Opioid Overdose — MRCPsych Paper B MCQ

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EasySubstance MisuseOpioid OverdoseMRCPsych Paper B

A 30-year-old man is brought to the emergency department unconscious after a suspected opioid overdose. His respiratory rate is 6/min and his pupils are pinpoint. Airway support, oxygen and assisted ventilation have been initiated. Which drug should now be administered to reverse the respiratory depression?

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Correct answer: B — Intravenous naloxone

Intravenous naloxone is the correct answer. Profound respiratory depression, unconsciousness and pinpoint pupils strongly indicate opioid toxicity. Naloxone is a rapidly acting competitive opioid-receptor antagonist used to reverse opioid-induced respiratory and central nervous system depression. It is given alongside, not instead of, airway management, oxygen and assisted ventilation. Its effect may be shorter than that of the ingested opioid, particularly with long-acting opioids, so repeated doses, close monitoring or an intravenous infusion may be required. Naltrexone is not used for emergency reversal of overdose. Buprenorphine is an opioid partial agonist and would not reverse toxicity. Flumazenil antagonises benzodiazepines and carries risks in mixed overdose. Adrenaline is not an opioid antidote.

Reference: electronic Medicines Compendium. Naloxone Hydrochloride 400 micrograms/ml Solution for Injection/Infusion, SmPC sections 4.1–4.4. Updated 2023. https://www.medicines.org.uk/emc/product/6589/smpc