Amiodarone is a drug used to slow the heart rate and help keep it in a regular rhythm. It is used to treat fast or other irregular heartbeats, called arrhythmias, including atrial fibrillation, ventricular tachycardia and ventricular fibrillation. Amiodarone belongs to a class of drugs called antiarrhythmics. Side effects are usually dose-related and regular follow-up is necessary to evaluate kidney, liver and lung function.