<PAGE>
                     FIRST AMENDMENT TO SECURITY AGREEMENT


     THIS FIRST AMENDMENT TO SECURITY AGREEMENT ("Amendment") is entered into 
as of March 7th, 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 (the "H&QGF Security Agreement") and certain Related 
Documents (as defined in the H&QGF Security Agreement).

     B. CVT intends to enter into certain transactions (the "Collaboration") 
contemplated by (i) a Research Collaboration and License Agreement 
substantially in the form attached hereto as Exhibit A; (ii) a Loan Agreement 
and Promissory Note substantially in the forms attached hereto as Exhibits B 
and C respectively; (iii) a Common Stock Purchase Agreement substantially in 
the form attached hereto as Exhibit D; and (iv) any related documents 
provided for by any of the foregoing ((i) through (ii), collectively, the 
"Collaboration 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 definition of "Collateral" in the Security Agreement is hereby 
amended by adding the following language at the end of Subsection (iv):

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.

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

                                      1.
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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/ Louis Lange
                                     ----------------------------
                                  Printed Name: L. Lange
                                               ------------------
                                  Title: CEO
                                        -------------------------


H&QGF                             HAMBRECHT & QUIST GUARANTY FINANCE, LLC,
                                  a California limited liability company


                                  By: /s/ Andrew W. Kahn
                                     ----------------------------
                                  Printed Name: Andrew W. Kahn
                                               ------------------
                                  Title: Manager
                                        -------------------------

                                      2.