Safety, Pharmacokinetics, Pharmacodynamics, and Disintegration Time of Vaginal Tablets Containing Tenofovir and/or Emtricitabine

This prospective, double-blinded, randomized, parallel cohort study will examine the genital and systemic safety, pharmacokinetics (PK), pharmacodynamics (PD), disintegration and disappearance times, and acceptability of four vaginal tablets: 1) Tenofovir (TFV) alone; 2) Emtricitabine (FTC) alone; 3) TFV combined with FTC; and 4) placebo. Participants will be randomized to treatment group, to number of tablets to be inserted in the Single Use Phase (1 tablet or 1 tablet followed by a second tablet two hours later to mimic the BAT24 dosing regimen), and to one of four collection time points (2, 4, 6, or 24 hours after tablet insertion) for assessments only after the last dose of the Multiple Use Phase. In the Single Use Phase of the study, the participant will insert one tablet in the clinic to estimate times to disintegration and disappearance. Those randomized to two tablets will insert a second tablet 2 hours later. In all women, sample collection will occur 5 hours after the initial tablet insertion. In the Multiple Use Phase of the study, participants will insert a tablet once daily for 14 days. The 1st, 7th, and 14th tablets will be inserted in the clinic; the remaining tablets will be inserted at home. The clinic will call the participant on day 3 of the multiple use phase to ask about any symptoms the participant may be experiencing. Each insertion in the clinic will be followed by sample collection and, at Visits 4 and 6, colposcopy at the participant's assigned time point.