- Clinical science
Amiodarone is a class III agent that blocks voltage-gated potassium channels. It is used in the treatment of acute ventricular tachycardia and persisting (VF) after unsuccessful defibrillation, as well as the long-term treatment of refractory supraventricular arrhythmia (atrial fibrillation). Since amiodarone has a very low negative inotropic effect, it can be used in patients with a reduced ejection fraction (EF). Side effects commonly involve the thyroid, liver, heart, eyes, and central nervous system. Pulmonary side effects, such as lung fibrosis and chronic interstitial pneumonitis, are rare but severe. Because amiodarone is a cytochrome P450 inhibitor, simultaneous administration of other drugs should be considered carefully to minimize the risk of interactions.
- Primary mechanism of action: antiarrhythmic effect via blockage of voltage-gated potassium channels → prolonged repolarization of the cardiac action potential
- Secondary mechanism of action: inhibits β-receptors and sodium and calcium channels → decreases conduction through the AV and sinus node
- Special uses: : only antiarrhythmic agent with (almost) no negative inotropic effect → use in patients with reduced EF
Although amiodarone is an extremely effective antiarrhythmic drug, its side-effect profile limits its use primarily to short-term administration. Amiodarone accumulation in tissues can cause damage to the thyroid, lungs, nerves, skin, eyes, and heart.
|Organ system||Side effects|
"Am-IOD-arone" consists of approx. 37% iodine!
We list the most important adverse effects. The selection is not exhaustive.
- Acute treatment (IV administration)
- Long-term treatment (oral administration)
- Severe sinus node dysfunction with marked sinus bradycardia
- Second- and third-degree heart block (except in patients with a functioning pacemaker)
- Hyperthyroidism and hypothyroidism
- Known allergy to iodine
- Pre-existing lung disease
We list the most important contraindications. The selection is not exhaustive.
- Amiodarone is very lipophilic → accumulation of amiodarone in myocardium and muscles → long duration of action
- Metabolized in the liver; by CYP3A4 with biliary excretion
|Oral treatment||IV bolus|
|Onset of action||2 days to 3 weeks||Within a few hours|
|Time to peak effect||1 week to 5 months||15 minutes|
|Half-life elimination||40–55 days||9–36 days|