Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 38-33: Digitalis & Other Cardiac Glycosides Overdose + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Intoxication may result from Acute single exposure Chronic accumulation from accidental overmedication, especially in patients with kidney disease taking digoxin Hyperkalemia common after acute overdose Many different arrhythmias can occur +++ General Considerations ++ Cardiac glycosides paralyze the Na+-K+-ATPase pump and have potent vagotonic effects Intracellular effects Enhancement of calcium-dependent contractility Shortening of the action potential duration Older age and chronic kidney disease are associated with greater risk of digoxin toxicity + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs +++ Acute overdose ++ Nausea and vomiting Bradycardia Atrioventricular (AV) block Junctional rhythm common in patients with underlying atrial fibrillation Hyperkalemia +++ Chronic overingestion ++ Hypokalemia and hypomagnesia are more likely owing to concurrent diuretic treatment Ventricular arrhythmias; for example Ectopy Bidirectional ventricular tachycardia Ventricular fibrillation +++ Differential Diagnosis ++ Beta-blocker overdose Calcium channel blocker overdose Cardiotoxic plant or animal ingestion Oleander Foxglove Lily of the valley + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Serum digoxin level (Note: Levels drawn within 6 h of ingestion may be falsely elevated before complete tissue distribution) Serum potassium (frequent measures useful because they correlate with tissue effects) +++ Diagnostic Procedures ++ Continuous ECG monitoring Pacemaker may be needed + Treatment Download Section PDF Listen +++ +++ Medications +++ Emergency measures ++ Ventricular arrhythmias: initially lidocaine, 2–3 mg/kg intravenously, or phenytoin, 10–15 mg/kg intravenously slowly over 30 min if digoxin-specific antibodies are not immediately available (see below) Bradycardia: initially atropine, 0.5–2.0 mg intravenously, or transcutaneous external cardiac pacemaker +++ Gut decontamination ++ After acute overdose, administer activated charcoal, 60–100 g orally or via gastric tube, mixed in aqueous slurry Emesis not recommended because it may enhance vagotonic effects (eg, bradycardia, AV block) +++ Activated charcoal ++ Repeated doses of activated charcoal, 20–30 g every 3–4 hours, may speed elimination of digitoxin (but not digoxin) by adsorbing drug excreted into gut lumen (gut dialysis) Sorbitol or other cathartics should not be used with each dose; resulting large stool volumes may lead to dehydration or hypernatremia +++ Specific treatment ++ Severe intoxication: administer digoxin-specific antibodies [digoxin immune Fab (ovine) DigiFab] Dose is estimated based on body burden of digoxin calculated from ingested dose or steady-state serum digoxin concentration Ingested dose Number of vials = ~1.5–2 × ingested dose (mg) Serum concentration Number of vials = serum digoxin (ng/mL) × body weight (kg) × 10–2 Note: This is based on equilibrium digoxin level; after acute overdose, serum levels are falsely high for several hours before tissue distribution is complete, and overestimation of DigiFab dose is likely More effective binding of digoxin may be achieved if the dose is given partly as a bolus and the remainder as an infusion over a few hours Empiric titration of DigiFab May be used if patient's condition is relatively stable and an underlying condition (eg, atrial fibrillation) favors retaining a residual level of digitalis activity Start with one or two vials and reassess clinical condition after 20–30 min Note: After administration of digoxin-specific Fab antibody fragment, serum digoxin levels may be falsely elevated depending on assay technique + Outcome Download Section PDF Listen +++ +++ Follow-Up ++ Monitor potassium levels and cardiac rhythm closely +++ Complications ++ Cardiac arrest +++ Prevention ++ Monitor kidney function in elderly patients and obtain serum digoxin levels if symptoms of digoxin toxicity + Reference Download Section PDF Listen +++ + +Arbabian H et al. Elderly patients with suspected chronic digoxin toxicity: a comparison of clinical characteristics of patients receiving and not receiving digoxin-Fab. Emerg Med Australas. 2018 Apr;30(2):242–8. [PubMed: 29316267] + +Manini AF et al. Prognostic utility of serum potassium in chronic digoxin toxicity: a case-control study. Am J Cardiovasc Drugs. 2011 Jun 1; 11(3):173–8. [PubMed: 21619380] + +Roberts DM et al. Pharmacological treatment of cardiac glycoside poisoning. Br J Clin Pharmacol. 2016 Mar;81(3):488–495. [PubMed: 26505271] + +Yang EH et al. Digitalis toxicity: a fading but crucial complication to recognize. Am J Med. 2012 Apr;125(4):337–43. [PubMed: 22444097]