The purpose of this study is to develop a predictive antiretroviral pharmacokinetic model of mucosal fluid and tissue distribution in genital tract fluid, rectal fluid and 3 mucosal tissues. This will be accomplished by determining the pharmacokinetic disposition and dose proportionality of four antiretrovirals (tenofovir, emtricitabine, maraviroc, and raltegravir) in human rectal and cervicovaginal fluid and rectal, cervical, and vaginal tissue.