Recommended Dosing of Oral Amiodarone for Atrial Fibrillation
For patients with atrial fibrillation, the recommended oral amiodarone dosing regimen is 600-800 mg daily in divided doses until a total loading dose of 10 g has been given, followed by a maintenance dose of 200 mg daily. 1
Initial Loading Phase
The loading phase is critical to achieve therapeutic levels in a reasonable timeframe:
- Inpatient setting: 600-800 mg daily in divided doses until a total of 10 g has been administered 1
- Outpatient setting: Same dosing of 600-800 mg daily in divided doses until reaching the 10 g total loading dose 1
Maintenance Phase
After completing the loading phase:
- Standard maintenance dose: 200 mg once daily 1
- For patients with more refractory ventricular arrhythmias, maintenance doses of 200-400 mg daily may be used, but this higher dose is generally not needed for atrial fibrillation 1
Special Dosing Scenarios
When transitioning from IV to oral amiodarone, the oral dosing depends on the duration of previous IV therapy:
- IV therapy <1 week: 800-1,600 mg oral amiodarone daily
- IV therapy 1-3 weeks: 600-800 mg oral amiodarone daily
- IV therapy >3 weeks: 400 mg oral amiodarone daily 1
Efficacy Considerations
- Amiodarone is reasonable for pharmacological cardioversion of AF (Class IIa recommendation, Level of Evidence A) 1
- Conversion rates with oral amiodarone range from 55-95% when proper loading doses are used 2
- For maintenance of sinus rhythm, amiodarone has been shown to be more effective than other antiarrhythmic drugs like sotalol 3
Safety Considerations and Monitoring
Potential adverse effects include:
- Bradycardia
- QT prolongation
- Gastrointestinal upset and constipation
- Rarely, torsades de pointes 1
More serious long-term toxicities include:
- Pulmonary toxicity: Most serious potential adverse effect, presenting as subacute cough and progressive dyspnea 1
- Thyroid dysfunction
- Liver abnormalities
- Ocular changes
- Skin discoloration
The frequency of most adverse effects is related to total amiodarone exposure (dosage and duration). Therefore, use the lowest possible effective dose and consider discontinuation if adverse effects occur 1.
Important Caveats
- Amiodarone should be used particularly in patients with structural heart disease and left ventricular dysfunction, as class IC drugs (propafenone, flecainide) are contraindicated in these patients 2
- Recent studies have shown that aggressive attempts to maintain sinus rhythm using amiodarone or other drugs do not improve outcomes in relatively asymptomatic patients 1
- Long-term amiodarone therapy with its potential toxicity may not be justified in patients taking anticoagulants if rate-control strategies provide satisfactory symptomatic improvement 1
Monitoring Recommendations
- ECG monitoring for conduction disturbances as therapy is initiated
- Specifically monitor PR interval, QRS duration, and QT interval
- Start at relatively low doses with upward titration as needed
- Reassess ECG with each dose change 1