• Metabolism: Amiodarone is extensively metabolized in the liver via CYP2C8 (under 1% unchanged in urine), and can effect the metabolism of numerous other drugs. 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. Route of Elimination: Amiodarone is eliminated primarily by hepatic metabolism and biliary excretion and there is negligible excretion of amiodarone or DEA in urine. Half Life: 58 days (range 15-142 days)
• Uses/Sources: Intravenously, for initiation of treatment and prophylaxis of frequently recurring ventricular fibrillation and hemodynamically unstable ventricular tachycardia in patients refractory to other therapy. Orally, for the treatment of life-threatening recurrent ventricular arrhythmias such as recurrent ventricular fibrillation and recurrent hemodynamically unstable ventricular tachycardia.
• Health Effects: Some side effects have a significant mortality rate: specifically, hepatitis, exacerbation of asthma and congestive failure, and pneumonitis.
• Route of Exposure: Slow and variable (about 20 to 55% of an oral dose is absorbed).

• Carcinogenicity: No indication of carcinogenicity to humans (not listed by IARC).
• Toxicity: Intravenous, mouse: LD₅₀ = 178 mg/kg.

The antiarrhythmic effect of amiodarone may be due to at least two major actions. It prolongs the myocardial cell-action potential (phase 3) duration and refractory period and acts as a noncompetitive a- and b-adrenergic inhibitor.