Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase exposure to unconjugated monomethyl auristatin E (MMAE), the anti-mitotic and cytotoxic component of polatuzumab vedotin. MMAE is a substrate for CYP450 3A4. Concomitant use of polatuzumab vedotin with ketoconazole, a potent CYP450 3A4 inhibitor, is predicted to increase unconjugated MMAE exposure (AUC) by 45% according to the product labeling. No data are available for other, less potent CYP450 3A4 inhibitors.

MANAGEMENT: Caution is advised when polatuzumab vedotin is used concomitantly with CYP450 3A4 inhibitors. Patients should be monitored for development or exacerbation of toxicities such as peripheral neuropathy, myelosuppression, opportunistic infections, tumor lysis syndrome and hepatotoxicity, and the dosing of polatuzumab vedotin adjusted or withheld as necessary in accordance with the product labeling.

GENERALLY AVOID: Grapefruit and grapefruit juice may significantly increase the plasma concentrations of orally administered ranolazine. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Because ranolazine prolongs QT interval in a dose-dependent manner, high plasma levels of ranolazine may increase the risk of ventricular arrhythmias such as ventricular tachycardia, ventricular fibrillation, and torsade de pointes.

MANAGEMENT: Patients treated with ranolazine should avoid consumption of grapefruit juice and other grapefruit products if possible. Otherwise, the dosage of ranolazine should be limited to 500 mg twice a day.