Fluconazole and Vardenafil interaction

Coadministration of other drugs known to prolong the QT interval and which are metabolized via the enzyme CYP3A4 such as erythromycin, pimozide, and quinidine are contraindicated in patients receiving fluconazole.

Potential for Drug Interactions with Strong or Moderate CYP3A4 Inhibitors Concomitant administration with strong CYP3A4 inhibitors (such as ritonavir, indinavir, cobicistat, ketoconazole) or moderate CYP3A4 inhibitors (such as erythromycin) increases plasma concentrations of vardenafil.

Dosage adjustment is necessary when vardenafil hydrochloride tablets are administered with certain CYP3A4 inhibitors [see Dosage and Administration (2.4) , and Drug Interactions (7.2) ].

In vivo studies Strong CYP3A4 inhibitors Ketoconazole (200 mg once daily) produced a 10-fold increase in vardenafil AUC and a 4-fold increase in maximum concentration (C max ) when co-administered with vardenafil hydrochloride tablets (5 mg) in healthy volunteers.

Moderate CYP3A4 inhibitors Erythromycin (500 mg t.i.d.) produced a 4-fold increase in vardenafil AUC and a 3-fold increase in C max when co­ administered with vardenafil hydrochloride tablets 5 mg in healthy volunteers.

…recommended not to exceed a single 5 mg dose of vardenafil hydrochloride tablets in a 24-hour period when used in combination with erythromycin. [See Dosage and Administration (2.4) and Warnings and Precautions (5) .] Although specific interactions have not been studied, other CYP3A4 inhibitors, including grapefruit juice would likely increase vardenafil exposure.