Amiodarone Dosing Regimen
The recommended amiodarone starting dose is 800-1600 mg daily for the loading phase, followed by a maintenance dose of 200-400 mg daily, with dosing adjusted based on response and side effects. 1
Initial Loading Dose
Oral Loading Dose
- Standard loading regimen: 800-1600 mg daily in divided doses until reaching a total of 10g 1
- Alternative loading approach: 600-800 mg daily for 7 days (total 4.2-5.6g) 1
Intravenous Loading Dose
- Initial 24 hours: 1000 mg administered as:
Maintenance Dose
- Standard maintenance: 200-400 mg daily 1
- Lower doses (200 mg daily) may be effective with fewer side effects 1
- Dose should be adjusted based on clinical response and side effects
Converting from IV to Oral Therapy
When transitioning from IV to oral amiodarone, adjust the oral dose based on duration of previous IV therapy:
| Duration of IV Use | Recommended Oral Amiodarone Dose |
|---|---|
| <1 week | 800-1600 mg daily |
| 1-3 weeks | 600-800 mg daily |
| >3 weeks | 400 mg daily |
Dose Adjustment Considerations
- Dose reduction is commonly needed due to side effects
- In one study, the dose was reduced from 572 ± 283 mg/day at 45 days to 372 ± 174 mg/day at 6 months due to side effects 4
- The European Society of Cardiology suggests using the lowest effective dose to minimize side effects 1
Important Monitoring and Side Effects
- Common side effects: Bradycardia, hypotension, QT prolongation, gastrointestinal upset, photosensitivity, pulmonary toxicity, and thyroid dysfunction 1
- Monitoring recommendations:
- ECG for QT prolongation and bradycardia
- Thyroid and liver function tests every 6 months
- Pulmonary function tests if respiratory symptoms develop
- Ophthalmologic examination if visual symptoms occur 1
Clinical Pearls
- Amiodarone has an extremely long half-life (average 58 days), which explains its prolonged loading phase and persistent effects after discontinuation 1
- Bioavailability is variable (22-95%) and enhanced when taken with food 1
- Significant drug interactions occur with warfarin, digoxin, and statins due to inhibition of multiple CYP450 enzymes 1
- Maintain potassium and magnesium levels >4.0 mEq/L before and during therapy 1
Cautions
- Amiodarone is contraindicated in severe sinus node dysfunction, AV block (without pacemaker), cardiogenic shock, and severe bradycardia 1
- When discontinuing, taper rather than stop abruptly due to long half-life 1
- Pulmonary toxicity is the most serious potential adverse effect, requiring prompt assessment of any new dyspnea or cough 2