The potential side effects documented in the studies could discourage some people from taking the drug every day, says Michael Horberg, M.D., director of HIV/AIDS at Kaiser Permanente, a large nonprofit health care provider headquartered in Oakland, Calif.
Although the most common side effects associated with Truvada—nausea, vomiting, and dizziness—were generally benign and short-lived, one of the trials found a decrease in bone density among people taking the drug, compared to placebo. And there are signs the drug also may impair liver and kidney function.
The long-term side effects of Truvada—for instance, whether the decrease in bone density might lead to fractures—are still largely unknown, which raises questions about the advisability of prescribing this expensive drug to healthy people, HIV experts say.
“There are probably patients who are motivated [and] eager who would probably benefit,” Horberg says. “But as a general strategy, this may or may not be a successful one.”
Some researchers and health-care providers have expressed concern that the sense of security offered by the drug could lead people at high risk of HIV infection to grow complacent about condom use, routine HIV testing, and other precautions.
For his part, Baeten stresses that all the couples in his study received counseling, condoms, and access to other preventive services, in addition to Truvada. Similarly, in their review of the drug, FDA officials emphasized that Truvada, if approved, should be accompanied by a program aimed at educating doctors and their patients about the importance of adherence and maintaining existing safeguards.
Truvada “would always be part of a more comprehensive prevention strategy,” says Timothy Mastro, M.D., coauthor of a study published today and a researcher at FHI 360, a nonprofit research organization based in Durham, N.C.
The FDA typically follows the recommendations of its advisory committees. The agency is expected to issue its decision on Truvada in mid-September, according to a statement released in June by the drug’s manufacturer, Gilead Sciences.