Drug Interaction Report

ADJUST DOSE: Coadministration with inhibitors of P-glycoprotein (P-gp) may increase the plasma concentrations of edoxaban, which is a substrate of the efflux transporter. In healthy volunteers, single-dose edoxaban systemic exposure (AUC) increased approximately 80% to 90% by erythromycin, dronedarone, and ketoconazole; 70% to 80% by cyclosporine and quinidine; 50% by verapamil; and 40% by amiodarone. The peak plasma concentration (Cmax) of edoxaban also increased by approximately 45% to 90% with these drugs.

MANAGEMENT: When used for the treatment of deep vein thrombosis and pulmonary embolism, the manufacturer recommends that edoxaban dosage be reduced to 30 mg once daily in patients receiving concomitant treatment with certain P-gp inhibitors including azithromycin, clarithromycin, erythromycin, oral itraconazole, oral ketoconazole, quinidine, and verapamil. This dosage recommendation is based on data from a clinical study, the Hokusai VTE study, and is limited to use with the specific P-gp inhibitors mentioned. Other P-gp inhibitors were not permitted in the study, and patients on antiretroviral therapy (ritonavir, nelfinavir, indinavir, saquinavir) as well as cyclosporine were excluded from the study. Following discontinuation of the P-gp inhibitor, edoxaban dosage should be returned to the regular dosage of 60 mg once daily. No dosage adjustment is recommended for edoxaban when used in the treatment of nonvalvular atrial fibrillation.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of nilotinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. Because nilotinib is associated with concentration-dependent prolongation of the QT interval, increased levels may potentiate the risk of ventricular arrhythmias such as torsade de pointes and sudden death.

ADJUST DOSING INTERVAL: Food increases the oral bioavailability of nilotinib. The mechanism of interaction is unknown. Compared to the fast state, nilotinib systemic exposure (AUC) increased by 82% when the dose was given 30 minutes after a high-fat meal. Because nilotinib is associated with concentration-dependent prolongation of the QT interval, increased levels may potentiate the risk of ventricular arrhythmias such as torsade de pointes and sudden death.

MANAGEMENT: Patients treated with nilotinib should avoid consumption of grapefruit, grapefruit juice, and any supplement containing grapefruit extract. In addition, no food should be consumed for at least 2 hours before and 1 hour after a nilotinib dose.