Quantification of Estradiol's Impact on Nucleotides in Different Cellular Populations of the Lower Gastrointestinal Tract

Detailed Summary

Purpose: To Assess the impact of high and low in vivo estradiol exposure on PrEP (Pre-exposure prophylaxis) nucleotide concentrations in different cellular populations of the lower GI (gastrointestinal) tract and to quantify the relationship between estradiol, progesterone, and testosterone on PrEP nucleotide concentrations in rectal and peripheral blood mononuclear cells. As well as the relationship between estradiol, progesterone, and testosterone on PrEP concentrations in plasma. Participants: Healthy, cisgender female, volunteers, aged 18-49 inclusive on the date of screening with an intact gastrointestinal system and regular menstrual cycle. Procedures (methods): Participants will take a single daily dose of study drug for five days before each sampling visit. The visits will be scheduled during the early follicular phase of the menstrual cycle (approximately days 2-5 after the first day of menses, Visit 1) when estradiol is predicted to be the lowest and the late follicular phase (approximately days 12-15 after the first day of menses, Visit 2) when estradiol is predicted to be highest. Samples of blood, rectal cells, and rectal tissue will be collected at both Visits 1 and 2. All participants will complete a follow-up safety visit within 14 days of completing study sampling.

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