Drug interactions between ketoconazole and Levitra

ADJUST DOSE: Coadministration with the azole antifungal agents, ketoconazole and itraconazole, may significantly increase the plasma concentrations of vardenafil. The mechanism is azole inhibition of CYP450 3A4, the isoenzyme primarily responsible for the metabolic clearance of vardenafil. According to vardenafil labeling, coadministration of ketoconazole (200 mg once a day) and vardenafil (5 mg) in healthy volunteers resulted in a 4-fold increase in the peak plasma concentration (Cmax) and a 10-fold increase in the area under the concentration-time curve (AUC) of vardenafil. No data are available for itraconazole, although a similar interaction may be anticipated due to the potent inhibiting effect of itraconazole on CYP450 3A4.

MANAGEMENT: Patients treated with ketoconazole or itraconazole at a dosage of 200 mg/day should not receive more than a single 5 mg dose of vardenafil within a 24-hour period. Since higher dosages of the azole antifungal agents may result in higher increases in vardenafil plasma concentrations, a single 2.5 mg dose of vardenafil should not be exceeded within a 24-hour period when used in combination with ketoconazole or itraconazole 400 mg/day. Patients should be advised to promptly notify their physician if they experience pain or tightness in the chest or jaw, irregular heartbeat, nausea, shortness of breath, visual disturbances, syncope, or prolonged erection (greater than 4 hours).