What is the recommended dosing regimen for amiodarone (antiarrhythmic medication)?

Amiodarone Dosing Regimen

For amiodarone therapy, the recommended dosing regimen includes a loading dose of 400-600 mg daily in divided doses for 2-4 weeks, followed by a maintenance dose of 100-200 mg daily to minimize long-term adverse effects. 1

Intravenous Administration for Acute Situations

Life-Threatening Arrhythmias

• Initial dose: 150 mg IV bolus over 10 minutes
  • May be repeated in 10-30 minutes if necessary
• Follow with: 1 mg/minute for 6 hours
• Then: 0.5 mg/minute for 18 hours
• Administration considerations:
  • Use volumetric infusion pump
  • Preferably administer through central venous catheter
  • Use in-line filter
  • Avoid concentrations >3 mg/mL due to phlebitis risk 1, 2

Oral Administration by Indication

Ventricular Arrhythmias

• Loading dose: 800-1,600 mg/day in divided doses until total of 10g is given
• Maintenance dose: 200-400 mg/day 1, 2

Atrial Fibrillation

• Loading dose: 600-800 mg/day in divided doses until total of 10g is given
• Maintenance dose: 200 mg/day 1, 2

Transition from IV to Oral Therapy

When switching from IV to oral administration, dosing depends on duration of IV therapy:

• IV therapy <1 week: 800-1,600 mg oral amiodarone daily
• IV therapy 1-3 weeks: 600-800 mg oral amiodarone daily
• IV therapy >3 weeks: 400 mg oral amiodarone daily 1

Dosing Considerations and Precautions

Dose Adjustments

• Use lowest effective dose (preferably ≤300 mg/day) when possible 2
• Maximum daily dose: Up to 1,200 mg daily may be considered in inpatient monitoring settings (loading dose) 1
• Reduce dose by 30%-50% when administering with digoxin 1
• Reduce warfarin dose by 50% when co-administered with amiodarone 1

Monitoring Requirements

• Baseline and follow-up (every 3-6 months) thyroid function tests (TSH, free T4, T3)
• Baseline pulmonary function tests including DLCO
• Chest imaging (X-ray or high-resolution CT) at baseline and periodically
• Regular clinical assessment for adverse effects 2

Common Adverse Effects to Monitor

• Cardiovascular: Bradycardia, QT prolongation, hypotension, AV block
• Pulmonary: Cough, dyspnea, interstitial infiltrates (serious complication)
• Gastrointestinal: GI upset, constipation
• Neurological: Tremor, ataxia
• Thyroid: Hypo/hyperthyroidism
• Ophthalmologic: Corneal microdeposits, visual disturbances 1, 2

Important Contraindications

• Severe sinus node dysfunction
• AV block greater than first degree (without pacemaker)
• Cardiogenic shock
• Known hypersensitivity to amiodarone or iodine
• Pregnancy and lactation 2

Amiodarone shows considerable interindividual variation in response, requiring close monitoring and dose adjustment. The drug has a very long half-life (approximately 30 days), which explains the prolonged loading phase and persistent effects after discontinuation 3, 4.

While high-dose amiodarone (600-800 mg/day) has been used historically 5, 6, current guidelines favor lower maintenance doses (100-200 mg daily) to minimize long-term adverse effects while maintaining efficacy 1, 2.

The key to successful amiodarone therapy is balancing efficacy with toxicity through appropriate dosing and vigilant monitoring of potential adverse effects.