24th April 2024

Amiodarone

Amiodarone is a class III antiarrhythmic drug which is used to treat atrial, nodal, and ventricular tachycardias. It primarily inhibits potassium channels preventing repolarisation, prolonging the action potential and refractory period in cardiac myocytes. Additional actions include inhibition of beta-adrenergic receptors, calcium and sodium channels which contributes to the large side effect profile. 

Side effects include thyroid dysfunction, corneal deposits, pulmonary and hepatotoxicity, peripheral neuropathy, photosensitivity, hypokalaemia, a ‘slate-grey’ appearance, bradycardia, QT interval prolongation and torsades de pointes. Amiodarone can cause thrombophlebitis and should ideally be given via central veins. The half-life is long, over several weeks, and loading doses are often used. It can take up to six weeks to see clinical effects following oral therapy and after discontinuation, effects can persist for 1-3 months. 

Prior to initiation, patients should have thyroid function, liver function, renal function and a chest x-ray. Thereafter, thyroid and liver function should be repeated six monthly. ECG monitoring is required for intravenous infusions.