Two cases of cardiac glycoside poisoning from accidental foxglove ingestion

Cardiac glycoside toxicity is primarily a clinical diagnosis. Serum digoxin levels should be obtained to confirm the diagnosis and to guide antidote administration (in the context of pharmaceutical digoxin poisoning).8 Although there is crossreactivity with other cardiac glycosides, the digoxin immu...

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Bibliographic Details
Published in:Canadian Medical Association journal (CMAJ) 2016-07, Vol.188 (10), p.747-750
Main Authors: Janssen, Renée M, Berg, Mattias, Ovakim, Daniel H
Format: Article
Language:English
Subjects:
Aged
Antidotes - administration & dosage
Arrhythmias, Cardiac - chemically induced
Cardiac arrhythmia
Cardiovascular disease
Digitalis - drug effects
Digitalis - poisoning
Digoxin - blood
Digoxin - toxicity
Drugs
Electrocardiography
Electrolytes
Family medical history
Female
Glycosides
Health aspects
Humans
Hyperkalemia
Immunoassay
Influence
Laboratories
Male
Nausea
Pharmaceuticals
Poisoning
Poisons
Potassium
Practice
Prescribing
Sinuses
Toxicity
Vomiting
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Summary:Cardiac glycoside toxicity is primarily a clinical diagnosis. Serum digoxin levels should be obtained to confirm the diagnosis and to guide antidote administration (in the context of pharmaceutical digoxin poisoning).8 Although there is crossreactivity with other cardiac glycosides, the digoxin immunoassay is specific for the detection of digoxin. Because of unpredictable cross-reactivity, the quantitative value has no relation to the degree of toxicity from exposure to nonpharmaceutical cardiac glycosides, and may even be undetectable.8 The serum digoxin level should therefore not be used to guide antidote dosage in cases of nonpharmaceutical cardiac glycoside ingestion. The management of cardiac glycoside poisoning includes supportive care and antidote therapy with digoxin-specific antibody fragments (digoxinFab). Digoxin-Fab is indicated for severe cases of cardiac glycoside toxicity (Box 2). It should be avoided in milder cases because of the theoretical risk of immunogenicity. Currently available commercial preparations include DigiFab and DigiBind (the latter of which is unavailable in North America); each vial, administered intravenously, binds 0.5 mg of digoxin.7 Following administration of digoxin-Fab, serum total digoxin levels should not be measured until the antidote has been eliminated from the body (up to three weeks in patients with impaired kidney function), due to interference with the immunoassay.7 Digoxin-Fab has also proven to be effective as an antidote for poisonings from other cardiac glycosides. A randomized controlled trial involving 66 patients with cardiac glycoside toxicity from ingestion of yellow oleander in Sri Lanka found that digoxin-Fab resulted in a significant resolution of dysrhythmias and hyperkalemia compared with saline placebo.9 Several other observational studies have reported favourable outcomes with use of digoxin-Fab in cases of plant-related cardiac glycoside poisonings.10 Dosing recommendations for symptomatic nondigoxin cardiac glycoside exposure suggest empiric administration of 10 vials of digoxin-Fab.7
ISSN:0820-3946
1488-2329
DOI:10.1503/cmaj.150676