Objectives: Self-administered vaginal rings are a promising method for delivery of topical anti-HIV microbicidesand might offer an adherence advantage over daily or coitally-dependent dosage forms such as gels. This trialassessed the safety and pharmacokinetic aspects of the Dapivirine Vaginal Ring-004 when worn as multiple rings oversequential periods of ring use by healthy, sexually-active, HIV-negative women.Methods: This double-blind trial was conducted among 48 women (18-40 years). Participants were randomlyassigned to two groups (A or B) and received (3:1) either the dapivirine or a placebo vaginal ring. Group A used tworings over a 56-day period and Group B used three rings over a 57-day period. Safety evaluations were conductedthroughout the trial. Dapivirine concentrations were measured in plasma, vaginal fluid and cervical tissue samplescollected during and after the 56 days (Group A) or 57 days (Group B) of vaginal ring use.Results: Ring-004 was safe and well tolerated in all participants. The pharmacokinetic profile demonstrated arapid increase in plasma and vaginal fluid concentrations and achieved concentrations in vaginal fluids and cervicaltissue well above the in vitro IC99 in cervical tissue (3.3 ng/mL) that were sustained for a 28 to 35-day ring use period(approximately 3000 times higher in vaginal fluids and 14 -1000 times higher in cervical tissue). Drug levels wereassociated with significant inhibitory activity of genital secretions against HIV ex vivo, a biomarker of pharmacodynamics.Individual plasma dapivirine concentrations did not exceed 553 pg/mL and were well below plasma concentrations atthe maximum tolerated dose for oral treatment (mean Cmax 2286 ng/mL).Conclusions: The consecutive use of several rings over a period of up to 57 days was safe and well tolerated, andPK data indicate that a single Ring-004 is likely to be protective for at least 35 days.
