Weinstein added that as an HIV treatment, he thinks Truvada is a “fabulous drug – it’s one pill once a day, and it has a low side-effect burden,” which include nausea, vomiting and weight loss.
This new pharmaceutical prevention approach to HIV and AIDS is known in scientific circles as “pre-exposure prophylaxis,” or PrEP, and it involves taking the antiretroviral medications on a daily basis. Clinical trials supported by the National Institutes of Health have shown that when taken daily, Truvada, a blue oval pill, reduced the risk for contracting HIV by between 44 percent among gay men in four countries and 73 percent by heterosexual couples in Uganda and Kenya. One trial among women in sub-Saharan Africa was stopped in April 2011.
Overall, these studies have generated enthusiasm among many medical researchers.
The drug is “an incredible achievement, a wonderful new tool that could be available to people who need additional protection against the acquisition of HIV,” said Veronica Miller, executive director of The Forum for Collaborative HIV Research and a visiting professor at the UC Berkeley School of Public Health.
But Weinstein said he’s not yet convinced by the research, and he wouldn’t want to see future mass marketing of the drug discourage gay men – the risk group most seriously affected [PDF] by HIV, according to the Centers for Disease Control and Prevention – from using condoms based on “the false belief that they are protected by this,” when there’s a possibility that those taking the medication still could contract the disease.
An article in the British medical journal The Lancet last year also argued that “although some of the trial results have been very impressive, the protection with pre-exposure prophylaxis is unlikely to be 100 percent, and making drugs available as prophylaxis could encourage high-risk sexual behaviour among those who believe themselves to be protected.”
Dr. Albert Liu of the San Francisco Department of Public Health's HIV Research Section is working on two studies, one that started last fall and one that will launch this spring, to determine who is interested in using the drug and how they adhere to it "in the real world." Whether widespread access to the pill would lead to unsafe sex practices is a "good question, and part of the goal of (the upcoming studies) is to evaluate what happens with people's sexual practices when they're taking PrEP," he said. "We don't know the answer, and that's why it's important to study it."
The Annals of the Forum for Collaborative HIV Research noted that the drug had performed well in clinical trials; the safety risk is relatively low; and as a result, doctors can currently prescribe the drug for prevention off-label. However, those who use the drug could develop resistance to it, and if they don’t use it daily, the risk for contracting HIV increases, the forum said.
An article [PDF] by UCLA public affairs and medical school professors in the American Journal of Public Health [PDF] also urged caution.
“These randomized clinical trial results suggest that PrEP is a promising strategy, but we must temper this promise with a healthy dose of caution," the authors wrote. "PrEP is an intensive intervention for which cost, feasibility, and behavioral considerations may be as important as clinical efficacy.”
But the forum’s Miller said that these concerns, while valid, “can be dealt with” through additional research and planning.
Other drug companies, including ViiV Healthcare, also are planning studies to sell similar prevention drugs, but given the number of clinical trials performed or under way on Truvada, Gilead's product is likely to be the first to make it to market.
Gilead's total product sales were $2 billion for the third quarter of 2011, driven primarily by sales of Truvada and other antiviral drugs. Gilead did not respond to requests for comment.
Some HIV and AIDS awareness organizations say that while they wouldn't want to see Truvada trump other forms of prevention, they are hopeful that the drug will help reach high-risk individuals.
“It comes down to choices,” said David Evans, director of research advocacy at Project Inform, a San Francisco organization focused on improving the health of people with HIV. “For those who are high at risk, we want them to know that there is something new and a better option available to them.”
Nevertheless, Evans said he shares some of the drug critics' concerns. “We don’t want to see people give up safe sex practices," he said. "We hope and expect that PrEP will not be given to people who do well with condoms, but to people who struggle with making safer choices.”
Read More:
Drug May Be First to Prevent HIV Transmission in Health (from KQED News Fix blog)
