<Page>


                                                                  Exhibit 10.1


                                  SEPRACOR INC.

                            2000 STOCK INCENTIVE PLAN

1. PURPOSE

     The purpose of this 2000 Stock Incentive Plan (the "Plan") of Sepracor
Inc., a Delaware corporation (the "Company"), is to advance the interests of the
Company's stockholders by enhancing the Company's ability to attract, retain and
motivate persons who make (or are expected to make) important contributions to
the Company by providing such persons with equity ownership opportunities and
performance-based incentives and thereby better aligning the interests of such
persons with those of the Company's stockholders. Except where the context
otherwise requires, the term "Company" shall include any of the Company's
present or future subsidiary corporations as defined in Section 424(f) of the
Internal Revenue Code of 1986, as amended, and any regulations promulgated
thereunder (the "Code") and any other business venture (including, without
limitation, joint venture or limited liability company) in which the Company has
a significant interest, as determined by the Board of Directors of the Company
(the "Board").

2. ELIGIBILITY

     All of the Company's employees, officers, directors, consultants and
advisors (and any individuals who have accepted an offer for employment) are
eligible to be granted options, restricted stock awards, or other stock-based
awards (each, an "Award") under the Plan. Each person who has been granted an
Award under the Plan shall be deemed a "Participant".

3. ADMINISTRATION, DELEGATION

     (a) ADMINISTRATION BY BOARD OF DIRECTORS. The Plan will be administered by
the Board. The Board shall have authority to grant Awards and to adopt, amend
and repeal such administrative rules, guidelines and practices relating to the
Plan as it shall deem advisable. The Board may correct any defect, supply any
omission or reconcile any inconsistency in the Plan or any Award in the manner
and to the extent it shall deem expedient to carry the Plan into effect and it
shall be the sole and final judge of such expediency. All decisions by the Board
shall be made in the Board's sole discretion and shall be final and binding on
all persons having or claiming any interest in the Plan or in any Award. No
director or person acting pursuant to the authority delegated by the Board shall
be liable for any action or determination relating to or under the Plan made in
good faith.

     (b) APPOINTMENT OF COMMITTEES. To the extent permitted by applicable law,
the Board may delegate any or all of its powers under the Plan to one or more
committees or subcommittees of the Board (a "Committee"). All references in the
Plan to the "Board" shall mean the Board or a Committee of the Board referred to
in Section 3(b) to the extent that the Board's powers or authority under the
Plan have been delegated to such Committee.


                                      -1-
<Page>


4. STOCK AVAILABLE FOR AWARDS

     (a) NUMBER OF SHARES. Subject to adjustment under Section 8, Awards may be
made under the Plan for up to 2,500,000 shares of common stock, $.10 par value
per share, of the Company (the "Common Stock"). If any Award expires or is
terminated, surrendered or canceled without having been fully exercised or is
forfeited in whole or in part or results in any Common Stock not being issued,
the unused Common Stock covered by such Award shall again be available for the
grant of Awards under the Plan, subject, however, in the case of Incentive Stock
Options (as hereinafter defined), to any limitation required under the Code.
Shares issued under the Plan may consist in whole or in part of authorized but
unissued shares or treasury shares.

     (b) PER-PARTICIPANT LIMIT. Subject to adjustment under Section 8, for
Awards granted after the Common Stock is registered under the Securities
Exchange Act of 1934 (the "Exchange Act"), the maximum number of shares of
Common Stock with respect to which Awards may be granted to any Participant
under the Plan shall be 500,000 per calendar year. The per-Participant limit
described in this Section 4(b) shall be construed and applied consistently with
Section 162(m) of the Code ("Section 162(m)").

5. STOCK OPTIONS

     (a) GENERAL. The Board may grant options to purchase Common Stock (each, an
"Option") and determine the number of shares of Common Stock to be covered by
each Option, the exercise price of each Option and the conditions and
limitations applicable to the exercise of each Option, including conditions
relating to applicable federal or state securities laws, as it considers
necessary or advisable. An Option which is not intended to be an Incentive Stock
Option (as hereinafter defined) shall be designated a "Nonstatutory Stock
Option".

     (b) INCENTIVE STOCK OPTIONS. An Option that the Board intends to be an
"incentive stock option" as defined in Section 422 of the Code (an "Incentive
Stock Option") shall only be granted to employees of the Company and shall be
subject to and shall be construed consistently with the requirements of Section
422 of the Code. The Company shall have no liability to a Participant, or any
other party, if an Option (or any part thereof) which is intended to be an
Incentive Stock Option is not an Incentive Stock Option.

     (c) EXERCISE PRICE. The Board shall establish the exercise price at the
time each Option is granted and specify it in the applicable option agreement,
provided, however, that the exercise price shall not be less than 100% of the
fair market value of the Common Stock, as determined by the Board, at the time
the Option is granted.

     (d) DURATION OF OPTIONS. Each Option shall be exercisable at such times and
subject to such terms and conditions as the Board may specify in the applicable
option agreement, provided however, that no Option will be granted for a term in
excess of ten years.


                                      -2-
<Page>


     (e) EXERCISE OF OPTION. Options may be exercised by delivery to the Company
of a written notice of exercise signed by the proper person or by any other form
of notice (including electronic notice) approved by the Board together with
payment in full as specified in Section 5(f) for the number of shares for which
the Option is exercised.

     (f) PAYMENT UPON EXERCISE. Common Stock purchased upon the exercise of an
Option granted under the Plan shall be paid for as follows:

         (1) in cash or by check, payable to the order of the Company;

         (2) except as the Board may, in its sole discretion, otherwise provide
in an option agreement, by (i) delivery of an irrevocable and unconditional
undertaking by a creditworthy broker to deliver promptly to the Company
sufficient funds to pay the exercise price or (ii) delivery by the Participant
to the Company of a copy of irrevocable and unconditional instructions to a
creditworthy broker to deliver promptly to the Company cash or a check
sufficient to pay the exercise price;

         (3) when the Common Stock is registered under the Exchange Act, by
delivery of shares of Common Stock owned by the Participant valued at their fair
market value as determined by (or in a manner approved by) the Board in good
faith ("Fair Market Value"), provided (i) such method of payment is then
permitted under applicable law and (ii) such Common Stock was owned by the
Participant at least six months prior to such delivery;

         (4) to the extent permitted by the Board, in its sole discretion by (i)
delivery of a promissory note of the Participant to the Company on terms
determined by the Board, or (ii) payment of such other lawful consideration as
the Board may determine; or

         (5) by any combination of the above permitted forms of payment.

     (g) SUBSTITUTE OPTIONS. In connection with a merger or consolidation of an
entity with the Company or the acquisition by the Company of property or stock
of an entity, the Board may grant Options in substitution for any options or
other stock or stock-based awards granted by such entity or an affiliate
thereof. Substitute Options may be granted on such terms as the Board deems
appropriate in the circumstances, notwithstanding any limitations on Options
contained in the other sections of this Section 5.

6. RESTRICTED STOCK

     (a) GRANTS. The Board may grant Awards entitling recipients to acquire
shares of Common Stock, subject to the right of the Company to repurchase all or
part of such shares at their issue price or other stated or formula price (or to
require forfeiture of such shares if issued at no cost) from the recipient in
the event that conditions specified by the Board in the applicable Award are not
satisfied prior to the end of the applicable restriction period or periods
established by the Board for such Award (each, a "Restricted Stock Award").


                                      -3-
<Page>


     (b) TERMS AND CONDITIONS. The Board shall determine the terms and
conditions of any such Restricted Stock Award, including the conditions for
repurchase (or forfeiture) and the issue price, if any. Any stock certificates
issued in respect of a Restricted Stock Award shall be registered in the name of
the Participant and, unless otherwise determined by the Board, deposited by the
Participant, together with a stock power endorsed in blank, with the Company (or
its designee). At the expiration of the applicable restriction periods, the
Company (or such designee) shall deliver the certificates no longer subject to
such restrictions to the Participant or if the Participant has died, to the
beneficiary designated, in a manner determined by the Board, by a Participant to
receive amounts due or exercise rights of the Participant in the event of the
Participant's death (the "Designated Beneficiary"). In the absence of an
effective designation by a Participant, Designated Beneficiary shall mean the
Participant's estate.

7. OTHER STOCK-BASED AWARDS

     The Board shall have the right to grant other Awards based upon the Common
Stock having such terms and conditions as the Board may determine, including the
grant of shares based upon certain conditions, the grant of securities
convertible into Common Stock and the grant of stock appreciation rights.

8. ADJUSTMENTS FOR CHANGES IN COMMON STOCK AND CERTAIN OTHER EVENTS

     (a) CHANGES IN CAPITALIZATION. In the event of any stock split, reverse
stock split, stock dividend, recapitalization, combination of shares,
reclassification of shares, spin-off or other similar change in capitalization
or event, or any distribution to holders of Common Stock other than a normal
cash dividend, (i) the number and class of securities available under this Plan,
(ii) the per-Participant limit set forth in Section 4(b), (iii) the number and
class of securities and exercise price per share subject to each outstanding
Option, (iv) the repurchase price per share subject to each outstanding
Restricted Stock Award, and (v) the terms of each other outstanding Award shall
be appropriately adjusted by the Company (or substituted Awards may be made, if
applicable) to the extent the Board shall determine, in good faith, that such an
adjustment (or substitution) is necessary and appropriate. If this Section 8(a)
applies and Section 8(c) also applies to any event, Section 8(c) shall be
applicable to such event, and this Section 8(a) shall not be applicable.

     (b) LIQUIDATION OR DISSOLUTION. In the event of a proposed liquidation or
dissolution of the Company, the Board shall upon written notice to the
Participants provide that all then unexercised Options will (i) become
exercisable in full as of a specified time at least 10 business days prior to
the effective date of such liquidation or dissolution and (ii) terminate
effective upon such liquidation or dissolution, except to the extent exercised
before such effective date. The Board may specify the effect of a liquidation or
dissolution on any Restricted Stock Award or other Award granted under the Plan
at the time of the grant of such Award.


                                      -4-
<Page>


     (c) ACQUISITION AND CHANGE IN CONTROL EVENTS

          (1)  DEFINITIONS

               (a)  An "Acquisition Event" shall mean:

                    (i)  any merger or consolidation of the Company with or into
                         another entity as a result of which the Common Stock is
                         converted into or exchanged for the right to receive
                         cash, securities or other property; or

                    (ii) any exchange of shares of the Company for cash,
                         securities or other property pursuant to a statutory
                         share exchange transaction.

               (b)  A "Change in Control Event" shall mean:

                    (i)  the acquisition by an individual, entity or group
                         (within the meaning of Section 13(d)(3) or 14(d)(2) of
                         the Securities Exchange Act of 1934, as amended (the
                         "Exchange Act")) (a "Person") of beneficial ownership
                         of any capital stock of the Company if, after such
                         acquisition, such Person beneficially owns (within the
                         meaning of Rule 13d-3 promulgated under the Exchange
                         Act) 30% or more of either (x) the then-outstanding
                         shares of common stock of the Company (the "Outstanding
                         Company Common Stock") or (y) the combined voting power
                         of the then-outstanding securities of the Company
                         entitled to vote generally in the election of directors
                         (the "Outstanding Company Voting Securities");
                         PROVIDED, HOWEVER, that for purposes of this subsection
                         (i), the following acquisitions shall not constitute a
                         Change in Control Event: (A) any acquisition directly
                         from the Company (excluding an acquisition pursuant to
                         the exercise, conversion or exchange of any security
                         exercisable for, convertible into or exchangeable for
                         common stock or voting securities of the Company,
                         unless the Person exercising, converting or exchanging
                         such security acquired such security directly from the
                         Company or an underwriter or agent of the Company), (B)
                         any acquisition by any employee benefit plan (or
                         related trust) sponsored or maintained by the Company
                         or any corporation controlled by the Company, or (C)
                         any acquisition by any corporation pursuant to a
                         Business Combination (as defined below) which complies
                         with clauses (x) and (y) of subsection (iii) of this
                         definition; or

                    (ii) such time as the Continuing Directors (as defined
                         below) do not constitute a majority of the Board (or,
                         if applicable,


                                      -5-
<Page>


                         the Board of Directors of a successor corporation to
                         the Company), where the term "Continuing Director"
                         means at any date a member of the Board (x) who was a
                         member of the Board on the date of the initial adoption
                         of this Plan by the Board or (y) who was nominated or
                         elected subsequent to such date by at least a majority
                         of the directors who were Continuing Directors at the
                         time of such nomination or election or whose election
                         to the Board was recommended or endorsed by at least a
                         majority of the directors who were Continuing Directors
                         at the time of such nomination or election; PROVIDED,
                         HOWEVER, that there shall be excluded from this clause
                         (y) any individual whose initial assumption of office
                         occurred as a result of an actual or threatened
                         election contest with respect to the election or
                         removal of directors or other actual or threatened
                         solicitation of proxies or consents, by or on behalf of
                         a person other than the Board; or

                   (iii) the consummation of a merger, consolidation,
                         reorganization, recapitalization or statutory share
                         exchange involving the Company or a sale or other
                         disposition of all or substantially all of the assets
                         of the Company (a "Business Combination"), unless,
                         immediately following such Business Combination, each
                         of the following two conditions is satisfied: (x) all
                         or substantially all of the individuals and entities
                         who were the beneficial owners of the Outstanding
                         Company Common Stock and Outstanding Company Voting
                         Securities immediately prior to such Business
                         Combination beneficially own, directly or indirectly,
                         more than 50% of the then-outstanding shares of common
                         stock and the combined voting power of the
                         then-outstanding securities entitled to vote generally
                         in the election of directors, respectively, of the
                         resulting or acquiring corporation in such Business
                         Combination (which shall include, without limitation, a
                         corporation which as a result of such transaction owns
                         the Company or substantially all of the Company's
                         assets either directly or through one or more
                         subsidiaries) (such resulting or acquiring corporation
                         is referred to herein as the "Acquiring Corporation")
                         in substantially the same proportions as their
                         ownership of the Outstanding Company Common Stock and
                         Outstanding Company Voting Securities, respectively,
                         immediately prior to such Business Combination and (y)
                         no Person (excluding the


                                      -6-
<Page>


                        Acquiring Corporation or any employee benefit plan (or
                        related trust) maintained or sponsored by the Company or
                        by the Acquiring Corporation) beneficially owns,
                        directly or indirectly, 30% or more of the
                        then-outstanding shares of common stock of the Acquiring
                        Corporation, or of the combined voting power of the
                        then-outstanding securities of such corporation
                        entitled to vote generally in the election of directors
                        (except to the extent that such ownership existed prior
                        to the Business Combination).

          (2)  EFFECT ON OPTIONS

               (a)  ACQUISITION EVENT. Upon the occurrence of an Acquisition
                    Event (regardless of whether such event also constitutes a
                    Change in Control Event), or the execution by the Company of
                    any agreement with respect to an Acquisition Event
                    (regardless of whether such event will result in a Change in
                    Control Event), the Board shall provide that all outstanding
                    Options shall be assumed, or equivalent options shall be
                    substituted, by the acquiring or succeeding corporation (or
                    an affiliate thereof); PROVIDED THAT if such Acquisition
                    Event also constitutes a Change in Control Event, except to
                    the extent specifically provided to the contrary in the
                    instrument evidencing any Option or any other agreement
                    between a Participant and the Company, such assumed or
                    substituted options shall be immediately exercisable in full
                    upon the occurrence of such Acquisition Event. For purposes
                    hereof, an Option shall be considered to be assumed if,
                    following consummation of the Acquisition Event, the Option
                    confers the right to purchase, for each share of Common
                    Stock subject to the Option immediately prior to the
                    consummation of the Acquisition Event, the consideration
                    (whether cash, securities or other property) received as a
                    result of the Acquisition Event by holders of Common Stock
                    for each share of Common Stock held immediately prior to the
                    consummation of the Acquisition Event (and if holders were
                    offered a choice of consideration, the type of consideration
                    chosen by the holders of a majority of the outstanding
                    shares of Common Stock); provided, however, that if the
                    consideration received as a result of the Acquisition Event
                    is not solely common stock of the acquiring or succeeding
                    corporation (or an affiliate thereof), the Company may, with
                    the consent of the acquiring or succeeding corporation,
                    provide for the consideration to be received upon the
                    exercise of Options to consist solely of common stock of the
                    acquiring or succeeding corporation (or an affiliate
                    thereof) equivalent in fair market value


                                      -7-
<Page>


                    to the per share consideration received by holders of
                    outstanding shares of Common Stock as a result of the
                    Acquisition Event.

                         Notwithstanding the foregoing, if the acquiring or
                    succeeding corporation (or an affiliate thereof) does not
                    agree to assume, or substitute for, such Options, then the
                    Board shall, upon written notice to the Participants,
                    provide that all then unexercised Options will become
                    exercisable in full as of a specified time prior to the
                    Acquisition Event and will terminate immediately prior to
                    the consummation of such Acquisition Event, except to the
                    extent exercised by the Participants before the consummation
                    of such Acquisition Event; provided, however, in the event
                    of an Acquisition Event under the terms of which holders of
                    Common Stock will receive upon consummation thereof a cash
                    payment for each share of Common Stock surrendered pursuant
                    to such Acquisition Event (the "Acquisition Price"), then
                    the Board may instead provide that all outstanding Options
                    shall terminate upon consummation of such Acquisition Event
                    and that each Participant shall receive, in exchange
                    therefor, a cash payment equal to the amount (if any) by
                    which (A) the Acquisition Price multiplied by the number of
                    shares of Common Stock subject to such outstanding Options
                    (whether or not then exercisable), exceeds (B) the aggregate
                    exercise price of such Options.

               (b)  CHANGE IN CONTROL EVENT THAT IS NOT AN ACQUISITION EVENT.
                    Upon the occurrence of a Change in Control Event that does
                    not also constitute an Acquisition Event, except to the
                    extent specifically provided to the contrary in the
                    instrument evidencing any Option or any other agreement
                    between a Participant and the Company, all Options
                    then-outstanding shall automatically become immediately
                    exercisable in full.

          (3)  EFFECT ON RESTRICTED STOCK AWARDS

               (a)  ACQUISITION EVENT THAT IS NOT A CHANGE IN CONTROL EVENT.
                    Upon the occurrence of an Acquisition Event that is not a
                    Change in Control Event, the repurchase and other rights of
                    the Company under each outstanding Restricted Stock Award
                    shall inure to the benefit of the Company's successor and
                    shall apply to the cash, securities or other property which
                    the Common Stock was converted into or exchanged for
                    pursuant to such Acquisition Event in the same manner and to
                    the same extent as they applied to the Common Stock subject
                    to such Restricted Stock Award.


                                      -8-
<Page>


               (b)  CHANGE IN CONTROL EVENT. Upon the occurrence of a Change in
                    Control Event (regardless of whether such event also
                    constitutes an Acquisition Event), except to the extent
                    specifically provided to the contrary in the instrument
                    evidencing any Restricted Stock Award or any other agreement
                    between a Participant and the Company, all restrictions and
                    conditions on all Restricted Stock Awards then-outstanding
                    shall automatically be deemed terminated or satisfied.

          (4)  EFFECT ON OTHER AWARDS

               (a)  ACQUISITION EVENT THAT IS NOT A CHANGE IN CONTROL EVENT. The
                    Board shall specify the effect of an Acquisition Event that
                    is not a Change in Control Event on any other Award granted
                    under the Plan at the time of the grant of such Award.

               (b)  CHANGE IN CONTROL EVENT. Upon the occurrence of a Change in
                    Control Event (regardless of whether such event also
                    constitutes an Acquisition Event), except to the extent
                    specifically provided to the contrary in the instrument
                    evidencing any other Award or any other agreement between a
                    Participant and the Company, all other Awards shall become
                    exercisable, realizable or vested in full, or shall be free
                    of all conditions or restrictions, as applicable to each
                    such Award.

          (5)  LIMITATIONS. Notwithstanding the foregoing provisions of this
               Section 8(c), if the Change in Control Event is intended to be
               accounted for as a "pooling of interests" for financial
               accounting purposes, and if the acceleration to be effected by
               the foregoing provisions of this Section 8(c) would preclude
               accounting for the Change in Control Event as a "pooling of
               interests" for financial accounting purposes, then no such
               acceleration shall occur upon the Change in Control Event.


9. GENERAL PROVISIONS APPLICABLE TO AWARDS

     (a) TRANSFERABILITY OF AWARDS. Except as the Board may otherwise determine
or provide in an Award, Awards shall not be sold, assigned, transferred, pledged
or otherwise encumbered by the person to whom they are granted, either
voluntarily or by operation of law, except by will or the laws of descent and
distribution, and, during the life of the Participant, shall be exercisable only
by the Participant. References to a Participant, to the extent relevant in the
context, shall include references to authorized transferees.


                                      -9-
<Page>


     (b) DOCUMENTATION. Each Award shall be evidenced by a written instrument in
such form as the Board shall determine. Each Award may contain terms and
conditions in addition to those set forth in the Plan.

     (c) BOARD DISCRETION. Except as otherwise provided by the Plan, each Award
may be made alone or in addition or in relation to any other Award. The terms of
each Award need not be identical, and the Board need not treat Participants
uniformly.

     (d) TERMINATION OF STATUS. The Board shall determine the effect on an Award
of the disability, death, retirement, authorized leave of absence or other
change in the employment or other status of a Participant and the extent to
which, and the period during which, the Participant, the Participant's legal
representative, conservator, guardian or Designated Beneficiary may exercise
rights under the Award.

     (e) WITHHOLDING. Each Participant shall pay to the Company, or make
provision satisfactory to the Board for payment of, any taxes required by law to
be withheld in connection with Awards to such Participant no later than the date
of the event creating the tax liability. Except as the Board may otherwise
provide in an Award, when the Common Stock is registered under the Exchange Act,
Participants may, to the extent then permitted under applicable law, satisfy
such tax obligations in whole or in part by delivery of shares of Common Stock,
including shares retained from the Award creating the tax obligation, valued at
their Fair Market Value. The Company may, to the extent permitted by law, deduct
any such tax obligations from any payment of any kind otherwise due to a
Participant.

     (f) AMENDMENT OF AWARD. The Board may amend, modify or terminate any
outstanding Award, including but not limited to, substituting therefor another
Award of the same or a different type, changing the date of exercise or
realization, and converting an Incentive Stock Option to a Nonstatutory Stock
Option, provided that the Participant's consent to such action shall be required
unless the Board determines that the action, taking into account any related
action, would not materially and adversely affect the Participant.

     (g) CONDITIONS ON DELIVERY OF STOCK. The Company will not be obligated to
deliver any shares of Common Stock pursuant to the Plan or to remove
restrictions from shares previously delivered under the Plan until (i) all
conditions of the Award have been met or removed to the satisfaction of the
Company, (ii) in the opinion of the Company's counsel, all other legal matters
in connection with the issuance and delivery of such shares have been satisfied,
including any applicable securities laws and any applicable stock exchange or
stock market rules and regulations, and (iii) the Participant has executed and
delivered to the Company such representations or agreements as the Company may
consider appropriate to satisfy the requirements of any applicable laws, rules
or regulations.

     (h) ACCELERATION. The Board may at any time provide that any Options shall
become immediately exercisable in full or in part, that any Restricted Stock
Awards shall be free of restrictions in full or in part or that any other Awards
may become exercisable in full or in part or


                                      -10-
<Page>


free of some or all restrictions or conditions, or otherwise realizable in full
or in part, as the case may be.


10. MISCELLANEOUS

     (a) NO RIGHT TO EMPLOYMENT OR OTHER STATUS. No person shall have any claim
or right to be granted an Award, and the grant of an Award shall not be
construed as giving a Participant the right to continued employment or any other
relationship with the Company. The Company expressly reserves the right at any
time to dismiss or otherwise terminate its relationship with a Participant free
from any liability or claim under the Plan, except as expressly provided in the
applicable Award.

     (b) NO RIGHTS AS STOCKHOLDER. Subject to the provisions of the applicable
Award, no Participant or Designated Beneficiary shall have any rights as a
stockholder with respect to any shares of Common Stock to be distributed with
respect to an Award until becoming the record holder of such shares.
Notwithstanding the foregoing, in the event the Company effects a split of the
Common Stock by means of a stock dividend and the exercise price of and the
number of shares subject to such Option are adjusted as of the date of the
distribution of the dividend (rather than as of the record date for such
dividend), then an optionee who exercises an Option between the record date and
the distribution date for such stock dividend shall be entitled to receive, on
the distribution date, the stock dividend with respect to the shares of Common
Stock acquired upon such Option exercise, notwithstanding the fact that such
shares were not outstanding as of the close of business on the record date for
such stock dividend.

     (c) EFFECTIVE DATE AND TERM OF PLAN. The Plan shall become effective on the
date on which it is adopted by the Board, but no Award granted to a Participant
that is intended to comply with Section 162(m) shall become exercisable, vested
or realizable, as applicable to such Award, unless and until the Plan has been
approved by the Company's stockholders to the extent stockholder approval is
required by Section 162(m) in the manner required under Section 162(m)
(including the vote required under Section 162(m)). No Awards shall be granted
under the Plan after the completion of ten years from the earlier of (i) the
date on which the Plan was adopted by the Board or (ii) the date the Plan was
approved by the Company's stockholders, but Awards previously granted may extend
beyond that date.

     (d) AMENDMENT OF PLAN. The Board may amend, suspend or terminate the Plan
or any portion thereof at any time, provided that to the extent required by
Section 162(m), no Award granted to a Participant that is intended to comply
with Section 162(m) after the date of such amendment shall become exercisable,
realizable or vested, as applicable to such Award, unless and until such
amendment shall have been approved by the Company's stockholders as required by
Section 162(m) (including the vote required under Section 162(m)).


                                      -11-
<Page>


     (e) GOVERNING LAW. The provisions of the Plan and all Awards made hereunder
shall be governed by and interpreted in accordance with the laws of the State of
Delaware, without regard to any applicable conflicts of law.




                         Adopted by the Board of Directors on February 24, 2000

                         Adopted by the Stockholders on May 24, 2000






                                      -12-
<Page>


                               AMENDMENT NO 1. TO
                            2000 STOCK INCENTIVE PLAN
                                       OF
                                  SEPRACOR INC.

     The 2000 Stock Incentive Plan (the "Plan") of Sepracor Inc. be, and hereby
is, amended as follows:

     1. Section 4, paragraph (a) is deleted in its entirety and the following is
substituted in its place:

     "(a) NUMBER OF SHARES. Subject to adjustment under Section 8, Awards may be
made under the Plan for up to 4,000,000 shares of common stock, $.10 par value
per share, of the Company (the "Common Stock"). If any Award expires or is
terminated, surrendered or cancelled without having been fully exercised or is
forfeited in whole or in part or results in any Common Stock not being issued,
the unused Common Stock covered by such Award shall again be available for the
grant of Awards under the Plan, subject, however, in the case of Incentive Stock
Options (as hereinafter defined), to any limitation required under the Code.
Shares issued under the Plan may consist in whole or in part of authorized but
unissued shares or treasury shares."


                         Adopted by the Board of Directors on February 21, 2002

                         Adopted by the Stockholders on May 22, 2002


                                      -13-
<Page>


                               AMENDMENT NO 2. TO
                            2000 STOCK INCENTIVE PLAN
                                       OF
                                  SEPRACOR INC.

     The 2000 Stock Incentive Plan (the "Plan") of Sepracor Inc. be, and hereby
is, amended as follows:

     1. Section 4, paragraph (a) is deleted in its entirety and the following is
substituted in its place:

     "(a) NUMBER OF SHARES. Subject to adjustment under Section 8, Awards may be
made under the Plan for up to 5,5000,000 shares of common stock, $.10 par value
per share, of the Company (the "Common Stock"). If any Award expires or is
terminated, surrendered or cancelled without having been fully exercised or is
forfeited in whole or in part or results in any Common Stock not being issued,
the unused Common Stock covered by such Award shall again be available for the
grant of Awards under the Plan, subject, however, in the case of Incentive Stock
Options (as hereinafter defined), to any limitation required under the Code.
Shares issued under the Plan may consist in whole or in part of authorized but
unissued shares or treasury shares."



                         Adopted by the Board of Directors on February 20, 2003

                         Adopted by the Stockholders on May 22, 2003


                                      -14-
<Page>


                               AMENDMENT NO 3. TO
                            2000 STOCK INCENTIVE PLAN
                                       OF
                                  SEPRACOR INC.

     The 2000 Stock Incentive Plan (the "Plan"), as amended, of Sepracor Inc.
be, and hereby is, further amended as follows:

     1. Section 4, paragraph (a) is deleted in its entirety and the following is
substituted in its place:

     "(a) NUMBER OF SHARES. Subject to adjustment under Section 8, Awards may be
made under the Plan for up to 8,000,000 shares of common stock, $.10 par value
per share, of the Company (the "Common Stock"). If any Award expires or is
terminated, surrendered or cancelled without having been fully exercised or is
forfeited in whole or in part or results in any Common Stock not being issued,
the unused Common Stock covered by such Award shall again be available for the
grant of Awards under the Plan, subject, however, in the case of Incentive Stock
Options (as hereinafter defined), to any limitation required under the Code.
Shares issued under the Plan may consist in whole or in part of authorized but
unissued shares or treasury shares."



                        Adopted by the Board of Directors on February 11, 2004.

                        Adopted by the Stockholders on May 19, 2004.



                                      -15-