Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 2C8 may increase the plasma concentrations of tucatinib, which is primarily metabolized by the isoenzyme. When gemfibrozil (600 mg twice daily), a potent CYP450 2C8 inhibitor, was administered with a single tucatinib dose of 300 mg, tucatinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 1.6-fold and 3-fold, respectively.

MANAGEMENT: Increased monitoring is advised if tucatinib is coadministered with CYP450 2C8 inhibitors. Dosage adjustments may be required based on clinical response and tolerance.

ADJUST DOSING INTERVAL: Food may significantly increase the oral bioavailability of some formulations of abiraterone acetate. Compared to administration in the fasted state, abiraterone peak plasma concentration (Cmax) and systemic exposure (AUC) were approximately 7- and 5-fold higher, respectively, when a single dose of abiraterone acetate was administered with a low-fat meal (7% fat; 300 calories) and approximately 17- and 10-fold higher, respectively, when it was administered with a high-fat meal (57% fat; 825 calories). Given the normal variation in the content and composition of meals, taking abiraterone acetate with meals has the potential to result in increased and highly variable exposures. The safety of these increased exposures during multiple dosing has not been assessed. However, the abiraterone acetate 125 mg tablet, commonly marketed as Yonsa, was found to have an approximately 6.5-fold higher Cmax and 4.4-fold higher AUC when a single dose of 500 mg (4 tablets) was administered with a high-fat meal (56% - 60% fat, 900 - 1000 calories) compared to overnight fasting in healthy volunteers. These differences were not considered clinically significant for this formulation.

MANAGEMENT: Some formulations of abiraterone acetate must be taken on an empty stomach. No food should be consumed for at least two hours before and one hour after the abiraterone acetate dose. However, the abiraterone acetate 125 mg tablet, commonly marketed as Yonsa, can be taken with or without food. The manufacturer's product labeling should be consulted for specific guidance.