Dronedarone-d 6 (hydrochloride) is the deuterium labeled Dronedarone. Dronedarone hydrochloride, a derivative of Amiodarone , is a class III antiarrhythmic agent for the study of atrial fibrillation (AF) and atrial flutter. Dronedarone hydrochloride is a potent blocker of multiple ion currents, including potassium current, sodium current, and L-type calcium current, and exhibits antiadrenergic effects by noncompetitive binding to β-adrenergic receptors. Dronedarone hydrochloride is a substrate for and a moderate inhibitor of CYP3A4.