Plasma levels of ethinyl oestradiol and norgestrel during hormone replacement therapy

Abstract

Plasma levels of levonorgestrel and ethinyl oestradiol were estimated in six women who took part in a double blind cross-over trial of hormone replacement therapy. Over a 12 mth period, each woman received each of the following oral drugs for 3 mth: ethinyl oestradiol 50 μg, levonorgestrel 250 μg, combination of ethinyl oestradiol 50 μg and levonorgestrel 250 μg (Nordiol), and placebo. Plasma samples were collected at 2, 8 and 26 h after morning medication each month. Plasma levels of norgestrel were increased when ethinyl oestradiol was added in the form of the combined preparation "Nordiol". The addition of ethinyl oestradiol to norgestrel therapy also resulted in significant differences b..