What is the dosing regimen for Amiodarone (antiarrhythmic medication) in treating non-sustained ventricular tachycardia (VTach)?

Amiodarone Dosing for Non-Sustained Ventricular Tachycardia

For non-sustained ventricular tachycardia, the recommended oral amiodarone dosing is 800-1,600 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

Oral Amiodarone Regimen

• Initial loading dose: 800-1,600 mg daily in divided doses until a total cumulative dose of 10 g has been administered 2, 1
• Maintenance dose: 200-400 mg daily after the loading period is complete 1
• The loading period typically lasts 1-2 weeks depending on the daily dose used 1, 3
• Higher initial loading doses (up to 1,600 mg daily) may be considered in an inpatient monitoring setting, though this increases the risk of adverse effects 3

Intravenous Amiodarone (If Required)

For patients requiring IV therapy for hemodynamically stable ventricular tachycardia:

• Initial bolus: 150 mg IV over 10 minutes (may be repeated in 10-30 minutes if necessary) 1, 4
• Followed by: 1 mg/min infusion for 6 hours (360 mg) 1, 4
• Then: 0.5 mg/min infusion for 18 hours (540 mg) 1, 4
• Total 24-hour dose should not exceed 2,200 mg 4

Transitioning from IV to Oral Therapy

When transitioning from IV to oral therapy, the oral dosing should be based on the duration of IV therapy:

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

Monitoring Requirements

• Continuous ECG monitoring during IV administration 5
• Regular monitoring for:
  • Bradycardia and QT prolongation 2, 1
  • Hypotension, especially with rapid IV administration 5, 4
  • Atrioventricular block 2, 5
  • Pulmonary toxicity (subacute cough, progressive dyspnea) 1
  • Thyroid and liver function abnormalities 3

Important Clinical Considerations

• Amiodarone has a very long half-life (IV: 9-36 days; Oral: 26-107 days), which affects dosing strategies 5
• The antiarrhythmic effect of IV amiodarone begins in less than 30 minutes 2, 1
• The full antiarrhythmic effect of oral amiodarone may take days to weeks to develop 3
• For patients with structural heart disease and life-threatening ventricular arrhythmias, implantable cardioverter-defibrillators (ICDs) should be considered as primary therapy, with amiodarone as an adjunct to reduce frequency of ICD shocks 2, 1
• The frequency of adverse effects correlates with total amiodarone exposure (dosage and duration), so use the lowest effective dose possible 1

Potential Adverse Effects

• Common adverse effects include bradycardia, QT prolongation, gastrointestinal upset, and constipation 2, 1
• Serious adverse effects include pulmonary toxicity, thyroid dysfunction, and hepatic toxicity 1, 3
• IV administration can cause hypotension, especially with rapid administration 5, 4
• Phlebitis can occur with IV concentrations >2 mg/mL 5, 4
• Rarely, torsades de pointes may occur 2, 1