Coital Pharmacokinetics/Pharmacodynamics (PK/PD) of Tenofovir Gel

Study Objectives: * To assess the impact of coitus (and semen) on the pharmacokinetics of tenofovir 1% gel in female genital tract secretions, vaginal and cervical tissue and rectal tract secretions * To assess the impact of coitus (and semen) on pharmacodynamics of luminal drug by measuring the anti-HIV-1 activity in CVL samples Study Summary: MTN-011 will enroll heterosexual monogamous, sexually active couples, in which both partners are healthy and HIV-negative. The female participants must be between the ages of 21-46 (inclusive) and currently using effective non-barrier contraception. Male participants must be 21 years of age or older. This Phase 1 expanded safety study will assess tenofovir PK in the genital tract secretions (CVL), rectal (rectal sponge) and both intracellular and extracellular tissue compartments (vaginal biopsy) in the absence of, or following coitus. Pharmacodynamics (antiviral activity) will also be assessed in CVL. MTN-011 will study the timing in which coitus might have the greatest impact on these variables, which is when gel is applied shortly prior to coitus in the absence of a drug reservoir. MTN-011 will examine PK/PD in response to a single dose of 1% tenofovir gel applied shortly before sex and compare to PK/PD assessments following a single gel application without sex. Additionally, data obtained from a visit in which participants do not dose with gel and do not have sex will serve as an additional control for the pharmacodynamic (PD) studies of the antiviral activity in CVL. If tenofovir retains its antiviral activity following sex, then the anti-HIV activity in CVL collected at the visit in which female participants dose with gel and have sex should be comparable to that of CVL collected at the visit in which females dose with gel and then do not engage in intercourse and significantly greater than the endogenous anti-HIV activity in CVL obtained at the visit in which participants do not dose with gel but do have sex and the visit in which no gel is administered and sex does occur. Data analysis performed after the completion of enrollment and follow-up procedures will demonstrate if there is an impact of coitus and semen on PK/PD when a single 1% tenofovir dose is applied shortly prior to sex.