amiodaron

Amiodaron, commonly known as amiodarone, is a class III antiarrhythmic medication used to treat and prevent a range of cardiac rhythms. It prolongs the cardiac action potential and the refractory period by blocking potassium channels, while also exerting effects on sodium and calcium channels and beta-adrenergic receptors. It is highly lipophilic and contains iodine, leading to widespread tissue distribution and a very long elimination half-life.

Indications for amiodaron include treatment of recurrent ventricular tachycardia and ventricular fibrillation, as well as suppression of atrial fibrillation and flutter in selected patients. It is often used when other antiarrhythmics are ineffective or unsuitable, and it may be employed in perioperative or critical care settings for rhythm control. Amiodaron can be given orally or intravenously, with the IV form commonly used for acute management and loading before transitioning to oral therapy.

Pharmacokinetics and pharmacodynamics are notable for extensive tissue uptake and a long half-life, typically weeks to months, due to storage in adipose tissue and other organs. It is metabolized in the liver by cytochrome P450 enzymes to active and inactive metabolites, including N-desethylamiodarone. The long duration of action means effects on arrhythmia control and adverse effects can persist after discontinuation.

Adverse effects are broad and substantial. Pulmonary toxicity, including interstitial pneumonitis and fibrosis, is a leading concern. Other serious issues include hepatotoxicity, thyroid dysfunction (hypo- or hyperthyroidism) due to iodine content, corneal deposits, photosensitivity, skin discoloration, and rare optic neuropathy. Cardiac effects such as bradycardia and hypotension can occur, especially with IV use. Drug interactions are common, notably with warfarin, digoxin, certain antidysrhythmics, and statins. Monitoring typically includes regular liver and thyroid function tests, chest imaging, and close clinical follow-up.