Benefits of On-demand Antiretroviral Pre-exposure Prophylaxis Among MSM
SOURCE: Molina JM, et al. On-demand preexposure prophylaxis in men at high risk for HIV-1 infection. N Engl J Med 2015;373:2237-2246.
There is no doubt that continuous pre-exposure prophylaxis (PrEP) with antiretroviral therapy in HIV-discordant men who have sex with men (MSM) substantially reduces the risk of seroconversion (> 40%). Curiously, similar trials among heterosexual women have not demonstrated the same risk reduction. Experts opine that failed efficacy in this population might be attributed to poor compliance. Might PrEP administration timed immediately before and after sexual activity, rather than daily, be effective?
Molina et al randomized MSM (n = 400) to antiretroviral treatment (tenofovir + emtricitabine) or placebo administered before and after sexual activity. The method of administration was two pills 2-24 hours before sex, a third pill 24 hours after the first dose, and a fourth pill 24 hours later. At a median of 9.3 months follow-up, there was a relative risk reduction in incident HIV infection of 86% (two cases in the antiretroviral group vs 16 in the placebo group).
These results stack up very favorably with continuous prophylaxis trials, and may be less cumbersome for some patients to administer. The authors cautioned that early enthusiasm for treatment might support better adherence, which could wane over time and potentially reduce efficacy.
Might pre-exposure prophylaxis administration timed immediately before and after sexual activity, rather than daily, be effective?
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