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Digoxin Toxicity — RACP Adult Medicine MCQ

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ModerateEmergency MedicineDigoxin ToxicityRACP Adult Medicine

A 70-year-old woman on digoxin 250 mcg daily for AF with heart failure develops nausea, visual disturbances (yellow-green halos), and confusion. Her potassium is 5.8 mmol/L and digoxin level is 4.2 nmol/L (therapeutic 1.0–2.6 nmol/L). ECG shows bidirectional ventricular tachycardia. What is the specific treatment?

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

Severe digoxin toxicity with life-threatening arrhythmia (bidirectional VT is virtually pathognomonic for digoxin toxicity) and hyperkalaemia requires digoxin-specific antibody fragments (DigiFab). These Fab fragments bind free digoxin, rapidly reversing toxicity. IV calcium is CONTRAINDICATED in digoxin toxicity as it may worsen cardiac arrhythmias ('stone heart'). Atropine can be used for bradyarrhythmias. Factors precipitating digoxin toxicity include renal impairment, hypokalaemia (paradoxically – though hyperkalaemia occurs WITH toxicity), and drug interactions.

Reference: eTG – 2025 – Toxicology; AMH – 2025 – Digoxin