Study Finds Popular Antiviral Pill May Be Used for HIV Prevention

Results from the first human trial using antiviral pills to prevent infection from HIV showed the drugs are safe and may offer some protection from the virus, according to a study discussed Monday at the International AIDS Conference here.

The study’s researchers reported that two women out of 469 taking the widely used AIDS drug tenofovir for one year became infected with human immune deficiency virus.

In comparison, six women were infected in a similarly sized group taking a placebo. The study was conducted in areas with high risks of infection.

The results were not statistically significant, the researchers cautioned.

Still, when coupled with the finding that tenofovir did not cause any serious side effects, the study’s results bolstered hopes for a prevention pill.

“The results are important but not definitive,” said Thomas J. Coates, an infectious-diseases expert at UCLA. “What’s nice is it looks like we’re going in the right direction.

“For every person on treatment, there are 10 people getting infected,” said Coates, who was not involved in the study. “The answer to the AIDS epidemic is prevention, not treatment.”

The drug trial, conducted by the nonprofit Family Health International, involved 936 women in Cameroon, Ghana and Nigeria.

Researchers selected tenofovir because it has few serious side effects and has a lower risk of causing the virus to become resistant, said lead author Leigh Peterson, a researcher with Family Health International.

Previous studies showed that tenofovir, sold as Viread by Gilead Sciences Inc., protected monkeys from the simian form of the immunodeficiency virus.

The women took 300 milligrams of tenofovir once a day for a year.

Counselors handed out condoms and discussed safe-sex practices with the women every month.

There had been some concern before the trial that the drug’s side effects, including bone weakening and liver and kidney damage, might harm volunteers.

The researchers, however, found toxicity levels in the women’s livers and kidneys were similar in both the tenofovir and placebo groups, Peterson said.

The study was the furthest along of four other prevention pill studies, said Yasmin Halima, a consultant with the International AIDS Society.

The studies have been controversial. Two other trials have been stopped, in part because of activists’ concerns that the subjects, who are healthy, could suffer side effects from the drugs.

The activists also said that the pills would be too expensive for many people in the developing world. For example, a daily dose of the pills in Thailand costs about a $1.