Vaginal ring achieves localized, sustained release of anti-HIV drugs

A novel intravaginal ring to prevent HIV transmission showed promise in pig-tailed macaque monkeys, demonstrating the benefits of sustained and controlled topical drug delivery over oral intake. 

"Issues such as adherence to a regular dosing schedule are significantly reduced by continuous release of the drugs into the vaginal mucosa independently of coitus and daily dosing," said researcher Marc Baum of the Oak Crest Institute of Science in a news release by the American Society for Microbiology.

The ring is an elastomer scaffold that hold tablets of medication and contains channel that expose the drugs to fluids in the vaginal mucosa, the news release says.

"The ring maintained steady state drug levels in the vaginal tissues, the key anatomic compartment for preventing sexual HIV transmission, and eliminated the concentration troughs encountered with oral medications," Baum said in the news release. "This should boost effectiveness."

Another benefit of the ring is that it doesn't activate the immune system, which would make HIV infection more likely. Baum added that the device's low cost makes it well suited for emerging markets.

The drugs delivered in the experiment were Truvada (emtricitabine and tenofovir disoproxil fumarate) and a combination of Truvada and maraviroc. The experiments were conducted at the U.S. Centers for Disease Control and Prevention in Atlanta.

Meanwhile, in March, researchers in Illinois, Utah and Virginia announced details of their own anti-HIV ring with multiple capabilities, this one with an antiretroviral and a contraceptive. They said they successfully achieved sustained release of both drugs in rabbits.  

The U.S. National Institutes of Health determined that its vaginal ring successfully delivered the antiretroviral drug dapivirine, but not maraviroc, which didn't have the same effect.

- read the news release
- read the study abstract in the journal Antimicrobial Agents and Chemotherapy