EXHIBIT
      10.1

    


    ***
      Confidential treatment has been requested for portions of this exhibit. The
      copy
      filed herewith omits the information subject to the confidentiality treatment
      request, and such omissions are designated as [***]. A complete version of
      this
      exhibit has been filed separately with the Securities and Exchange Commission
      pursuant to the request for confidential treatment.

    


    AMENDMENT

    


    This
      Amendment (“Amendment”), dated as of August 5, 2005 (the “Amendment Effective
      Date”), is made by and between MSD Warwick (Manufacturing) Ltd. (“Merck”) and
      DOV Pharmaceutical, Inc. (“DOV”) with respect to the Exclusive License,
      Development and Commercialization Agreement by and between Merck and DOV dated
      August 5, 2004 (the “Agreement”)

    


    Whereas
      the parties have held discussions on amending the Agreement on an interim basis
      such that Merck’s obligations to commence a certain Phase II Clinical Trial on
      DOV 21,947 would be transferred to DOV and re-assumed by Merck under certain
      conditions; 

    


    Now
      therefore the parties agree as follows, employing where capitalized terms are
      used and not otherwise defined the definitions used in the
      Agreement:

    


    
      	1.  	
              IND.
                Merck shall transfer, or cause to be transferred, to DOV the current
                open
                IND for DOV 21,947 to enable DOV to conduct Clinical Trials including
                those contemplated by this Amendment. Upon the transfer of the IND
                to DOV,
                DOV shall be solely responsible for performance of all Clinical Trials
                pursuant to the IND and compliance with the conditions of the IND.
                The
                exclusive license granted to Merck pursuant to Section 3.1 of the
                Agreement shall have any and all exceptions (the “License Exceptions”)
                sufficient to permit DOV, and one or more third parties engaged by
                DOV on
                its behalf, to conduct and perform any and all research and development,
                Clinical Trials including those required by Paragraphs 3, 4 and 5
                below
                and any other activities necessary or appropriate to fulfill DOV’s rights
                and obligations under this Amendment. Additionally, Merck hereby
                grants to
                DOV (a) a non-exclusive license under Merck Patent Rights (if any)
                and
                Merck Know-How (if any) and (b) the right to permit, under Merck
                Patent
                Rights (if any) and Merck Know-How (if any), one or more third parties
                engaged by DOV to make or use, on DOV’s behalf, DOV 21,947 and any Product
                containing DOV 21,947 and methods, in the case of either of the foregoing
                clauses (a) or (b), sufficient to permit DOV to conduct and perform
                any
                and all research and development, Clinical Trials including those
                required
                by Paragraphs 3, 4 and 5 below and any other activities necessary
                or
                appropriate to fulfill DOV’s rights and obligations under this Amendment.
                

            


    

    


    
      	2.  	
              Drug
                Supply.
                Merck shall supply to DOV at Merck’s expense all Merck’s supply existing
                as of the Amendment Effective Date of DOV 21,947 that is qualified
                as of
                the Amendment Effective Date for use in
                humans.

            


    

     

    
      
         

      

      
        1

        
          

        

      

      
         

      

    

    

      	3.  	
              Phase
                Ib and R&D.
                DOV shall conduct at its expense a Phase Ib Clinical Trial with respect
                to
                DOV 21,947 (the “Phase Ib”) on normal volunteers in order to form a basis
                for a Phase II Clinical Trial with respect to DOV 21,947, as more
                fully
                described below (the “First Phase II”). DOV shall have the right, during
                the Phase Ib, First Phase II and Second Phase II (as defined below),
                and
                upon consultation with Merck, to conduct at DOV’s expense further
                development activities on DOV 21,947 including formulation, longer
                term
                toxicology, ADME and other pre-clinical development and Clinical
                Trials
                (collectively, “Further R&D”).

            


    

    


    
      	4.  	
              First
                Phase II.
                DOV shall conduct at its expense the First Phase II, which shall
                be a
                dose-response, placebo controlled study. The results of the First
                Phase II
                shall be taken into account in designing a successive Phase II Clinical
                Trial, as more fully described below (the “Second Phase II”).
                

            


    

    


    
      	5.  	
              Second
                Phase II.
                DOV shall conduct at its expense the Second Phase II, which shall
                have as
                its objective determining the superiority of DOV 21,947 over an SSRI
                in
                the treatment of outpatients with major depressive disorder. No later
                than
                the commencement of the Second Phase II, the parties shall agree
                in
                writing on the design of the Second Phase II and what constitutes
                successful completion of the Second Phase II (“Successful”). Whether such
                study is Successful shall be determined without reference to Section
                1.74
                of the Agreement. 

            


    

    


    
      	6.  	
              DOV
                Development Plan and Budget.
                Within ninety (90) days following the Amendment Effective Date DOV
                shall
                present to Merck the development plan and budget for the Phase Ib
                and
                First Phase II (the “DOV Plan”). The DOV Plan shall include spending caps
                for the DOV personnel involved in carrying out the DOV Plan for up
                to
                $[***] for the Phase Ib and $[***] for the Second Phase II. DOV shall
                update the DOV Plan based on new information developed for Further
                R&D
                and Second Phase II. 

            


    

    


    
      	7.  	
              Reimbursement
                of DOV.
                If the Second Phase II is Successful or if Merck otherwise elects
                as
                contemplated by this Paragraph 7 or Paragraphs 8 or 11 below, Merck
                shall
                reimburse DOV as follows (the “Reimbursement Payment): [***]% of DOV’s
                actual costs for the Phase Ib and Second Phase II and [***]% of its
                actual
                costs for the First Phase II and Further R&D, in each case upon
                presentation of an itemization of such costs calculated to include
                out of
                pocket and internal professional time at CRO rates to be agreed upon
                by
                the parties; provided that Merck shall not be required to reimburse
                DOV
                for Further R&D expenses that were not approved by Merck prior to
                being incurred. If the Second Phase II is not Successful, Merck may
                elect
                but is not required to make the Reimbursement Payment. The Reimbursement
                Payment shall be due (a) forty-five (45) days following the later
                of (i)
                the date that DOV provides Merck with all Information and Inventions
                generated as a result of Phase Ib, First Phase II, Second Phase II
                and
                Further R&D, and (ii) the date on which DOV delivers to Merck data
                demonstrating that the Second Phase II is Successful, (b) in the
                event
                that the Second Phase II is not Successful and Merck nevertheless
                elects
                to make the Reimbursement Payment, no later than sixty (60) days
                after the
                delivery to Merck of data demonstrating that the Second Phase II
                was not
                Successful or (c) in the event that DOV terminates this Amendment
                in
                accordance with Paragraph 11 below after the commencement of the
                Second
                Phase II, and if Merck exercises its rights under Paragraph 11, not
                later
                than the date specified in Paragraph
                11.

            


    

    


    
      
         

      

      
        2

        
          

        

      

      
         

      

    

     

    
      	8.  	
              Merck
                Payment and Continuing Obligations.
                (a) If the Second Phase II is Successful or if Merck otherwise elects
                to
                make the Reimbursement Payment, it shall re-assume all development
                and
                other obligations under the Agreement with respect to DOV
                21,947.

            


    

    


    (b) Upon
      the
      Amendment Effective Date, the penalty payments in respect of Initiation of
      a
      first Phase II Clinical Trial for DOV 21,947 called for by Section 5.3(d) of
      the
      Agreement shall be eliminated and replaced by payments in the same amounts
      to be
      due in the event of Merck’s failure to Initiate a further Phase II Clinical
      Trial or Phase III Clinical Trial for DOV 21,947 or such Additional Compound
      selected by Merck pursuant to Paragraph 10 within [***] following the
      Reimbursement Payment for the initial penalty, [***] thereafter for the second
      penalty and [***] after the second penalty for each subsequent penalty, provided
      that DOV has promptly transferred the IND for DOV 21,947 and all Information
      and
      Inventions pursuant to paragraph 13. 

    


    
      	9.  	
              Pivotal
                Trial Milestone.
                If the Second Phase II is Successful, Merck shall, notwithstanding
                anything to the contrary in the Agreement (including without limitation
                Section 5.3(c) of the Agreement), make the development milestone
                payment
                called for by Section 5.3(a)(i) of the Agreement.
                

            


    

    


    
      	10.  	
              Additional
                Licenses to Merck.
                Within thirty (30) days of the Amendment Effective Date, DOV shall
                transfer all Information and Inventions relating to the Additional
                Compounds (defined below) (the “Transfer Date”). DOV hereby grants to
                Merck, free of charge, for a period commencing on the date of this
                Amendment and ending 12 months following the Transfer Date, an exclusive
                license in the Territory under the DOV Patent Rights, DOV’s and its
                Controlled Affiliates’ rights in the Joint Patent Rights, and DOV
                Know-How, but with no right to sublicense, to conduct pre-clinical
                testing
                on three additional triple reuptake inhibitor compounds of DOV, namely,
                [***] (“Additional Compounds”), whereupon Merck shall be entitled to
                select (in writing no later than 30 days after the end of such 12-month
                period) with no up-front payment to DOV one of such Additional Compounds
                for inclusion in the Agreement as a Compound and all references in
                the
                Agreement to DOV 21,947 shall be deemed to mean DOV 21,947 and/or
                the
                Additional Compound that has been selected by Merck. Upon such selection,
                all know-how, data and related inventions and/or intellectual property
                related to such other two Additional Compounds created or developed
                by or
                on behalf of Merck during such 12 month period (the “Rejected Compound
                IP”) shall be returned or transferred to and be owned by DOV. In
                furtherance thereof, Merck hereby assigns and transfers, and shall
                assign
                and transfer, to DOV all ownership and interest in the Rejected Compound
                IP and any and all intellectual property rights in and to any Rejected
                Compound IP. 

            


    

     

    
      
         

      

      
        3

        
          

        

      

      
         

      

    

     

    
      	11.  	
              Termination
                by DOV.
                DOV shall have the right, prior to conclusion of the Second Phase
                II and
                before clinical results are known, to terminate this Amendment upon
                30
                days’ written notice provided pursuant to Section 12.4 of the Agreement
                in
                which case (a) all references in the Agreement to DOV 21,947 including
                in
                Section 1.15 shall be deleted and the compound selected by Merck
                pursuant
                to Paragraph 10 shall be substituted therefor and (b) Section 9.4
                of the
                Agreement shall apply to DOV 21,947 as if the Agreement were terminated
                by
                Merck pursuant to Section 9.2 of the Agreement; provided that such
                termination shall not affect the parties’ rights and obligations under
                Paragraph 10 of this Amendment. In the event of such a termination
                by DOV,
                DOV will provide to Merck copies of all DOV’s Information relating to DOV
                21,947 that has not previously been provided to Merck. Merck will
                have the
                right, no later than sixty (60) days after DOV has provided such
                Information to Merck, upon written notice and payment of the Reimbursement
                Payment, to re-assume all development and other rights and obligations
                under the Agreement with respect to DOV 21,947; provided,
                however,
                that, in the event that Merck’s election to make a Reimbursement Payment
                relates to a termination by DOV prior to the commencement of the
                Second
                Phase II, the component of the Reimbursement Payment payable pursuant
                to
                this sentence that is attributable to the First Phase II shall be
                [***]%
                of DOV’s actual costs for the First Phase II ( rather than [***]% of DOV’s
                actual costs for the First Phase II).


            


    

    


    
      	12.  	
              Termination
                by Merck.
                During the term of this Amendment, in addition to the rights Merck
                has
                pursuant to Sections 9.2 and 9.3 of the Agreement, Merck shall have
                the
                right to terminate the Agreement upon 30 days’ written notice (i) within
                sixty (60) days of DOV presenting to Merck the DOV Plan, or (ii)
                if the
                Parties do not agree in writing on the design of the Second Phase
                II or
                what constitutes Successful completion of the Second Phase II. Termination
                pursuant to this Paragraph 12 of the Amendment shall be deemed a
                termination by Merck pursuant to Section 9.2 of the Agreement. Merck
                shall
                not elect to terminate the Agreement pursuant to Section 9.2 prior
                to the
                date that is ninety (90) days following the Amendment Effective
                Date.

            


    

    


    
      	13.  	
              Reversion
                of Rights to Merck.
                If Merck makes the payments required by Paragraphs 7 and 9 above,
                the
                License Exceptions shall terminate, and DOV shall promptly transfer
                to
                Merck under the Agreement all Information and Inventions created
                or
                developed by DOV during the term of this Amendment relating to DOV
                21,947
                and any Information and Inventions created or developed during the
                period
                shall be governed by the Agreement and the IND for DOV 21,947. Thereupon
                the parties shall have all rights and obligations set forth in the
                Agreement except as expressly amended by this Amendment.
                

            


    

    


    
      	14.  	
              Joint
                Development Committee.
                Notwithstanding the provisions of Section 2.3 of the Agreement, during
                the
                term of this Amendment, and until the reversion of rights to Merck
                pursuant to Paragraph 13 of this Amendment, JDC meetings shall be
                chaired
                by DOV, and Merck shall have the right to waive its participation
                in JDC
                meetings. DOV shall inform Merck during the JDC meetings of all
                correspondence sent to and received from the FDA regarding the
                Phase
                Ib, First Phase II, and Second Phase II and with respect to the Further
                R&D.
                

            


    

    


    
      
         

      

      
        4

        
          

        

      

      
         

      

    

     

    
      	15.  	
              DOV
                216,303 Public Communications.
                DOV shall be entitled to publish the results of the DOV 216,303 study
                entitled “A Multi-Centered, Double-blind Safety, Efficacy and Tolerability
                Study Comparing DOV 216,303 BID 50 mg to Citalopram HBr 20 mg BID
                for Two
                Weeks in Hospitalized and Outpatient Patients with Major Depressive
                Disorder” [***].

            


    

    


    
      	16.  	
              Construction.
                The parties intend that this Amendment supersede any inconsistent
                terms of
                the Agreement or, if not directly inconsistent, be construed so as
                to
                harmonize the two documents to the extent that the intent of this
                Amendment is carried out. 

            


    

    


    
      	17.  	
              Further
                Assurances.
                Each party agrees to execute such further papers, agreements, documents,
                instruments and the like as may be necessary or desirable to effect
                the
                purpose of this Amendment and to carry out its
                provisions.

            


    

    


    
      	18.  	
              Counterparts.
                This Amendment may be executed in two or more counterparts, each
                of which
                will be deemed an original, but all of which will constitute one
                and the
                same instrument.

            


    

    


    [The
      remainder of this page has been left blank intentionally.]

     

    
      
         

      

      
        5

        
          

        

      

      
         

      

    

    


    Agreed:
      

    


    MSD
      Warwick (Manufacturing) Ltd.

    


    By:   
      /s/
      Caroline Dorsa                        
      

    
      	Name:	
              Caroline
                Dorsa

            


    

    
      	Title:	
              Treasurer 

            


    

    


    DOV
      Pharmaceutical, Inc.

    


    By:    
      /s/
      Dr.
      Leslie
      Hudson               
      

    
      	Name:	
              Dr.
                Leslie Hudson

            


    

    
      	Title:	
              President
                and Chief Executive 

            


    

    Officer

     

    
      
         

      

      
        6