Drug Interactions between aprepitant and ceritinib

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of ceritinib, which is a substrate of the isoenzyme. In 19 healthy subjects, administration of a single 450 mg dose of ceritinib with the potent CYP450 3A4 inhibitor ketoconazole (200 mg twice daily for 14 days) increased ceritinib peak plasma concentration (Cmax) by 22% and systemic exposure (AUC) by 2.9-fold. The steady-state AUC of ceritinib at reduced doses after coadministration with ketoconazole 200 mg twice daily for 14 days was predicted by simulations to be similar to the steady-state AUC of ceritinib administered alone. Because ceritinib 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. Other, more common side effects such as diarrhea, nausea, vomiting, abdominal pain, hyperglycemia, and bradycardia may also increase.

MANAGEMENT: Caution is advised if ceritinib is prescribed with CYP450 3A4 inhibitors. Pharmacologic response to ceritinib should be monitored more closely whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy, and the ceritinib dosage adjusted as necessary. Patients should have periodic ECGs and be monitored for arrhythmias when QT interval is prolonged. A QTc interval exceeding 500 msec on at least two separate ECGs will require suspension of ceritinib therapy and immediate action to correct any concomitant risk factors before resuming treatment with a 150 mg dosage reduction. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. Following discontinuation of the CYP450 3A4 inhibitor, ceritinib therapy should be resumed at the dosage that was taken prior to initiating the CYP450 3A4 inhibitor if an adjustment was made.