Basics

Amiodarone is a class III antiarrhythmic drug used to treat some cardiac arrhythmias. Chemically, it is assigned to the group of benzofurans. Its main field of application is the treatment of ventricular tachycardia. In this field, it is one of the most widely used drugs. Like almost all antiarrhythmic drugs (exception: class II), amiodarone is associated with many side effects. Therefore, it should only be used to treat life-threatening arrhythmias, such as ventricular fibrillation.

Amiodarone is mainly administered intravenously.

Pharmacology

Pharmacodynamics

The mechanism of action of amiodarone is based on blockade of voltage-gated potassium channels in the cells of the heart muscles. As a result, amiodarone has the ability to prolong the action potential of the heart and thus break certain arrhythmias. In addition to its effect on potassium channels, amiodarone also has properties of a sodium and calcium channel blocker, as well as an alpha and beta blocker, and an inhibitory effect on muscarinic receptors. Thus, amiodarone can theoretically be assigned to all four classes of antiarrhythmic agents.

Pharmacokinetics

Amiodarone is 96% bound to plasma proteins. Degradation occurs via the liver and is catalyzed by the CYP3A4 and CYP2C8 enzymes. The plasma half-life for amiodarone is extremely long, averaging 9-100 days. In some cases, times of 200 days have been measured. Excretion is mainly via feces and to a small extent via urine.

Drug Interactions

Drugs that interact with (inhibit or induce) the enzyme CYP3A4 may interact, sometimes dangerously. Especially with CYP3A4 inhibiting agents, increased and sometimes toxic plasma levels of amiodarone may occur. Life-threatening effects may be the consequence.

Toxicity

Side effects

Amiodarone, in addition to possibly causing arrhythmias, can lead to sometimes serious side effects away from the heart.

These include:

Pulmonary fibrosis
Hyper- or hypothyroidism
Deposits in the cornea
Photosensitivity of the skin
Neuropathies
Gastrointestinal disorders

Toxicological Data

LD50 (oral, rat): >3000 mg-kg-1

Author

Markus Falkenstätter, BSc

Pharmacy student

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Reviewer

Mag. pharm. Stefanie Brandauer

Pharmacist

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

Editorial principles

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