Hormonal Contraceptives, Including Oral, Injectable, Transdermal, and Implantable Contraceptives: An interaction study demonstrated that co-administration of bosentan and the oral hormonal contraceptive Ortho-Novum produced average decreases of norethindrone and ethinyl estradiol levels of 14% and 31%, respectively.
<bosentan, mechanism, Ortho-Novum>