Oral contraceptives containing 20 or 30 micrograms ethinylestradiol and 150 micrograms desogestrel: pharmacokinetics...

The serum concentrations of ethinylestradiol (EE) and 3-keto-desogestrel (KDG) were compared during treatment with a combination of 20 micrograms EE + 150 micrograms DG (20EE/DG) or of 30 micrograms EE + 150 micrograms DG (30EE/DG). During intake of both preparations, the peak levels and the areas under the curve (AUC) of EE increased significantly by approximately 100% between days 1 and 10. In the steady state, the maximal EE levels were 75 +/- 34 pg/ml (20EE/DG) and 136 +/- 55 pg/ml (30EE/DG), and the AUC were 464 +/- 236 pg.h/ml and 840 +/- 492 pg.h/ml. The KDG levels, which were identical with both preparations, increased between days 1 and 21 by approximately 300% up to values of 4.5 +/- 1.6 ng/ml. There were large interindividual variations in the AUC of EE and KDG and no correlation between the levels of EE and KDG. On day 21 of intake of 30EE/DG, the serum concentrations of sex-hormone- and corticosteroid-binding globulin were higher by 16% and 12%, respectively than with 20EE/DG. Although the morning peak levels of cortisol did not differ, the decrease which occurred thereafter, according to the circadian rhythm, was slower with 30EE/DG. There was no relationship between the serum concentrations of EE and/or KDG and the occurrence of irregular bleedings, which was similar during treatment with both preparations. As most of the women who bled had bleedings both with 20EE/DG and 30EE/DG, an influence of predisposition can be assumed.(ABSTRACT TRUNCATED AT 250 WORDS)