How to restart an amiodarone (antiarrhythmic medication) drip after a 24-hour pause?

Restarting Amiodarone Drip After a 24-Hour Pause

When restarting an amiodarone drip after a 24-hour pause, you should administer a new loading dose of 150 mg over 10 minutes, followed by a maintenance infusion of 1 mg/min for 6 hours, then 0.5 mg/min thereafter. 1

Rationale for Restarting with Loading Dose

Amiodarone has complex pharmacokinetics with considerable interindividual variation in response. After a 24-hour pause, plasma levels will have declined significantly due to redistribution, even though the drug has a long terminal half-life. The initial distribution half-life (t1/2 alpha) may be as short as 4 hours 2, which means that after 24 hours, the central compartment concentration would be substantially reduced.

Recommended Restart Protocol

1. Initial Loading Dose: 150 mg in 100 mL D5W infused over 10 minutes 1
2. Follow with: 1 mg/min for 6 hours (360 mg)
3. Maintenance: 0.5 mg/min thereafter (720 mg per 24 hours)

Administration Considerations

• Use a volumetric infusion pump for accurate delivery 1
• Administer through a central venous catheter when possible, especially for concentrations >2 mg/mL 1
• Use an in-line filter during administration 1
• For infusions longer than 1 hour, do not exceed concentrations of 2 mg/mL unless using a central line, as higher concentrations increase risk of phlebitis 1
• Amiodarone infusions exceeding 2 hours must be administered in glass or polyolefin bottles containing D5W 1

Monitoring During Restart

1. Continuous cardiac monitoring for:

   • Bradycardia
   • QT prolongation
   • Heart blocks
   • Hypotension

2. Blood pressure monitoring every 5-15 minutes during loading dose, then hourly during maintenance

3. ECG monitoring for QT interval changes

Potential Complications to Watch For

• Hypotension: Common during rapid infusion; if occurs, slow the infusion rate and consider vasopressors 3, 4
• Bradycardia and AV block: May require reduction in infusion rate or discontinuation 1
• Phlebitis: More common with peripheral administration and concentrations >2 mg/mL 1
• QT prolongation: Monitor for torsades de pointes, especially in patients on other QT-prolonging medications 3
• Anaphylactic reactions: Rare but potentially life-threatening 5

Special Considerations

• Heart failure: Use with caution in patients with heart failure; amiodarone may be the only option despite risks in severe cases 6
• Pre-existing conduction disorders: Patients with first-degree AV block, bundle branch block, or sinus node dysfunction have higher incidence of bradycardia (24%) 6
• Contraindications: Do not restart in patients with:
  • Cardiogenic shock
  • Marked sinus bradycardia
  • Second- or third-degree AV block without a functioning pacemaker 1
  • Known hypersensitivity to amiodarone components 1

Breakthrough Arrhythmias

If breakthrough episodes of ventricular fibrillation or hemodynamically unstable ventricular tachycardia occur during the restart, administer a supplemental 150 mg infusion of amiodarone mixed in 100 mL of D5W over 10 minutes 1.

Remember that the maximum recommended daily dose is 2100 mg, as higher doses are associated with increased risk of hypotension 1.