Pharmacokinetic interaction between bosentan and the oral contraceptives norethisterone and ethinyl estradiol.

OBJECTIVE Bosentan has been shown in vitro and in vivo to induce the cytochrome P450 enzymes CYP2C9 and CYP3A4. The present study was conducted to investigate the effect of bosentan on the pharmacokinetics of a combined oral contraceptive. SUBJECTS AND METHODS In a randomized, 2-way crossover study, 20 healthy female subjects received Treatments A and B… (More)