Drug Interactions between cabozantinib and sirolimus

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.

ADJUST DOSING INTERVAL: Food may alter the oral bioavailability of cabozantinib. When healthy subjects were given a single 140 mg oral dose with a high-fat meal, cabozantinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 41% and 57%, respectively, relative to administration under fasting conditions. In clinical studies, patients were administered cabozantinib without food.

GENERALLY AVOID: Coadministration with grapefruit juice is likely to increase the plasma concentrations of cabozantinib, 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: Cabozantinib should be administered at least one hour before or two hours after a meal. The consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit extract should be avoided.