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Prevention In A Pill: Gilead Med Lowers HIV Risk In Injectable Drug Users

Less than a year after the FDA endorsed the notion of using medications to prevent HIV, a new study has found using the Viread pill sold by Gilead Sciences reduced the risk that addicts who inject drugs by nearly half. The findings are the latest to demonstrate that the PrEP, or pre-exposure prophylaxis, approach to prevention can protect people at high risk for being infected with HIV.

Earlier studies found that using either Viread or Truvada, another Gilead (GILD) treatment that combines Viread with its Emtriva pill, can lower the risk of infection with men who have sex with men, in heterosexual men and women, and in heterosexual couples where one partner has HIV but the other is not infected.

“This study completes the picture of PrEP efficacy for all major HIV risk groups,” says principal investigator Michael Martin, chief of clinical research for the Thailand Ministry of Public Health–US CDC Collaboration, in a statement. “We now know (PrEP) can be a potentially vital option for HIV prevention in people at very high risk for infection, whether through sexual transmission or injecting drug use.”

“Injection drug use accounts for a substantial portion of the HIV epidemic around the world and we are hopeful that PrEP can play a role in reducing the continued toll of HIV infection in this population,” says Jonathan Mermin, who heads the Division of HIV/AIDS Prevention at the US Centers for Disease Control and Prevention, in a statement. The CDC is updating clinical guidance this week.

The study, which was published in The Lancet, recruited over 2,400 participants at 17 drug treatment clinics in Bangkok.  Around half of the participants were assigned a daily oral dose of Viread and the other group was given a placebo. All of the trial participants, who tracked for an average of four years, were offered monthly HIV testing, risk-reduction counseling and access to drug rehabilitation treatment (here is the abstract).

Overall, 17 participants in the Viread group became infected compared with 33 in the placebo group. A further analysis showed that the protective effect was best when participants adhered closely to the prescribing regimen, reaching more than 70 percent in this subgroup. This finding underscores the ongoing need for patient monitoring and education to lower the risk of resistance to the drugs.

The FDA approval last year came after a long-running debate among AIDS activists, reflecting a spectrum of views on making a preventive pill available on a large-scale basis. To some, FDA approval offers needed assistance in containing HIV and possibly clarify the extent to which such preventive measures are useful. To others, however, FDA approval raised the specter of creating a form of resistance to HIV due to widespread use, which would undermine effectiveness for people who already took Truvada and, therefore, diminish prevention efforts.

In an accompanying essay, Salim Karim, who heads the Centre for the AIDS Programme of Research in South Africa at the University of KwaZulu-Natal, noted that the reduction in HIV infections reported in the latest study may not be specifically attributable to a protective effect of the drugs on people who become infected through injecting drugs.

“The introduction of PrEP for HIV prevention in injecting drug users should be considered as an additional component to accompany other proven prevention strategies like needle exchange programs, methadone programs, promotion of safer sex and injecting practices, condoms, and HIV counseling and testing,” he concluded.


Posted: June 2013