via EurekAlert

In the first clinical trial of a vaginal ring combining two antiretroviral (ARV) drugs, researchers from the Microbicide Trials Network (MTN) are collaborating with the International Partnership for Microbicides (IPM) to evaluate whether the ring is safe for use in women. If the ring does prove to be safe, it could be considered for further testing, and eventually be evaluated for its effectiveness as a microbicide for protecting women against HIV infection through vaginal sex.
The trial, which is funded by U.S. National Institutes of Health and goes by the name MTN-013/IPM 026, is evaluating a ring that contains the ARVs dapivirine and maraviroc. Each of these drugs works against HIV in a different way. Dapivirine belongs to a class of ARVs called non-nucleoside reverse transcriptase inhibitors (NNRTIs) that prevent HIV from making copies of itself. Maraviroc, on the other hand, is an entry inhibitor that blocks HIV from getting inside target cells.

The dapivirine-maraviroc ring is the first combination microbicide to enter clinical trials. It is also the first vaginal microbicide containing an entry inhibitor.

The ring was developed by IPM, a non-profit product development partnership headquartered in Silver Spring, Maryland, in collaboration with Queens University Belfast (Belfast, Northern Ireland). The belief is that combining the two drugs, which act at different points in the HIV “life cycle,” may provide greater protection against HIV than a single drug alone.

Globally, women comprise half of the 34 million people living with HIV. In sub-Saharan Africa, women represent nearly 60 percent of adults with the virus. In most cases women – especially young women – acquire HIV through unprotected heterosexual sex with an infected partner. Because the use of condoms is often not an option, there is an urgent need for effective prevention strategies that women can control themselves. Toward this end, vaginal microbicides in the form of a gel or a ring, for example, are being developed to provide women with new tools to protect themselves against HIV.

Vaginal rings provide slow, continuous delivery of a drug or multiple drugs to cells inside the vagina over a period of weeks or months. Marketed vaginal ring products include those used for contraceptive delivery and hormone replacement. However, vaginal rings can also be used as a vehicle for delivering potent ARV drugs into the vagina to prevent HIV infection. Because they could be used for one month at a time, vaginal rings may offer a long-acting and convenient prevention option for women.

MTN-013/IPM 026, which is now screening potential participants, will enroll 48 healthy, HIV-negative women ages 18-40 at the University of Pittsburgh, Fenway Institute in Boston and the University of Alabama at Birmingham. Researchers will evaluate the ring’s safety and how well women like or are willing to use the ring. In addition, different tests will be performed to help determine how much of each drug is taken up by the cells usually targeted by HIV and whether drug levels are sustained throughout the four weeks the ring is worn.

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