Effect of two oral contraceptives containing ethinylestradiol and gestodene or norgestimate upon androgen parameters and serum binding proteins.

The effect of a triphasic oral contraceptive containing ethinylestradiol and gestodene (EE/GSD) on various serum hormonal parameters was compared with that of a monophasic formulation containing 35 micrograms ethinylestradiol and 250 micrograms norgestimate (EE/NGM). Blood samples were collected from 46 women on days 2, 11, and 21 of the preceding control cycle and of the third, sixth and twelfth treatment cycle. There was no significant difference in the influence on any hormonal parameter between both formulations. Both EE/GSD and EE/NGM caused a time-dependent suppression of serum dehydroepiandrosterone sulphate (DHEA-S) by 20-30% (p < 0.01) and a reduction of 5 alpha-androstane-3 alpha, 17 beta-diol glucuronide by 50-60% (p < 0.01) during each treatment cycle, while androstenedione levels were reduced by 25% (p < 0.01). There was also a significant decrease in the levels of total testosterone by 30-35% (p < 0.01) and free testosterone by 60% (p < 0.01), while sex hormone-binding globulin (SHBG) was increased by 200-240% on days 11 and 21 (p < 0.01). During the pill-free interval the SHBG levels were reduced to a certain degree but remained elevated by 100% as compared to the pretreatment values. The serum levels of corticosteroid-binding globulin (CBG) which is known to be influenced only by the estrogenic component of combination pills, increased significantly by 170% (p < 0.01) during each treatment cycle. During the pill-free interval of 7 days, the CBG levels decreased but were still elevated by 90-100% as compared to the control cycle. Similarly, the serum levels of cortisol were significantly elevated by 110-140% (p < 0.01) during treatment with both preparations. The results demonstrate a profound suppression of androgen levels and peripheral androgen metabolism.