Drug Interactions between dalfopristin / quinupristin and Multaq

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of dronedarone, which is primarily metabolized by the isoenzyme. According to the product labeling for dronedarone, administration of repeated doses of the potent inhibitor ketoconazole led to a 9-fold increase in dronedarone peak plasma concentration (Cmax) and a 17-fold increase in systemic exposure (AUC). Because dronedarone is associated with concentration-dependent prolongation of the QT interval, increased levels may potentiate the risk of ventricular arrhythmias such as torsade de pointes and sudden death. Data are not available for dronedarone in combination with other, less potent CYP450 3A4 inhibitors.

MANAGEMENT: Caution is advised if dronedarone is prescribed in combination with CYP450 3A4 inhibitors. Pharmacologic response to dronedarone should be monitored more closely whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy. Patients should be advised to seek medical attention if they experience symptoms that could indicate dronedarone toxicity such as excessive fatigue, fainting, difficulty breathing, chest pain or tightness, bradycardia, or symptoms of torsade de pointes such as dizziness, palpitations, and syncope. Dronedarone should be discontinued if QTc Bazett interval increases to 500 ms or greater.

Switch to consumer interaction data