Digoxin toxicity: 1 or 2 amps of immune fab only, no maths required.
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Dr Betty Chan is an emergency physician and clinical toxicologist in Sydney, Australia who is an expert in digoxin toxicity. She discusses her research and a simplified method of when to give digoxin immune fab in acute and chronic overdose.
While equations exist to calculate the body load of digoxin and subsequent dose of Fab fragment required this overestimates the total amount required due to the toxicokinetics (specifically the distribution) of digoxin.
A far more practical approach is:
- Acute toxicity: give 2 vials & repeat hourly as required
- Chronic toxicity: give 1 vial & repeat hourly as required
The DORA study has questioned the role of digoxin-Fab in patients with chronic toxicity as it produced a median increase in heart rate of 8 beats per minute and a median decrease of 0.3 mmol/L potassium in a group of 36 patients with chronic digoxin toxicity. This group typically has multiple co-morbidities and take multiple cardiovascular medications such as beta blockers, calcium channel blockers and ACE inhibitors. Digoxin-Fab should not be relied upon in isolation to improve heart rate nor correct hyperkalaemia.
LITFL Further Reading
- Tox Library: Digoxin
- Tox Library Antidote: Digoxin Immune Fab
- ECG Library: Digoxin effect
- ECG Library: Digoxin toxicity
- Chan B and Buckley N. “Digoxin-specific antibody fragments in the treatment of digoxin toxicity.” Clin Toxicol 2014; DOI: 10.3109/15563650.2014.943907
- Chan B, Isbister G, O’Leary M, Chiew A & Buckley N. Efficacy and effectiveness of anti-digoxin antibodies in chronic digoxin poisonings from the DORA study (ATOM-1), Clin Toxicol. 2016; DOI: 10.1080/15563650.2016.1175620
- Abad-Santos F, Carcas A, Ibanez C and Frias J. “Digoxin level and clinical manifestations as determinants in the diagnosis of digoxin toxicity.” Therapeutic Drug Monitoring 2000;22(2):163-8
- Wikitox Digoxin 126.96.36.199.2
- Eddleston M et al. “Anti-digoxin Fab fragment in cardiotoxicity induced by ingestion of yellow oleander: a randomised controlled trial.” Lancet 2000; 355:967-72
Emergency Physician & Head of Clinical Toxicology at Prince of Wales Hospital. VMO toxicologist for New South Wales Poisons Information Centre. PhD on the renal excretory mechanism of Paraquat. Current research interests include digoxin, methotrexate, dihydropyridine and sodium channel blocker toxicity.