Drug Interaction Report

GENERALLY AVOID: Coadministration with potent and moderate inducers of CYP450 3A4 may significantly decrease the plasma concentrations of bosutinib, which is primarily metabolised by the isoenzyme. In 24 healthy volunteers, administration of a single 500 mg dose of bosutinib with the potent CYP450 3A4 inducer rifampin (600 mg/day for 6 days) under fed conditions resulted in an 86% decrease in bosutinib peak plasma concentration (Cmax) and 94% decrease in systemic exposure (AUC) compared to administration of bosutinib alone. In addition, when two or more medications with similar adverse effect profiles are given concurrently, the likelihood of experiencing these adverse reactions may be increased. For example, coadministration with other agents that can prolong the QT interval (e.g., apalutamide, encorafenib, enzalutamide) may result in additive effects and an increased risk of ventricular arrhythmias like torsade de pointes.

MANAGEMENT: Concomitant use of bosutinib with potent and moderate CYP450 3A4 inducers should be avoided due to the potential for reduced efficacy.

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of bosutinib. When given with a high-fat meal, bosutinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 1.8- and 1.7-fold, respectively.

GENERALLY AVOID: Coadministration with grapefruit juice is likely to increase the plasma concentrations of bosutinib, which is primarily metabolized by CYP450 3A4. However, the interaction has not been studied. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit.

MANAGEMENT: Bosutinib should be administered with a meal. The consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit extract should be avoided.