2011 Articles

Drug concentrations after topical and oral antiretroviral pre-exposure prophylaxis: implications for HIV prevention in women

Abdool Karim, Salim; Kashuba, Angela D. M.; Werner, Lise; Abdool Karim, Quarraisha

The early closure of a clinical trial assessing the effectiveness of oral antiretroviral pre-exposure prophylaxis (PrEP) in women, FEM-PrEP, is a substantial setback for HIV prevention. Expectations of this trial were high in view of favourable results from the pre-exposure prophylaxis initiative (iPrEX) trial, which studied the same drug and dosing strategy in men who have sex with men, and the Centre for the AIDS Programme of Research in South Africa (CAPRISA 004) trial,3 which tested tenofovir gel (a topical PrEP formulation) in heterosexual women. As a result, the interim FEM-PrEP trial results, announced on April 18, 2011, which showed no protection against HIV infection, were disappointing. Using publicly available information and data from other PrEP studies, we offer a potential explanation for the results of the FEM-PrEP trial.