Makindo Medical Notes

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Check local/national poisons advice. Establish where to get stocks of Digoxin immune FAB as they are expensive, and local stocks may be limited. Hyperkalaemia is a useful sign of severe Digoxin toxicity.

About

• Digoxin is a therapeutic drug but is also found in plants like foxglove, oleander, and lily of the valley.

Aetiology

• Digoxin blocks the Na/K ATPase pump, indirectly increasing intracellular calcium, which enhances cardiac contractility.
• Decreases AV conduction and can cause bradycardia while increasing vagal tone and automaticity.
• The lethal dose can be as little as 10 times the daily dose (10 mg in adults, 4 mg in children).
• Well absorbed orally, with a half-life of 30-40 hours. Peak toxicity occurs at 6 hours, with potential death within 6-12 hours post-ingestion.
• Hyperkalaemia is a common sign of severe toxicity.

Factors that Increase Toxicity

• Low K, Low Mg, High Ca
• Amiodarone (due to altered protein binding)
• Calcium channel blockers

Clinical Presentation

• Anorexia, nausea, and vomiting; may also have yellow vision, diarrhoea, and abdominal pain.
• Bradycardias, AV block, SVT (with AV block), atrial fibrillation, VT, and even VF.

Investigations

• FBC, U&E, and serum digoxin level at 4 hours post-ingestion.
• ECG to detect characteristic changes; hyperkalaemia suggests digoxin toxicity.
• Serial ECGs and continuous cardiac monitoring (preferably in CCU or HDU).

Management: Avoid Calcium Chloride or Gluconate