Exhibit
      10.48

    Fifth
      Amendment

    To

    DOV
      Pharmaceutical, Inc.

    2000
      Stock Option and Grant Plan

    As
      Amended and Restated as of March 28, 2002 and 

    Amended
      May 30, 2003, May 24, 2004, May 23, 2005 and May 22, 2006

     

    The
      DOV
      Pharmaceutical, Inc. 2000 Stock Option and Grant Plan, as amended and restated
      as of March 28, 2002 and as further amended May 30, 2003, May 24, 2004, May
      23,
      2005 and May 22, 2006 (the “2000 plan”) is hereby amended as
      follows:

    


    1.
      Section 3(c) of the 2000 plan shall be deleted in its entirety and replaced
      with
      the following:

    


    Mergers
      and Other Sale Events.
      In the
      case of and subject to the consummation of (i) the dissolution or liquidation
      of
      the Company, (ii) the sale of all or substantially all the assets of the
      Company to an unrelated person or entity, (iii) a merger, reorganization or
      consolidation in which the outstanding shares of Stock are converted into or
      exchanged for a different kind of securities of the successor entity such that
      the holders of the Company’s outstanding voting power immediately prior to such
      transaction do not own a majority of the outstanding voting power of the
      successor entity immediately upon completion of such transaction, (iv) the
      sale
      of all the Stock of the Company to an unrelated person or entity, or (v) any
      other transaction in which the owners of the Company’s outstanding voting power
      prior to such transaction do not own at least a majority of the outstanding
      voting power of the successor entity immediately upon completion of the
      transaction (in each case, a “Sale Event”), all Options and Stock Appreciation
      Rights that are not exercisable immediately prior to the effective time of
      the
      Sale Event shall become fully exercisable as of the effective time of the Sale
      Event and all other Awards shall become fully vested and nonforfeitable as
      of
      the effective time of the Sale Event, except as the Committee may otherwise
      specify with respect to particular Awards in the relevant Award documentation,
      and Awards with conditions and restrictions relating to the attainment of
      performance goals may become vested and nonforfeitable in connection with a
      Sale
      Event in the Committee’s discretion.  Upon the effective time of the Sale
      Event, the Plan and all outstanding Awards granted hereunder shall terminate,
      unless provision is made in connection with the Sale Event in the sole
      discretion of the parties thereto for the assumption or continuation of Awards
      theretofore granted by the successor entity, or the substitution of such Awards
      with new Awards of the successor entity or parent thereof, with appropriate
      adjustment as to the number and kind of shares and, if appropriate, the per
      share exercise prices, as such parties shall agree (after taking into account
      any acceleration hereunder).  In the event of such termination, each
      grantee shall be permitted, within a specified period of time prior to the
      consummation of the Sale Event as determined by the Committee, to exercise
      all
      outstanding Options and Stock Appreciation Rights held by such grantee,
      including those that will become exercisable upon the consummation of the Sale
      Event; provided, however, that the exercise of Options and Stock Appreciation
      Rights not exercisable prior to the Sale Event shall be subject to the
      consummation of the Sale Event.

    


    Notwithstanding
      anything to the contrary in this Section 3(c), in the event of a Sale Event
      pursuant to which holders of the Stock of the Company will receive upon
      consummation thereof a cash payment for each share surrendered in the Sale
      Event, the Company shall have the right, but not the obligation, to make or
      provide for a cash payment to the grantees holding Options and Stock
      Appreciation Rights, in exchange for the cancellation thereof, in an amount
      equal to the difference between (A) the value as determined by the Committee
      of
      the consideration payable per share of Stock pursuant to the Sale Event (the
      “Sale Price”) times the number of shares of Stock subject to outstanding Options
      and Stock Appreciation Rights (to the extent then exercisable at prices not
      in
      excess of the Sale Price) and (B) the aggregate exercise price of all such
      outstanding Options and Stock Appreciation Rights.

     

    
      
         

      

      
         

        
          

        

      

      
         

      

    

    


    2.
       Except
      as
      otherwise expressly modified herein, the 2000 plan is, and shall continue to
      be,
      in full force and effect and is hereby ratified and confirmed in all
      respects.

    


    APPROVED
      AND ADOPTED BY THE BOARD OF DIRECTORS OF

    DOV
      PHARMACEUTICAL, INC.:

    


    By:
      /s/
      Arnold S.
      Lippa                                            


    Name:
      Arnold S. Lippa, Ph.D.

    Title:
      Chairman of the Board of Directors

    


    Date:
      May
      30, 2006