Safety, PK, and PD Study of IVRs Releasing TFV and LNG

Inclusion Criteria: * Female, age 18-50 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) and with an intact gastrointestinal tract, uterus, and cervix. * Currently having regular menstrual cycles (approximately 26-35 days) by participant report * History of Pap smears and follow-up consistent with standard clinical practice as outlined in the Study Manual or willing to undergo a Pap smear at Visit 1 * Protected from pregnancy by one of the following: * Sterilization of either partner * Abstinence from vaginal intercourse * Consistent use of non-spermicidal condoms * Willing to abstain from use of vaginal products (other than the study product and condoms) including tampons (except for menses), spermicides, lubricants, and douches for the whole study * Willing to abstain from any vaginal and anal intercourse/activity starting 48 hours before cervical mucus collection, as possible, and 48 hours before Visits 4 and 29, and for 5 days after tissue collection * Vaginal and cervical anatomy that, in the opinion of the investigator, lends itself to easy genital tract sample collection * Negative urine pregnancy test * P4 ≥3 ng/ml * Willing to give voluntary consent and sign an informed consent form * Willing and able to comply with protocol requirements Exclusion Criteria: * BMI ≥ 30 kg/m2 * 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 IUD * 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 the study products, topical anesthetic, or to both silver nitrate and Monsel's solution * Contraindication to LNG * In the last three months, diagnosed with or treated for any 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 (TV), Neisseria gonorrhea (GC), Chlamydia trachomatis (CT), HIV-1, or Hepatitis B surface antigen (HBsAg) * Known bleeding disorder, including deep vein thrombosis (DVT) and pulmonary embolism (PE), or those that could lead to prolonged or continuous bleeding with biopsy * Chronic or acute vulvar or vaginal symptoms (pain, irritation, spotting/bleeding, discharge, etc.) * Known current drug or alcohol abuse which could impact study compliance * Grade 2 or higher laboratory abnormality, per the 2014 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, or antivirals or antiretrovirals (e.g. acyclovir, valacyclovir, Viread®, Atripla®, Emtriva®, or Complera®), or CYP3A4 inducers or inhibitors as detailed in the Study Manual (e.g., St. John's Wort or erythromycin). Note: Participants should avoid non-steroidal anti-inflammatory drugs (NSAIDs) except for treatment of dysmenorrhea during menses. Participants may use acetaminophen on an as-needed but not daily basis during the study. * Participation in any other investigational trial with use of a drug/device within the last 30 days or planned participation in any other investigational trial with use of a drug/device 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 in the volunteer which, in the opinion of the investigator, would make participation in the study unsafe or would complicate interpretation of data