Makindo Medical Notes

About: Always check the BNF link here

• Check BNF or equivalent for UpToDate prescribing advice
• Follow local guidelines and get senior advice

Mode of action

• Digoxin immune fab or digoxin-specific antibody is an antidote for overdose of digoxin.
• It is made from immunoglobulin fragments from sheep that have already been immunized with a digoxin derivative
• Onset is rapid. 50-90% of patients demonstrate clinical improvement within 45 minutes.

Indication/Dose

• A vial of 40 mg digoxin-Fab is capable of neutralising 0.5 mg digoxin
• Life-threatening digoxin toxicity associated with ventricular arrhythmias or bradyarrhythmias
• In acute poisoning based on ingested digoxin dose
  • Adults: > 10 mg in healthy adults, lower if renal insufficiency or underlying heart disease*
  • Children: > 4 mg (or > 0.1 mg/kg)
• In acute and chronic poisoning based on clinical features
  • Haemodynamic instability or life-threatening dysrhythmia, with elevated steady-state serum digoxin concentration > 2.6 nmol/l (2 ng/ml)
  • Progressive (severe) sinus bradycardia (40–60/min) or second- or third-degree heart block unresponsive to atropine
  • Increased automaticity (e.g. multiple ventricular ectopics or SVT), severe VT or VF
  • Presence of manifestations of digoxin toxicity along with serum potassium > 5.0 mmol/l (5 mEq/l) K > 5.0 mmol/l is a clinical marker for acute digoxin toxicity requiring treatment. This criterion may not be useful in chronic toxicity for several reasons, e.g. renal failure, or drugs interfering with the homeostatic mechanisms for excretion of potassium through the renin/angiotensin/aldosterone axis
• In acute and chronic poisoning based on serum digoxin concentrations – Independent of clinical features:
  • Serum digoxin concentration ≥ 13 nmol/l (10 ng/ml) soon after ingestion in acute poisoning
  • Serum digoxin concentration > 10 nmol/l (7.8 ng/ml) 6 h post-ingestion
  • Serum digoxin concentration > 7.7 nmol/l (6 ng/ml) in chronic poisoning (adults)
  • Serum digoxin concentration > 5.1 nmol/l (4 ng/ml) in chronic poisoning (children)

Dose range: You must check with BNF or drug datasheet

Contraindications

• Allergy

Side effects

• Anaphylaxis, serum sickness or febrile reactions
• Angioedema and anaphylactoid reactions
• Hypokalaemia and hypotension

References

• BNF entry
• Wikipedia
• Digoxin-specific antibodies: a novel dosing strategy