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
Advice for healthcare professionals (2):
- amiodarone can cause serious adverse reactions affecting the eyes, heart, lung, liver, thyroid gland, skin, and peripheral nervous system
- review regularly patients on long-term amiodarone treatment – some of these reactions may be life-threatening but onset can be delayed
- check liver and thyroid function before treatment, and at 6-monthly intervals; thyroid function should also be monitored for several months after discontinuation
- although routine lung imaging is not necessary in patients taking amiodarone long-term, make patients aware of the need to seek advice if they have new or worsening respiratory symptoms and consider using computerised tomography (CT) scans if pulmonary toxicity is suspected
- report suspected adverse drug reactions associated with amiodarone on a Yellow Card
Advice for healthcare professionals to give to patients and carers (2):
- amiodarone is used to treat serious heart conditions in which your heart beats unevenly or too fast
- always read the Patient Information Leaflet provided with your medicines and follow the advice on other medicines to avoid and what to do if you have a side effect
- your doctor may perform tests of your blood, lungs, heartbeat, and eyes before and during treatment – it’s important to have these tests because they can identify if there’s a problem
- stop taking amiodarone and see a doctor or go to a hospital straight away if you experience any of the following during treatment or in the period after stopping amiodarone:
- new or worsening shortness of breath or coughing that will not go away
- yellowing of the skin or eyes (jaundice), feeling tired or sick, loss of appetite, stomach pain, or high temperature
- weakness, weight loss or weight gain, heat or cold intolerance, hair thinning, sweating, changes in menstrual periods, swelling of the neck (goitre), nervousness, irritability, restlessness, or decreased concentration
- your heartbeat becomes even more uneven or erratic, or becomes very slow
- any loss of eyesight
Reference:
- Ponamgi SP et al. Screening and management of atrial fibrillation in primary care. BMJ 2021;372:mn379 http://dx.doi.org/10.1136/bmj.mn379
- MRHA (March 2022).Amiodarone (Cordarone X): reminder of risks of treatment and need for patient monitoring and supervision Drug Safety Update volume 15, issue 8: March 2022: 2.