Contraception and Menstrual Cycle Effect on Pharmacokinetics, Pharmacodynamics and Safety in Tenofovir Vaginal Gel Use

Inclusion Criteria: * Willing and able to use OCs or DMPA * General good health (by volunteer history and investigator assessment) without any clinically significant systemic disease * Currently having regular menstrual cycles of 25 to 35 days by volunteer report * History of Pap smears and follow-up consistent with American Congress of Obstetricians and Gynecologists (ACOG) practice bulletin #99 or #109 or willing to undergo a Pap smear at Visit 1 * Willing to follow protocol requirements including abstinence, use of study condoms, and prohibited use of intravaginal products * Willing to follow post-biopsy restrictions for at least 5 days following genital biopsies * Meets one of the following criteria: 1. Sexually abstinent and planning to remain abstinent for the duration of the study. 2. In a mutually monogamous relationship for at least the last 4 months with a male partner who is at least 18 years of age, willing to use condoms, and has no known HIV infection or risks for sexually transmitted infections (STIs) 3. In a mutually monogamous same-sex relationship for at least the last 4 months with a partner who is at least 18 years of age and has no known HIV infection or risks for STIs * Vaginal and cervical anatomy that, in the opinion of the investigator, lends itself to easy genital tract sample collection * Negative urine pregnancy test * Willing to give voluntary consent, sign an informed consent form and comply with study procedures, as required by the protocol Exclusion Criteria: * History of hysterectomy * Currently pregnant or within 2 calendar months from the last pregnancy outcome. (Note: If recently pregnant must have had at least 2 spontaneous menses since pregnancy outcome.) * Use of any hormonal contraceptive method in the last 30 days (oral, transdermal, transvaginal, implant, or hormonal intrauterine contraceptive device) * Injection of DMPA in the last 6 months * Protection from pregnancy by presence of a copper IUD * Currently breastfeeding or having breastfed an infant in the last 2 months, or planning to breastfeed during the course of the study * History of sensitivity/allergy to any component of the study product, or topical anesthetic, or allergy to both silver nitrate and Monsel's solution * Diagnosed with or treated for any STI or pelvic inflammatory disease in the last 6 months. (Note: Women with a history of genital herpes or condylomata who have been asymptomatic for at least 6 months may be considered for eligibility.) * Positive test for Trichomonas vaginalis, Neisseria gonorrhoeae or Chlamydia trachomatis * Symptomatic vulvovaginal candidiasis, Nugent score greater than or equal to 7 at screening or bacterial vaginosis (BV) at Visit 2, or urinary tract infection (UTI) * Deep epithelial genital findings such as abrasions, ulcerations, or lacerations, or vesicles suspicious for STIs * Positive test for HIV * Positive test for Hepatitis B surface antigen (HBsAg) * Known bleeding disorder that could lead to prolonged or continuous bleeding with biopsy * Chronic or acute vulvar or vaginal symptoms (e.g., pain, irritation, or spotting) * Contraindications to the chosen contraceptive method * Known current drug or alcohol abuse which could impact study compliance * Grade 1 or higher laboratory abnormality, per the August 2009 update of the DAIDS Table for Grading the Severity of Adverse Events * Participation in any other investigational trial (device, drug, or vaginal trial) in the last 30 days or planned participation in any other investigational trial during the study * History of gynecological procedures (including genital piercing) on the external genitalia, vagina or cervix in the last 14 days * Abnormal finding on laboratory or physical examination or a social or medical condition which, in the opinion of the investigator, would make participation in the study unsafe or would complicate interpretation of data * Systemic use in the last two weeks or anticipated use during the study of any of the following: corticosteroids, antibiotics, antifungals, antivirals or antiretrovirals