Pharmacodynamics of the contraceptive patch

Abstract

Objective: To select a contraceptive patch size that provides ovulation suppression and cycle control equal to or greater than a well accepted oral contraceptive (OC).Methods: Subjects were randomly assigned to 1 of 4 treatment groups (for 4 cycles): 10-cm2 patch (3.0 mg of 17-deacetylnorgestimate [17d-NGM]/0.38 mg of ethinyl estradiol [EE]) (n = 153), 15-cm2 patch (4.5 mg of 17d-NGM/0.56 mg of EE) (n = 157), 20-cm2 patch (6.0 mg of 17d-NGM/0.75 mg of EE) (n = 150), or oral NGM 250 μg/EE 35 μg (n = 150). Regimens: Three 7-day patches (21 days) plus 1 patch-free week; 1 pill daily (21 days) plus 1 pill-free week, with a 1-day late start in cycle 4 for all subjects. Suppression of ovarian activity was determined by serum progesterone levels on days 7, 14, 21 and 28 of cycles 1, 3, and 4, ovarian follicle size by ultrasonography in 109 subjects on days 2 (or 3), 7, 14, 21, and 28 of cycles 1, 3 and 4, and cycle control via diary cards.Results: The proportions of subjects with progesterone values greater than 3 ng/mL in cycles 1 and 3 were 41.9%, 10.2%, 5.5%, and 6.1% for the 10-, 15-, and 20-cm2 patch and OC groups, respectively. Maximum mean follicular diameter in cycles 1, 3, and 4 ranged from 10 to 11.1 mm in the 20-cm2 patch (EVRA) group and from 10.7 to 14 mm for the OC group. The percentages of subjects in the 20-cm2 patch (EVRA) and OC groups with breakthrough bleeding/spotting were similar for cycles 1 and 2 and, in cycle 3, were better for EVRA (10.5% vs 15%).Conclusion: The 20-cm2 contraceptive patch (EVRA) provides high levels of suppression of ovarian activity and effective cycle control compared with a widely accepted OC, while providing more complete suppression of follicular development.