Digoxin immune Fab

DIGIFAB

What it isDigoxin-specific antibody fragments; digoxin toxicity.

Why this oneIt binds digoxin directly and reverses arrhythmia and hyperkalemia within an hour.

What limits itTotal digoxin assays become useless afterwards because they measure bound drug. Rebound toxicity if dosing is inadequate.

FDA label

FDA dosing	Population	Start
Digoxin toxicity — acute ingestion, unknown amount, no serum level	All	20 vials IV (children <20 kg: start 10 vials, then 10 more if needed)
Chronic digoxin toxicity — no serum level	Adults & children ≥20 kg	6 vials IV
Chronic digoxin toxicity — no serum level	Infants & children <20 kg	1 vial IV
Acute ingestion of known amount	All	Vials = mg digoxin ingested ÷ 0.5 mg/vial
Chronic toxicity with known serum level	All	Vials = (serum digoxin ng/mL × weight kg) ÷ 100

Renal Fab fragments are eliminated renally; impaired renal function may prolong elimination — monitor for recurrent toxicity.

Hepatic Undefined

Dose according to the amount of digoxin to be neutralized (0.5 mg neutralized per vial).

For intravenous use only
Monitor serum potassium frequently, especially in the first several hours
In small children (<20 kg), monitor for volume overload; give in split increments to avoid febrile reaction
Postpone re-digitalization until Fab fragments are eliminated (several days; longer with renal impairment)

Rapid drop in serum potassium after treatment — monitor frequently
Anaphylaxis and hypersensitivity reactions possible (higher risk with papain, chymopapain, papaya extract, or bromelain allergy)
Patients with poor cardiac function may deteriorate from withdrawal of digoxin's inotropic action
Interference with digitalis immunoassays — standard serum digoxin readings become clinically misleading after administration

Pregnancy No human or animal data; use only if clearly needed.

Lactation Unknown whether excreted in human milk; exercise caution in nursing mothers.

NO BOXED WARNINGS

Principal riskDigoxin assays become uninterpretable afterwards

Direct muscarinic antagonism0 / 4