Amiodarone, a class III antiarrhythmic agent, is a mild non-competitive alpha and beta adrenergic receptor blocker with mild class I and IV antiarrhythmic properties. The main electrophysiological effect is to prolong the action potential and effective inactivity period of various myocardial tissues, and to facilitate the elimination of fold excitation. It inhibits the inward flow of fast sodium ions in the atria and myocardial conduction fibers and slows down conduction velocity. Decreases sinus node autoregulation. No effect on resting membrane potential and action potential height. Inhibition of antegrade conduction in the atrioventricular bypass is greater than that in the reverse direction. There is prolongation of Q-T interval and T-wave changes in ECG due to excessive prolongation of repolarization. Mild negative inotropic effect by static injection, but usually does not inhibit left ventricular function. Direct dilating effect on coronary arteries and peripheral vessels. May affect the metabolism of thyroxine.