A phase I/II study evaluating the pharmacokinetics, pharmacodynamics, and safety of drospirenone as an oral contraceptive in Japanese women.

AIM: Drospirenone (DRSP) is a synthetic progestogen approved as a progestin-only pill for contraception in both the United States and Europe. Herein, we conducted a phase I/II study to evaluate the pharmacokinetics, pharmacodynamics, and safety of DRSP in Japanese women.

METHODS: Single and multiple doses of 4 mg of DRSP were orally administered to healthy premenopausal Japanese women. In the multiple-dose period, 4 mg of DRSP was administered once daily for 24 days. Pharmacokinetics, hormone levels, and adverse events (AEs) were investigated.

RESULTS: Twelve Japanese women participated in this study. The single- and multiple-dose pharmacokinetics of DRSP was similar to that reported in previous studies in Caucasians. In the multiple-dose period, no subject displayed a progesterone level of more than 5.03 ng/mL. AEs were observed in 11 (91.7%) subjects. The most common AE was genital hemorrhage, which was observed in six (50.0%) subjects, followed by diarrhea and acne in four (33.3%) subjects each. All AEs resolved or improved at the end of the study, and complete recovery was confirmed in all subjects at follow-up.

CONCLUSIONS: The pharmacokinetics of DRSP in Japanese women was similar to that of previous studies performed in Caucasian women. Repeated administration of DRSP maintained low plasma progesterone levels indicating effective inhibition of ovulation. No notable safety concerns were observed. In this phase I/II study, DRSP had no obvious pharmacokinetic, pharmacodynamic, or safety issues to consider in Japanese women.