METABASIS THERAPEUTICS, INC. ANNOUNCES SENIOR MANAGEMENT CHANGES IN WAKE OF GAINING INDEPENDENCE

SAN DIEGO, CA, July 7, 1999 -- Metabasis Therapeutics, Inc. today announced senior management changes following a management buy-out, announced July 1, 1999, from SICOR, Inc., Irvine, California. Paul Laikind, Ph.D., Chairman of the Board of Directors and Chief Executive Officer has been appointed to the additional post of President. Dr. Mark Erion, formerly Vice President of Research, has been promoted to Executive Vice President of Research and has been appointed to the Metabasis Board of Directors. John Beck, formerly Director of Finance and Corporate Controller, has been named Vice President of Finance and Chief Financial Officer. Dr. Gene Tutwiler, formerly President and Chief Operating Officer, and a member of the Metabasis Board of Directors, has resigned and will no longer serve on the Board of Directors.

Paul Laikind stated, "Over the past few years, we have taken advantage of the Company's status as a SICOR subsidiary to completely restructure and refocus the research and development efforts at Metabasis. Now, as an independent, private company, we are setting a course that we believe will build Metabasis into an exciting, profitable business. The management changes announced today, combined with our strong platform technologies, new projects and robust pipeline, position us well for future success."

Laikind continued, "The relationship we have developed with Sankyo Co., Ltd., our partner on our diabetes project, is an important part of our new business strategy. In December 1998, we announced that Metabasis achieved a milestone in our diabetes project when a clinical candidate was selected. I believe that Sankyo's significant participation in funding the newly independent Metabasis, as reported last week, demonstrates their continued commitment to both the project and the Company."

Metabasis, in collaboration with Sankyo, is developing novel drugs that act by lowering liver glucose production to treat Type II diabetes. Metabasis has also developed a platform technology that allows liver-specific delivery of new and existing drugs and is developing several new approaches for treating cardiovascular disease.

Metabasis Therapeutics, Inc. is a privately held biopharmaceutical company that develops proprietary products for the treatment of human disease. Metabasis utilizes its proprietary know-how and expertise in medicinal chemistry, computer-assisted drug design and pharmacology to identify its novel products. The Company is a leader in the field of purine metabolism and chemistry and has proprietary expertise in liver biology and organ-specific drug delivery. Metabasis' patent portfolio includes over 21 issued patents in its fields of study. The Company occupies state of the art research facilities in San Diego, California.