Drug Interaction Report

ADJUST DOSE: Coadministration with inducers of P-glycoprotein (P-gp) may decrease the plasma concentrations of afatinib, which is a substrate of the efflux transporter. In study subjects, administration of afatinib in combination with the P-gp inducer rifampin (600 mg once daily for 7 days) resulted in a 34% decrease in afatinib systemic exposure.

MANAGEMENT: For patients who require chronic therapy with a P-gp inducer, it may be necessary to increase the daily dose of afatinib by 10 mg as tolerated. The previous dose may be resumed 2 to 3 days after discontinuation of the P-gp inducer.

ADJUST DOSING INTERVAL: Food may reduce the oral bioavailability of afatinib. According to the product labeling, administration of afatinib with a high-fat meal decreased peak plasma concentration (Cmax) by 50% and systemic exposure (AUC) by 39% compared to administration in the fasted state.

MANAGEMENT: Afatinib should be taken at least 1 hour before or 2 hours after a meal.