Drug Interaction Report

MONITOR: Coadministration with gilteritinib may increase the plasma concentrations and the risk of adverse effects of orally administered drugs that are substrates of the intestinal P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and/or organic cation transporter 1 (OCT1) transporters, such as dabigatran, digoxin, rosuvastatin, methotrexate, and metformin. The proposed mechanism, based on in vitro data, is decreased clearance due to gilteritinib-mediated inhibition of intestinal P-gp, BCRP, and/or OCT1 efflux transport proteins.

MANAGEMENT: Until more information is available, caution is advised if gilteritinib is used concomitantly with drugs that are substrates of the intestinal P-gp, BCRP, and/or OCT1 transport proteins, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring should be considered whenever gilteritinib is added to or withdrawn from therapy with these drugs. Patients should be monitored for the development of adverse effects.

ADJUST DOSING INTERVAL: Food may reduce the oral bioavailability of eltrombopag. In healthy volunteers, a standard high-fat breakfast significantly decreased plasma eltrombopag peak plasma concentration (Cmax) by 65% and systemic exposure (AUC) by 59% and delayed Tmax by one hour. The calcium content of this meal may have also contributed to this decrease in exposure. In another study, adult subjects administered a single 25 mg dose of eltrombopag for oral suspension with a high-calcium, moderate-fat, moderate-calorie meal exhibited a 79% decrease in Cmax and 75% decrease in AUC of eltrombopag. Administration of eltrombopag 2 hours after the high-calcium meal decreased eltrombopag Cmax by 48% and AUC by 47%, while administration 2 hours before the high-calcium meal decreased eltrombopag Cmax by 14% and AUC by 20%.

ADJUST DOSING INTERVAL: Polyvalent cations such as aluminum, calcium, iron, magnesium, and zinc can significantly reduce the gastrointestinal absorption of eltrombopag due to chelation. In one clinical trial, administration of a single 75 mg dose of eltrombopag with an antacid containing 1524 mg aluminum hydroxide and 1425 mg magnesium carbonate resulted in an approximately 70% decrease in eltrombopag Cmax and AUC.

MANAGEMENT: Eltrombopag should be taken on an empty stomach one hour before or two hours after a meal. Additionally, eltrombopag should be taken at least 2 hours before or 4 hours after any products that contain polyvalent cations such as antacids, mineral supplements, dairy products, and fortified juices.