DigiFab
Liverpool Hospital Emergency Department
Indications for use:
- Acute digoxin overdose
- Cardiac arrest presumed due to digoxin
- Hyperkalaemia >5.5mmol/L with digoxin ingestion
- Life-threatening ventricular arrhythmias or runs of ventricular ectopics
- Decompensation with bradycardia
- Dig level (predigifab) >15nmol/L (>12ng/ml) and toxicity
- Chronic digoxin toxicity
- Cardiac arrest
- Ventricular arrythmias and runs of ectopics
- Bradyarrhythmia with hypotension
- Cardiac Glycoside overdose:
- Foxglove
- Oleander
Formulation: (Sterile Powder in Fridge)
Digoxin binding Antibody fragments (Fab)
- 1 vial = 40mg Digifab -> binds 0.5mg Digoxin
- Reconstitute each vial with 4ml sterile water for injection
- Dilute up to 100ml 0.9% Normal Saline
- Infusion over 15-30mins as below, with 0.22micron filter
Dosage and Administration
- ACUTE POISONING – If no response, discuss with Toxicologist
- Cardiac Arrest:
- X5 Digifab vials (200mg) as a rapid injection (5-10 minutely) (20 vials)
- NOT in Cardiac Arrest:
- Titrate to effect giving x2 vials initially over 15-30 minutes
- Partial response – repeat after 30 minutes
- Cardiac Arrest:
Monitor for 12 hours post
- Digoxin may be mobilised from tissues leading to further toxicity requiring and require an additional 1-2 vials
- CHRONIC POISONING – If no response, discuss with Toxicologist
- Cardiac Arrest:
- Follow ALS / Treat hyperkalaemia and use 2 vials of Digifab
- NOT in Cardiac Arrest:
- 1 vial and assess response
- Cardiac Arrest:
Monitor until cardiac effects resolve. Second dosing may be needed
Side Effects
- Poor cardiac baseline function (CCF) may worsen due to withdrawal of digoxin’s inotropic support
- If BG of AF may develop -> AF + RVR due to removal of digoxin AV Blockade
- Rapid Hypokalaemia (from reactivation of Na/K ATPase)
- Hypersensitivity (relative contraindication, very rare)
Pit Falls
- Treat Bradyarrhythmia with Atropine initially
- Prompt Electrolyte correction is key
- Hypokalaemia worsens Digoxin toxicity – Rapid correction required
- Note Digifab will lead to further hypokalaemia initially
- Hypomagnesaemia worsens digoxin toxicity – Rapid correction
- Hyperkalaemia
- Treat HyperK with IV Bicarb + Insulin/Dex + Digifab
- Calcium can be considered with evidence of ECG changes.
- The risk of the stone heart theory is overstated
- K>5.5 from Digoxin toxicity is 100% fatal if not treated
NB – Digifab Binding Digoxin -> increased total serum digoxin concentrations (however free digoxin concentrations are reduced).