Pharmacokinetic differences between Caucasian and Japanese subjects after single and multiple doses of a potential combined oral contraceptive (Org 30659 and EE)

Abstract

Objectives To compare the pharmacokinetic parameters and safety of the progestagen, Org 30659, (17α)-17-hydroxy-11-methylene-19-norpregna-4,15-dien-20-yn-3-one), and ethinyl estradiol (EE) in Caucasian and Japanese women after single and multiple doses. Methods This was an open-label parallel design of a single dose followed by a multiple dose period in healthy young Japanese and Caucasian subjects. Results The area under the curve (AUC) of Org 30659 after single dosing was increased by a factor of 1.75 [90% confidence interval (CI): 1.48–2.08] in Japanese women compared to Caucasian women. At steady state, this difference increased to a factor of 1.90 (90% CI: 1.60–2.25). The AUC of EE after single dosing was similar in Caucasian and Japanese women, but at steady state it was increased by a factor 1.38 (90% CI: 1.15–1.64) in the Japanese group. Weight normalization reduced, but did not remove, all the observed differences. Sex hormone binding globulin played no significant role in the differences between Caucasian and Japanese subjects. Both the single- and multiple-dose treatments with Org 30659/EE were generally well tolerated by all subjects. The Japanese population reported more and different treatment-related adverse events than the Caucasian population. Conclusions The peak concentration and extent of exposure of Org 30659, and to a lesser extent of EE, in Japanese women are higher than in Caucasian women. Furthermore, the peak concentration and extent of exposure at steady state of Org 30659, and to a lesser extent of EE, are higher than would be predicted assuming linear pharmacokinetics over time. No major safety issues were observed.