Drug Interaction Report

GENERALLY AVOID: Coadministration with mobocertinib may decrease the plasma concentrations and therapeutic effects of drugs that are substrates of CYP450 3A4. The interaction may be significant for sensitive CYP450 3A4 substrates or those that demonstrate a narrow therapeutic index. The proposed mechanism is increased clearance due to mobocertinib-mediated induction of CYP450 3A4. Concomitant use of mobocertinib 160 mg once daily with oral or intravenous midazolam (a sensitive CYP450 3A4 substrate) decreased the midazolam systemic exposure (AUC) by 32% and 16%, respectively.

MANAGEMENT: Use of mobocertinib with sensitive CYP450 3A4 substrates or those that demonstrate a narrow therapeutic index (e.g., cisapride, ergot alkaloids, colchicine, fentanyl, macrolide immunosuppressants, midazolam, pimozide, triazolam, vinca alkaloids) should generally be avoided. If coadministration is required, patients should be monitored for diminished therapeutic effects. Clinical and laboratory monitoring should be considered whenever mobocertinib is added to or withdrawn from therapy with these drugs, and the dosage of the sensitive CYP450 3A4 substrate drug adjusted in accordance with the approved product label.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of mobocertinib. The mechanism may involve inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice. Based on drug interaction studies using model-informed approaches, coadministration of mobocertinib with multiple doses of itraconazole or ketoconazole (strong CYP450 3A4 inhibitors) is predicted to increase the steady-state combined molar AUC (systemic exposure) of mobocertinib and its active metabolites by 374% to 419%, while coadministration with multiple doses of a moderate CYP450 3A4 inhibitor is predicted to increase this value by approximately 100% to 200%. 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. Elevated plasma concentrations of mobocertinib may increase the risk for adverse effects such as QT prolongation, heart failure or reduced ejection fraction, cardiomyopathy, heart block, diarrhea, rash, stomatitis, fatigue, and musculoskeletal pain.

MANAGEMENT: Patients should avoid consumption of grapefruit and grapefruit juice during treatment with mobocertinib.

GENERALLY AVOID: Acute ethanol ingestion may potentiate the CNS effects of many benzodiazepines. Tolerance may develop with chronic ethanol use. The mechanism may be decreased clearance of the benzodiazepines because of CYP450 hepatic enzyme inhibition. Also, it has been suggested that the cognitive deficits induced by benzodiazepines may be increased in patients who chronically consume large amounts of alcohol.

MANAGEMENT: Patients should be advised to avoid alcohol during benzodiazepine therapy.