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.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.