What is the recommended dosage of amiodarone for a 60 kg patient with atrial fibrillation?

Amiodarone Dosing for Atrial Fibrillation in a 60 kg Patient

For a 60 kg patient with atrial fibrillation, the recommended amiodarone dosage is a loading dose of 600-800 mg per day in divided doses until a total of 10 g has been given, followed by a maintenance dose of 200-400 mg per day. 1

Loading Dose Calculation

For oral administration in atrial fibrillation:

• Initial loading phase options:

  • 600-800 mg per day in divided doses until a total of 10 g has been given 2, 1
  • Alternative: 1000 mg per day for 1 week (7 g total) 2

• For this 60 kg patient:

  • The standard loading dose is weight-independent and should follow the guideline recommendation of 600-800 mg daily in divided doses until reaching a total of 10 g 2, 1
  • This typically means 600-800 mg daily for approximately 12-16 days

Maintenance Dose

After completing the loading phase:

• Maintenance dose: 200-400 mg daily 2, 1
• Lower doses (200 mg daily) may be effective with fewer side effects 2

Administration Route Considerations

Oral Administration

• For outpatient management: 600-800 mg/day in divided doses until 10 g total, then 200-400 mg/day maintenance 2

Intravenous Administration (if needed for urgent control)

• Initial: 5-7 mg/kg over 30-60 minutes (300-420 mg for a 60 kg patient)
• Followed by: 1.2-1.8 g/day continuous IV or divided oral doses until 10 g total 2
• Then transition to oral maintenance dose

Monitoring Requirements

During amiodarone therapy, monitor:

• ECG every 3-6 months (QT interval, heart rate)
• Thyroid function tests every 6 months
• Liver function tests every 6 months
• Pulmonary function if symptoms develop
• Ophthalmologic examination if visual symptoms occur or therapy continues beyond 1 year 1

Important Precautions

• Drug interactions: Amiodarone inhibits multiple CYP450 enzymes and P-glycoprotein, requiring dose adjustments of concomitant medications:

  • Warfarin: Reduce dose by 30-50% and monitor INR closely
  • Digoxin: Reduce dose by approximately 50%
  • Statins: Limit simvastatin to 20 mg daily 1

• Electrolyte management: Maintain potassium and magnesium levels >4.0 mEq/L 1

• Common side effects to monitor:

  • Bradycardia and hypotension (especially with IV administration)
  • QT prolongation
  • Gastrointestinal upset
  • Photosensitivity
  • Pulmonary toxicity (long-term)
  • Thyroid dysfunction 2, 1

Contraindications

Amiodarone is contraindicated in:

• Severe sinus node dysfunction
• AV block without a pacemaker
• Cardiogenic shock
• Severe bradycardia without a pacemaker 1

Following these dosing guidelines will help maximize efficacy while minimizing the risk of adverse effects in this 60 kg patient with atrial fibrillation.