that one-half of this payment or $1.5 million, shall
                           not be subject to any contingencies whatsoever. The
                           Parties agree that with respect to the other half of
                           this payment or $1.5 million, $375,000 shall be
                           earned and shall accrue in each quarter of calendar
                           year 2006 in which Sepracor achieves Pediatric Sales
                           for the Product of at least $[**].

                    13.5.3 The contingencies established in Section 13.5.1 and
                           13.5.2 above shall not apply and Sepracor shall be
                           responsible for payment in full of the contingent
                           payments described above if the failure to satisfy
                           the contingencies results from any action or failure
                           to act on the part within the control of Sepracor.

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     7.   This Third Amendment may be executed in counterparts, each of which
          shall be deemed to be an original and all of which, when taken
          together, shall constitute the Third Amendment.

     8.   Except as expressly amended by this Third Amendment, the Agreement
          shall be and remain in full force and effect in accordance with its
          terms.

IN WITNESS WHEREOF, the parties hereto have caused this three (3) page Third
Amendment to be executed in duplicate by their duly authorized representatives
and entered into and effective as of the day and year first set forth above.

Sepracor Inc.                              Abbott Laboratories Inc.


By:   /s/William James O'Shea              By: /s/Gary McCullough
   -------------------------------------      ----------------------------------
   William James O'Shea                        Gary McCullough
   President and Chief Operating Officer       President, Ross Products Division

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