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As reported in a previous DynaMed Weekly Update (Volume 5, issue 48), preexposure prophylaxis with combination emtricitabine/tenofovir (Truvada) has been shown to reduce the risk of HIV transmission in men who have sex with men (N Engl J Med 2010 Dec 30;363(27):2587). The PrEP trial recently evaluated the prophylactic efficacy of this combination drug and of tenofovir alone in Uganda and Kenya among heterosexual couples in which 1 partner had HIV-1 infection.
A total of 4,758 couples serodiscordant for HIV-1 infection were randomized to 1 of 3 daily oral regimens for the partner without HIV-1 infection: tenofovir 300 mg/day, combination of tenofovir 300 mg plus emtricitabine 200 mg, or placebo. The partner without infection (male partner in 62% of couples) had monthly HIV-1 testing for up to 36 months. All patients received risk reduction counseling, condoms, and HIV-1 prevention information. Various outreach interventions were used to maintain adherence based on local plans and resources. After randomization, 11 couples were excluded for ineligibility.
HIV-1 seroconversion occurred in 22 partners with tenofovir alone, 16 partners with emtricitabine/tenofovir, and 58 partners with placebo. The seroconversion rates per 100 person-years were 0.84 for tenofovir alone (p < 0.001 vs. placebo, NNT 73 for 1 year), 0.61 for emtricitabine/tenofovir (p < 0.001 vs. placebo, NNT 63 for 1 year) and 2.22 for placebo (level 1 [likely reliable] evidence). The seroconversion rates between the 2 active treatments were not significantly different, and both tenofovir-based regimens were associated with significant reductions in seroconversion compared to placebo in subgroup analyses of male and female partners. If the seronegative partner was female, the risk reduction was 71% with tenofovir and 66% with combination therapy. For male seronegative participants the risk reduction was 63% with tenofovir and 84% with combination therapy. There were no significant differences in adverse events across groups (N Engl J Med 2012 Jul 11 early online).
Truvada has recently been approved by the FDA for preexposure prophylaxis in persons at high risk of HIV infection and who engage in sexual activity with partners with HIV infection (FDA Press Release 2012 Jul 16).
For more information, see the HIV infection topic in DynaMed.