Drug Interaction Report

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of midostaurin and its active metabolites, which are all substrates of the isoenzyme. When a single 50 mg dose of midostaurin was administered to healthy volunteers on day 9 of treatment with the potent CYP450 3A4 inducer rifampin (600 mg daily for 14 days), midostaurin systemic exposure (AUC) decreased by 96% compared to administration with placebo. The AUC of the two active metabolites, CGP62221 and CGP52421, decreased by 92% and 59%, respectively. It is not known to what extent midostaurin may interact with weak and moderate CYP450 3A4 inducers.

MANAGEMENT: The potential for diminished pharmacologic effects of midostaurin should be considered during coadministration with CYP450 3A4 inducers. Alternative treatments may be required if an interaction is suspected.

GENERALLY AVOID: Grapefruit juice may significantly increase the plasma concentrations of midostaurin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. 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. Ketoconazole, a potent CYP450 3A4 inhibitor, has been shown to increase midostaurin systemic exposure (AUC) by greater than 10-fold in healthy volunteers. Increased exposure to midostaurin may increase the risk of adverse effects such as nausea, vomiting, diarrhea, edema, hyperglycemia, hyperuricemia, QT prolongation, neutropenia, lymphopenia, thrombocytopenia, and anemia.

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of midostaurin. Relative to fasting conditions, midostaurin systemic exposure (AUC) increased by approximately 1.2-fold when administered with a standard meal (457 calories; 50 g fat, 21 g proteins, 18 g carbohydrates) and 1.6-fold when administered with a high-fat meal (1007 calories; 66 g fat, 32 g proteins, 64 g carbohydrates), while midostaurin peak plasma concentration (Cmax ) decreased by 20% and 27%, respectively.

MANAGEMENT: The manufacturer recommends taking midostaurin with food. Midostaurin was administered with food in clinical trials. Patients should avoid consumption of grapefruit and grapefruit juice during treatment with midostaurin.

MONITOR: Isolated case reports have suggested that the ingestion of alcohol during griseofulvin therapy may rarely cause disulfiram-like reactions, flushing, tachycardia, or increased effects of alcohol. The mechanism is unknown.

MANAGEMENT: Patients should be advised of the possibility of increased adverse effects or a disulfiram-like reaction.