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Digoxin Toxicity — EECC MCQ

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ModerateCardiac PharmacologyDigoxin ToxicityEECC

A 78-year-old woman on digoxin 125 micrograms daily for rate control in AF presents with nausea, visual disturbance (yellow-green halos), and new-onset complete heart block. Her serum digoxin level is 3.8 nmol/L (therapeutic range 1.0-2.6 nmol/L). Potassium is 5.8 mmol/L. What is the most appropriate specific treatment?

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Correct answer: B — Digoxin-specific antibody fragments (Digibind/DigiFab)

This patient has digoxin toxicity with life-threatening manifestations (complete heart block, severe hyperkalaemia). Digoxin-specific antibody fragments (Fab) are the definitive treatment for severe digoxin toxicity (Class I) — they bind free digoxin, rendering it pharmacologically inactive, and rapidly reverse both cardiac and non-cardiac toxicity. Importantly, IV calcium is relatively contraindicated in digoxin toxicity as it can worsen cardiac toxicity (theoretical 'stone heart' phenomenon). Haemodialysis is ineffective for digoxin removal due to its large volume of distribution and high protein binding. Temporary pacing may be needed as a bridge but does not treat the underlying toxicity. Atropine may temporarily improve bradycardia but is not definitive.

Reference: BNF; Toxbase; ESC Pharmacology Guidelines