INFLUENCE OF ETHINYLESTRADIOL-CONTAINING COMBINATION ORAL-CONTRACEPTIVES WITH GESTODENE OR LEVONORGESTREL

In a controlled clinical trial, the elimination of caffeine was examin ed in 20 healthy women prior to and during one cycle of treatment with either of two oral contraceptive formulations, one containing 0.075 m g gestodene and 0.03 mg ethinylestradiol and one containing 0.125 mg l evonorgestrel and 0.03 mg ethinylestradiol. In addition, caffeine clea rance was determined 1 month after the last intake of the oral contrac eptives. Compared with pretreatment values, the clearance of caffeine was reduced by about 54% and 55% after one treatment cycle with gestod ene- and the levonorgestrel-containing oral contraceptive, respectivel y. Other pharmacokinetic parameters of caffeine, such as t(max) and C- max were not affected. Clearance values returned to pretreatment value s 1 month after the last administration of the oral contraceptives. Th ere was no difference in the reduction of caffeine clearance between c ontraceptive formulations. A small, but significant difference in the AUC(0-24 h) values of ethinylestradiol was noted between both preparat ions. There was no correlation between the AUC(model) values of caffei ne and the AUC(0-24 h) values of ethinylestradiol. In the present stud y, a somewhat more pronounced effect on the elimination of caffeine wa s observed than in previous investigations, where several contraceptiv e steroids were administered only for a period of 2 weeks.