Clinical trials to test Viread's effectiveness in preventing HIV

Clinical trials will begin this month in San Francisco and Atlanta to test whether Gilead Sciences' nucleotide reverse transcriptase inhibitor Viread is effective at preventing HIV infections, the San Francisco Chronicle reports. The drug already has been approved by the Food and Drug Administration to treat HIV infection in combination with other anti-HIV medications, but some scientists believe it may also help protect against HIV infections by keeping the virus from replicating in those exposed to it. The San Francisco and Atlanta studies are part of three separate Viread pre-exposure prophylaxis clinical trials that are being funded by the National Institutes of Health, the Centers for Disease Control and Prevention, and the Bill and Melinda Gates Foundation. Another is already under way with HIV-negative volunteers in Cambodia, Ghana, Cameroon, Nigeria, and Malawi. The third, a planned trial focusing on Cambodian sex workers, is currently on hold because of concerns by the nation's prime minister over the possible adverse side effects of the drug. The clinical trial in Atlanta and San Francisco will look at not only whether daily Viread use can help prevent sexually acquired HIV infections but also whether use of the drug increases instances of unsafe sex because of its perceived protection against the virus. Two hundred men in each city will take the drug or a placebo each day for two years. The participants will be regularly counseled on safer-sex practices, including condom use, and will be warned that there is no way to determine whether they are receiving Viread or the placebo, say researchers. They also will be told that even if they receive Viread, there is no proof yet that it can help prevent HIV infections. The clinical trial will wrap up in late 2006.