The daily use of tenofovir reduced the risk of new HIV infections by almost 50% in a Thai study of intravenous drug users, results that are the basis of a recommendation to consider this approach in the United States, according to the Centers for Disease Control and Prevention.
"Based on these findings, CDC recommends that preexposure prophylaxis (PrEP) be considered as one of several prevention options for persons at very high risk for HIV acquisition through the injection of illicit drugs," the CDC concluded in an update on the interim guidance for PrEP for preventing HIV infection. The report will appear in the June 14 issue of the Morbidity and Mortality Weekly Report (MMWR 2013;62:463-5).
The CDC previously issued interim guidelines on the use of PrEP for men who have sex with men and heterosexually active adults.
Providing PrEP to IV drug users "at very high risk for HIV acquisition could contribute to the reduction of HIV incidence in the United States," the report stated. In 2010, 8% of the new HIV infections in the United States were due to intravenous drug use and every year, about 50,000 people in the United State become infected with HIV, according to the CDC.
Although tenofovir was the only oral antiretroviral drug in the study, the CDC is recommending the fixed-dose combination of 300 mg of tenofovir with 200 mg of emtricitabine, marketed as Truvada, as the "preferred PrEP regimen" for IV drug users.
Truvada was approved by the FDA in 2012 for preexposure prophylaxis of sexually acquired HIV in men who have sex with men and heterosexually active men and women, based on studies in these two populations, but not in IV drug users. And the addition of emtricitabine is not associated with increased side effects. Both drugs are nucleoside analog HIV-1 reverse transcriptase inhibitors.
In the Bangkok Tenofovir Study, a randomized-double blind study of 2,413 IV drug users aged 20-60 years, participants received a daily dose of 300 mg of tenofovir or placebo. Over a mean follow-up of 4.6 years, 17 people in the tenofovir group and 33 people in the placebo group became infected with HIV. The HIV incidence was 0.35 per 100 person-years among those on tenofovir vs. 0.68 per 100 person-years among those on placebo-a 48.9% reduction in HIV incidence. The drug was taken for an average of 84% of days.
There were no significant differences in the rates of adverse events, serious adverse events, mortality, grade 3-4 laboratory abnormalities, or elevated serum creatine in the two groups. Those on tenofovir experienced more nausea and vomiting in the first 2 months, but not after that time. The results of the study were published by the Thailand Ministry of Health online in the Lancet [doi: 10.1016/S0140-6736(13)61127-7]).
The CDC is working with other federal agencies to prepare guidelines on the use of PrEP in men who have sex with men, heterosexually active men and women, and IV drug users, which are expected to be released this year.