What is the recommended dosing for Amiodarone (antiarrhythmic medication)?

Amiodarone Dosing Recommendations

The recommended dosing for amiodarone includes an oral loading dose of 600-800 mg daily in divided doses until a total of 10g has been given for atrial fibrillation, followed by a maintenance dose of 100-400 mg daily, with dose adjustments based on clinical response and side effects. 1

Oral Dosing Regimens

For Atrial Fibrillation

• Loading phase options:

  • 600-800 mg daily in divided doses until a total of 10g has been given 1
  • Alternative loading: 800 mg daily for 1 week (total 10g) 1
  • A loading dose of 600 mg per day is usually given for one month or 1000 mg per day for 1 week 2

• Maintenance phase:

  • 100-400 mg daily 2, 1
  • Dose should be adjusted based on clinical response and side effects

For Ventricular Arrhythmias

• Loading phase:

  • 800-1,600 mg per day in divided doses until a total of 10g has been given 1

• Maintenance phase:

  • 200-400 mg daily 1

Intravenous Dosing

• Initial loading:

  • 1000 mg over the first 24 hours 3
  • Initial infusion rate should not exceed 30 mg/min 3

• Maintenance infusion:

  • 0.5 mg/min (720 mg/24 hours) 3
  • Use concentration of 1-6 mg/mL (concentrations >2 mg/mL require central venous access) 3

• For breakthrough arrhythmias:

  • 150 mg supplemental infusions mixed in 100 mL D5W administered over 10 minutes 3

Converting from IV to Oral 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

Important Considerations

Dose Adjustments

• Reduce dose if bradycardia occurs while taking 200mg daily 1
• Consider reducing doses of concomitant rate control medications when amiodarone is initiated 1
• Elderly patients may be more susceptible to hypotensive effects 1

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
• Annual ophthalmologic examination if therapy continues beyond 1 year 1

Common Pitfalls and Caveats

1. Drug Interactions:

   • Amiodarone inhibits multiple CYP450 enzymes and P-glycoprotein 1
   • Adjust doses of concomitant medications, especially:
     • Warfarin (reduced clearance, increased INR)
     • Digoxin (levels may double)
     • Statins (limit simvastatin to 20 mg daily) 1

2. Administration Precautions:

   • IV amiodarone must be delivered by volumetric infusion pump 3
   • Use central venous catheter for concentrations >2 mg/mL 3
   • Use in-line filter during administration 3
   • Avoid rapid infusion rates which can cause hepatocellular necrosis and acute renal failure 3

3. Electrolyte Management:

   • Maintain potassium and magnesium levels >4.0 mEq/L before and during therapy 1

4. Discontinuation:

   • Taper rather than stop abruptly due to long half-life 1
   • Effects may persist for up to 150 days after discontinuation 4

Amiodarone has a narrow therapeutic-toxic window, with virtually all patients developing side effects at higher maintenance doses (e.g., 600 mg daily) 5. Lower maintenance doses (100-400 mg daily) are generally effective for most arrhythmias while minimizing toxicity 2, 4.