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 t…