What is the protocol for administering an amiodarone (antiarrhythmic medication) drip for 24 hours?

Amiodarone 24-Hour Infusion Protocol

For a 24-hour amiodarone infusion, administer 150 mg IV over 10 minutes as a loading dose, followed by 1 mg/min for 6 hours (360 mg), then 0.5 mg/min for the remaining 18 hours (540 mg), with a maximum total dose of 2.2 g over 24 hours. 1, 2, 3

Standard Dosing Regimen

The three-phase protocol recommended by the American Heart Association and FDA consists of:

Phase 1: Rapid Loading (First 10 Minutes)

• Initial bolus: 150 mg IV infused over 10 minutes 1, 2, 3
• May repeat this 150 mg bolus if breakthrough ventricular arrhythmias occur during maintenance infusion 3
• Maximum infusion rate: Do not exceed 30 mg/min during any bolus 3

Phase 2: Early Maintenance (Hours 1-6)

• Infusion rate: 1 mg/min for 6 hours 1, 2, 3
• Total delivered: 360 mg over this 6-hour period 2, 4, 3

Phase 3: Late Maintenance (Hours 7-24)

• Infusion rate: 0.5 mg/min for 18 hours 1, 2, 3
• Total delivered: 540 mg over this 18-hour period 2, 4, 3

Total 24-Hour Dose

• Maximum: 2.2 g (2200 mg) total over 24 hours 1, 2, 4, 3
• Initial bolus (150 mg) + early maintenance (360 mg) + late maintenance (540 mg) = 1050 mg baseline regimen 3
• Additional supplemental boluses may be given for breakthrough arrhythmias but must not exceed the 2.2 g total 3

Administration Requirements

Delivery Method

• Must use a volumetric infusion pump (drop counter sets can underdose by up to 30%) 3
• Use a central venous catheter whenever possible, especially for concentrations >2 mg/mL 1, 3
• In-line filter required during administration 3

Concentration Guidelines

• Peripheral vein: Maximum concentration 2 mg/mL (higher concentrations cause phlebitis) 1, 3
• Central line: Can use concentrations up to 6 mg/mL 3
• For infusions >1 hour, do not exceed 2 mg/mL unless using central access 3

Solution Preparation

• Only use D5W (5% dextrose in water) for dilution 3
• Use glass or polyolefin bottles for infusions >2 hours (not evacuated glass containers) 3
• PVC tubing is acceptable (all clinical trials used PVC) but leaches plasticizers 3
• Inspect for particulate matter before administration 3

Critical Monitoring Requirements

Continuous Monitoring During Infusion

• Cardiac monitoring: Continuous ECG throughout infusion 2, 4
• Blood pressure: Frequent monitoring for hypotension 1, 2, 4
• Heart rate: Watch for bradycardia <50 bpm 1, 2, 4
• AV conduction: Monitor for heart block 1, 2, 4

When to Stop or Slow Infusion

• Systolic blood pressure <100 mmHg 1
• Heart rate <50 bpm 1
• Development of significant AV block 1, 2

Common Pitfalls and Precautions

Infusion Rate Errors

• Never exceed 30 mg/min during loading doses—faster rates cause hepatocellular necrosis and acute renal failure leading to death 3
• Concentrations >3 mg/mL in peripheral veins cause severe phlebitis 3

Drug Interactions

• Reduce warfarin dose by 50% when starting amiodarone 4
• Reduce digoxin dose by 30-50% when starting amiodarone 4
• Avoid combining with other QT-prolonging medications 2, 4

Patient-Specific Cautions

• Use with extreme caution in moderate-to-severe left ventricular failure (negative inotropic effects) 1, 2
• Avoid in patients with baseline bradycardia <60 bpm 1
• Particularly valuable in patients with structural heart disease where class IC drugs are contraindicated 2, 5

Continuation Beyond 24 Hours

• Maintenance infusion of 0.5 mg/min can continue for 2-3 weeks if needed 3
• Limited experience exists beyond 3 weeks of continuous IV therapy 3
• Transition to oral amiodarone when clinically appropriate 3

Expected Onset and Efficacy

• Antiarrhythmic effect begins in <30 minutes 4
• Most conversions to sinus rhythm occur after 6-8 hours of therapy 2, 5
• Conversion rates: 34-69% with bolus-only regimens, 55-95% with bolus plus continuous infusion 2, 5