Digoxin-specific Antibody Fragments (DigiFab)

How it works

The Fab fragments bind free digoxin with high affinity, forming an inactive complex that is renally excreted, thereby reversing the cardiac and systemic effects of digoxin.

Prescribing in practice

• Reserve for life-threatening toxicity such as severe ventricular arrhythmias, significant bradyarrhythmia or marked hyperkalaemia attributable to digoxin, and dose according to the body load of digoxin as directed.
• After administration, total serum digoxin assays become unreliable because they also measure bound drug, so do not interpret subsequent levels conventionally.
• Hypokalaemia may develop as toxicity reverses and digoxin's effect is removed, so potassium must be watched closely.

Monitoring

Monitor cardiac rhythm by continuous ECG, serum potassium and renal function during and after administration.

Counselling the patient

• This is an emergency antidote given and monitored in a hospital setting.
• Team members should anticipate falling potassium as digoxin effect reverses.
• Standard digoxin levels are not interpretable after this treatment.

Evidence & guidelines

Digoxin-specific antibody fragments are the established antidote for life-threatening cardiac glycoside toxicity, supported by MHRA-approved product information and toxicology guidance.