Single- and Multiple-Dose Pharmacokinetics and Safety of Vilaprisan in Healthy Postmenopausal Japanese Women: A Randomized Clinical Trial

As the prevalence of some gynecological conditions depends on patient characteristics such as race/ethnicity, it is important to study therapies for these conditions in diverse populations. The study described in this article was conducted to investigate the safety, tolerability, and pharmacokinetics of vilaprisan, a selective progesterone receptor modulator, in Japanese women in Japan. It supplements two comparable studies that were conducted in healthy postmenopausal European and Chinese women, respectively.

In this exploratory randomized, placebo-controlled, double-blind, ascending-dose study, five groups of healthy postmenopausal Japanese women received vilaprisan as immediate-release tablets (1, 5, or 15 mg as a single dose or 1 or 5 mg/day for 28 days) or placebo tablets (single dosing: 8 subjects/dose step, thereof 2 subjects randomized to placebo; multiple dosing: 12 subjects/dose step, thereof 4 subjects randomized to placebo). Blood samples for pharmacokinetic profiles were collected over 14–19 days. Safety assessments were based on adverse event data, vital signs, electrocardiograms, clinical laboratory tests, and transvaginal ultrasound examinations.

48 participants were randomized, treated, and analyzed. Vilaprisan was rapidly absorbed, reaching maximum plasma concentrations (C_max) between 1 and 3 h post dose. Post maximum, plasma concentrations rapidly declined, indicating pronounced distribution into tissues. The exposure of vilaprisan increased roughly dose-proportionally: The geometric mean (geometric coefficients of variation) areas under the concentration time curves from time zero to infinity (AUC_∞) after single administration of 1, 5, or 15 mg vilaprisan were 67 µg·h/l (34%), 249 µg·h/l (15%), and 788 µg·h/l (37%), respectively. The AUC in the dosing interval after multiple administrations (AUC_24,md) of 1 mg/day was 76 µg·h/l (59%), and the AUC_24,md after 5 mg/day was 311 µg·h/l (20%). Geometric mean C_max values also increased roughly dose-proportionally: They amounted to 6 µg/l (22%), 16 µg/l (33%), and 52 µg/l (27%) after single administration and to 8 µg/l (28%) and 31 µg/l (22%) after multiple administrations of the above doses. Mild adverse events were observed, similar to those observed in other clinical studies of vilaprisan.

Overall, vilaprisan was safe and well tolerated. The exposure in Japanese women was similar to that observed in European and Chinese women in separate studies.

15 Nov 2011 (no registration number assigned).