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Paracetamol NAPQI toxicity — MRCPCH TAS MCQ

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EasyPharmacologyParacetamol NAPQI toxicityMRCPCH TAS

A 3-year-old presents after accidental ingestion of a large amount of paracetamol. Initial examination is normal but treatment is started to prevent hepatic injury. What toxic metabolite is most relevant?

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Correct answer: A — N-acetyl-p-benzoquinone imine

Paracetamol overdose causes hepatic injury through accumulation of N-acetyl-p-benzoquinone imine when glutathione is depleted. Salicylate anion is relevant to aspirin poisoning rather than paracetamol. The pearl is that early symptoms may be mild despite significant future hepatotoxic risk.

Reference: BNFc; Nelson Textbook of Pediatrics; RCPCH Theory examination syllabi