A Pill to Prevent HIV

Posted by Jean-Marie Pflomm, Pharm.D.

An FDA advisory committee has recommended approval of Truvada, a fixed-dose combination of emtricitabine and tenofovir, to prevent HIV infection in healthy people at high risk. The combination is already approved and widely used as part of multi-drug regimens to treat patients with active HIV infection. The panel’s recommendation was based on 2 studies in high-risk patients, one in men who have sex with men (MSM) and the other in heterosexual partners of people infected with HIV. The trial in MSM showed that daily use of the drug, in addition to counseling and condom distribution, reduced the risk of HIV seroconversion by 42%. The rate of infection was reduced by 87.5% in those who were adherent to the drug regimen (had detectable tenofovir serum levels). In January 2011, based on the preliminary results of this study in MSM, the CDC released interim guidelines recommending daily use of Truvada for HIV prevention in MSM who are at high risk of acquiring the virus.

A 90% reduction in the risk of becoming infected with a potentially fatal virus is impressive. But that 90% reduction only occurred in patients who faithfully took the drug. The reduction was much lower in those who were less adherent. Healthy people in real life may be less likely to take the drug every day than those in a clinical trial, especially if they have to pay $900 a month for it, or they experience side effects (diarrhea, nausea, fatigue, headache, dizziness, depression, insomnia, abnormal dreams and rash). Plus, bone mineral density can decrease with long-term use. There are also potential behavioral implications; people taking the drug may have a false sense of protection and so be more likely to engage in risky behavior and less likely to use condoms. It is also unknown whether people who become infected while taking the drug will be more likely to quickly acquire resistance to one of the primary treatments for the disease.

The FDA’s final decision is expected soon. Chances are it will be positive. After all, the combination is generally well tolerated and highly effective in preventing HIV infection, and whether or not it is granted FDA approval for such use, Truvada is already available and being used off-label for this indication. Hopefully in carefully selected patients.

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