Recommended Oral Loading Dose of Amiodarone
The recommended oral loading dose of amiodarone is 400-600 mg daily in divided doses for 2-4 weeks (loading phase), followed by a maintenance dose of 100-200 mg daily. 1
Detailed Loading Regimens
Standard Loading Protocol
- Initial loading phase: 400-600 mg daily in divided doses for 2-4 weeks
- Total loading amount: Approximately 10 g total
- Maintenance phase: 100-200 mg daily
Alternative Higher-Dose Loading Protocol
For more urgent situations requiring faster therapeutic effect:
- Week 1: 800 mg daily in divided doses
- Week 2: 600 mg daily in divided doses
- Weeks 3-6: 400 mg daily in divided doses
- Maintenance: 200 mg daily 1, 2
Clinical Considerations
Patient Monitoring
- ECG monitoring is essential during the loading phase
- Watch for QT prolongation, bradycardia, and heart block
- Monitor for hypotension, especially in patients with compromised cardiac function
Dose Adjustments
- Dose reduction may be necessary based on:
- Patient tolerance
- Development of side effects
- Renal or hepatic dysfunction
- Concomitant medications
Efficacy Timeline
- Therapeutic effects may take days to weeks when given orally
- Full antiarrhythmic effect may not be achieved until adequate tissue loading occurs
- Amiodarone has an extremely long half-life (14-58 days), contributing to delayed onset of full effect 3
Important Precautions
Contraindications
- Severe sinus node dysfunction
- AV block (in absence of pacemaker)
- Cardiogenic shock
- Severe bradycardia
Drug Interactions
- Warfarin: Reduce warfarin dose by 50% 1
- Digoxin: Reduce digoxin dose by 30-50% 1
- Other QT-prolonging medications: Use with extreme caution
Monitoring Requirements
- Baseline and periodic:
- Thyroid function tests
- Liver function tests
- Pulmonary function tests
- Ophthalmologic examination
- ECG
Common Side Effects
- Gastrointestinal: Constipation, nausea
- Neurological: Tremor, ataxia
- Cardiovascular: Bradycardia, QT prolongation
- Pulmonary: Interstitial pneumonitis (rare during loading phase)
- Dermatological: Photosensitivity
- Ophthalmologic: Corneal microdeposits
Clinical Efficacy
Amiodarone is highly effective for various arrhythmias, with studies showing:
- Maintenance of sinus rhythm in 65-69% of patients at 16 months compared to 37-39% with other antiarrhythmics 2
- Effective control of refractory ventricular arrhythmias in approximately 75% of patients when dose is properly adjusted 4
While high-dose loading regimens (>1,800 mg/day) have been studied 5, 6, the standard loading dose of 400-600 mg daily provides the best balance between efficacy and safety for most patients.