It is used both in supraventricular arrhythmias and ventricular arrhythmias. Cardiac arrest
Defibrillation is the treatment of choice for ventricular fibrillation and pulseless ventricular tachycardia resulting in cardiac arrest. While amiodarone has been used in shock-refractory cases, evidence of benefit is poor. Amiodarone does not appear to improve survival or positive outcomes in those who had a cardiac arrest. Ventricular tachycardia
Amiodarone may be used in the treatment of ventricular tachycardia in certain instances. Individuals with hemodynamically unstable ventricular tachycardia should not initially receive amiodarone. These individuals should be cardioverted. Amiodarone can be used in individuals with hemodynamically stable ventricular tachycardia. In these cases, amiodarone can be used regardless of the individuals underlying heart function and the type of ventricular tachycardia; it can be used in individuals with monomorphic ventricular tachycardia, but is contraindicated in individuals with polymorphic ventricular tachycardia as it is associated with a prolonged QT interval which will be made worse with anti-arrhythmic drugs. Atrial fibrillation
Individuals who have undergone open heart surgery are at an increased risk of developing atrial fibrillation (or AF) in the first few days post-procedure. In the ARCH trial, intravenous amiodarone (2 g administered over 2 d) has been shown to reduce the incidence of atrial fibrillation after open heart surgery when compared to placebo. However, clinical studies have failed to demonstrate long-term efficacy and have shown potentially fatal side effects such as pulmonary toxicities.
Dose reduction of warfarin is as follows: 40% reduction if amiodarone dose is 400 mg daily, 35% reduction if amiodarone dose is 300 mg daily, 30% reduction if amiodarone dose is 200 mg daily, and 25% reduction if amiodarone dose is 100 mg daily. The effect of amiodarone on the warfarin concentrations can be as early as a few days after initiation of treatment; however, the interaction may not peak for up to seven weeks. Amiodarone inhibits the action of the cytochrome P450 isozyme family. This reduces the clearance of many drugs, including the following:

Ciclosporin
Digoxin
Flecainide
Procainamide
Quinidine
Sildenafil
Simvastatin
Theophylline
WarfarinIn 2015, Gilead Sciences warned health care providers about people that began taking the hepatitis C drugs ledipasvir/sofosbuvir or sofosbuvir along with amiodarone, who developed abnormally slow heartbeats or died of cardiac arrest. Metabolism
Amiodarone is extensively metabolized in the liver by cytochrome P450 3A4 and can affect the metabolism of numerous other drugs. It interacts with digoxin, warfarin, phenytoin, and others. The major metabolite of amiodarone is desethylamiodarone (DEA), which also has antiarrhythmic properties. The metabolism of amiodarone is inhibited by grapefruit juice, leading to elevated serum levels of amiodarone. On 8 August 2008, the FDA issued a warning of the risk of rhabdomyolysis, which can lead to kidney failure or death, when simvastatin is used with amiodarone. This interaction is dose-dependent with simvastatin doses exceeding 20 mg. This drug combination especially with higher doses of simvastatin should be avoided. Excretion
Excretion is primarily via the liver and the bile duct with almost no elimination via the kidney and it is not dialyzable.