What is the recommended Amiodarone (antiarrhythmic medication) loading dose intravenously (IV) and subsequent maintenance dose?

Amiodarone IV Loading and Maintenance Dosing

For intravenous amiodarone, the recommended loading dose is 150 mg over 10 minutes, followed by 1 mg/min for 6 hours, then 0.5 mg/min for 18 hours, with subsequent maintenance infusion of 0.5 mg/min (720 mg per 24 hours). 1

Initial Loading Dose Protocol

The FDA-approved dosing regimen for IV amiodarone consists of three phases:

1. Rapid Loading Phase:

   • 150 mg over 10 minutes (15 mg/min)
   • May be repeated in 10-30 minutes if necessary for life-threatening arrhythmias 1

2. Early Maintenance Phase:

   • 1 mg/min for 6 hours (360 mg total)

3. Later Maintenance Phase:

   • 0.5 mg/min for 18 hours (540 mg total)
   • This completes approximately 1000 mg over the first 24 hours 1

Continued Maintenance Infusion

After the first 24 hours, continue with:

• Maintenance infusion rate of 0.5 mg/min (720 mg per 24 hours)
• Use concentration of 1-6 mg/mL 1
• For concentrations >2 mg/mL, a central venous catheter is required 1

Administration Considerations

• Delivery method: Must be delivered by volumetric infusion pump 1
• Concentration limits: Do not exceed 2 mg/mL for peripheral administration to avoid phlebitis 1
• Infusion duration: Can be continued for 2-3 weeks regardless of patient's age, renal function, or left ventricular function 1
• Monitoring: Continuous ECG monitoring is essential during administration 2, 3

Breakthrough Arrhythmias

For breakthrough episodes of ventricular fibrillation or hemodynamically unstable ventricular tachycardia:

• Administer 150 mg supplemental infusions
• Mix in 100 mL of D5W
• Infuse over 10 minutes to minimize hypotension risk 1

Important Precautions

• Do not exceed an initial infusion rate of 30 mg/min 1
• Mean daily doses above 2100 mg are associated with increased risk of hypotension 1
• High concentration infusions (>3 mg/mL) have been associated with hepatocellular necrosis and acute renal failure 1
• Amiodarone adsorbs to PVC tubing and can leach plasticizers 1

Transition from IV to Oral Therapy

When transitioning from IV to oral amiodarone, dosing depends on duration of IV therapy:

• IV therapy <1 week: 800-1600 mg oral daily
• IV therapy 1-3 weeks: 600-800 mg oral daily
• IV therapy >3 weeks: 400 mg oral daily 3

Oral Maintenance Dosing

For long-term oral maintenance:

• Typical dose range: 100-400 mg daily 2, 3
• For most supraventricular arrhythmias: 100-200 mg daily is often sufficient 4
• For ventricular arrhythmias: 200-400 mg daily is typically required 3, 4

Contraindications and Monitoring

• Contraindicated in severe sinus node dysfunction, marked bradycardia, and second/third-degree AV block without pacemaker 2
• May cause hypotension, bradycardia, heart block, QT prolongation, and torsades de pointes 2
• Should not be used with other QT-prolonging drugs without expert consultation 2

Remember that amiodarone shows considerable interindividual variation in response, and close monitoring with dose adjustment is essential for safe and effective therapy.