Background: Nonoccupational postexposure prophylaxis (NPEP) has been used to decrease HIV transmission after high-risk exposures. However, suboptimal adherence in completing the recommended 28-day course has resulted in prophylaxis failures. Fenway Community Health, the largest center caring for HIV-infected and high-risk men who have sex with men (MSM) in New England, began an NPEP program in 1997, initially using zidovudine-based regimens.
Methods: Two phase 4 studies, using tenofovir DF regimens combined with either lamivudine or emtricitabine, were conducted. This paper evaluates the experience of those who used tenofovir-based NPEP regimens, comparing the subjects to historical controls who used zidovudine-containing regimens.
Results: Between May 2004 and March 2005, 44 individuals who presented after high-risk sexual exposure were prescribed tenofovir DF/lamivudine for NPEP. Between March 2005 and March 2006, 68 individuals with 72 high-risk experiences received tenofovir DF/emtricitabine, and were compared to122 historical controls who were prescribed 126 courses of zidovudine plus lamivudine between January 2000 and May 2004. Seventy-two percent of those who took tenofovir DF and emtricitabine, and 87.5% of the participants who took tenofovir DF and lamivudine, for NPEP completed their regimens as prescribed, whereas only 42.1% of those who took zidovudine plus lamivudine did so (P < 0.0001). Participants who took tenofovir DF-containing regimens were more likely to report diarrhea or abdominal discomfort; patients who took zidovudine-containing regimens were more likely to report nausea and vomiting, which was often severe enough to lead to product discontinuation.
Conclusions: Tenofovir DF-containing regimens for NPEP are generally well tolerated with high completion rates. Tolerability and adherence compared favorably to zidovudine-containing regimens used previously. Tenofovir DF-containing regimens should be considered for PEP to enhance adherence and regimen completion.