Drug Interaction Report

MONITOR: Coadministration with inducers of hepatic CYP450 isoenzymes may decrease the plasma concentrations of montelukast, which is metabolized by CYP450 2C8, 2C9, and 3A4 . When a single 10 mg dose of montelukast was administered in combination with phenobarbital, montelukast systemic exposure (AUC) decreased by approximately 40%.

MANAGEMENT: No dosage adjustment for montelukast is recommended when used concomitantly with CYP450 inducers. However, clinical monitoring for potentially reduced therapeutic effects may be appropriate, especially for potent inducers such as carbamazepine, dexamethasone, enzalutamide, phenobarbital, phenytoin, rifamycins, and St. John's wort.

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.