A VAGINAL ring that slowly releases an antiviral medication could protect women against HIV for up to three months, a preliminary trial suggests. It assessed two formulations of a vaginal ring that releases the antiretroviral dapivirine in the vagina over the course of 90 days. One version contained 100 milligrams (mg) of dapivirine and the other contained 200 mg. The trial was conducted at two U.S. sites affiliated with the U.S. National Institutes of Health-funded Microbicide Trials Network (MTN). It included 49 healthy HIV-negative women. They were divided into three groups: one used the 100 mg dapivirine ring continuously for 13 weeks; a second group used the 200 mg ring continuously for 13 weeks; and a third group used a 30-day ring, replacing it every four weeks during the study period. All three rings were well tolerated by the participants and there were no safety concerns. Compared to those with the monthly ring, those with the two 90-day rings had 1.3 to 1.9 times higher concentrations of dapivirine in blood plasma and 1.5 to 2.9 times higher levels of the drug in vaginal fluid, as well as higher concentrations of the drug in cervical tissue. The results suggest that the 90-day ring may provide long-acting and sustained HIV protection, according to the researchers. But such research is considered preliminary until published in a peer-reviewed journal. The three-month ring builds on the development by the nonprofit International Partnership for Microbicides (IPM) of a monthly dapivirine ring, which last year received a positive opinion from the European Medicines Agency for its use among women aged 18 and older in developing countries. Soon after, the monthly ring was added to the World Health Organization list of pre-qualified medicines, and earlier this year WHO recommended the ring as another HIV prevention choice for women at high risk of HIV. IPM is seeking approval of the monthly dapivirine ring in eastern and southern Africa, and the first of these decisions could be made by mid-year. IPM is also seeking regulatory approval of the ring from the U.S. Food and Drug Administration. “Regulatory approval of the monthly ring would be an incredible milestone for women,” study chair Dr. Albert Liu said in an MTN news release. (SD-Agencies) | 