Drug Interaction Report

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of maribavir, which is primarily metabolized by the isoenzyme. When maribavir (400 mg twice daily) was administered with the potent CYP450 3A4 inducer, rifampin (600 mg once daily), maribavir peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 39% and 60%, respectively. The interaction has not been studied with other, less potent inducers.

MANAGEMENT: The potential for diminished pharmacologic effects of maribavir should be considered during coadministration with CYP450 3A4 inducers. Alternative treatments may be required if an interaction is suspected.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of brigatinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Itraconazole, a potent CYP450 3A4 inhibitor, has been shown to double brigatinib systemic exposure (AUC) in healthy volunteers. Increased exposure to brigatinib may increase the risk of adverse effects such as nausea, vomiting, diarrhea, hypertension, bradycardia, hyperglycemia, visual disturbances, lymphopenia, anemia, and elevations in pancreatic enzymes and creatine phosphokinase.

Food does not significantly affect the oral bioavailability of brigatinib. When brigatinib was administered to healthy volunteers after a high-fat meal (920 calories; 59 g fat, 58 g carbohydrates, 40 g proteins), brigatinib peak plasma concentration (Cmax) decreased by 13% and systemic exposure (AUC) did not change compared to administration after overnight fasting.

MANAGEMENT: Brigatinib may be taken with or without food. Patients should avoid consumption of grapefruit and grapefruit juice during treatment with brigatinib.