Drug Interactions between alfuzosin and amoxicillin / clarithromycin / vonoprazan

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of alfuzosin, which is primarily metabolized by the isoenzyme. Severe hypotension and priapism may occur. In pharmacokinetic studies, repeated oral administration of 400 mg/day of ketoconazole, a potent CYP450 3A4 inhibitor, increased alfuzosin peak plasma concentration (Cmax) and systemic exposure (AUC) by 2.3- and 3.2-fold, respectively, following a single 10 mg dose. Repeated oral administration of ketoconazole 200 mg/day increased alfuzosin Cmax by 2.1-fold and AUC by 2.5-fold following a single 10 mg dose.

MANAGEMENT: Concomitant use of alfuzosin with potent CYP450 3A4 inhibitors such as itraconazole, ketoconazole, posaconazole, voriconazole, conivaptan, nefazodone, cobicistat, delavirdine, protease inhibitors, and ketolide and certain macrolide antibiotics is considered contraindicated. Some authorities recommend avoiding concomitant use of alfuzosin during and for 2 weeks after treatment with itraconazole.

Although some in vitro data indicate synergism between macrolide antibiotics and penicillins, other in vitro data indicate antagonism. When these drugs are given together, neither has predictable therapeutic efficacy. Data are available for erythromycin, although theoretically this interaction could occur with any macrolide. Except for monitoring of the effectiveness of antibiotic therapy, no special precautions appear to be necessary.