zafirlukast and Orlaam Interactions

Interactions between zafirlukast and Orlaam (levomethadyl acetate)

levomethadyl acetate and zafirlukast (Major Drug-Drug)

CONTRAINDICATED: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations and duration of action of levomethadyl acetate, which is a substrate of the isoenzyme. High plasma levels of levomethadyl acetate may increase the risk of QT interval prolongation, which is thought to be associated with serious cardiac events such as ventricular arrhythmias (e.g., torsade de pointes, ventricular tachycardia), cardiac arrest, and sudden death. Cases of QT prolongation and torsade de pointes have been reported with levomethadyl acetate alone during postmarketing use.

MANAGEMENT: The concomitant use of levomethadyl acetate with drugs that inhibit CYP450 3A4 is considered contraindicated.