Dronedarone or N-[2-Butyl-3-[4-[3-(dibutylamino)propoxy]benzoyl]-5-benzofuranyl]-methanesulfonamide is a class III antiarrhythmic, chemically related to amiodarone developed by Sanofi-Aventis. It prolongs the duration of action potentials and has antiadrenergic and coronary vasodilatory effects. It is launched in the US as dronedarone hydrochloride under the tradename MULTAQ. This drug is indicated in adult stable patients with history of, or current non-permanent atrial fibrillation (AF) to prevent recurrence of AF or to lower ventricular rate.
Its chemical structure is as follows:

USPTO Backgrounds
USPTO Backgrounds