Last Updated: 2008-04-17 16:23:35 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Use of once-daily tenofovir DF along with lamivudine or emtricitabine may be more effective than previous regimens for non-occupational postexposure prophylaxis (NPEP) in people at high risk for HIV infection, investigators report in the April 1st issue of the Journal of Acquired Immune Deficiency Syndromes.

"Several earlier studies," lead investigator Dr. Kenneth H. Mayer told Reuters Health, "have suggested that adherence to post-exposure prophylaxis regimens was compromised by ... drug side effects."

Dr. Mayer of Brown University, Providence, Rhode Island and colleagues studied 68 patients who presented after high-risk sexual exposure and were prescribed a course of tenofovir DF 300 mg and lamivudine 300 mg, each given as one pill once a day, and a further 44 patients who received a course of tenofovir DF 300 mg and emtricitabine 200 mg given as a single fixed-dose tablet once daily, for NPEP.

The treatment courses were completed by 87.5% of patients in the tenofovir/lamivudine group and 72.7% of those in the tenofovir/emtricitabine group. Adherence was significantly higher than the 42.1% reported in 122 historical controls who were prescribed 126 courses of zidovudine and lamivudine for NPEP.

Abdominal complaints were the most common side effects in the tenofovir DF patients and they were more likely to report diarrhea than had the historical controls. However, the controls had been more likely to report nausea and vomiting and this was often severe enough to prompt them to discontinue their medication.

Thus, concluded Dr. Mayer, "the advent of simpler regimens, using the fixed dose combination of tenofovir and emtricitabine given as one pill once a day, creates opportunities for better adherence, regimen completion and fuller protection among those exposed to HIV."

As for efficacy, the investigators report that "no one in the tenofovir DF-containing NPEP groups became HIV-infected during the study period, whereas three individuals who used zidovudine-containing regimens became infected during or shortly after their course of NPEP (not statistically significant)."

J Acquir Immune Defic Syndr 2008;47:494-499.