Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 3A4 and/or P-glycoprotein (P-gp) may increase the plasma concentrations of idelalisib, which is a substrate of both the isoenzyme and efflux transporter. In healthy volunteers, administration of a single 400 mg dose of idelalisib with the potent CYP450 3A4 and P-gp inhibitor ketoconazole (400 mg daily for 4 days) resulted in a 1.8-fold increase in mean idelalisib systemic exposure (AUC). No change was observed in mean peak plasma concentration (Cmax).

MANAGEMENT: Caution is advised if idelalisib is prescribed in combination with CYP450 3A4 and/or P-gp inhibitors. Pharmacologic response to idelalisib should be monitored more closely whenever a CYP450 3A4/P-gp inhibitor is added to or withdrawn from therapy, and the idelalisib dosing adjusted or interrupted as necessary in accordance with the product labeling. Patients should be closely monitored for idelalisib toxicity such as hepatotoxicity, diarrhea, colitis, intestinal perforation, pneumonitis, neutropenia, and thrombocytopenia.

ADJUST DOSING INTERVAL: Food significantly enhances the oral bioavailability of boceprevir. When given at 800 mg three times daily with food, boceprevir exposure increased by up to 65% relative to administration in the fasting state. The bioavailability of boceprevir was similar regardless of meal type (e.g., high-fat versus low-fat) or whether taken 5 minutes prior to eating, during a meal, or immediately following completion of the meal. Therefore, boceprevir may be taken without regard to either meal type or timing of the meal.

MANAGEMENT: To ensure maximal oral absorption, boceprevir should be administered with a meal or light snack.