In the News
Preexposure antiretroviral prophylaxis should be considered as part of an HIV-prevention package for injection-drug users, according to updated interim guidance from the Centers for Disease Control and Prevention (CDC). Injection-drug use accounts for 10% of new HIV infections worldwide and more than 80% in some countries, and effective interventions to prevent HIV infection in injection-drug users are needed.
The CDC recommendation is based on a randomized controlled clinical trial in Thailand in which a daily oral dose of tenofovir reduced the incidence of HIV infection in injection-drug users by nearly 50%. In 2012 the U.S. Food and Drug Administration approved the use of tenofovir in combination with emtricitabine to prevent sexual transmission of HIV.
In the Bangkok Tenofovir Study, 2,413 HIV-negative volunteers from 17 drug-treatment clinics were randomized to receive daily doses of 300 mg of tenofovir (n = 1,204) or placebo (n = 1,209). Participants could choose daily directly observed therapy or monthly visits with a month's supply provided at each. At follow-up visits, adherence and adverse effects were assessed, HIV and pregnancy tests were conducted, and individualized adherence and risk-reduction counseling were provided. The clinics also provided free primary medical care, social services, methadone, condoms, and bleach for cleaning injection equipment.
During a mean follow-up of 4.6 years, 50 patients acquired HIV infection—17 in the tenofovir group and 33 in the placebo group, indicating a 48.9% reduction in HIV incidence. Adherence had an important effect on efficacy. In a case–control analysis that compared the 50 participants with incident HIV infection with 282 HIV-negative participants, detection of tenofovir in the blood was associated with a 70% lower risk of HIV infection.
Nausea and vomiting were more common in the tenofovir group than in the placebo group but only in the first two months of the study. Rates of other adverse effects and laboratory abnormalities were similar in the two groups.
The CDC advises that preexposure prophylaxis with daily tenofovir–emtricitabine be targeted to adults at very high risk for HIV acquisition, delivered as part of a comprehensive set of prevention services and accompanied by quarterly monitoring of HIV status, pregnancy status, adverse effects, medication adherence, and risk behaviors.—Karen Rosenberg
Centers for Disease Control and Prevention. MMWR Morb Mortal Weekly Rep. 2013;62(23):463–5
Choopanya K, et al. Lancet. 2013;381(9883):2083–90