Organophosphate poisoning — DTM&H MCQ

Correct answer: D — Atropine with oxime where indicated

Atropine with oxime where indicated (option A) is correct because the vignette describes classic acute organophosphate (OP) insecticide poisoning: salivation, bronchorrhoea, miosis and wheeze reflect muscarinic overstimulation, while fasciculations reflect nicotinic overstimulation, both due to acetylcholinesterase inhibition and synaptic acetylcholine accumulation. Atropine is titrated against secretions, bronchospasm and bradycardia (reversing the muscarinic 3Bs) and is the immediate life-saving antidote, with an oxime (such as pralidoxime) added where there is significant cholinesterase inhibition to reactivate the enzyme before ageing occurs. Decontamination (removing soaked clothing, washing skin) and airway/respiratory support run alongside antidote therapy, as respiratory failure from secretions and neuromuscular weakness is the principal cause of death in OP poisoning. This is standard UK toxicology practice as advised by the National Poisons Information Service/TOXBASE for occupational pesticide exposures. Why the other options are wrong: E. Praziquantel: this is an antihelminthic used for schistosomiasis and other fluke/tapeworm infections; it has no cholinergic antagonist or antidote action and does not address acetylcholinesterase inhibition. B. Naloxone alone: naloxone reverses opioid-induced miosis and respiratory depression but does nothing for muscarinic hypersecretion, bronchospasm or nicotinic fasciculations seen in OP toxicity, and the mixed cholinergic picture here is not an opioid overdose. C. High-dose vitamin C: this has no recognised role in acute cholinergic toxidrome management and will not reduce secretions, bronchospasm or fasciculations. A. Intravenous artesunate: this is antimalarial therapy for severe falciparum malaria and is irrelevant to a chemical exposure causing a cholinergic crisis. Key point: a combined muscarinic (salivation, bronchorrhoea, miosis, wheeze) and nicotinic (fasciculations) picture after pesticide exposure is diagnostic of organophosphate poisoning, treated with atropine titrated to secretions/bronchospasm plus an oxime when cholinesterase inhibition is significant.

Reference: NPIS/TOXBASE guidance as reported in Faiz et al., Accidental Organophosphate Poisoning Due to a Bed Bug Pesticide in the UK, PMC, 2024 (https://pmc.ncbi.nlm.nih.gov/articles/PMC11699842/); BNF: Atropine sulfate, medicines.org.uk