<PAGE>
                     SECOND AMENDMENT TO SECURITY AGREEMENT


     THIS SECOND AMENDMENT TO SECURITY AGREEMENT ("Amendment") is entered 
into as of May 19, 1997, by and among Hambrecht & Quist Guaranty Finance, LLC 
("H&QGF"), a California limited liability company, and CV Therapeutics, Inc. 
a Delaware corporation ("CVT").

                                    RECITALS

     A. H&QGF and CVT are parties to that certain Security Agreement, dated 
as of September 27, 1996, amended by that certain First Amendment to Security 
Agreement dated March 7, 1997 (the "H&QGF Security Agreement") and certain 
Related Documents (as defined in the H&QGF Security Agreement).

     NOW THEREFORE, in consideration of the foregoing recitals and other good 
and valuable consideration, the receipt and adequacy of which is hereby 
acknowledged, and intending to be legally bound, the parties hereto agree to 
amend the H&QGF Security Agreement only as follows:

     THEREFORE, the Security Agreement is amended only as follows:

1.   The last sentence at the end of Subsection (iv) in the definition of 
"Collateral" in the Security Agreement that currently reads as follows:

     Notwithstanding any provision to the contrary herein, or in any Related 
     Document, the terms "Collateral" and "IP Collateral" shall not include 
     any of the foregoing which comprises, claims, contains, relates to, or 
     is the molecule defined as CVT-124 in that certain IND filed on 
     September 20, 1995 (as further described in U.S. Patent Application 
     Serial No. 08/330,640 filed on October 28, 1994), or any other 
     Adenosine A1 Antagonist, or the manufacture or use of such molecules, 
     or is derived therefrom.

Shall be amended so that it reads as follows:

     Notwithstanding any provision to the contrary herein, or in any Related 
     Document, the terms "Collateral" and "IP Collateral" shall not include 
     any of the foregoing which comprises, claims, contains, relates to, or 
     is the molecule defined as CVT-124 in that certain IND filed on 
     September 20, 1995 (as further described in U.S. Patent Application 
     Serial No. 08/330,640 filed on October 28, 1994), or any other 
     Adenosine A1 Antagonist, or the manufacture or use of such molecules, 
     or is derived therefrom (the "CVT-124"), except that the terms 
     "Collateral" and "IP Collateral" shall refer without limitation to the 
     right to payments under license agreements, joint venture agreements 
     and other collaborative agreements relating to CVT-124, including the 
     Collaboration Agreement and any and all other contracts with relate to 
     CVT-124, including those rights to payment thereunder which are 
     included as Collateral under clause (v) below.

2.   Except as specifically amended hereby, the Security Agreement shall 
remain in full force and effect.

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     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be 
executed by their respective officers thereunto duly authorized, as of the 
date first above written.



CVT                               CV Therapeutics, Inc.,
                                  a Delaware corporation


                                  By: /s/ K A Stafford
                                     --------------------------------
                                  Printed Name: K A Stafford
                                               ----------------------
                                  Title: CFO
                                        -----------------------------


H&QGF                             Hambrecht & Quist Guaranty Finance, LLC,
                                  a California limited liability company


                                  By: /s/ Donald M. Campbell
                                     --------------------------------
                                  Printed Name: Donald M. Campbell
                                               ----------------------
                                  Title: Chief Executive Officer
                                        -----------------------------