Mapping Pathways is a multi-national project to develop and nurture a research-driven, community-led global understanding of the emerging evidence base around the adoption of antiretroviral-based prevention strategies to end the HIV/AIDS epidemic. The evidence base is more than results from clinical trials - it must include stakeholder and community perspectives as well.

16 August 2011

Human behaviour complicates prophylactic measures

Public-health workers in Thika, Kenya,
perform a skit to advertise a prophylactic
HIV drug trial

When the US Food and Drug Administration approved Viagra in 1998, officials never considered one possible side effect of the drug: higher rates of sexually transmitted diseases among men who, thanks to Viagra, would become more sexually active. A powerful tool in the fight against HIV is raising similar questions about the possibility of unintended public-health consequences if drugs are approved for use in healthy people and cause them to alter their behaviour.

Several studies in the past year have reported that the very drugs used to treat people with HIV can also stop healthy people from becoming infected (see table). But people taking the drugs may adopt riskier behaviours because they feel protected — a phenomenon known as 'risk disinhibition' — undermining the benefit of the drugs and potentially infecting others. Moreover, those who become infected while taking the preventive regimen might develop drug-resistant viruses that they could then transmit to others. "You have this wonderful scientific breakthrough," says Kevin Frost, chief executive of the Foundation for AIDS Research in New York City. "But what are the practical implications?"

Researchers will mull over these issues on 19 August at a meeting convened by the Forum for Collaborative HIV Research in Washington DC. The questions have become more urgent since January, when the drug firm Gilead of Foster City, California, announced that it plans this year to ask the Food and Drug Administration (FDA) to approve its HIV drug Truvada for use in healthy people — in what is known as pre-exposure prophylaxis, or PrEP. Truvada, which contains the antiretroviral drugs tenofovir and emtricitabine, has been used in many of the PrEP trials. In the three clinical trials that have reported benefits for PrEP so far, once-a-day pills have cut a person's risk of acquiring HIV by between 44% and 73%, a variation that is due primarily to differences in how strictly patients stuck to the daily regimen. Although the need for PrEP is greatest in poor countries, approval in the United States could greatly expand the market for Truvada, which generated US$2.65 billion in sales last year.

Read the rest here.

[Content that is linked from other sources is for informational purposes and should not construe a Mapping Pathways position.]

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