Amiodarone Contraindications
Amiodarone is absolutely contraindicated in patients with known hypersensitivity to any components including iodine, cardiogenic shock, marked sinus bradycardia, and second- or third-degree AV block without a functioning pacemaker. 1
Absolute Contraindications
- Hypersensitivity to amiodarone components, including iodine 1
- Cardiogenic shock 1
- Severe sinus node dysfunction 2
- Second- or third-degree AV block without a functioning pacemaker 2, 1
- Heart transplant patients 2
Cardiovascular Contraindications and Precautions
- Prolonged QT interval (relative contraindication) 2
- Concomitant use with other QT-prolonging medications without expert consultation 2
- Bradycardia (heart rate less than 60 bpm) 3
- Hypotension (systolic blood pressure less than 100 mmHg) 3
- Moderate or severe left ventricular failure 3
Pulmonary Contraindications and Precautions
Other Significant Contraindications and Precautions
- Severe hepatic dysfunction 2
- Thyroid disorders (requires careful monitoring) 2
- Severe peripheral vascular disease 3
- Insulin-dependent diabetes 3
Drug Interactions Requiring Special Attention
- Warfarin: Requires 50% dose reduction when starting amiodarone due to significant increase in INR 2
- Digoxin: Requires 50% dose reduction when starting amiodarone 2
- Statins: Increased risk of myopathy/rhabdomyolysis 2
- Procainamide and other QT-prolonging medications 2
Monitoring Requirements
Baseline assessment before starting amiodarone should include 3, 2:
- Complete history and physical examination
- Chest radiograph
- Thyroid studies and liver transaminase levels
- Pulmonary function tests
- Ophthalmologic examination (if preexisting visual impairment)
Regular monitoring during treatment should include 3, 2:
- Thyroid studies and liver transaminase levels every six months
- Chest radiograph if pulmonary toxicity is suspected
- Heart rate surveillance, especially during the first week of treatment
Important Clinical Considerations
- Intravenous amiodarone can cause heart block or bradycardia in 4.9% of patients and hypotension in 16% of patients 3
- Discontinue amiodarone if liver enzyme levels are three times higher than normal, unless the patient is at high risk for recurrence of life-threatening arrhythmia 3
- Pulmonary toxicity is the most serious potential adverse effect, presenting as subacute cough and progressive dyspnea 3
- Photosensitivity is common; patients should use sunblock and cover exposed skin when outdoors 3
Common Pitfalls and Caveats
- Amiodarone has an extremely long half-life (14-58 days), meaning adverse effects may persist long after discontinuation 4
- Despite QT interval prolongation in almost all patients, torsades de pointes is rare 3
- Amiodarone has numerous drug interactions due to its effects on hepatic metabolism, requiring careful medication reconciliation 5
- Neurologic toxicity including ataxia, paresthesias, and tremor can occur and are often dose-related 3