METABASIS THERAPEUTICS, INC. COMPLETES $24.9 MILLION PRIVATE FINANCING

SAN DIEGO, CA - October 28, 2003 -- Metabasis Therapeutics, Inc. announced today that it has raised $24.9 million through the private placement of preferred stock with existing and new investors. Major new investors that participated in the financing included Maverick Capital (Dallas, TX), Wellcome Trust (United Kingdom), ITOCHU Corporation (Japan) and Pan-Pacific Venture Capital (Taiwan). All three of the Company's major existing investors, MPM Capital, InterWest Partners and The Sprout Group, also participated in the financing. This was the Company's third round of funding from financial investors since its inception.

Metabasis intends to use the funds primarily to continue the development of MB07133, its product candidate currently being studied in patients for the treatment of primary liver cancer, and the development of a second generation gluconeogenesis inhibitor for the treatment of type 2 diabetes. The Company's first generation gluconeogenesis inhibitor, CS-917, is currently being studied in Phase II clinical trials. In addition, Metabasis will use the funds to continue to expand its product pipeline and fund other working capital and general corporate purposes.

Dr. Paul Laikind, Chairman, President and CEO said, "We are very pleased to have completed this private financing and welcome the new investors in our company. The additional capital will allow us to continue to build our product pipeline based on our continuing focus on the discovery of novel small molecule drugs principally to treat liver diseases and metabolic diseases linked to pathways in the liver."

Metabasis Therapeutics, Inc. (www.mbasis.com) is a privately held, biopharmaceutical company that develops proprietary products principally for the treatment of liver and liver-related metabolic diseases. Metabasis has expertise in the fields of nucleoside/nucleotide chemistry and metabolism, liver biology and liver-specific drug delivery. Metabasis has discovered and developed a new class of drug candidates for treating diabetes that act to lower liver glucose production in diabetic patients. The first drug candidate from this program, CS-917, is being developed in collaboration with Sankyo Co., Ltd. and is currently undergoing clinical testing. Metabasis has also developed its HepDirect technology that allows liver-specific delivery of new and existing drugs. Two novel drug candidates derived from the HepDirect technology are in clinical testing: a drug for hepatitis B called Hepavir B, developed in collaboration with Ribapharm, Inc., and a drug for primary liver cancer called MB7133, to which Metabasis retains exclusive rights.