Practical aspects of the use of amiodarone.

Amiodarone is a class III antiarrhythmic drug with sympatholytic properties, which prolongs the refractory period of all cardiac tissues, depresses sinus node automaticity and atrioventricular nodal conduction. It is active on all cardiac arrhythmias, its use being limited by the risk of side effects, mainly extracardiac, which are dependent upon dosage and duration of treatment. The use of an oral loading dose of intravenous infusion to rapidly obtain an efficacious blood concentration may minimise the delay in onset of drug action. Amiodarone progressively accumulates in cardiac muscle and is eliminated slowly, allowing drug free periods (2 days a week) on long term therapy. Pharmacokinetic interaction with digoxin, class I antiarrhythmic drugs and warfarin must be considered during combination therapy, as well as the potentiation of electrophysiological effects when amiodarone is co-administered with combined calcium antagonists and beta-blockers.