Drug Interaction Report

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 that can also inhibit P-glycoprotein (P-gp) may significantly increase the plasma concentrations of darolutamide, which is a substrate of both the isoenzyme and the efflux transporter. When darolutamide was coadministered with itraconazole, a dual P-gp and potent CYP450 3A4 inhibitor, mean darolutamide peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 40% and 70%, respectively, compared to administration of darolutamide alone.

MANAGEMENT: Caution is advised when darolutamide is used with dual P-gp and potent CYP450 3A4 inhibitors. Patients should be monitored more frequently for adverse effects such as fatigue, hypertension, neutropenia and abnormal liver function tests, and the darolutamide dosage adjusted as necessary in accordance with the product labeling.

ADJUST DOSING INTERVAL: Food enhances the oral absorption of darolutamide. According to the prescribing information, bioavailability of darolutamide increased by 2.0 to 2.5-fold when administered with food. A similar increase in exposure was observed for the active metabolite keto-darolutamide.

MANAGEMENT: Darolutamide should be administered with food.

Food enhances the oral absorption and bioavailability of tenofovir, the active entity of tenofovir disoproxil fumarate. According to the product labeling, administration of the drug following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of tenofovir by approximately 14% and 40%, respectively, compared to administration in the fasting state. However, administration with a light meal did not significantly affect the pharmacokinetics of tenofovir compared to administration in the fasting state. Food delays the time to reach tenofovir Cmax by approximately 1 hour. Tenofovir disoproxil fumarate may be administered without regard to meals.