Digoxin-specific antibody fragments

How it works

The antibody fragments bind free digoxin with high affinity, forming inactive complexes that are renally excreted, lowering free digoxin concentration and reversing its cardiac and systemic effects.

Prescribing in practice

• Reserve for life-threatening features such as significant arrhythmias, severe bradycardia or hyperkalaemia due to glycoside toxicity, where it can be rapidly life-saving.
• After administration, total serum digoxin assays become unreliable because they also measure antibody-bound drug and should not guide further dosing.
• Treated patients may develop recurrence of the underlying arrhythmia or rapid swings in potassium, so continuous cardiac monitoring is essential.

Monitoring

Monitor continuous ECG, serum potassium and renal function, watching for re-digitalisation effects and recurrence of toxicity.

Counselling the patient

• This is an antidote that neutralises a toxic level of your heart medication.
• Your heart rhythm and blood tests will be monitored closely for several hours.
• Tell the team about any palpitations, dizziness or fainting.

Evidence & guidelines

Digoxin immune Fab for life-threatening glycoside toxicity is endorsed by UK toxicology guidance (TOXBASE).