Progesterone Pharmacokinetics and Pharmacodynamics With 3 Dosages and 2 Regimens of an Effervescent Micronized Progesterone Vaginal Insert

Context: Progesterone vaginal insert (PVI), an effervescent delivery system, dissolves rapidly, is absorbed through the vaginal epithelium, and achieves higher endometrial tissue concentrations than those achieved with progesterone in oil (PIO) given im. Objective: Our objective was to examine the pharmacokinetics and pharmacodynamics of PVI compared with PIO. Design, Setting, and Participants: Fifty-eight healthy premenopausal women were randomized to 50, 100, or 200 mg PVI once daily; 100 or 200 mg PVI twice daily; or 50 to 100 mg PIO via im injection once daily for 10 days. Serum samples were obtained after the first dose; serum and endometrial tissue were obtained after the last dose. Main Outcome Measures: Maximum observed serum concentration (Cmax), time to Cmax, and area under the serum-concentration time curve over the dosing interval were calculated after correcting for baseline progesterone concentrations. ANOVA and paired t test were used to compare results across and within groups. Results: A ...