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Pre-exposure Prophylaxis (PrEP)

Truvada PrEP Cuts HIV Infection by 44% among Gay/Bisexual Men in Worldwide Study

Pre-exposure prophylaxis (PrEP) using a daily combination of tenofovir and emtricitabine (the drugs in the Truvada coformulation) reduced the risk of acquiring HIV by 44%, according to a large international study of men who have sex with men. As described in the November 23, 2010 advance online edition of the New England Journal of Medicine, the iPrEx study found that men who achieved good adherence had more than a 70% reduction in new infections. The drug combo was well-tolerated over nearly 3 years of follow-up, with mostly mild, transient side effects.

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AIDS 2010: Oral Tenofovir for Pre-exposure Prophylaxis Appears Safe and Does Not Discourage Safer Sex

HIV pre-exposure prophylaxis (PrEP) using once-daily oral tenofovir appeared safe and did not increase the likelihood of risky sexual behavior among men who have sex with men in 3 U.S. cities, researchers reported in a late-breaker presentation at the XVIII International Conference on AIDS (AIDS 2010) last week in Vienna. The study found no indication of significant safety issues including kidney problems or bone loss. None of the 7 men who became HIV infected during the 2-year follow-up period were taking tenofovir, but this analysis was not powered to determine effectiveness.

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Pre-Exposure Prophylaxis with Tenofovir plus Emtricitabine Prevents HIV Infection in

Mice genetically engineered to have a human immune system were protected from infection with both injected and rectally administered HIV if they were first given tenofovir plus emtricitabine, the drugs in the Truvada combination pill, researchers reported in the January 21, 2010 issue of the open access journal PLoS One. While most of the mice given a placebo became HIV infected, this was the case for only 1 of the mice that received tenofovir/emtricitabine pre-exposure prophylaxis (PrEP). This strategy is currently being tested in humans in a series of ongoing clinical trials.

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Antiretroviral Therapy for HIV Prevention Could Lead to Drug Resistance If Not Carefully Implemented

Widespread use of antiretroviral therapy (ART) for HIV pre-exposure prevention (PrEP) could lead to an increase in drug resistance if people are not screened to ensure they are really HIV negative before starting preventive therapy, according to presentations at the International Microbicides Conference (M2010) last month in Pittsburgh. Drug resistance expert John Mellors warned that using PrEP inappropriately might lead to a rapid increase in resistance to tenofovir and emtricitabine (the 2 drugs in the Truvada coformulation), making the most common first-line regimen less effective.

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CROI 2009: Pre-exposure Prophylaxis Using Oral or Vaginal Tenofovir plus Emtricitabine Protects Monkeys from SIV Infection

Two studies presented at the 16th Conference on Retroviruses and Opportunistic Infections (CROI 2009) this week in Montreal showed that pre-exposure prophylaxis using tenofovir plus emtricitabine -- the 2 drugs in the Truvada fixed-dose combination pill -- protected monkeys from infection with a virus related to HIV. Researchers from the U.S. Centers for Disease Control and Prevention (CDC) demonstrated that these drugs were highly effective in preventing simian immunodeficiency virus infection when administered either orally or in a vaginal microbicide gel.

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