Antidote
Pregnancy: There are no data on the use of DigiFab in pregnant women; use should be considered only if the expected clinical benefit of treatment to the mother outweighs any possible risk to the developing foetus. It is not known whether DigiFab is excreted in human milk and a risk to the breast-feeding child cannot be excluded, so breast-feeding should be discontinued during treatment. There are no fertility data.
Digoxin-specific Antibody Fragments (DigiFab)
Brand names: DigiFab, Digibind
Used in: Atrial Fibrillation
Digoxin-specific antibody fragments are an antidote used for life-threatening digoxin (or digitalis) toxicity, including severe poisoning and overdose.
Adult dose
Dose: Life-threatening digoxin toxicity or cardiac glycoside poisoning. Cardiac arrest due to digoxin toxicity — IV bolus by weight: over 40 kg, 5 vials (200 mg); 20-40 kg, 2 vials (80 mg); 20 kg or less, 1 vial (40 mg). Severe bradyarrhythmia, life-threatening ventricular arrhythmia, or severe hyperkalaemia (for example potassium greater than 6.5 mmol/L) resistant to adequate rehydration and conventional treatments — calculate the number of vials: where a plasma digoxin concentration is available (measured 6 hours after overdose, unless urgently indicated in a patient with arrhythmia), vials = serum digoxin concentration (ng/mL) x weight (kg) divided by 200; where only the ingested dose is known, vials = amount of digoxin ingested (mg) x 0.8. Round up to the nearest vial.
Route: Intravenous. In cardiac arrest give as an IV bolus; otherwise, depending on clinical circumstances, the reconstituted and diluted solution may be infused intravenously over a 30 minute period.
Frequency: Single calculated dose. In cardiac arrest, further doses may be required if an adequate clinical response is not seen after 30 minutes.
Each vial contains 40 mg and is reconstituted with 4 mL of sterile water by gentle mixing. Round up to the nearest vial for both formulae. Digoxin concentrations reported in nmol/L are converted first: nmol/L x 0.781 = ng/mL. The dose is set by the digoxin burden rather than by a ceiling, and the label states no maximum dose. For poisoning by cardiac glycosides other than pharmaceutical digoxin, cardiac arrest is treated with the same weight bands, while severe bradyarrhythmia, life-threatening ventricular arrhythmia or severe hyperkalaemia is treated with 2 vials (80 mg) above 40 kg and 1 vial (40 mg) at 40 kg or below, repeated after 15-30 minutes if the response is inadequate; digoxin assay levels must NOT be used to dose DigiFab in these cases, because digoxin assays react unpredictably with non-digoxin cardiac glycosides. Digoxin assay kits may not measure concentrations above 5 ng/mL accurately, so exercise caution when using higher concentrations to calculate the dose. DigiFab itself interferes with digoxin immunoassays: total serum digoxin may rise rapidly after administration because the digoxin is bound and no longer able to react with receptors, and standard measurements can remain misleading until the fragments are eliminated, which may take several days or more than a week in renal impairment. The SPC advises discussing management with TOXBASE, the UK National Poisons Information Service, on 0344 892 0111 (in Ireland, NPIC (01) 809 2566), and referring to the current TOXBASE guidance at https://www.toxbase.org/.
Paediatric dose
Dose: Cardiac arrest: over 40 kg, 5 vials (200 mg); 20-40 kg, 2 vials (80 mg); 20 kg or less, 1 vial (40 mg)
Route: Intravenous — IV bolus in cardiac arrest; otherwise may be infused over a 30 minute period
Frequency: Single dose; further doses may be required if an adequate clinical response is not seen after 30 minutes
These are the label's own children's figures, not scaled from an adult dose — the §4.2 weight-band tables are headed 'Weight (adult and children)'. Dosing is by weight band and vial count rather than per kilogram, so no per-kilogram figure is recorded and no weight calculator applies. Each vial contains 40 mg and is reconstituted with 4 mL of sterile water. §4.2 states that data on the safety and efficacy of DigiFab in children are limited, and no paediatric patients were included in the clinical studies for the treatment of digoxin toxicity.
Dose adjustments
Renal
No renal dose adjustment is stated in the fetched sections. §4.4 notes that after DigiFab the digoxin immunoassay remains unreliable until the Fab fragments are cleared, which may take more than a week in renal impairment.
Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.
Contraindications
- Hypersensitivity to the active substance or any of the excipients
Side effects
- Common: hypersensitivity reactions
- Common: hypokalaemia, hyperkalaemia
- Common: headache, confusional state
- Common: worsening of cardiac failure, chest pain, hypotension, orthostatic hypotension
- Common: nausea, vomiting, diarrhoea, constipation, abdominal distension
- Common: influenza-like illness
- Common: renal failure
- Common: fatigue, infusion site phlebitis
- Exacerbation of low cardiac output states and congestive heart failure, or a rapid ventricular response in patients with atrial fibrillation, may occur owing to withdrawal of the effect of digoxin
- Adverse reactions may occur up to 14 days after the infusion has been administered
- Frequencies are derived from clinical studies in 23 subjects with digoxin toxicity and 57 subjects with yellow oleander (Thevetia peruviana) toxicity
Monitoring
- Monitor for signs and symptoms of anaphylaxis and acute allergic reaction — as with any intravenous protein product, infusion-related or hypersensitivity reactions are possible. Medical support must be readily available, and administration must be stopped immediately if an anaphylactic reaction occurs during the infusion
- Repeat dosing may give rise to an anaphylactic reaction and must only be done when the clinical benefit is considered to outweigh the risk
- Allergy risk is higher in patients allergic to sheep-derived proteins (digoxin immune Fab is produced from sheep protein), to papain (used to cleave the antibody, and sharing allergenic structures with chymopapain and other papaya extracts, bromelain in pineapple, dust mite allergens and latex allergens), or to alpha-gal / with alpha-gal syndrome
- Serum potassium — both hypokalaemia and hyperkalaemia are listed as common adverse reactions, and severe hyperkalaemia is itself one of the treatment indications
- Cardiac status after reversal — withdrawal of the digoxin effect can exacerbate low cardiac output states and congestive heart failure, or produce a rapid ventricular response in atrial fibrillation
- Do not use serum digoxin immunoassay results to guide further dosing after DigiFab has been given; the assay is unreliable until the Fab fragments are cleared, which may take several days or more than a week in renal impairment
- Record the name and batch number of the administered product, to improve the traceability of biological medicinal products
- Discuss management with TOXBASE / the UK National Poisons Information Service on 0344 892 0111 (in Ireland, NPIC (01) 809 2566)
Clinical monograph
How it works
The Fab fragments bind free digoxin with high affinity, forming an inactive complex that is renally excreted, thereby reversing the cardiac and systemic effects of digoxin.
Prescribing in practice
- Reserve for life-threatening toxicity such as severe ventricular arrhythmias, significant bradyarrhythmia or marked hyperkalaemia attributable to digoxin, and dose according to the body load of digoxin as directed.
- After administration, total serum digoxin assays become unreliable because they also measure bound drug, so do not interpret subsequent levels conventionally.
- Hypokalaemia may develop as toxicity reverses and digoxin's effect is removed, so potassium must be watched closely.
Monitoring
Monitor cardiac rhythm by continuous ECG, serum potassium and renal function during and after administration.
Counselling the patient
- This is an emergency antidote given and monitored in a hospital setting.
- Team members should anticipate falling potassium as digoxin effect reverses.
- Standard digoxin levels are not interpretable after this treatment.
Evidence & guidelines
Digoxin-specific antibody fragments are the established antidote for life-threatening cardiac glycoside toxicity, supported by MHRA-approved product information and toxicology guidance.
Reference: UK Toxbase; NPIS Clinical Toxicology 2023; ERC Resuscitation Guidelines 2021; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
Pathways
- Difficult Airway Algorithm (DAS) · DAS 2015; Royal College of Anaesthetists
- Major Haemorrhage Protocol · NICE NG24; UK MHP guidelines
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
Featured in these MRCEM clinical pathways
Digoxin-specific Antibody Fragments (DigiFab) is a core drug in the following exam-focused workups on our sister siteReviseMRCEM.
MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.