Exhibit 10.48

                          REGISTRATION RIGHTS AGREEMENT

      THIS REGISTRATION RIGHTS AGREEMENT is made as of March 29, 2004, by and
among DOV Pharmaceutical, a Delaware corporation (the "Company"), and Acqua
Wellington Opportunity I Limited (the "Investor").

      WHEREAS, the Company proposes to issue and sell to the Investor shares
(the "Shares") of the Company's Common Stock, par value $.0001 per share (the
"Common Stock") pursuant to the Securities Purchase Agreement dated the date
hereof by and between the Investors and the Company (the "Purchase Agreement");

      WHEREAS, as a condition to the Investor entering into the Purchase
Agreement, the Company has agreed to effect the registration of the shares of
Common Stock on the terms and conditions set forth herein;

      WHEREAS, reference is made to that certain Registration Rights Agreement
by and between Elan International Services, Ltd, a Bermuda corporation ("EIS")
and the Company dated as of January 21, 1999, as amended by the agreement
between the Company and EIS dated as of June 20, 2000 (the "EIS Agreement");

      WHEREAS, reference is made to that certain Registration Rights Agreement
dated as of June 20, 2000, by and between the Company and the other persons
party thereto, as amended by the Series D Agreement (as defined below) (the
"Series C Agreement");

      WHEREAS, reference is made to that certain Registration Rights Agreement
dated as of August 30, 2001, by and between the Company and the other Persons
party thereto (the "Series D Agreement)";

      WHEREAS, reference is made to that certain Registration Right Agreement
dated as of July 1, 2003, by and between the Company and the other persons party
thereto (the "Orbimed Agreement" and together with the EIS Agreement, Series C
Agreement and the Series D Agreement, the "Existing Registration Rights
Agreements"); and

      WHEREAS, it is the intent of the parties hereto that the rights granted
hereunder not conflict with the rights existing under the Existing Registration
Rights Agreements, and that the holders of Registrable Securities only have the
rights that the Company is permitted to grant under the Existing Registration
Rights Agreements without the consent of the holders of registrable securities
thereunder.


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<PAGE>

      NOW, THEREFORE, in consideration of the covenants and agreements set forth
herein, to induce the parties hereto to enter into the Purchase Agreement and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby mutually acknowledged, the parties hereto covenant and agree as
follows:

                                    ARTICLE I
                                   DEFINITIONS

      SECTION 1.1 DEFINITIONS. As used in this Agreement, the following terms
shall have the following respective meanings:

      "AFFILIATE" of any Person as of any date means (a) any other Person
controlled by, controlling or under "common control" as that term is defined in
the Securities Act with that Person as of such date (including Persons under
common investment management); (b) in the case of any trust that is a
stockholder of the Company, any beneficiary of that trust as of such date who is
entitled to the majority of the assets of that trust; and (c) in the case of any
custodial account that is a stockholder of the Company, any beneficiary of that
custodial account as of such date who is then entitled to the majority of the
assets of that account.

      "BUSINESS DAY" shall mean any day except a Saturday, Sunday or other day
on which commercial banks are authorized by law to close in the State of New
York.

      "CLOSING DATE" shall mean the Closing Date under the Purchase Agreement.

      "COMMISSION" shall mean the Securities and Exchange Commission and any
successor agency of the Federal government administering the Securities Act and
the Exchange Act.

      "COMMON STOCK" shall mean the Common Stock, par value $.001 per share, of
the Company and any other securities into which or for which such Common Stock
may be converted or exchanged pursuant to a plan of recapitalization,
reorganization, merger, consolidation, sale of assets or other similar
transaction.

      "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, as amended,
and any similar or successor Federal statute, and the rules and regulations of
the Commission thereunder, all as the same shall be in effect from time to time.

      "PERSON" shall mean an individual, corporation, partnership, limited
liability company, joint venture, trust or unincorporated organization, or a
government or any agency or political subdivision thereof.

      "REGISTER", "REGISTERED" and "REGISTRATION" shall refer to a registration
effected by preparing and filing a registration statement in compliance with the
Securities Act and applicable rules and regulations thereunder, and the
declaration or ordering of the effectiveness of such registration statement, or,
as the context may require, under the Exchange Act or applicable state
securities laws.


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<PAGE>

      "REGISTRABLE SECURITIES" shall mean the Shares and any shares of Common
Stock or other securities issued or issuable in respect of such shares of Common
Stock upon any stock split, stock dividend, recapitalization, reorganization,
or, merger, consolidation or similar event. Notwithstanding the foregoing, the
term Registrable Securities shall not include (a) any such securities that have
been registered under the Securities Act pursuant to an effective registration
statement filed thereunder and disposed of in accordance with the registration
statement covering them, (b) any such securities that have been publicly sold
pursuant to Rule 144(k) under the Securities Act or (c) any such securities held
by and issuable to such holder of Registrable Securities (and its Affiliates)
that have been sold under Rule 144 under the Securities Act.

      "SECURITIES ACT" shall mean the Securities Act of 1933, as amended, and
any similar or successor Federal statute, and the rules and regulations of the
Commission thereunder, all as the same shall be in effect from time to time.

                                   ARTICLE II

                               REGISTRATION RIGHTS

      SECTION 2.1 REGISTRATION RIGHTS.

            (a) At any time on or after the Closing Date, the Company shall
prepare and file with the Commission a registration statement (the "Registration
Statement") on Form S-3 (or, if Form S-3 is not then available to the Company,
on such form of registration statement as is then available to effect a
registration for resale, subject to Section 2.1 (b), of their Registrable
Securities). The Company shall promptly deliver required notices to all holders
of securities having rights under the Existing Registration Rights Agreements to
notify the Company in writing of their desire to include their securities in
such registration in accordance with the terms of under such Existing
Registration Rights Agreements. The registration statement shall also cover, to
the extent allowable under the Securities Act and the rules promulgated
hereunder, including Rule 416, such indeterminate number of additional shares of
Common Stock resulting from stock splits, stock dividends or similar
transactions with respect to the Registrable Securities registered hereunder.
The Company shall use its best efforts to prepare and file the registration
statement and cause it to be declared effective within 90 days of the Closing
Date provided that if the Company takes action pursuant to Section 2.6(b) to
delay registration effectiveness based upon a "Suspension Event" as defined
therein such period shall be extended to 111 days from the Closing Date and
provided further that if the registration statement is not declared effective
within such 90-day or 111-day period as the case may be, the Company shall pay
the Investor as liquidated damages, and not as a penalty, without regard to
whether it has used its best efforts to cause the registration to be declared
effective, an amount equal to two percent (2%) of the Purchase Price paid by the
Investor for all Registrable Securities then held by the Holder plus 0.75% of
such purchase price paid therefor for each additional thirty (30) day period
during which the registration statement is not declared effective, pro rated for
any period less than thirty (30) days, until the registration statement is
declared effective and provided further that no such payment shall change the
Company's obligation to continue to use its best efforts to cause the
registration statement to be declared effective and remain effective for the
earlier of 12 months from the Closing Date and the time when all Registrable
Securities are sold thereunder. Any dispute whether the Company has so used its
best efforts shall be referred at the request by notice of either party to
binding arbitration before a neutral arbitrator selected by the parties or,
failing selection in five days, by the flip of a coin from a list furnished by
the American Arbitration Association, with the hearing to be held within 20 days
following completion of any discovery period permitted by the arbitrator,
post-hearing briefs within five days and award without opinion within ten days
thereafter.


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<PAGE>

            (b) The Registration Statement filed pursuant to this Section 2.1
may, in addition to the Registrable Securities requested to be registered,
include (i) shares of Common Stock for sale by the Company for its own account
and (ii) shares of Common Stock held by persons having rights under the Existing
Registration Rights Agreements in accordance with the terms thereof, in each
case for sale in accordance with the method of disposition specified by the
requesting holders of Registrable Securities. If such registration is
underwritten, the Company and each Person requesting to distribute their shares
through such underwritten registration shall enter into an underwriting
agreement in customary form with the representative of the underwriter or
underwriters selected for such underwriting. If and to the extent that the
managing underwriter (which managing underwriter shall be selected by the
Company) determines that the number of securities sought to be offered should be
limited because of market conditions, the number of securities to be included in
such underwritten offering shall be reduced to a number deemed satisfactory by
such managing underwriter. In such event securities to be included in such
registration shall be allocated as follows: first, to the holders of Registrable
Securities and Persons having rights under the Existing Registration Rights
Agreements pro rata based on their ownership of the securities to be included in
such registration, second, to the Company and third, to any other Person having
registration rights pursuant to a written agreement with the Company. No
Registrable Securities or any other security excluded from the underwriting by
reason of the underwriter's marketing limitation shall be included in such
registration. If any holder who has requested inclusion in such registration as
provided above, disapproves of the terms of the underwriting, such holder of
securities may elect to withdraw there from by written notice to the Company and
the managing underwriter. The securities so withdrawn shall also be withdrawn
from registration.

      SECTION 2.2. REGISTRATION PROCEDURES. The Company shall use its best
efforts to effect the effectiveness of the Registration Statement and maintain
the effectiveness of such registration pursuant to Section 2.1 hereof, to permit
the sale of the Registrable Securities in accordance with the intended method or
methods of disposition thereof, subject to the Company's right to withdraw the
registration statement or terminate any proposed offering as it may determine in
its sole discretion, and pursuant thereto (and subject to such right) the
Company shall:

            (a) Prepare and file with the Commission a registration statement
with respect to such securities, including executing an undertaking to file
post-effective amendments and use best to cause such registration statement to
become and remain effective for the period of the distribution contemplated
thereby;

            (b) Prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective
until the completion of the offering specified therein and comply with the
provisions of the Securities Act with respect to the disposition of all
Registrable Securities covered by such registration statement in accordance with
the sellers' intended method of disposition set forth in such registration
statement until completion of the offering;


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<PAGE>

            (c) Furnish to each seller of Registrable Securities and to each
underwriter such number of conformed copies of the registration statement and
each such amendment and supplement thereto (in each case including all exhibits
and documents filed therewith) and the prospectus included therein (including
each preliminary and summary prospectus) and any other prospectus filed under
Rule 424 under the Securities Act in conformity with the requirements of the
Securities Act as such Persons reasonably may request in order to facilitate the
public sale or other disposition of the Registrable Securities covered by such
registration statement;

            (d) Use its best efforts to register or qualify the Registrable
Securities covered by such registration statement under the securities or "blue
sky" laws of such jurisdictions as the sellers of Registrable Securities
provided that the Company shall not for any such purpose be required to qualify
generally to transact business as a foreign corporation in any jurisdiction
where it is not so qualified or to consent to general service of process or
submit to taxation in any such jurisdiction, unless the Company is already
subject to service or subject to taxation in such jurisdiction;

            (e) Use its best efforts to list the Registrable Securities covered
by such registration statement on any securities exchange or quotation system on
which the equity securities of the Company are then listed;

            (f) Immediately notify each seller of Registrable Securities, at any
time when a prospectus relating thereto is required to be delivered under the
Securities Act, of the happening of any event of which the Company has knowledge
as a result of which the prospectus contained in such registration statement, as
then in effect, includes an untrue statement of a material fact or omits to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in light of the circumstances then existing,
and promptly prepare and furnish to such seller a reasonable number of copies of
a prospectus supplemented or amended so that, as thereafter delivered to the
purchasers of such Registrable Securities, such prospectus shall not include an
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 not misleading in
light of the circumstances then existing;

            (g) Notify each seller of Registrable Securities covered by such
registration statement (i) when the prospectus or any prospectus supplement or
post-effective amendment has been filed, and, with respect to such registration
statement or any post-effective amendment, when the same has become effective,
(ii) of any request by the Commission for amendments or supplements to such
registration statement or to amend or to supplement such prospectus or for
additional information, (iii) of the issuance by the Commission of any stop
order suspending the effectiveness of such registration statement or the
initiation of any proceeding for that purpose and (iv) of the suspension of the
qualification of such securities for offering or sale in any jurisdiction, or of
the institution of any proceeding for any of such purposes;

            (h) Use its reasonable efforts to take all other steps necessary to
effect the registration of such Registrable Securities contemplated hereby.

            (i) Immediately notify each seller of Registrable Security at any
time when the Company becomes eligible to file a registration statement on form
S-3 and shall consult with the Investor to determine whether to file an
amendment to the Registration Statement on form S-3.


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<PAGE>

      SECTION 2.3 EXPENSES.

            (a) All expenses incurred by the Company in complying with Sections
2.1 and 2.2, including, without limitation, all registration and filing fees,
printing expenses, fees and disbursements of counsel and independent public
accountants for the Company, fees and expenses (including counsel fees) incurred
in connection with complying with state securities or "blue sky" laws, transfer
taxes, fees of transfer agents and registrars, excluding any Selling Expenses
(as defined below), are referred to herein as "REGISTRATION EXPENSES." All fees
and disbursements of counsel to the sellers of Registrable Securities and
underwriting discounts and selling commissions applicable to the sale of
Registrable Securities are referred to herein as "SELLING EXPENSES."

            (b) The Company shall pay all Registration Expenses in connection
with each registration statement under Section 2.1 and the fees based upon
activity invoices and expenses of one counsel to the holders of Registrable
Securities and holders of registration rights under the Existing Registration
Rights Agreements in connection with the review of the registration documents in
an amount not to exceed $20,000. All Selling Expenses in connection with each
registration statement under Section 2.1 shall be borne by the participating
sellers in proportion to the number of shares registered by each, or by such
participating sellers other than the Company as they may agree.

      SECTION 2.4 INDEMNIFICATION AND CONTRIBUTION.

            (a) To the extent permitted by law, the Company shall indemnify and
hold harmless each holder of Registrable Securities, any underwriter (as defined
in the Securities Act) for such holder in a registration pursuant to this
Article II and each Person, if any, who controls such holder or underwriter
within the meaning of the Securities Act or the Exchange Act, against any
losses, claims, damages, or liabilities (joint or several) to which they may
become subject under the Securities Act, the Exchange Act or other federal or
state law, insofar as such losses, claims, damages, or liabilities (or actions
in respect thereof) arise out of or are based upon any of the following
statements, omissions or violations (collectively a "VIOLATION"): (i) any untrue
statement of a material fact contained in such registration statement, including
any preliminary prospectus or final prospectus contained therein or any
amendments or supplements thereto; (ii) the omission to state therein a material
fact required to be stated therein, or necessary to make the statements therein
not misleading; or (iii) any violation by the Company of the Securities Act, the
Exchange Act, any state securities law or any rule or regulation promulgated
under the Securities Act, the Exchange Act or any state securities law; and the
Company will pay to each such holder, underwriter or controlling Person, as
incurred, any legal or other expenses reasonably incurred by them in connection
with investigating or defending any such loss, claim, damage, liability or
action provided that the indemnity agreement contained in this subsection 2.4(a)
shall not apply to amounts paid in settlement of any such loss, claim, damage,
liability or action if such settlement is effected without the consent of the
Company (which consent shall not be unreasonably withheld), nor shall the
Company be liable to any holder, underwriter or controlling Person for any such
loss, claim, damage, liability or action to the extent that it arises out of or
is based upon a Violation that occurs in reliance upon and in conformity with
written information furnished expressly for use in connection with such
registration by such holder, underwriter or controlling Person seeking
indemnification.


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<PAGE>

            (b) To the extent permitted by law, each selling holder of
Registrable Securities, severally and not jointly, shall indemnify and hold
harmless the Company, each of its directors, each of its officers who has signed
the registration statement, each Person, if any, who controls the Company within
the meaning of the Securities Act, any underwriter for the Company in a
registration pursuant to this Article II, any other holder selling Registrable
Securities, severally and not jointly, in such registration statement and any
controlling Person of any such underwriter or other holder, against any losses,
claims, damages, or liabilities (joint or several) to which any of the foregoing
Persons may become subject, under the Securities Act, the Exchange Act or other
federal, state or local law, insofar as such losses, claims, damages, or
liabilities (or actions in respect thereto) arise out of or are based upon any
Violation, in each case to the extent (and only to the extent) that such
Violation occurs in reliance upon and in conformity with written information
furnished by such holder for use in connection with such registration; and each
such holder shall pay, as incurred, any legal or other expenses reasonably
incurred by any Person intended to be indemnified pursuant to this subsection
2.4(b), in connection with investigating or defending any such loss, claim,
damage, liability or action provided that the indemnity agreement contained in
this subsection 2.4(b) shall not apply to amounts paid in settlement of any such
loss, claim, damage, liability or action if such settlement is effected without
the written consent of the holder, which written consent shall not be
unreasonably withheld or delayed.

            (c) Promptly after receipt by an indemnified party hereunder of
notice of the commencement of any action, such indemnified party shall, if a
claim in respect thereof is to be made against the indemnifying party hereunder,
notify the indemnifying party in writing thereof, but the omission so to notify
the indemnifying party shall not relieve it from any liability which it may have
to such indemnified party other than under this Section 2.4 and shall only
relieve it from any liability which it may have to such indemnified party under
this Section 2.4 if and to the extent that the indemnifying party is prejudiced
by such omission. In case any such action is brought against any indemnified
party and it notifies the indemnifying party of the commencement thereof, the
indemnifying party shall be entitled to participate in and, to the extent it
shall wish, to assume and undertake the defense thereof with counsel reasonably
satisfactory to such indemnified party, and, after notice from the indemnifying
party to such indemnified party of its election so to assume and undertake the
defense thereof, the indemnifying party shall not be liable to such indemnified
party under this Section 2.4 for any legal expenses subsequently incurred by
such indemnified party in connection with the defense thereof other than
reasonable costs of investigation and of liaison with counsel so selected
provided that if the defendants in any such action include both the indemnified
party and the indemnifying party, and the indemnified party reasonably concludes
that there may be reasonable defenses available to it that are different from or
additional to those available to the indemnifying party or that the interests of
the indemnified party reasonably may be deemed to conflict with the interests of
the indemnifying party, the indemnified party shall have the right to select a
separate counsel and to assume such legal defenses and otherwise to participate
in the defense of such action, with the expenses and fees of such separate
counsel and other expenses related to such participation to be reimbursed by the
indemnifying party as incurred, provided that only one such separate counsel
shall be retained to represent the indemnified parties in any jurisdiction
unless the use of one counsel for such indemnified parties would present such
counsel with a conflict of interest. No indemnifying party, in the defense of
any such claim or action, shall, except with the consent of each indemnified
party, consent to entry of any judgment or enter into any settlement that does
not include as an unconditional term thereof the giving by the claimant or
plaintiff to such indemnified party of a release from all liability in respect
to such claim or action. Each indemnified party shall furnish such information
regarding itself or the claim in question as an indemnifying party may
reasonably request in writing and as shall be reasonably required in connection
with the defense of such claim and litigation so resulting.


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<PAGE>

            (d) In order to provide for just and equitable contribution to joint
liability under the Securities Act in any case in which either (i) any holder of
Registrable Securities exercising rights under this Agreement, or any
controlling person of any such holder, makes a claim for indemnification
pursuant to this Section 2.4 but it is judicially determined (by the entry of a
final judgment or decree by a court of competent jurisdiction and the expiration
of time to appeal or the denial of the last right of appeal) that such
indemnification may not be enforced in such case notwithstanding the fact that
this Section 2.4 provides for indemnification in such case, or (ii) contribution
under the Securities Act may be required on the part of any such selling holder
or any such controlling person in circumstances for which indemnification is
provided under this Section 2.4 then, and in each such case, the Company and
such holder shall contribute to the aggregate losses, claims, damages or
liabilities to which they may be subject (after contribution from others) in
such proportion so that such holder is responsible for the portion represented
by the percentage that the aggregate public offering price of its Registrable
Securities offered by the registration statement bears to the aggregate public
offering price of all securities offered by such registration statement, and the
Company and other holders, as the case may be, are responsible for the remaining
portion provided that, in any such case (A) no such holder shall be required to
contribute any amount in excess of (i) the public offering price of all such
Registrable Securities offered by it pursuant to such registration statement or
(ii) the amount such holder would have been obligated to pay pursuant to Section
2.4(b) had such provisions been enforceable; and (B) no person or entity guilty
of fraudulent misrepresentation (within the meaning of Section 11(f) of the
Securities Act) shall be entitled to contribution from any person or entity who
was not guilty of such fraudulent misrepresentation.

      SECTION 2.5 DELAY OF REGISTRATION; FURNISHING INFORMATION.

            (a) No holder of Registrable Securities shall have any right to
obtain or seek an injunction restraining or otherwise delaying any such
registration as the result of any controversy that might arise with respect to
the interpretation or implementation of this Article II.

            (b) It shall be a condition precedent to the obligations of the
Company to take any action pursuant to this Article II that the holder of
Registrable Securities requesting the inclusion of Registrable Securities in a
registration furnish to the Company a completed and executed Questionnaire, in
the form attached hereto, containing such information regarding themselves, the
Registrable Securities held by them and the intended method of disposition of
such securities as shall be required to effect the registration of their
Registrable Securities.


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<PAGE>

      SECTION 2.6 SUSPENSION OF REGISTRATION; BLACKOUT; MARKET STAND-OFF.

            (a) The Company shall promptly notify each holder of Registrable
Securities requesting registration of the issuance by the Commission of any stop
order suspending the effectiveness of any registration statement or the
initiation or threat of any proceedings for that purpose. The Company shall use
its reasonable efforts to obtain the withdrawal of any order suspending the
effectiveness of such registration statement as soon as practicable.

            (b) The Company's obligation under this Agreement to use reasonable
efforts to cause a registration statement to become effective or to amend or
supplement a registration statement may be suspended, in the sole discretion of
the Company's Board of Directors, in the event of the consummation of, and
during the period of negotiations relating to, any transaction (which shall
include any financing, the acquisition or disposition of assets by transfer,
sale or license or any merger, consolidation, tender offer or similar
transaction) or the occurrence of any other event that, in the sole discretion
of the Company's Board of Directors, would require additional disclosure of
material information by the Company in such registration statement (such
circumstances being hereinafter referred to as a "Suspension Event") that would
make it impractical or inadvisable to cause such registration statement to be
made or to become effective or to amend or supplement the registration statement
provided that such suspension subsequent to effectiveness shall continue only
for a period not to exceed thirty-five (35) consecutive days, provided that the
Company may not suspend its obligation to amend or supplement subsequent to
effectiveness for more than ninety (90) days in the aggregate, and provided
further that no such Suspension Event shall be permitted to exceed consecutive
twenty (20) day periods during the first sixty (60) days following the
Registration Statement is declared effective (each, a "Blackout Period"),
arising out of the same set of facts, circumstances or transactions. The Company
shall notify each holder of Registrable Securities of the existence of such
Suspension Event. If a Suspension Event continues beyond the limits prescribed
above, the Company shall pay as liquidated damages for such continuation and not
as a penalty (the "Liquidated Damages") to the Holder an amount equal to two
percent (2%) of the purchase price paid by the Holder for all Registrable
Securities then held by the Holder for each thirty (30) day period, pro rated
for any period less than thirty (30) days until the Suspension Event has ended.

            (c) A holder of Registrable Securities may re-commence sales of the
Registrable Securities pursuant to such registration statement or such filings
following further notice to such effect from the Company, which notice shall be
given by the Company not later than five (5) business days after the conclusion
of any such Suspension Event or correction or update of such registration
statement. Any such notice of a Suspension Event may constitute material
non-public information and, in any case, a holder of Registrable Securities
shall keep confidential the receipt and existence of any such notice or any
subsequent notice that such holder may re-commence sales.


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<PAGE>

                                   ARTICLE III
                                  MISCELLANEOUS

      SECTION 3.1 NOTICES. All notices, requests and other communications to any
party hereunder shall be in writing (including telecopier or similar writing)
and shall be given to such party at its address or telecopier number as set
forth below, or such other address or telecopier number as such party may
hereinafter specify for the purpose of giving notice hereunder to the party
giving such notice. Each such notice, request or other communication shall be
effective (i) if given by telecopier, when such telecopier is transmitted to the
telecopier number specified pursuant to this Section 3.1 and the appropriate
confirmation is received or; (ii) if given by mail, 72 hours after such
communication is deposited in the mails, certified mail, return receipt
requested, postage prepaid, addressed as aforesaid or; (iii) if given by any
other means, when delivered at the address as follows:

         If to the Company, to:

                  DOV Pharmaceutical, Inc.
                  Continental Plaza
                  433 Hackensack Avenue
                  Hackensack NJ 07601
                  Attention: General Counsel
                  Telecopier: 201-968-0986

         With a copy to:

                  Goodwin Procter LLP
                  599 Lexington Avenue
                  New York, New York 10022
                  Attention: Joseph R. Siegelbaum, Esq.
                  Telecopier: (212) 355-3333

         If to the Investor, to:

                  Acqua Wellington Opportunity I Limited
                  Shirlaw House
                  87 Shirley Street
                  Nassau, Bahamas
                  Attention:  Michael Taylor

         With a copy to:

                  Jenkens & Gilchrist Parker Chapin LLP
                  The Chrysler Building
                  405 Lexington Avenue
                  New York, New York
                  Attention: Christopher S. Auguste, Esq.
                  Telecopier (212) 704-6288


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<PAGE>

      SECTION 3.2 ENTIRE AGREEMENT. This Agreement constitutes the entire
agreement and understanding between the parties hereto and supersedes any and
all prior agreements and understandings, written or oral, relating to the
subject matter of this Agreement.

      SECTION 3.3 MODIFICATIONS AND AMENDMENTS. This Agreement may not be
amended or modified, and no provision hereof may be waived, without the written
consent of the Company and holders of at least fifty percent (50%) of the
outstanding Registrable Securities.

      SECTION 3.4 BENEFIT; ASSIGNMENT. All statements, representations,
warranties, covenants and agreements in this Agreement shall be binding on the
parties hereto and shall inure to the benefit of the respective successors and
permitted assigns of each party hereto. The Investor may fully and freely
transfer or assign the registration rights set forth in this Agreement to any
person that acquires at least 50% of the Registrable Securities purchased at the
Closing, but may not otherwise transfer or assign the registration rights set
forth in this Agreement. As a condition to the transfer of the registration
rights set forth in this Agreement, a transferee shall consent in writing to be
bound by the terms and conditions of this Agreement.

      SECTION 3.5 GOVERNING LAW. This Agreement and the rights and obligations
of the parties hereunder shall be construed in accordance with and governed by
the law of the State of New York without giving effect to the conflict of law
principles thereof.

      SECTION 3.6 DISPUTE RESOLUTION.

      (a) All disputes, claims, or controversies arising out of or relating to
this Agreement or the negotiation, breach, validity or performance hereof and
thereof or the transactions contemplated hereby and thereby that are not
resolved by mutual agreement other than a dispute over best efforts to cause a
registration statement to become effective governed by Section 2.1 shall be
resolved solely and exclusively by binding arbitration to be conducted before
the Center for Public Resources or its successor ("CPR") in New York, New York
before a single arbitrator (the "Arbitrator"). The parties understand and agree
that this arbitration shall apply equally to claims of fraud or fraud in the
inducement.

      (b) The parties covenant and agree that the arbitration shall commence
within 60 days of the date on which a written demand for arbitration is filed by
any party hereto (the "Filing Date"). In connection with the arbitration
proceeding, the Arbitrator shall have the power to order the production of
documents by each party and any third-party witnesses. In addition, each party
may take up to three depositions as of right, and the Arbitrator may in his or
her discretion allow additional depositions upon good cause shown by the moving
party. However, the Arbitrator shall not have the power to order the answering
of interrogatories or the response to requests for admission or more definite
statement. In connection with any arbitration, each party shall provide to the
other, no later than seven business days before the date of the arbitration, the
identity of all persons that may testify at the arbitration and a copy of all
documents that may be introduced at the arbitration or considered or used by a
party's witnesses or experts. The parties shall be entitled to file post-hearing
briefs within 20 days. The Arbitrator's decision and award shall be made and
delivered within 60 days of final submission to the Arbitrator. The Arbitrator's
decision shall set forth a reasoned basis for any award of damages or finding of
liability.


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<PAGE>

      (c) The parties covenant and agree that they will participate in the
arbitration in good faith and that they will (i) bear their own attorneys' fees,
costs and expenses in connection with the arbitration, and (ii) share equally in
the fees and expenses charged by the Arbitrator. Any party unsuccessfully
refusing to comply with an order of the Arbitrators shall be liable for costs
and expenses, including attorneys' fees, incurred by the other party in
enforcing the award. This Section 8.06 applies equally to requests for
temporary, preliminary or permanent injunctive relief, except that in the case
of temporary or preliminary injunctive relief any party may proceed in court
without prior arbitration for the purpose of avoiding immediate and irreparable
harm. (d) Except as provided in Section 3.6 (c) above, each of the parties
hereto irrevocably and unconditionally consents to the jurisdiction of CPR to
resolve all disputes, claims or controversies arising out of or relating to this
Agreement or any other agreement executed and delivered pursuant to this
Agreement or the negotiation, breach, validity or performance hereof and thereof
or the transactions contemplated hereby and thereby and further consents to the
sole and exclusive jurisdiction of the courts of New York for the purposes of
enforcing the arbitration provisions of Section 3.6 of this Agreement. Each
party further irrevocably waives any objection to proceeding before the
Arbitrator based upon lack of personal jurisdiction or to the laying of venue
and further irrevocably and unconditionally waives and agrees not to make a
claim in any court that arbitration before the Arbitrator has been brought in an
inconvenient forum. Each of the parties hereto hereby consents to service of
process by registered mail at the address to which notices are to be given. Each
of the parties hereto agrees that its submission to jurisdiction and its consent
to service of process by mail is made for the express benefit of the other
parties hereto.

      SECTION 3.7 SEVERABILITY. Any provision of this Agreement that is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof but shall be interpreted as if it
were written so as to be enforceable to the maximum extent permitted by
applicable law, and any such prohibition or unenforceability in any jurisdiction
shall not invalidate or render unenforceable such provision in any other
jurisdiction. To the extent permitted by applicable law, the parties hereby
waive any provision of law which renders any provisions hereof prohibited or
unenforceable in any respect.

      SECTION 3.8 HEADINGS AND CAPTIONS. The headings and captions of the
various subdivisions of this Agreement are for convenience of reference only and
shall in no way modify or affect the meaning or construction of any of the terms
or provisions hereof.


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      SECTION 3.9 NO WAIVER OF RIGHTS, POWERS AND REMEDIES. No failure or delay
by a party hereto in exercising any right, power or remedy under this Agreement,
and no course of dealing among the parties hereto, shall operate as a waiver of
any such right, power or remedy of the party. No single or partial exercise of
any right, power or remedy under this Agreement by a party hereto, nor any
abandonment or discontinuance of steps to enforce any such right, power or
remedy, shall preclude such party from any other or further exercise thereof or
the exercise of any other right, power or remedy hereunder. The election of any
remedy by a party hereto shall not constitute a waiver of the right of such
party to pursue other available remedies. No notice to or demand on a party not
expressly required under this Agreement shall entitle the party receiving such
notice or demand to any other or further notice or demand in similar or other
circumstances or constitute a waiver of the rights of the party giving such
notice or demand to any other or further action in any circumstances without
such notice or demand.

      SECTION 3.10 COUNTERPARTS; FACSIMILE. This Agreement may be executed in
counterparts, each of which shall be deemed an original agreement, but all of
which together shall constitute one and the same instrument. Execution and
delivery of this Agreement by facsimile transmission shall constitute execution
and delivery of this Agreement for all purposes, with the same force and effect
as execution and delivery of an original manually signed copy hereof.


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      IN WITNESS WHEREOF, the parties hereto have executed this Agreement or
caused this Agreement to be executed by their duly authorized representatives,
as of the date first written above.

                                        DOV PHARMACEUTICAL, INC.


                                        By: /s/ J. R. Horton
                                           -------------------------------------
                                           Name:  J. R. Horton
                                           Title: Vice President and
                                                    General Counsel

                                        ACQUA WELLINGTON OPPORTUNITY I LIMITED


                                        By: /s/ Michael Taylor
                                           -------------------------------------
                                           Name:   Michael Taylor
                                           Title:  Director

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