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Diltiazem Overdose — RACP Adult Medicine MCQ

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HardEmergency MedicineDiltiazem OverdoseRACP Adult Medicine

A 35-year-old has hypotension, anticholinergic features, seizures and a QRS duration of 160 ms after amitriptyline overdose. Which treatment directly addresses the cardiotoxic sodium-channel blockade?

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Correct answer: AGive IV sodium bicarbonate boluses guided by QRS narrowing and haemodynamic response

The best answer is “Give IV sodium bicarbonate boluses guided by QRS narrowing and haemodynamic response”. Tricyclic cardiotoxicity causes fast sodium-channel blockade that worsens with acidaemia. IV sodium bicarbonate provides sodium loading and alkalinisation, with repeated dosing guided by QRS width, blood pressure and pH. High-dose insulin is used for severe calcium-channel or selected beta-blocker toxicity; flumazenil can precipitate seizures, and sodium-channel-blocking antiarrhythmics can worsen conduction.

Reference: NSW Agency for Clinical Innovation: Toxicology resources: https://aci.health.nsw.gov.au/networks/eci/clinical/clinical-resources/toxicology