Phase I One-month Safety, PK, PD, and Acceptability Study of IVR Releasing TFV and LNG or TFV Alone

Inclusion Criteria: * Age 18-45 years, inclusive * General good health (by volunteer history and per investigator discretion) without any clinically significant systemic disease (including, but not limited to significant liver disease/hepatitis, gastrointestinal disease, kidney disease, thyroid disease, osteoporosis or bone disease, and diabetes) * Currently having regular menstrual cycles of 26-35 days by participant report * History of Pap smears and follow-up consistent with standard medical practice as outlined in the study manual or willing to undergo a Pap smear * Protected from pregnancy by one of the following: 1) Sterilization of either partner. Note: Women protected from pregnancy by sterilization of either partner must abstain from vaginal intercourse from 48 hours prior to Visit 3 until the sixth day after the last study visit; or 2) Willing to abstain from vaginal intercourse from Visit 1 until the sixth day after the last study visit. * Willing to abstain from any other vaginal activity and the use of vaginal product other than the study product including tampons, spermicides, lubricants, and douches starting 48 hours before Visit 3 until the sixth day after the last study visit * Vaginal and cervical anatomy that, in the opinion of the investigator, lends itself to easy colposcopy and genital tract sample collection * Negative urine pregnancy test * P4 ≥3 ng/ml * 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 two calendar months from the last pregnancy outcome. Note: If recently pregnant must have had at least two spontaneous menses since pregnancy outcome. * Use of any hormonal contraceptive method in the last 3 months (oral, transdermal, transvaginal, implant, or hormonal intrauterine contraceptive device) * Injection of Depo-Provera in the last 10 months * Use of copper intrauterine device (IUD) after Visit 1 * Currently breastfeeding or having breastfed an infant in the last two months, or planning to breastfeed during the course of the study * History of sensitivity/allergy to any component of: TFV 1% gel, topical anesthetic, or allergy to both silver nitrate and Monsel's solution. * Contraindication to LNG * In the last six months, diagnosed with or treated for any sexually transmitted infection (STI) or pelvic inflammatory disease. Note: Women with a history of genital herpes or condylomata who have been asymptomatic for at least six months may be considered for eligibility. * Nugent score greater than or equal to 7 or symptomatic bacterial vaginosis (BV) as defined by Amsel's criteria * Positive test for Trichomonas vaginalis, Neisseria gonorrhea (GC), Chlamydia trachomatis (CT), HIV, or 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 (pain, irritation, spotting, etc.) * Known current drug or alcohol abuse which could impact study compliance * Grade 2 or higher laboratory abnormality, per the August 2009 update of the Division of AIDS, National Institute of Allergy and Infectious Disease (DAIDS) Table for Grading the Severity of Adverse Events, or clinically significant laboratory abnormality as determined by the clinician * Systemic use in the last two weeks or anticipated use during the study of any of the following: corticosteroids, antibiotics, anticoagulants or other drugs known to prolong bleeding and/or clotting, antifungals, antivirals (e.g., acyclovir or valacyclovir) or antiretrovirals (e.g., Viread, Atripla®, Emtriva®, Complera®). Note: Participants should avoid non-steroidal anti-inflammatory drugs (NSAIDs) except for treatment of dysmenorrhea during menses. Participants may use Tylenol® on an as-needed but not daily basis during the study * Participation in any other investigational trial (device, drug, or vaginal trial) within 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 within 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