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Amiodarone is the most important class III antiarrhythmic drug.

Amiodarone prolongs the refractory period of the cardiac conducting system.

Proarrhythmic activity and negative inotropicity are not marked.

Click here for example ECG of amiodarone related changes and further information

Amiodarone is the most effective antiarrhythmic in atrial fibrillation, but owing to its toxicity profile it is reserved as a last resort option in patients who have not responded to or not tolerated other antiarrhythmic drugs or catheter ablation (1)

  • risk of cardiac, pulmonary, thyroid, liver, and ocular toxicities, among other toxicities, is time and dose dependent
  • amiodarone should be avoided in younger patients
  • when necessary, it is prescribed at the lowest necessary dose, for the shortest time possible, and under close monitoring

Amiodarone Monitoring (1)

  • any opportunity should be taken for clinical screening for symptoms or signs of hepatic, thyroid, pulmonary, skin, and eye toxicities
  • guidance on laboratory monitoring varies across practices, but hepatic and thyroid function should be assessed six months after drug initiation and every
    six to 12 months thereafter
  • pulmonary function should be assessed annually
  • patients should be referred for eye examination annually
  • should also undergo electrocardiography at least annually to assess for sinoatrial or conduction system dysfunction related to amiodarone
    • note that amiodarone also prolongs the QTc interval in most patients, but unlike other QT interval prolonging drugs, this effect is very rarely torsadogenic


  • Ponamgi SP et al. Screening and management of atrial fibrillation in primary care. BMJ 2021;372:mn379

Last edited 04/2021 and last reviewed 05/2021