Pharmacy & Acute Care University
Pharmacy & Acute Care University

Digoxin Poisoning Management

Pharmacy Friday Pearl – Pharmacy & Acute Care University

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Introduction

  • Digoxin treats atrial flutter, atrial fibrillation, and heart failure.
  • Toxicity occurs when Na+/K+-ATPase inhibition raises intracellular Na+/Ca2+, triggering dysrhythmias.
  • EKG red flags: PVCs, biphasic T waves, shortened QT interval, variable AV block.
  • Therapeutic range 0.8 – 2.0 ng/mL; toxicity often begins > 2 ng/mL.

Digoxin Immune Fab (DigiFab / DigiBind)

Parameter Key Details
Dose 1 vial = 40 mg (binds 0.5 mg digoxin).
Unknown ingestion → 10-vial empiric dose.
Alternative: vials = 2 × total body load (mg).
Chronic unknown: adults 3 – 6 vials; children 1 – 2 vials.
Administration IV infusion over 30 min (rapid bolus if arrest imminent).
Onset / Duration Onset 20 – 90 min • Duration 15 – 20 h.
Adverse Effects Orthostatic hypotension, ventricular tachycardia, hypokalemia.
Mechanism Fab fragments swiftly bind circulating digoxin, neutralising toxicity.
Compatibility Compatible only with 0.9 % sodium chloride.

Clinical pearl: monitor serum K+ closely—intracellular shifts often trigger hypokalemia post-Fab.

Overview of Key Evidence

Author / Year Design (n) Key Findings
Wei 2021 Case series (121) FAERS: DigiBind serious AEs 87 % vs DigiFab 63 %; hypotension, cardiac arrest, death most frequent.
Ward 2000 Observational (16) Both Fab products reduced free digoxin below assay limits; total digoxin ↑ ≈10-fold (binding confirmed).
Renard 1997 Observational (16) Fab clearance declined linearly with renal impairment & age; t½ 11 – 34 h; all patients recovered without AEs.
Antman 1990 Open-label (150) 90 % toxicity resolved/improved; median dose 5 vials (200 mg); maximum 40 vials.
Roberts 2016 Systematic review Fab therapy remains first-line; hyperkalemia & ventricular arrhythmias are key toxicity predictors.
Ujhelyi 1995 PK review Fab exhibits two-compartment kinetics; repeat dosing may be needed in large body-load poisonings.

Clinical Conclusions

  • Digoxin toxicity is life-threatening but rapidly reversible with Digoxin Immune Fab.
  • If the ingested amount is unknown, administer an empiric 10-vial dose.
  • Do not delay Fab therapy for age- or renal-based calculations.

Full Reference List

  1. Bismuth C, Gaultier M, Conso F, Efthymiou ML. Hyperkalemia in acute digitalis poisoning. Clin Toxicol. 1973;6(2):153-162.
  2. David MNV, Shetty M. Digoxin. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022.
  3. Lexicomp Online, Lexi-Drugs Online. Waltham, MA: UpToDate, Inc. January 2023.
  4. Antman EM et al. Treatment of life-threatening digitalis intoxication with digoxin-specific Fab fragments. Circulation. 1990;81(6):1744-1752.
  5. Renard C et al. Pharmacokinetics of digoxin-specific Fab: effects of renal function & age. Br J Clin Pharmacol. 1997;44(2):135-138.
  6. Roberts DM et al. Pharmacological treatment of cardiac glycoside poisoning. Br J Clin Pharmacol. 2016;81(3):488-495.
  7. Ujhelyi MR, Robert S. Pharmacokinetic aspects of digoxin-specific Fab therapy. Clin Pharmacokinet. 1995;28(6):483-493.
  8. Wei S et al. Adverse events with digoxin Immune Fab in FAERS 1986-2019. Drugs - Real World Outcomes. 2021;8:253-262.
  9. Ward SB et al. Pharmacokinetics & bioaffinity of DigiTAb vs Digibind. Ther Drug Monit. 2000;22(5):599-607.