Pfizer Announces Restriction on Use of Experimental HIV Drug in Human Trials
Pfizer on Thursday announced that it has "restricted" the human testing of capravirine, an experimental HIV drug, citing side effects that occurred in animal testing as the reason for the move. During a 12-week animal safety study, high doses of the drug caused vasculitis, or blood vessel inflammation, a side effect that had not previously occurred in animal testing and that has not been documented in humans. Capravirine, a non-nucleoside reverse transcriptase inhibitor, is currently in phase II and phase III studies, with about 650 patients enrolled in six clinical trials. The FDA will allow patients who have previously failed NNRTIs and who are responding to capravirine to continue using the drug, but all other patients will discontinue the drug. Dr. Barry Quart, senior vice president of Pfizer Global Research and Development and site director of La Jolla Laboratories, said, "Patient safety is always paramount in our clinical studies. We remain committed to the capravirine program and expect to resume clinical trials once these safety issues have been resolved." Capravirine will be marketed by Agouron Pharmaceuticals if it passes FDA approval (Pfizer release, 1/25).
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