Drug Interaction Report

ADJUST DOSE: Coadministration with moderate inducers of CYP450 2C9 or 3A4 may decrease the plasma concentrations and therapeutic effects of erdafitinib. The mechanism is induction of CYP450 2C9- or 3A4-mediated metabolism of erdafitinib, which has been shown to be metabolized by these isoenzymes.

MANAGEMENT: According to the manufacturer, if a moderate CYP450 2C9 or 3A4 inducer is coadministered at the start of erdafitinib therapy, the recommended dose of erdafitinib should be administered. If a moderate CYP450 2C9 or 3A4 inducer is coadministered after the initial dose increase period, the dose of erdafitinib may be increased up to 9 mg once daily based on serum phosphate levels and tolerability. When a moderate CYP450 2C9 or 3A4 inducer is discontinued, the current dose of erdafitinib may be continued in the absence of erdafitinib toxicity.

ADJUST DOSING INTERVAL: Food may reduce as well as delay the absorption of dabrafenib. In study subjects, administration of dabrafenib with a high-fat meal decreased peak plasma concentration (Cmax) and systemic exposure (AUC) by 51% and 31%, respectively, and delayed median Tmax by approximately 3.6 hours compared to administration in the fasted state.

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

The recommended maximum number of medicines in the 'multikinase inhibitors' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'multikinase inhibitors' category:

• dabrafenib
• erdafitinib

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.