Amiodarone Dosing for Atrial Fibrillation
For atrial fibrillation, the recommended oral amiodarone dosage is 600-800 mg daily in divided doses until a total of 10 g has been given, followed by a maintenance dose of 200 mg daily. 1
Detailed Dosing Regimen
Oral Administration
- Loading phase: 600-800 mg daily in divided doses until a total of 10 g has been administered 1
- Maintenance phase: 200 mg daily 1
- Higher initial dosages may be used in unstable inpatients 1
- For outpatient treatment, the 600-800 mg daily divided dose regimen is appropriate 1
Intravenous Administration (for unstable patients)
- For patients requiring rapid control, IV administration may be used 1
- Initial 150 mg IV bolus over 10 minutes (may be repeated in 10-30 minutes if necessary) 1
- Followed by 1 mg/minute for 6 hours 1
- Then 0.5 mg/minute for 18 hours 1
- Convert to oral dosing when possible 1
Conversion from IV to Oral Therapy
- IV therapy <1 week: Switch to 800-1600 mg oral amiodarone daily 1
- IV therapy 1-3 weeks: Switch to 600-800 mg oral amiodarone daily 1
- IV therapy >3 weeks: Switch to 400 mg oral amiodarone daily 1
Efficacy and Considerations
- Amiodarone is effective for both conversion to sinus rhythm and maintenance therapy 1
- Conversion rates with IV amiodarone range from 34-69% with bolus-only regimens and 55-95% with bolus-plus-infusion regimens 2
- Most conversions occur after 6-8 hours of therapy initiation 2
- Success predictors include shorter duration of AF, smaller left atrial size, and higher amiodarone dose 2
- Long-term success rates of 53-79% have been reported with maintenance therapy 3, 4
Adverse Effects and Monitoring
- Common adverse effects: Bradycardia, QT prolongation, GI upset, constipation 1
- Serious but rare: Torsades de pointes 1
- Long-term concerns: Pulmonary toxicity (most serious), thyroid dysfunction, liver abnormalities, ocular deposits, skin discoloration, and neuropathy 1
- Adverse effects are dose-related; use the lowest effective dose 1
- Approximately 35-51% of patients experience adverse effects, necessitating dose reduction in many cases 3, 5
Special Considerations
- Amiodarone is particularly useful in patients with structural heart disease or left ventricular dysfunction, where class IC drugs are contraindicated 2
- For patients with chronic AF lasting >1 year, success rates are lower (57%) but still relatively high 3
- Aggressive attempts to maintain sinus rhythm with amiodarone do not improve outcomes in relatively asymptomatic patients 1
- Amiodarone should be reserved for highly symptomatic patients when rate-control strategies with anticoagulation are inadequate 1