Daily use of a pill approved to protect against HIV infection cuts a man’s risk of getting the virus by 99 percent, a new study indicates.
The research also offers the first evidence that even imperfect adherence to the treatment regimen can provide a big reduction in the risk of acquiring the virus, which causes AIDS. Participants in the research were found to be able to cut their HIV infection risk by 76 percent merely by taking two doses a week.
The study, published in the Sept. 12 online issue of the research journal Science Translational Medicine, examines the effectiveness of a FDA-approved drug known as tenofovir disoproxil fumarate (brand name Truvada).
The research builds on a 2010 study by Robert Grant at the University of California, San Francisco and the Gladstone Institute in San Francisco, along with colleagues. The team found that Truvada—which had been used for years to treat HIV-positive patients—could also prevent new infections in people likely to come in contact with the virus.
But questions about the drug’s real-world effectiveness remained—in particular concerning the issue of adherence to a regimen of a pill a day. “There was concern that the protective effect of Truvada was fragile, and that individuals taking the drug would need to adhere perfectly to daily regimen for it to work,” said Grant. “This new study suggests that Truvada can help block the virus even if the person on a daily regimen doesn’t always adhere perfectly.”
The study examined the risk of HIV acquisition in men who have sex with men. Participants different doses of the drug. Men came into a clinic every day and were given either two pills per week, four pills per week or seven pills per week. The researchers then compared drug concentrations from their study to drug concentrations from a previous study.
The research team estimates that participants could reduce their risk of HIV by 76 percent taking two doses per week, 96 percent by taking four doses per week, and 99 percent by taking seven doses per week.
The timing of the dosing relative to sexual intercourse likely matters, based on research done in non-human primates, although this could not be investigated in detail in people, the researchers added. Higher drug concentrations and more frequent use may be required for women because the drugs are not concentrated as much in the female genital tract, the authors noted.
“Patients should still take one pill a day to achieve the best results, and we encourage people to explore multiple methods to prevent HIV—such as regular condom use, early treatment of HIV infection in partners, good communication and male circumcision,” Grant said. “We hope that our findings lead to more effective use of prevention tools that finally squash the HIV/AIDS epidemic.”
Source : http://www.world-science.net/