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Calcium channel blocker overdose — RCPSC EM MCQ

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HardToxicologyCalcium channel blocker overdoseRCPSC EM

A 19-year-old with diphenhydramine overdose is delirious, hypotensive and has QRS 138 ms with terminal R in aVR. Which antidotal treatment is indicated?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: EGive IV sodium bicarbonate boluses with serial ECG and electrolyte reassessment

Explanation lettering: E = shown as A · C = shown as B · D = shown as C · A = shown as D · B = shown as E

B is correct for drug-induced sodium-channel blockade. C is hazardous with conduction delay. D adds sodium-channel and QT effects without correcting toxicity. E has no role and can provoke seizures. A targets a different poisoning mechanism.

Reference: Ontario Poison Centre, Drug-induced QRS widening treatment: https://www.ontariopoisoncentre.ca/siteassets/pdfs/english/patient-care-resources-documents/faxable-sheet_drug-induced-qrs-widening-treatment.pdf