How does amiodarone work as an antiarrhythmic drug?

Amiodarone as an anti arrhythmic agent has multiple mechanisms of action. The most important is a class III action, on the potassium channel, prolonging the repolarization phase. But amiodarone has all classes of action. Class I is action on the rapid phase of depolarization. Class II is beta blocker action and class IV calcium channel blockade.

As amiodarone has multiple mechanisms of action, it less likely to cause worsening of arrhythmia, unlike other class I or class III drugs. Other class I and III drugs may produce arrhythmia by prolonging the QT interval in the ECG. The iodine content of amiodarone can rarely cause thyroid dysfunction. In general it is a safe drug, especially if used in lower doses, with proper monitoring for potential adverse effects.