PRNewswire - November 17, 2004

The study surveyed 200 HIV-positive subjects between the ages of 18 and 70, all of whom were currently receiving highly active antiretroviral therapy (HAART). In the survey, 62 percent of HIV patients reported episodes of heartburn, 30 percent reported GERD and 13 percent reported ulcers since starting HAART therapy. Of that population, 56 percent used only over the counter drugs to manage gastrointestinal (GI) adverse events, 39 percent used both OTC and prescription drugs and 5 percent used only prescription drugs.

These medications, including proton pump inhibitors (PPIs) such as Prilosec OTC(R), antacids such as Tums(R) and H2 antagonists such as Zantac(R), work by reducing the gastric acidity of the stomach. The frequent use of drugs that reduce gastric acid among HIV patients may be a cause for concern because some antiretroviral agents require acidic conditions in the GI tract for proper absorption.

"The potential for antacids, proton-pump inhibitors and H2 antagonists to affect the absorption of antiretroviral drugs is an emerging and important issue facing HIV patients and their caregivers," said Andrew Luber, PharmD, Consultant to The Division of Infectious Diseases at the University of Pennsylvania and principal author of the study. "The high frequency of self- reported use of agents that affect gastric pH among HIV patients highlights the need for increased patient education regarding concomitant use of these products, and may also have implications for choice of antiretroviral therapy."

The frequency and use of antacids and other anti-ulcer medications was similar among HIV subjects taking HIV protease inhibitors (PIs) as part of their combination regimens and subjects who were taking non-protease inhibitor-based regimens. Among HIV subjects in this study, antacids were used most frequently, with 57 percent of patients reporting use within the last year. Patients reported using PPIs for the longest period of time compared to antacids and H2 antagonists, with 88 percent of all PPI users on therapy for more than eight weeks in the past year.

"HIV providers need to inquire about their patients' use of over-the- counter medications that lower gastric acidity, as they have the potential to also lower the concentration of some antiretroviral agents," said Ian Frank, M.D., Associate Professor of Medicine at the University of Pennsylvania Medical Center, Division of Infectious Disease. "This type of drug-drug interaction has the same potential to contribute to treatment failure as lack of adherence to therapy."

Clinical pharmacokinetic studies have been conducted and more such studies are underway to better define the nature of drug-drug interactions between medicines treating GI adverse events and antiretrovirals used in HIV treatment regimens. These studies will help to provide the data necessary to improve physicians' awareness of this issue, and improve patient education around potential drug-drug interactions.

About Vertex

Vertex Pharmaceuticals Incorporated is a global biotechnology company committed to the discovery and development of breakthrough small molecule drugs for serious diseases. The Company's strategy is to commercialize its products both independently and in collaboration with major pharmaceutical partners. Vertex's product pipeline is principally focused on viral diseases, inflammation, autoimmune diseases and cancer.

This press release may contain forward-looking statements, including statements that (i) HIV patients are at risk for unfavorable drug-drug interaction that may negatively impact absorption of certain antiretroviral therapies and (ii) the frequent use of antacids and other anti-ulcer medications among HIV patients is cause for concern because many anti-HIV drugs require an acidic environment for optimal absorption. While management makes its best efforts to be accurate in making forward-looking statements, such statements are subject to risks and uncertainties that could cause Vertex's actual results to vary materially. These risks and uncertainties include those listed under Risk Factors in Vertex's Form 10-K filed with the Securities and Exchange Commission on March 15, 2004 and amended on September 8, 2004.

Vertex Contacts:

Michael Partridge, Director, Corporate Communications, (617) 444-6108

Zachry Barber, Specialist, Media Relations, (617) 444-6470

SOURCE Vertex Pharmaceuticals Incorporated

Web Site: http://www.vrtx.com

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