Drug Interaction Report

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of ticagrelor, which is primarily metabolized by the isoenzyme. In healthy volunteers, administration of ticagrelor in combination with the potent CYP450 3A4 inhibitor ketoconazole resulted in increased ticagrelor peak plasma concentration (Cmax) and systemic exposure (AUC) by 2.4-fold and 7.3-fold, respectively, and reduced Cmax and AUC of the active metabolite by 89% and 56%, respectively.

MANAGEMENT: Concomitant use of ticagrelor with potent CYP450 3A4 inhibitors is considered contraindicated by some foreign authorities. The U.S. labeling for ticagrelor recommends avoiding use with potent CYP450 3A4 inhibitors. Labeling for itraconazole, a potent CYP450 3A4 inhibitor, specifically contraindicates use with ticagrelor during and for 2 weeks after treatment with itraconazole.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of ceritinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. 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.

ADJUST DOSING INTERVAL: Food increases the oral bioavailability of ceritinib. The mechanism of interaction is unknown. Compared to the fast state, administration of a single 500 mg dose of ceritinib with a high-fat meal (approximately 1000 calories; 58 grams of fat) increased ceritinib peak plasma concentration (Cmax) and systemic exposure (AUC) by 41% and 73%, respectively, and administration with a low-fat meal (approximately 330 calories; 9 grams of fat) increased ceritinib Cmax and AUC by 43% and 58%, respectively. A dose of 600 mg or higher taken with a meal is expected to produce systemic exposure exceeding that from a 750 mg dose taken in the fasted state, which may lead to increased adverse effects.

MANAGEMENT: Patients treated with ceritinib should avoid consumption of grapefruit, grapefruit juice, and any supplement containing grapefruit extract. Ceritinib should be administered on an empty stomach (i.e., avoid administration within 2 hours of a meal).