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
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| 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).
Instructions
- 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)
Available strengths
- inj 40 mg
Cautions
- 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
Adverse reactions
- Worsening congestive heart failure (13%)
- Hypokalemia (13%)
- Worsening atrial fibrillation (7%)
Pregnancy No human or animal data; use only if clearly needed.
Lactation Unknown whether excreted in human milk; exercise caution in nursing mothers.
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 40 mg | inj | per unit | not offered |
NO BOXED WARNINGS
Principal riskDigoxin assays become uninterpretable afterwards
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityRapid hypokalemia, hypersensitivity and reversal of needed digoxin support