News

Female-controlled strategies for HIV prevention

Burnet Institute

08 July, 2013

Head of Burnet’s Tachedjian Laboratory, Associate Professor Gilda Tachedjian has written about microbicides as a female-controlled HIV and sexually transmitted infections prevention strategy for the Positive Women Victoria newsletter. Here is an excerpt of that article.

Microbicides contain an active ingredient that blocks HIV that can be delivered to the vagina in a gel, film, tablet or ring.

Microbicides for rectal use are also under development. The first evidence that microbicides can prevent HIV infection in women was from the CAPRISA 004 study that was undertaken in Africa.

The outcome of this study was heralded as a major breakthrough in the HIV prevention field. It showed that a vaginal gel containing the anti-HIV drug tenofovir when applied not more than 12 hours before and not more than 12 hour after sex prevented 39 per cent of HIV infections compared to women using a dummy gel.

However, the results from VOICE (a second microbicide gel study) announced in March 2013 at an international HIV conference failed to show HIV protection despite testing the same tenofovir-containing gel which was administered daily.

The rationale for daily dosing was to deliver steady drug levels in the vagina to provide protection independent of when the women had sex (i.e. “coitally–independent dosing”).

Analysis of drug levels indicated that only a third of women used the gel. This low adherence indicates that women were not using the gel as required and that acceptability by women is a critical factor for a microbicide to be effective.

Alternative strategies to vaginal gels that do not require daily or coitally-dependent use are in the pipeline for HIV prevention. These include intravaginal rings similar to the concept of a contraceptive ring.

Rings are loaded with drug and inserted in the vagina for a month to release the HIV blocking agent into the vagina.

The success of this strategy in preventing vaginal HIV transmission has been shown in animal models and clinical trials evaluating their safety and efficacy are underway.

A second coitally-independent strategy under evaluation involves injecting individuals with a slow release anti-HIV drug with the aim of providing several months of protection against being infected by the virus.

It is anticipated that these methods will be more successful in preventing HIV since they are less dependent on human behavior.

Preventing new HIV infections is critical to make a significant dent in the HIV epidemic.

Given that women will have individual preferences for using gels, films, rings or oral pills in addition to cultural differences it is important to understand what women want in a biomedical prevention strategy.

Since ‘not one size fits all’ the biomedical prevention tool-box needs to provide a range of methods that women can choose for HIV prevention.

Staff Member

Country

Health Issue

Contact Details

For more information in relation to this news article, please contact:

Professor Gilda Tachedjian

Head of Life Sciences; Head of Tachedjian Laboratory (Retroviral Biology and Antivirals)

Telephone

+61392822256

Email

gilda.tachedjian@burnet.edu.au

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