A substance used to treat an abnormal heart rhythm. Commonly prescribed include: amiodarone (Cordarone, Pacerone) bepridil hydrochloride (Vascor), disopyramide (Norpace), dofetilide (Tikosyn), dronedarone (Multaq), flecainide (Tambocor), ibutilide (Corvert), lidocaine (Xylocaine), procainamide (Procan, Procanbid), propafenone (Rythmol), propranolol (Inderal), quinidine (many trade names), sotalol (Betapace) and tocainide (Tonocarid)