<p>Progestogens including Dienogest are metabolized mainly by the cytochrome P450 3A4 system . Therefore, inducers or inhibitors of CYP3A4 may affect the progestogen drug metabolism. Known CYP3A4 inhibitors like azole antifungals (e.g, ketoconazole, itraconazole, fluconazole), cimetidine, verapamil, macrolides (e.g, erythromycin, clarithromycin and roxithromycin), diltiazem, protease inhibitors (e.g, ritonavir, saquinavir, indinavir, nelfinavir), antidepressants (e.g, nefazodone, fluvoxamine, fluoxetine) may increase plasma levels of progestogens and result in adverse reactions.</p>