Prometheus Announces Co-Pay Assistance Savings Program For LOTRONEX® (Alosteron Hcl) Tablets

San Diego, September 9, 2009 – Prometheus Laboratories Inc., a specialty pharmaceutical and diagnostic company, announced today that it is providing a co-pay assistance savings program for LOTRONEX® (alosteron HCl) patients.

The savings program is available through physicians enrolled in the Prescribing Program for Lotronex and local pharmacies. Patients are responsible for the first $50 of their LOTRONEX prescription co-pay, after which they are eligible to receive a savings of up to $250. This new offering complements Prometheus’ two-week sample voucher program currently in place to support new patients. Patients can contact Prometheus customer service at 888.423.5227 to request information and learn more about the program. Note that certain restrictions apply.

“Prometheus is doing its part to ensure that LOTRONEX patients who may be facing tough financial times have better access to their medication,” said Joseph Limber, President and Chief Executive Officer of Prometheus. “This program is another step in our continuing effort to support women who suffer from severe diarrhea-predominant irritable bowel syndrome (IBS).”

About LOTRONEX
LOTRONEX is indicated for use only for women with severe diarrhea-predominant IBS who have chronic IBS symptoms (generally lasting 6 months or longer), had anatomic or biochemical abnormalities of the gastrointestinal tract excluded, and not responded adequately to conventional therapy. Diarrhea-predominant IBS is severe if it includes diarrhea and one or more of the following: frequent and severe abdominal pain/discomfort, frequent bowel urgency or fecal incontinence, disability or restriction of daily activities due to IBS. Because of infrequent but serious gastrointestinal adverse reactions associated with LOTRONEX, the indication is restricted to those patients for whom the benefit-to-risk balance is most favorable. Clinical studies have not been performed to adequately confirm the benefits of LOTRONEX in men. Safety and effectiveness in pediatric patients have not been established. Use of LOTRONEX is not recommended in the pediatric population, based upon the risk of serious complications of constipation and ischemic colitis in adults.

LOTRONEX has a boxed warning regarding serious gastrointestinal adverse events that have been reported with the use of LOTRONEX. These events, including ischemic colitis and serious complications of constipation, have resulted in hospitalizations, blood transfusions, surgery and fatalities. LOTRONEX should be discontinued immediately in patients who develop constipation or symptoms of ischemic colitis. LOTRONEX should not be resumed in patients who develop ischemic colitis. Physicians should instruct patients who report constipation to immediately contact them if the constipation does not resolve after discontinuation of LOTRONEX. Patients with resolved constipation should resume LOTRONEX only on the advice of their treating physician.

Contraindications to LOTRONEX include constipation, history of severe bowel or hepatic disorders, lack of understanding of Patient-Physician Agreement and concomitant use of fluvoxamine.

New ACG Recommendations Published for IBS
The American College of Gastroenterology (ACG) recently published a new evidence-based systematic review of the management of IBS. After conducting a comprehensive meta-analysis of IBS therapies, the ACG IBS Task Force concluded that the benefit and risk balance for LOTRONEX is most favorable in women with severe IBS and diarrhea who have not responded to conventional therapies (Grade 1B).

Only physicians who have enrolled in the Prometheus Prescribing Program for Lotronex, based on their understanding of the benefits and risks, should prescribe LOTRONEX. The Prescribing Program for Lotronex was implemented to help reduce risks of serious gastrointestinal adverse events. Information about the Prescribing Program for Lotronex is available by calling 888.423.5227 or visiting www.Lotronex.com. Please see the accompanying complete prescribing information, including Boxed Warning, for LOTRONEX at www.Lotronex.com/PDF/us_lotronex.pdf.

About IBS
According to the National Institute of Diabetes and Digestive and Kidney Diseases, in 2007, almost 60 million, or 20%, of the U.S. population had symptoms of IBS, making it one of the most common disorders diagnosed by physicians. At least twice as many women as men are affected by IBS, of which more than 35% have IBS-D. ,4 IBS is characterized most commonly by cramping, abdominal pain, bloating, constipation and diarrhea. Although it significantly impairs health-related quality of life, many people suffer from IBS for years before being properly diagnosed and treated.

About Prometheus
Prometheus Laboratories Inc. is a specialty pharmaceutical and diagnostic company committed to developing and commercializing novel pharmaceutical and diagnostic products to help physicians individualize patient care. Prometheus is a leader in applying the principles of personalized medicine to the diagnosis and treatment of gastrointestinal diseases and intends to apply these principles to oncology. Its strategy includes the marketing and delivery of pharmaceutical products complemented by proprietary, high-value diagnostic testing services. By integrating pharmaceutical products and diagnostic testing services, Prometheus believes it can address the full continuum of care, thereby providing physicians with a comprehensive solution to treat chronic diseases. Prometheus’ corporate offices are located in San Diego.

Contact
Pete De Spain
Director, Investor Relations
& Corporate Communications
Prometheus Laboratories Inc.
(858) 587-4117
pdespain @prometheuslabs.com