This phase I, single center, open-label, randomised (allocation to treatment), balanced, single dose trial was performed in a parallel-group design. The subjects were randomly assigned to one of the 3 possible treatments (single vaginal application of 1 vaginal ring containing 100, 300 or 600 mg estriol, with delivery rate of 0.125, 0.250 or 0.500 mg/day over 21 days.~Blood samples were collected at 0.5 h prior to drug application, 1, 2, 4, 6, 12, 24, 48, 96, 144, 216, 288, 360, 432 h after application; 5 min prior to removal, i.e., 21 d after application (study day 22), as well as 6, 12 and 24 h after removal to characterise pharmacokinetic parameters of estriol in plasma.~Serum concentrations of follicle stimulating hormone (FSH), luteinising hormone (LH) and sex hormone binding globulin (SHBG) and gynaecological parameters (cytology of vaginal smear, the maturation index and the vaginal pH) were evaluated as pharmacodynamic parameters.~The safety and tolerability was assessed by endometrial thickness and documentation of adverse events.
This clinical trial evaluated the pharmacokinetics and pharmacodynamics of estriol in healthy post-menopausal women after the application of one vaginal ring containing one of three different dosages of estriol (100 mg (Test 1), 300 mg (Test 2) or 600 mg (Test 3)) with continuous delivery (0.125, 0.250 or 0.500 mg/day) for 21 days. And also, characterized its safety and tolerability.