Drug Interactions between entrectinib and sirolimus

GENERALLY AVOID: Grapefruit juice and Seville oranges may increase the plasma concentrations of entrectinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit and Seville oranges Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice, but pharmacokinetic data are available for the potent CYP450 3A4 inhibitor, itraconazole. When a single 100 mg dose of entrectinib was administered with itraconazole, entrectinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 1.7- and 6-fold, respectively. Coadministration of entrectinib with a moderate CYP450 3A4 inhibitor is predicted to increase entrectinib Cmax and AUC by 2.9- and 3-fold, respectively. 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. Increased exposure to entrectinib may increase the risk and/or severity of adverse effects such as cognitive impairment, mood disorders, dizziness, sleep disturbances, liver enzyme elevations, hyperuricemia, congestive heart failure, edema, myocarditis, QT prolongation, vision problems, anemia, and neutropenia.

MANAGEMENT: Patients should avoid consumption of grapefruit, grapefruit juice, and Seville oranges during treatment with entrectinib.

ADJUST DOSING INTERVAL: Consumption of food can decrease the rate and extent of gastrointestinal absorption of sirolimus. Also, the consumption of grapefruit juice may result in increased sirolimus trough concentrations.

MANAGEMENT: Experts recommend that this drug be taken either at least one hour prior to eating or consistently with or without food to avoid variations in sirolimus blood levels. The manufacturer recommends against using grapefruit juice for dilution of sirolimus doses. Patients should be monitored for clinical and laboratory evidence of altered immunosuppressant effects.