Figure 2: Pharmacokinetics of Dapivirine in Plasma and Vaginal Fluids Mean (SD) dapivirine concentrations in (A) plasma during the first and third ring use periods, and in (B) vaginal fluid collected from near the ring, at the cervix and near the introïtus during the first ring use periods in Groups A and B. Group A participants (n=17) used the first vaginal ring for 28 days, and Group B participants (n = 16) used the first vaginal ring for 35 days and the third vaginal ring for 24 hours.