IPrEx

Clinical trial of HIV prevention

Logo of the IPrEx study

The IPrEx study (Pre-exposure Prophylaxis Initiative) was a landmark clinical trial that investigated the efficacy of pre-exposure prophylaxis (PrEP) in preventing HIV infection among men who have sex with men (MSM) and transgender women. Conducted across several countries, the study provided critical evidence supporting the use of PrEP as a preventive measure against HIV.

Background

The IPrEx study was initiated in response to the growing need for effective HIV prevention strategies, particularly among high-risk populations such as MSM and transgender women. Prior to IPrEx, prevention efforts primarily focused on condom use and behavioral interventions. The advent of antiretroviral therapy (ART) opened new avenues for prevention, leading to the exploration of PrEP.

Study Design

The IPrEx trial was a randomized, double-blind, placebo-controlled study. It enrolled 2,499 participants from sites in Peru, Ecuador, Brazil, Thailand, South Africa, and the United States. Participants were randomly assigned to receive either a daily oral dose of emtricitabine/tenofovir (Truvada) or a placebo.

Results

The study found that participants who received Truvada had a 44% lower risk of acquiring HIV compared to those who received the placebo. Adherence to the medication regimen was a significant factor in efficacy, with higher adherence correlating with greater protection.

Impact

The results of the IPrEx study were pivotal in the approval of Truvada for PrEP by the United States Food and Drug Administration (FDA) in 2012. The study's findings have been instrumental in shaping global HIV prevention strategies and have led to the widespread adoption of PrEP in many countries.

Further Developments

Following the success of the IPrEx study, additional research has been conducted to explore PrEP in other populations and with different antiretroviral drugs. Studies such as the PROUD study and the Partners PrEP Study have further validated the effectiveness of PrEP.

Logo of the IPrEx OLE study

IPrEx OLE

The IPrEx Open Label Extension (OLE) study was a follow-up to the original trial, allowing participants to continue using PrEP and providing further data on long-term safety and adherence. The OLE study reinforced the importance of adherence and provided additional insights into the real-world use of PrEP.

Related pages

• Pre-exposure prophylaxis
• HIV prevention
• Antiretroviral therapy
• Men who have sex with men