METABASIS THERAPEUTICS, INC. ANNOUNCES APPOINTMENT OF DANIEL D. BURGESS, M.B.A. TO ITS BOARD OF DIRECTORS

SAN DIEGO, CA - April 29, 2004 -- Metabasis Therapeutics, Inc. today announced that Daniel D. Burgess, M.B.A. has joined the company's Board of Directors and was appointed as the Chairman of the Audit Committee of the Board. Mr. Burgess has been the Chief Operating Officer and Chief Financial Officer of Hollis-Eden Pharmaceuticals, Inc. since August 1999. Prior to joining Hollis-Eden, Mr. Burgess served as Vice President and Chief Financial Officer of Nanogen, Inc. Mr. Burgess also spent ten years with Gensia, Inc., including with Gensia Automedics, Inc., a partially owned subsidiary of Gensia. He served as President and a director of Gensia Automedics, where he was responsible for all functional areas of this medical products company. In addition, he was Vice President and Chief Financial Officer of Gensia, where he was responsible for finance, investor relations, business development and other administrative functions. During his career, Mr. Burgess has also held positions at Castle & Cooke, Inc. and Smith Barney, Harris Upham and Company. He received a degree in economics from Stanford University and an M.B.A. from Harvard Business School.

About Metabasis:

Metabasis Therapeutics, Inc. (www.mbasis.com) is a biopharmaceutical company focused on the discovery, development and commercialization of novel small molecule drugs principally to treat metabolic diseases linked to pathways in the liver and to treat liver diseases. The company has established a broad product pipeline targeting large markets with significant unmet medical needs. Metabasis currently has three internally discovered product candidates in clinical trials indicated for the treatment of type 2 diabetes, hepatitis B and primary liver cancer.