 Subjects will be counseled to abstain from sexual intercourse and all other insertive vaginal practices for 10 days following each administered dose or 7 days after the last cervicovaginal sampling at 72 hours. Following a safety evaluation visit, the research participant will return to the research unit and receive a second tenofovir dose formulation followed by the same schedule of sample collection and a final safety visit. PK parameters of TFV and TFV-DP will be estimated and compared between the gel and film formulations. PK parameters will include peak concentration Cmax, area under the concentration-time curve AUC, time to peak concentration Tmax, elimination half-life t12. Tenofovir gel and film ex vivo pharmacodynamics will also be assessed and analyzed for correspondence to pharmacokinetics. 