What is the typical dose of amiodarone (antiarrhythmic medication) for treating arrhythmias?

Amiodarone Dosing for Arrhythmias

The typical dosing regimen for amiodarone consists of a loading dose of 600-800 mg per day for atrial fibrillation or 800-1600 mg per day for ventricular arrhythmias until a total of 10g has been given, followed by a maintenance dose of 200-400 mg daily. 1

Dosing by Arrhythmia Type

Atrial Fibrillation

• Loading phase: 600-800 mg daily in divided doses until a total of 10g has been given 1
• Maintenance phase: 200-400 mg daily 1

Ventricular Arrhythmias

• Loading phase: 800-1600 mg daily in divided doses until a total of 10g has been given 1
• Alternative loading: 600 mg twice daily for 7 days (total 8.4g) 1
• Maintenance phase: 200-400 mg daily 1

Conversion from IV to Oral Therapy

When transitioning from intravenous to oral amiodarone, adjust the oral loading dose based on the 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

1

Important Clinical Considerations

Dose Adjustments

• Lower maintenance doses (100-400 mg daily) are generally effective for most arrhythmias while minimizing toxicity 1, 2
• Consider patient-specific factors such as age, renal function, and hepatic function when determining dose 1
• Dose reduction is often necessary due to side effects - in one study, the mean dose was reduced from 572 mg/day at 45 days to 372 mg/day at 6 months due to side effects 3

Monitoring Requirements

• ECG monitoring every 3-6 months for QT interval prolongation 1
• Thyroid function tests every 6 months 1
• Liver function tests every 6 months 1
• Pulmonary function tests if respiratory symptoms develop 1
• Ophthalmologic examination annually if therapy continues beyond 1 year 1

Drug Interactions

• Requires dose adjustments of concomitant medications due to CYP450 enzyme inhibition 1
• Key interactions:
  • Warfarin: reduced clearance, monitor INR closely 1
  • Digoxin: levels may double 1
  • Statins: limit simvastatin to 20 mg daily 1

Common Side Effects and Toxicity

• Side effects are dose-dependent and extremely common (93% of patients in one study) 3
• Maintain potassium and magnesium levels >4.0 mEq/L before and during therapy 1
• Major side effects include:
  • Gastrointestinal (especially constipation) 3
  • Corneal microdeposits (nearly universal) 3
  • Neurologic (tremor, ataxia) 3
  • Pulmonary toxicity (requires immediate attention) 3
  • Thyroid dysfunction 3
  • Cutaneous abnormalities 3

Clinical Pearls

• Amiodarone has an extremely long half-life (15-100 days), resulting in:
  • Delayed onset of full therapeutic effect (90-150 days) 2
  • Persistent antiarrhythmic effects for up to 150 days after discontinuation 2
  • Need for tapering rather than abrupt discontinuation 1
• Consider discontinuation after 6-12 months of arrhythmia-free period or if significant toxicity develops 1