<PAGE>

Confidential treatment has been requested for portions of this document. 
Brackets indicate portions of text that have been omitted. A separate filing 
of such omitted text has been made with the Commission as part of the 
Company's application for confidential treatment.

                                                               Exhibit 10.44


                        AMENDMENT TO LICENSE AGREEMENT
                                       
                                       
     THIS AMENDMENT TO LICENSE AGREEMENT (the "Amendment") is made and 
entered into effective as of July 3, 1997 (the "Amendment Date"), by and 
between CV THERAPEUTICS, INC., a Delaware corporation having its principal 
place of business at 3172 Porter Drive, Palo Alto, California  94304 ("CVT"), 
and SYNTEX (U.S.A.), INC., a Panamanian corporation whose address is 3401 
Hillview Avenue, Palo Alto, California  94304 ("Syntex").  Capitalized terms 
used in this Amendment that are not otherwise defined herein shall have the 
same meanings as such terms are defined in the Prior Agreement (as defined 
below).

                                   RECITALS
                                       
     A.   CVT and Syntex entered into a License Agreement dated March 27, 
1996 (the "Prior Agreement"), under which Syntex granted to CVT an exclusive 
license in the CVT Territory to develop, register, make or have made, use, 
offer for sale, sell, or import the Compound.

     B.   The parties desire to amend the terms of the Prior Agreement to set 
forth new milestone payments to replace those in the Agreement, to provide 
for CVT to issue to Syntex a certain number of shares of CVT registered 
common stock and to establish royalty rates on Net Sales of Licensed Products 
marketed [ * ].  The Prior Agreement, as amended by this Amendment, shall 
constitute the "Agreement."

     NOW, THEREFORE, the parties agree as follows:

1.   AMENDMENT OF THE PRIOR AGREEMENT

     The parties hereby agree to amend the terms of the Prior Agreement as of 
the Amendment Date as provided below.

     1.1  AMENDMENT OF SECTION 5.1(b).  Section 5.1(b) of the Prior Agreement 
is hereby amended and restated to read in its entirety as follows:

          "b)  CVT will pay Syntex the following additional amounts in
               milestone payments upon the first occurrence of each of the
               following milestones in the CVT Territory as follows:
               
               1)   Subject to 5.1(c) below, [ * ] upon the [ * ] but in no 
                    event later than [ * ];
                 
               2)   [ * ] upon the approval of the [ * ].


* Confidential Treatment Requested.
<PAGE>

                    For the purposes of this Section 5.1(b), [ * ] shall mean 
                    any of the following [ * ] and [ * ] shall mean [ * ].
                 
               3)   [ * ] upon the [ * ].  In the event that [ * ] then a 
                    [ * ] milestone payment shall be due from CVT to Syntex at 
                    the [ * ] milestone payment in the event that such [ * ] 
                    milestone payment is subsequently made by CVT to Syntex.
                    In the event [ * ].
                 
     1.2  EQUITY.  The parties hereby agree to amend Section 5.1 of the Prior 
Agreement to add new subsections 5.1(d) and 5.1(e) which will read in their 
entirety as follows:

          "EQUITY
          
             d)   Upon the Amendment Date, CVT shall issue to Syntex [ * ] 
                  shares of CVT's common stock (the "Shares").  As soon as 
                  practicable after November 22, 1997, CVT shall file a 
                  registration statement with the Securities and Exchange 
                  Commission under the Securities Act of 1933, as amended
                  (the "Securities Act") covering the registration of the 
                  Shares.  CVT shall use all reasonable efforts to cause such 
                  registration statement to be declared effective, and to 
                  keep such registration statement effective until the earlier
                  of three hundred sixty five (365) days following the 
                  effective date or the date that Syntex has completed the 
                  distribution related thereto.
                
             e)   Syntex understands that the Shares have not been registered 
                  under the Securities Act.  Syntex understands that the 
                  Shares are being offered and sold pursuant to an exception 
                  from registration contained in the Securities Act based on 
                  Syntex's representations contained in this Amendment.  
                  Syntex hereby represents and warrants as follows:


* Confidential Treatment Requested.


                                      2.
<PAGE>

                    (1)  Syntex has substantial experience in evaluating and 
                         investing in private placement transactions of 
                         securities in companies similar to CVT so that it is
                         capable of evaluating the merits and risks of its 
                         investment in CVT and has the capacity to protect 
                         its own interests.  Syntex must bear the economic 
                         risk of this investment indefinitely unless the 
                         Shares are registered pursuant to the Securities Act 
                         or an exemption from registration is available.
                         
                    (2)  Syntex is acquiring the Shares for its own account 
                         for investment only, and not with a view towards 
                         their distribution. 

                    (3)  Syntex represents that by reason of its management's 
                         business or financial experience, Syntex has the 
                         capacity to protect its interests in connection with
                         the transactions contemplated by this Amendment.  
                         Syntex is not aware of any publication or 
                         advertisement in connection with the transactions 
                         contemplated in the Amendment.

                    (4)  Syntex represents that it is an accredited investor 
                         within the meaning of Regulation D under the 
                         Securities Act.

                    (5)  Syntex has received: (i) CVT's Annual Report on Form 
                         10-K for the year ended December 31, 1996, including 
                         the audited financial statements contained therein; 
                         (ii) CVT's Quarterly Report on Form 10-Q for the 
                         quarter ended March 31, 1997, including the unaudited 
                         financial statements contained therein; (iii) CVT's 
                         Annual Report to Stockholders; and (iv) CVT's Annual 
                         Proxy Statement for the 1997 Annual Meeting of 
                         Stockholders.  Syntex has had an opportunity to
                         discuss CVT's business, management and financial 
                         affairs with CVT's directors, officers and management 
                         and has had the opportunity to ask questions of and
                         receive answers from CVT and its management regarding 
                         the terms and conditions of this investment.

                    (6)  Syntex understands that the Shares may not be sold, 
                         transferred or otherwise disposed of without 
                         registration under the Securities Act or an exemption 
                         therefrom, and that in the absence of an effective 
                         registration statement covering the Shares or an 
                         available exemption from registration under the 
                         Securities Act, the Shares must be held indefinitely.
                         In particular, Syntex is aware that the Shares many 
                         not be sold pursuant to Rule 144 promulgated 


                                      3.
<PAGE>

                         under the Securities Act unless all of the conditions 
                         of that Rule are met.

                    (7)  The certificate evidencing the Shares shall be 
                         endorsed with the following legend:

                         "THE SHARES REPRESENTED HEREBY HAVE NOT BEEN
                         REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
                         AMENDED, AND MAY NOT BE SOLD, TRANSFERRED, ASSIGNED,
                         PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED
                         UNDER SUCH ACT, OR UNLESS THE COMPANY HAS RECEIVED AN
                         OPINION OF COUNSEL OR OTHER EVIDENCE, SATISFACTORY TO
                         THE COMPANY AND ITS COUNSEL THAT SUCH REGISTRATION IS
                         NOT REQUIRED."
                         
     1.3  AMENDMENT OF SECTION 5.2.  Section 5.2 of the Prior Agreement is 
hereby amended and restated to read in its entirety as follows:

     "5.2 CVT shall pay the following royalties to Syntex on Net Sales of the
          Licensed Products.  Such royalties shall be paid on a product-by-
          product and country-by-country basis according to the following
          rates:
          
          a)   For Net Sales of a Licensed Product as to which Syntex Patents 
               and Know-How cover the manufacture, use, sale, offer for sale, 
               or import of the Licensed Product, and which Licensed Product 
               is [ * ] a rate of [ * ].
            
          b)   For Net Sales of a Licensed Product as to which Syntex Patents 
               and Know-How cover the manufacture, use, sale, offer for sale, 
               or import of the Licensed Product and which Licensed Product is 
               [ * ] the royalty rate shall be determined under the following 
               schedule for the applicable amount of world-wide Net Sales on an
               annual basis, incrementally applied.
            
               ANNUAL NET SALES OF LICENSED        APPLICABLE ROYALTY RATE
               PRODUCT [ * ]                
          
               Up to [ * ] million                          [ * ]
          
               Greater than [ * ] million but               [ * ]
               less than [ * ] million
                                     


* Confidential Treatment Requested.


                                      4.
<PAGE>

               Greater than [ * ] million                   [ * ]
          


               For example, in the event that Net Sales of Licensed Products
               during a particular calendar year under Section 5.2 b) are 
               [ * ] million, the royalty rate on the first [ * ] million of 
               Net Sales will be [ * ] and the royalty rate on the subsequent 
               [ * ] million of Net Sales will be [ * ].
            
           c)  For sales of a Licensed Product in a country of the CVT 
               Territory in which competition by products having the same 
               active compound as the Licensed Product exceeds [ * ] in terms
               of unit sales, based on IMS data or equivalent independent 
               survey, a royalty reduced to [ * ] of the rates shown in
               Section 5.2 a) or 5.2 b) above for as long as such competition
               continues to exceed [ * ]."
            
2.   MISCELLANEOUS

     2.1  FULL FORCE AND EFFECT.  This Amendment amends the terms of the 
Prior Agreement and is deemed incorporated into, and governed by all the 
other terms of, the Prior Agreement.  The provisions of the Agreement, as 
amended by this Amendment, remain in full force and effect.


* Confidential Treatment Requested.


                                      5.
<PAGE>


2.2  COUNTERPARTS.  This Amendment may be executed in two or more 
counterparts, each of which shall be deemed an original, but both of which 
together shall constitute one and the same instrument.

     IN WITNESS WHEREOF, the parties have executed this Amendment in 
duplicate originals by their authorized officers as of the date and year 
first above written.
                                   
                                   SYNTEX (U.S.A.), INC.
                                   
                                   By:  /s/ David R. Austin
                                      -----------------------------------

                                   Name:    David R. Austin
                                        ---------------------------------

                                   Title:   V.P.
                                         --------------------------------

                                   Date:    8/4/97
                                        ---------------------------------


                                   CV THERAPEUTICS, INC.
                                   
                                   By:   /s/ Louis Lange
                                      -----------------------------------

                                   Name:     Louis Lange
                                        ---------------------------------

                                   Title:    CEO
                                         --------------------------------

                                   Date:     7/23/97
                                        ---------------------------------
                                   
                                   
                                       6.