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.
Amiodarone is an antiarrhythmic medication used to treat and prevent a number of types of cardiac dysrhythmias. This includes ventricular tachycardia (VT), ventricular fibrillation (VF), and wide complex tachycardia, as well as atrial fibrillation and paroxysmal supraventricular tachycardia. Evidence in cardiac arrest, however, is poor. It can be given by mouth, intravenously, or intraosseously. When used by mouth, it can take a few weeks for effects to begin.Common side effects include feeling tired, tremor, nausea, and constipation. As amiodarone can have serious side effects, it is mainly recommended only for significant ventricular arrhythmias. Serious side effects include lung toxicity such as interstitial pneumonitis, liver problems, heart arrhythmias, vision problems, thyroid problems, and death. If taken during pregnancy or breastfeeding it can cause problems in the fetus. It is a class III antiarrhythmic medication. It works partly by increasing the time before a heart cell can contract again.Amiodarone was first made in 1961 and came into medical use in 1962 for chest pain believed to be related to the heart. It was pulled from the market in 1967 due to side effects. In 1974 it was found to be useful for arrhythmias and reintroduced. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. In 2019, it was the 183rd most commonly prescribed medication in the United States, with more than 3 million prescriptions. Medical uses
Amiodarone has been used both in the treatment of acute life-threatening arrhythmias as well as the long term suppression of arrhythmias.