MDCalc

DigiFab® (Digoxin Immune Fab-Ovine) Dosing for Digoxin Poisoning

Doses DigiFab® in patients with confirmed digoxin poisoning or overdose.

This dosing tool is intended to assist with calculation, not to provide comprehensive or definitive drug information. Always double-check dosing of any drug and consult a pharmacist when necessary.

Therapeutic range for serum digoxin level is 0.5–2.0 ng/mL (0.6–2.6 nmol/L). If acute poisoning and serum digoxin confirmed >10 ng/mL (13nmol/L), give empiric dose (10-20 vials for adults and children) or if digoxin dose ingested is >10mg in adults or acute ingestion >4mg in a child, with signs of hemodynamically unstable dysrhythmia (ventricular tachycardia, ventricular fibrillation, asystole, complete heart block, symptomatic bradycardia). See Evidence for details.

Additional considerations for treatment of digoxin toxicity include:

  • Atropine 0.5 mg IV for adults; 0.02mg/kg IV for children for acute toxicity if bradydysrhythmias or high degree AV block.

  • Cautious correction of electrolyte abnormalities, specifically hypokalemia and hypomagnesemia (may result in dysrhythmias at lower serum digoxin levels).

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Advice
  • Therapeutic range for serum digoxin level is 0.5–2.0 ng/mL (0.6–2.6 nmol/L). 
  • If acute poisoning and serum digoxin concentration is confirmed >10 ng/mL (13nmol/L), give empiric dose (10-20 vials).
  • If digoxin dose ingested is >10mg with signs of hemodynamically unstable dysrhythmia (ventricular tachycardia; ventricular fibrillation; asystole; complete heart block, symptomatic bradycardia), give empiric dose (10-20 vials).
Management

Additional treatment considerations include atropine 0.5 mg IV for adults (0.02mg/kg IV for children) for acute toxicity if bradydysrhythmias or high degree AV block are present.

 

Tips from the Creator:

  • The DigiFab® calculator is appropriate for vials containing (approximately) 40 mg of antibodies which will bind ~0.5mg of digoxin. 
  • Slow infusion (i.e., 30 minutes) improves Fab efficacy; this infusion method is preferable when rhythm disturbances are not life-threatening. 
  • In the case of chronic overdose and if digoxin level is not available (in prehospital setting for example), a dose of 3 vials may be considered. (experience-based recommendation).
Critical Actions
  • Potassium abnormalities, specifically hypokalemia, may worsen digoxin toxicity, even at therapeutic digoxin levels. 
  • If mild hyperkalemia, correction is not advised, as treatment with DigiFab® will decrease potassium concentrations. 
  • Treatment to lower serum potassium concentrations should be performed prior to DigiFab administration only if both are true:
    • Hyperkalemia is believed to be worsening AV nodal block and bradycardia.
    • DigiFab is not immediately available. 
  • Though debated, calcium salts should not be administered to patients with hyperkalemia secondary to digoxin toxicity.
  • In hypokalemia, cautious correction is advised prior to the administration of DigiFab®.
  • If worsening toxicity/dysrhythmia or if toxicity does not improve with correction of hypokalemia, DigiFab® should be immediately administered.
  • Transcutaneous and especially transvenous pacing should be avoided in patients with digoxin toxicity due to risk for precipitating dysrhythmias.
  • Frequent premature ventricular complexes (PVCs) may be closely followed by ventricular dysrhythmias.
  • Extracorporeal removal is not beneficial due to digoxin’s large volume of distribution and molecular weight.
  • Digoxin maintenance therapy should not be restarted in the acute setting following a presentation with digoxin toxicity that required digoxin immune Fab treatment, except in rare circumstances and after risk-benefit assessment.

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