Digoxin Immune Fab Schedule (India)

Schedule H

Digoxin Immune Fab Routes

Intravenous

Digoxin Immune Fab Formulations

Lyophilized powder for injection: 40 mg per vial (each vial neutralizes approximately 0.5 mg of digoxin)

Digoxin Immune Fab Adult indications

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

Life-threatening Digoxin Toxicity or Overdose

Includes:

Ventricular arrhythmias (ventricular tachycardia, ventricular fibrillation)

Bradyarrhythmias with haemodynamic compromise unresponsive to atropine

Hyperkalaemia (>5.5 mmol/L) in setting of digoxin toxicity

Cardiac arrest attributed to digoxin toxicity

Dose Calculation Methods:

Clinical Scenario Dose Calculation Formula

Known quantity of digoxin ingested (acute) Number of vials = Amount ingested (mg) × 1.6

Known steady-state serum digoxin level Number of vials = [Serum digoxin (ng/mL) × Body weight (kg)] ÷ 100

Empiric Dosing (when ingested amount and serum level unknown):

Severity Dose

Cardiac arrest / Life-threatening arrhythmia 10–20 vials IV

Severe toxicity (haemodynamically unstable) 10 vials IV

Moderate toxicity (stable but symptomatic) 3–6 vials IV

Administration:

Reconstitution: Add 4 mL sterile water for injection to each vial

Dilution: Further dilute in 50–100 mL normal saline

Infusion rate: Administer over 30 minutes

Cardiac arrest: May give as rapid IV bolus

Repeat dosing: Additional vials may be given based on clinical response; reassess after 30–60 minutes

Secondary Indications – Adults (Off-label, if any)

Not documented in Indian practice

Digoxin Immune Fab Paediatric indications

PAEDIATRIC DOSING (Specialist Only)

Primary Indication: Life-threatening Digoxin Toxicity

Dose Calculation (same principles as adults):

Clinical Scenario Dose Calculation

Known quantity ingested Number of vials = Amount ingested (mg) × 1.6

Known serum digoxin level (steady-state) Number of vials = [Serum digoxin (ng/mL) × Body weight (kg)] ÷ 100

Empiric Dosing (when above values unavailable):

Weight Category Empiric Dose

< 20 kg 1 vial

20–40 kg 1–2 vials

40 kg 3–6 vials

Safety Monitoring:

Continuous cardiac monitoring mandatory

Serial serum potassium measurement

Avoid relying on serum digoxin levels for 3–5 days post-Fab (falsely elevated due to assay interference)

Minimum Age Limit:

No lower age limit established

May be used in neonates and infants under paediatric intensivist/toxicologist supervision

Secondary Indications – Paediatric (Off-label, if any)

Not documented in Indian specialist guidelines

Digoxin Immune Fab Renal Adjustments

eGFR (ml/min/1.73m²)	Recommendation
eGFR (ml/min/1.73m²)	Recommendation
Haemodialysis	Fab-digoxin complexes not significantly dialyzable; no supplemental dosing needed

Note: Renal impairment may prolong elimination of Fab-digoxin complexes, but free digoxin remains neutralized. Monitor for delayed rebound toxicity in severe renal failure.

Digoxin Immune Fab Hepatic adjustment

Hepatic Impairment	Recommendation
Mild impairment	No dose adjustment required
Moderate impairment	No dose adjustment required
Severe impairment	No dose adjustment required

Note: Fab fragments undergo proteolytic degradation; hepatic metabolism is not a significant elimination pathway.

Digoxin Immune Fab Contraindications

Known hypersensitivity to ovine (sheep) proteins

Known hypersensitivity to papain or papaya (cross-reactivity due to manufacturing process)

Elevated serum digoxin level without clinical evidence of toxicity (high level alone is NOT an indication)

Digoxin Immune Fab Cautions

Pre-existing hypokalaemia — correct before or concurrent with Fab administration; risk of severe hypokalaemia post-neutralization

Pre-existing heart failure dependent on digoxin effect — may decompensate after reversal

Renal impairment — prolonged clearance of Fab-digoxin complexes; monitor for delayed rebound

Atopic individuals or history of allergic reactions — increased anaphylaxis risk

Ensure resuscitation equipment and adrenaline available before administration

Re-digitalization should be delayed for several days after Fab therapy

Digoxin Immune Fab Pregnancy

Parameter Details

Overall safety No contraindication when clinically indicated for life-threatening toxicity

Risk to fetus Fab fragments are large molecules; unlikely to cross placenta significantly

Preferred alternatives None — Fab therapy is the definitive treatment for severe digoxin toxicity

When to use Always use if maternal life at risk; benefit clearly outweighs theoretical risk

Monitoring Continuous fetal heart rate monitoring if mother haemodynamically unstable; post-resuscitation obstetric evaluation

Digoxin Immune Fab Lactation

Parameter Details

Compatibility Not contraindicated during breastfeeding

Transfer to milk Fab fragments unlikely to be present in milk at significant levels due to large molecular size

Oral absorption by infant Not absorbed orally; no systemic effect expected

Preferred alternatives Not applicable — emergency antidote

Infant monitoring General feeding behaviour and wellbeing

Digoxin Immune Fab Elderly

No specific dose adjustment required

Higher baseline risk of digoxin toxicity due to reduced renal clearance — may require Fab therapy more frequently

Calculate dose based on actual clinical severity; empiric dosing should be used cautiously

Monitor closely for hypokalaemia and rebound toxicity

Pre-existing cardiac conditions may mask or complicate clinical response

Digoxin Immune Fab Major drug interactions

Interacting Agent Effect Recommendation

Other cardiac glycosides (oleander, yellow oleander poisoning — bufadienolides) Cross-reactivity possible but unpredictable; Fab may partially bind plant glycosides Consider higher doses; consult toxicologist

Digoxin re-administration Fab fragments may still be present, binding and inactivating newly administered digoxin Avoid re-digitalization for minimum 5–7 days after Fab therapy

Digoxin Immune Fab Moderate drug interactions

Not applicable — Digoxin immune Fab is used as acute antidote therapy; no clinically relevant moderate drug interactions documented.

Digoxin Immune Fab Common Adverse effects

Hypokalaemia (due to rapid intracellular potassium shift when digoxin effect reversed)

Fever and chills during or after infusion

Infusion site reactions (pain, erythema, phlebitis)

Nausea

Digoxin Immune Fab Serious Adverse effects

Adverse Effect Clinical Notes

Anaphylaxis Rare; higher risk with prior sheep protein or papain allergy; immediate discontinuation and adrenaline required

Serum sickness Delayed hypersensitivity reaction; may occur 7–14 days post-infusion; presents with fever, arthralgia, rash

Rebound digoxin toxicity May occur if Fab clears before all digoxin eliminated; more common in renal impairment

Acute pulmonary oedema Rare; may occur in patients with heart failure dependent on digoxin for rate control or inotropy

Worsening heart failure Due to loss of digoxin's positive inotropic effect

Digoxin Immune Fab Monitoring requirements

Phase Parameters

Baseline ECG, serum potassium, serum digoxin level (if available), renal function, vital signs

During infusion Continuous cardiac monitoring, blood pressure, watch for infusion reactions or anaphylaxis

After administration ECG monitoring for minimum 6 hours post-infusion; serum potassium every 4–6 hours for 24 hours; clinical reassessment at 30–60 minutes for need of additional doses

Long-term Not applicable — single-use antidote; note that serum digoxin assays will be unreliable for 3–5 days post-Fab due to assay interference

Digoxin Immune Fab Brands in India

DigiFab® (BTG/Pfizer) — CDSCO-approved imported product

DigiBind® — previously available; currently limited or unavailable in Indian market

Note: Limited availability; typically stocked only in major tertiary care centres with toxicology or cardiac intensive care units. Advance procurement may be necessary.

Digoxin Immune Fab Price range (INR)

Product Approximate Cost

DigiFab 40 mg vial ₹35,000–₹50,000 per vial

Not included in NLEM

Not under NPPA price control

High cost; availability primarily in tertiary care emergency settings

Government supply: NOT AVAILABLE in standard government supply chains

Digoxin Immune Fab Clinical pearls

Rapid onset of action — clinical improvement in arrhythmias typically seen within 30–60 minutes of administration

Do not rely on post-Fab digoxin levels — total serum digoxin concentration remains falsely elevated for 3–5 days due to assay cross-reactivity with Fab-bound digoxin; only free digoxin levels (rarely available) are reliable

Anticipate hypokalaemia — digoxin toxicity causes potassium to shift extracellularly; once digoxin is neutralized, potassium rapidly re-enters cells; be prepared to supplement potassium

Conservative empiric dosing in stable patients — dose calculations often overestimate need; in non-arrest situations, start with lower empiric doses and reassess

Avoid early re-digitalization — Fab fragments persist in circulation; newly administered digoxin will be bound and inactivated for several days

Consider in plant cardiac glycoside poisoning — may have partial efficacy in yellow oleander (Thevetia peruviana) or common oleander poisoning, though cross-reactivity is incomplete; specialist consultation recommended

Digoxin Immune Fab Tags

Digoxin immune fab; digoxin toxicity; cardiac glycoside poisoning; antidote; Fab fragment; arrhythmia emergency; hyperkalaemia; emergency medicine; toxicology; paediatric-specialist; renal-safe

Digoxin Immune Fab Version

RxIndia v1.0 — 15 May 2024

Digoxin Immune Fab Reference

CDSCO Import Drug Database

Indian Pharmacopoeia

AIIMS Emergency Medicine Protocols

API Textbook of Medicine — Cardiology and Clinical Toxicology sections

Harrison's Principles of Internal Medicine

Goodman & Gilman's The Pharmacological Basis of Therapeutics

Published Indian case reports on digitalis and oleander poisoning management

RxIndia

The Drug Registry

Digoxin Immune Fab