A biomedical vaginal ring that slowly releases an antiretroviral (ARV) drug is on the anvil

A monthly vaginal ring that slowly releases an antiretroviral (ARV) drug called dapivirine is currently undergoing regulatory review.

If approved, the dapivirine ring would be the first biomedical HIV prevention method developed specifically for women. Importantly, it would also provide women with another option besides oral PrEP (pre-exposure prophylaxis). PrEP involves daily use of a tablet called Truvada which is being rolled out in many countries.

Dapivirine belongs to a class of antiretroviral drugs known as non-nucleoside reverse transcriptase inhibitors (NNRTIs) and it has been developed exclusively for HIV prevention. Other drugs in its class of NNRTIs (such as efavirenz and nevirapine) are used for treatment of HIV. Truvada, which contains the ARVs emtricitabine and tenofovir, is used for both HIV prevention and, in combination with other drugs, also for treating HIV.

Risk of dapivirine-related resistance in someone using the dapivirine ring was the same as the risk in someone who wasn’t using the ring

The main concern with dapivirine and potentially any prevention method containing an ARV is drug resistance. While one ARV may be sufficient for preventing HIV, it is not enough to suppress the virus from continuing to replicate in someone who is infected.

Moreover, if that individual were to infect others with drug-resistant virus, it would be increasingly more difficult to control HIV with mainstay drugs.

These findings were reported at the biennial HIV Research for Prevention conference (HIVR4P 2018). The results also suggest the risk that drug resistance could develop with use of the dapivirine ring is minimal, though researchers caution that their results represent only one study.

“In this study, we found that the risk of dapivirine-related resistance in someone using the dapivirine ring was the same as the risk in someone who wasn’t using the ring,” said Urvi Parikh, Ph.D., associate director of the Microbicide Trials Network (MTN) Laboratory Center Virology and Pharmacodynamics Core at the University of Pittsburgh.

“Dapivirine primarily stays in the vagina where it is needed to protect against HIV infection. Very little drug gets into the blood and goes elsewhere in the body. But should any HIV pass the drug barrier in the vagina and start multiplying in the bloodstream, there probably isn’t enough dapivirine circulating to be noticed and to cause resistant virus to emerge,” explained Dr. Parikh.