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.

08 March 2012

CROI Reports First Trial Results on HIV Injectable Treatment

via, by Gus Cairns

The first trial in humans of an injectable, once-a-month formulation of an HIV drug has found that drug levels were maintained at a level that should in theory be high enough to protect recipients against infection, and that the drug has so far produced very few side effects. The research was presented at the 19th Conference on Opportunistic Infections (CROI), in Seattle.

The small trial at the St Stephen’s AIDS Trust (SSAT) at London’s Chelsea and Westminster Hospital gave 27 women and six men a single injection of the long-acting formulation of the drug rilpivirine, which was licensed as an oral HIV treatment last year as Edurant and is also in the tenofovir/FTC/rilpivirine pill Complera. Rilpivirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) drug and is especially suitable to be turned into a long-lasting injectable form because the daily dose of it required to suppress HIV is very small.

No other HIV drugs are currently in a usable long-lasting injectable form, which will limit the use of long-acting rilpivirine (RPV-LA) in combination therapy, but it could conceivably make an ideal candidate as a prevention drug, as people would not need to remember to take it every day. Other preventative drugs already formulated as monthly injections include the injectable contraceptive Depo Provera and some anti-psychotic drugs.

SSAT recruited 27 HIV-negative women aged 18 to 50, more than 50% of them black African or Caribbean, for the trial and gave them one of three doses of RPV-LA as an intramuscular injection: 300, 600 or 1200mg (the oral dose of RPV is 25 mg/day). Drug levels were then measured over the course of the next twelve weeks in blood, vaginal fluid and in vaginal tissue samples. A substudy gave six men the 600mg dose and measured RPV-LA levels in blood, rectal fluid and rectal tissue samples.

Thirty days after injection, blood and vaginal fluid levels of rilpivirine were about 60 nanograms per millilitre (ng/ml) in both blood and vaginal fluid in women given the 600mg dose, and about 80 and 120ng/ml respectively in women given the 1200mg dose. Blood levels in men given the 600mg dose were about 70ng/ml at 30 days. For comparison, the trough levels of rilpivirine in people taking daily oral doses is about 140ng/ml; but the EC50 (the amount needed to reduce viral replication by 50%) in newly-infected T-cells is 27ng/ml. It is thought these levels should be adequate to prevent HIV infection. 

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