[Amiodarone: a general antiarrhythmic agent]

Amiodarone, a molecule initially developed as an antianginal agent, is considered to be the most powerful antiarrhythmic drug. It prolongs ventricular repolarisation and the refractory periods of all cardiac fibres uniformly, and, at high doses, blocks the transmembrane sodium influx. Amiodarone exerts a non competitive alpha and beta adrenolytic effect and interferes with the metabolism of the thyroid hormones. Its accumulation is slow and excretion progressive. The main metabolite (desethylamiodarone) also has electrophysiological properties and contributes to the antiarrhythmic effect. The efficacy of amiodarone in cardiac arrhythmias is limited in chronic administration by the possibility of dose-dependent secondary effects.