December 1, 2004

Prometheus Laboratories to Market Entocort(R) EC

SAN DIEGO, Dec. 1 /PRNewswire/ -- Prometheus Laboratories Inc., a specialty pharmaceutical company, announced today that it has entered into an agreement with AstraZeneca LP for the exclusive marketing, sales and distribution of Entocort(R) EC (budesonide) Capsules in the United States beginning January 1, 2005. Entocort EC is the only FDA approved drug indicated for the treatment of mild to moderate active Crohn's disease involving the ileum and/or the ascending colon. It is anticipated that net sales for Entocort EC will approximate $30 million for AstraZeneca in 2004.

"Consistent with our strategy to gain access to and build our pharmaceutical business with proprietary products, we are excited to have entered into this agreement with AstraZeneca. Entocort EC is extremely well-suited to our existing business and we believe that it offers tremendous benefits to patients," said Joseph M. Limber, President and Chief Executive Officer of Prometheus. "We anticipate that Entocort EC will provide a significant commercial opportunity for Prometheus and will be the first of a number of proprietary products which we believe will be integral to the growth of our company."

"AstraZeneca is pleased to have entered into this agreement with Prometheus," said Jim Helm, Vice President, AstraZeneca, AZENITY Business unit. "As a company that focuses on the diagnosis and treatment of gastrointestinal diseases, Prometheus is well positioned to continue the work that AstraZeneca has started of educating patients and physicians on the benefits and appropriate use of Entocort EC. This partnership will help ensure that patients and physicians are aware of Entocort EC as an important therapeutic option."

Entocort EC is a first-line therapy and the only pharmacological product indicated for the treatment of mild to moderate active Crohn's disease involving the ileum and/or the ascending colon. Entocort EC is a non-systemic glucocorticosteriod, which means that it works locally or in one area of the body. AstraZeneca launched Entocort EC Capsules in November 2001. The most common side effects of Entocort EC observed in clinical trials were headache, respiratory infection, nausea and symptoms of hypercorticism.

The five-year agreement includes an upfront payment with potential milestones and royalties based on sales. AstraZeneca will continue to manufacture the product and is responsible for all clinical and regulatory processes relating to the product. Specific terms of the agreement are not being disclosed.

Crohn's disease is a chronic inflammatory bowel disease of unknown origin. An estimated 500,000 Americans have the disorder. Flare-ups of the disease can range from mild to severe and involve symptoms such as diarrhea, abdominal pain, fever and sometimes rectal bleeding. The condition can be difficult to manage clinically and consumes a substantial amount of healthcare resources in terms of physician time, procedures and medications.

About Prometheus

Prometheus Laboratories Inc. is a specialty pharmaceutical company committed to developing new ways to help physicians individualize patient care. Prometheus focuses on the treatment, diagnosis and detection of gastrointestinal, autoimmune and inflammatory diseases and disorders. Prometheus' strategy includes the marketing and delivery of pharmaceutical products complemented by its proprietary, high-value diagnostic testing services. By integrating therapeutics and diagnostic services, Prometheus addresses the continuum of patient care, thereby providing physicians with a comprehensive solution to treat chronic diseases. Prometheus' corporate offices are located in San Diego, California. Additional information about Prometheus can be found at

This press release contains certain "forward-looking" statements within the meaning of the Private Securities Litigation Reform Act of 1995. To the extent that any statements made in this news release contain information that is not historical, these statements are essentially forward-looking and are subject to risks and uncertainties. Actual events or results may differ materially from those projected in any of such statements due to various factors. Prometheus cautions that any forward-looking information is not a guarantee of future performance. The Company may not successfully maintain or grow the market for Entocort EC for a variety of reasons. The Company is aware of other products under development and in clinical testing for the treatment of Crohn's disease. To market Entocort EC, the Company plans to expand its sales force. The market for personnel is competitive, and there is no assurance that the Company can recruit new personnel on a timely basis. It is difficult to predict the impact of competitive products and pricing. The number of products available for acquisition is limited and the market for such products is competitive and expensive. There can be no assurance that the Company will successfully acquire new products.

Entocort is a registered trademark of the AstraZeneca Group of companies.

Prometheus Laboratories Inc.

CONTACT: Beth Kriegel, Senior Director, Financial Planning and InvestorRelations of Prometheus Laboratories Inc., +1-858-410-2516

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