Paracetamol Overdose — MFDS Part 1 MCQ
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Correct answer: A — N-acetylcysteine
N-acetylcysteine is the specific antidote for paracetamol overdose. It acts as a precursor for glutathione synthesis, helping the liver inactivate NAPQI, the reactive metabolite responsible for hepatotoxicity. It is most effective when started within 8–10 hours, but later administration may still provide benefit and should not be dismissed solely because of delay. Activated charcoal may reduce absorption after a recent ingestion but is a gastrointestinal decontamination measure, not the specific antidote. Flumazenil reverses benzodiazepines, naloxone reverses opioids, and vitamin K is used to reverse vitamin K antagonist anticoagulation.
Reference: Electronic Medicines Compendium. Acetylcysteine 200 mg/ml Injection, Summary of Product Characteristics, sections 4.1, 4.4 and 5.1. Updated 2025. https://www.medicines.org.uk/emc/product/3447/smpc