As the U.S. Food and Drug Administrationweighs approval of a radical new method of
The pill was developed to treat people already infected with
A growing number of doctors in the U.S. are already prescribing the drug to uninfected high-risk patients as an off-label use, and some insurers are covering the considerable expense.
"It's not officially monitored, but its use is on the rise," said Dr. Robert M. Grant of UC San Francisco's Gladstone Institute of Virology and Immunology, who worked on one of the new studies. "We're already starting to see support groups for users."
The blue tablets, which are sold under the brand name
Publication of the Africa drug trials comes less than two weeks before the International AIDS Conference convenes inWashington, D.C.The results, as well as the FDA's deliberations, are likely to be hot-button issues there, since both advocates and critics of using Truvada for prevention have found ammunition for their views in the studies' findings.
Most notably, the Los Angeles-based AIDS Healthcare Foundation is vehemently opposed to the drug's approval as a prophylaxis in the U.S. because it says the pill is dangerous, overly expensive and will detract from proven methods of AIDS prevention, such as condom use.
"Our culture is always looking for a quick fix," said Michael Weinstein, the foundation's president. "We want to pop a pill.... Well, there are better methods."
In each of the three trials published Wednesday, test subjects were given Truvada or a
The study that showed the highest rate of success involved 4,747 married couples in
However, a related study that focused exclusively on healthy women in Kenya,
"We hypothesize that the women's perception that they were at low risk for HIV infection may have contributed to the poor adherence," wrote the study authors, who were from the U.S., South Africa, Kenya, Britain and Belgium. Daily pill regimens may have also posed a difficulty for some of the women, though the researchers weren't sure why.
The third study involved healthy single men and women in
But the study had important limitations. Many volunteers dropped out, which prevented the researchers from determining whether the drug was protective for men and women independently, as it was in the trial involving married couples.
The report also raised questions about Truvada's effect on bone mineral density, as the researchers observed a "small but significant decline." Other side effects, such as nausea, vomiting and dizziness, occurred more frequently in those who took the drug instead of a placebo, but those symptoms lessened after the third month, the authors wrote. The other studies also noted side effects of gastrointestinal problems and fatigue during the first month.
The pills were supplied byGilead Sciences Inc., the Bay Area firm that makes Truvada and is seeking fast-track approval from the FDA.
For study researchers and many AIDS advocacy groups, the take-away message from the three trials was that Truvada could be an effective tool in the battle against AIDS, if used correctly.
"Adherence matters," said Dr. Lynn Paxton, who coordinated the Botswana study at the CDC. "If you don't take the pill, it won't work, no matter what else you do."
Groups like the AIDS
Last year, the CDC issued advice on using Truvada in gay men who are HIV-negative, but the agency has not yet done the same for heterosexuals. On Wednesday, CDC officials urged physicians to wait for those guidelines before prescribing the drug. However, they said that in urgent situations, doctors should follow the cautions and procedures laid out for gay men, including requirements for pre-treatment screening, dosages, periodic testing and counseling.
Truvada's chief critics contend that the drug is prohibitively expensive in the U.S., where an annual supply can cost about $10,000. They also fear it will reduce the use of condoms.
"You have to be really paranoid about your pants falling down to wear a belt and suspenders," Weinstein said.
But Grant, of UCSF, said the drug's detractors were overstating the effectiveness of condoms. Although they are more likely to be used during casual relationships, their use tapers as relationships grow more intimate.
"We need to be realistic about the limits of condom use," he said.