What is the management of digoxin toxicity?

Management of Digoxin Toxicity

For patients with digoxin toxicity, administration of digoxin-specific antibody fragments (digoxin-Fab) is the recommended treatment for severe toxicity, especially with serum digoxin concentrations exceeding 4 ng/mL and serious arrhythmias such as ventricular tachycardia. 1

Diagnosis and Assessment

• Typical manifestations of digoxin toxicity include:

  • Cardiac arrhythmias: Enhanced atrial, junctional, or ventricular automaticity, often with atrioventricular block 1
  • Ventricular tachycardia (particularly fascicular or bidirectional) 1
  • Neurological symptoms: Visual disturbances (yellow-green halos), confusion, disorientation 2
  • Gastrointestinal symptoms: Nausea, vomiting, anorexia 3

• Risk factors for toxicity:

  • Renal dysfunction
  • Hypokalemia and hypomagnesemia (can cause toxicity even at therapeutic levels) 2
  • Hypothyroidism
  • Drug interactions (verapamil, clarithromycin, amiodarone) 2

Management Algorithm

Mild Toxicity

1. Discontinue digoxin immediately 4
2. Monitor cardiac rhythm continuously
3. Correct electrolyte abnormalities:
   • Maintain potassium between 4.0-5.5 mmol/L 4
   • Replete magnesium to normal values (≥2.0 mmol/L) 1

Moderate to Severe Toxicity

1. Administer digoxin-specific Fab antibody fragments (digoxin-Fab) for:

   • Serum digoxin concentrations >4 ng/mL with serious arrhythmias 1
   • Life-threatening ventricular arrhythmias 4
   • Progressive bradyarrhythmias or heart block 4
   • Massive overdose (>10 mg in adults, >4 mg in children) 4

2. For symptomatic bradyarrhythmias or heart block:

   • Consider temporary cardiac pacing 4
   • Atropine may be used temporarily 4

3. For ventricular arrhythmias:

   • Correct electrolyte disorders (especially hypokalemia and hypomagnesemia) 4
   • Administer digoxin-Fab for life-threatening arrhythmias 4

Gastrointestinal Decontamination (for acute ingestion)

• If presenting within 2 hours of ingestion:
  • Administer activated charcoal to prevent absorption 4
  • Consider gastric lavage if recent ingestion (within 30 minutes) 4
• Do not induce emesis in obtunded patients or if presenting >2 hours after ingestion 4

Special Considerations

Dosing of Digoxin-Fab

• Dose is based on amount of digoxin ingested or serum concentration 4
• Lower doses than full neutralizing dose may be sufficient if cardiac arrest is not imminent 1

Monitoring After Treatment

• Continue cardiac monitoring after Fab administration due to risk of rebound toxicity 3
• Digoxin concentration monitoring becomes unreliable after Fab administration 1

Renal Impairment

• Patients with renal failure require special attention as they cannot efficiently clear digoxin 5
• Neither digoxin nor Fab fragments are efficiently removed by hemodialysis 5
• Peritoneal dialysis is not associated with enhanced clearance of digoxin 5

Prevention of Recurrence

• When restarting therapy, consider:
  • Lower doses for patients over 70 years old 2
  • Dose adjustment based on renal function 2
  • Regular monitoring of serum digoxin concentration, electrolytes, and renal function 2
  • Maintaining digoxin levels in the lower therapeutic range (0.5-0.9 ng/mL) 2

Common Pitfalls

• Failing to recognize digoxin toxicity when serum levels are within therapeutic range (can occur with electrolyte abnormalities) 3
• Inducing emesis in patients presenting late or with altered mental status 4
• Administering potassium to patients with bradycardia or heart block due to digoxin toxicity 4
• Inadequate monitoring after Fab administration (risk of rebound toxicity) 3