From the Guidelines
Management of digoxin toxicity due to increasing dosage requires immediate discontinuation of the medication and supportive care based on symptom severity, with administration of digoxin-specific antibody fragments (Digibind or DigiFab) being the definitive treatment for moderate to severe toxicity. For mild toxicity with minimal symptoms, stopping digoxin and monitoring may be sufficient 1. The treatment approach should prioritize correcting electrolyte abnormalities, managing bradyarrhythmias, and treating ventricular arrhythmias, while also considering the use of activated charcoal in acute ingestions and the importance of continuous cardiac monitoring 1.
Key Considerations in Management
- Discontinuation of digoxin is the first step in managing toxicity.
- Supportive care includes correcting electrolyte imbalances, particularly potassium, magnesium, and calcium levels.
- Digoxin-specific antibody fragments (Digibind or DigiFab) are the definitive treatment for moderate to severe toxicity, with dosing typically at 40-80 mg IV for acute overdose or calculated based on the amount ingested or serum digoxin level 1.
- Atropine may be used to manage bradyarrhythmias, and lidocaine or phenytoin can be considered for ventricular arrhythmias, though with caution to avoid precipitating ventricular fibrillation 1.
- Activated charcoal may be useful if administered within 1-2 hours of acute ingestion.
- Continuous cardiac monitoring is essential, and while serum digoxin levels should be measured, treatment decisions should be based primarily on clinical presentation rather than absolute levels 1.
Underlying Pathophysiology
Digoxin toxicity occurs due to the drug's narrow therapeutic window and its mechanism of inhibiting the sodium-potassium ATPase pump, leading to increased intracellular calcium and enhanced cardiac contractility, which becomes toxic at higher doses 1. Factors such as hypothyroidism, hypokalemia, or renal dysfunction can potentiate toxicity 1.
Recent Guidelines and Evidence
Recent guidelines and studies emphasize the importance of prompt recognition and treatment of digoxin toxicity, with a focus on the use of digoxin-specific antibody fragments for severe cases 1. The management approach should be tailored to the severity of symptoms and the presence of complicating factors, with a focus on minimizing morbidity, mortality, and improving quality of life.
From the FDA Drug Label
OVERDOSAGE Digoxin should be temporarily discontinued until the adverse reaction resolves. Every effort should also be made to correct factors that may contribute to the adverse reaction (such as electrolyte disturbances or concurrent medications). Treatment of Adverse Reactions Produced by Overdosage: Withdrawal of digoxin may be all that is required to treat the adverse reaction. If the rhythm disturbance is a symptomatic bradyarrhythmia or heart block, consideration should be given to the reversal of toxicity with DIGIBIND® [Digoxin Immune Fab (Ovine)] If the rhythm disturbance is a ventricular arrhythmia, consideration should be given to the correction of electrolyte disorders, particularly if hypokalemia or hypomagnesemia is present DIGIBIND is a specific antidote for digoxin and may be used to reverse potentially life-threatening ventricular arrhythmias due to digoxin overdosage.
The management for digoxin toxicity due to increasing dosage includes:
- Temporary discontinuation of digoxin until the adverse reaction resolves
- Correction of contributing factors such as electrolyte disturbances or concurrent medications
- Withdrawal of digoxin as the primary treatment for adverse reactions
- Reversal of toxicity with DIGIBIND® [Digoxin Immune Fab (Ovine)] for symptomatic bradyarrhythmia or heart block
- Correction of electrolyte disorders for ventricular arrhythmias, particularly hypokalemia or hypomagnesemia
- Administration of DIGIBIND as a specific antidote for potentially life-threatening ventricular arrhythmias due to digoxin overdosage 2
From the Research
Management of Digoxin Toxicity
The management of digoxin toxicity due to increasing dosage involves the use of digoxin-specific antibody fragments (Fab) [ 3, 4,5,6,7 ].
Indications for Digoxin-Fab
The indications for digoxin-Fab include:
- Life-threatening tachy-bradyarrhythmias
- Hyperkalaemia (> 6 mmol/L)
- Haemodynamic instability with an elevated digoxin concentration (> 2 μg/L or 2.6 nmol/L) [ 3 ]
Dosage of Digoxin-Fab
The dosage of digoxin-Fab varies depending on the severity of the toxicity and the serum digoxin concentration.
- In acute poisoning, a small bolus of 80 mg, repeated if necessary, titrated against clinical effect, is likely to achieve equivalent benefits with much lower total doses [ 3 ]
- In chronic poisoning, it may be simplest to give 40 mg (1 vial) digoxin-Fab at a time and repeat after 60 min if there is no response [ 3 ]
- Empiric dosing for adult patients involves utilization of 3-6 vials for chronic poisoning and 10-20 vials for acute poisoning [ 7 ]
Safety and Efficacy of Digoxin-Fab
Digoxin-Fab is safe and effective in severe toxicity, with adverse events such as exacerbation of heart failure, increased ventricular rate, and hypokalaemia being uncommon (< 10%) [ 3 ].