- Concomitant treatment with strong CYP3A4 inductors (such as rifampicin, St. John´s Wort) or CYP3A4 inhibitors (such as ketoconazole, voriconazole, itraconazole, diltiazem, verapamil, erythromycin). Moderate or weak CYP3A4 modifiers should be used concomitantly only after careful assessment of risk-benefit ratio. Concomitant use of carbamazepine, phenobarbital, phenytoin or chronic use of dexamethasone is excluded