Ondansetron Antiemetic — MFDS Part 1 MCQ

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ModeratePharmacologyOndansetron AntiemeticMFDS Part 1

An adult develops established nausea and vomiting in recovery after dental surgery performed under general anaesthesia. Which drug is licensed for this indication and acts as a selective 5-HT3 receptor antagonist?

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Correct answer: C — Ondansetron

Ondansetron is the correct answer. It is licensed in the UK for prevention and treatment of postoperative nausea and vomiting and is a selective 5-HT3 receptor antagonist. Its antiemetic effects involve peripheral vagal afferent and central emetic pathways. Cyclizine is predominantly an H1-antihistamine with antimuscarinic activity, while metoclopramide mainly antagonises dopamine D2 receptors and also has prokinetic actions. Dexamethasone is a glucocorticoid that may be used as perioperative antiemetic prophylaxis but is not a 5-HT3 antagonist. Flumazenil reverses benzodiazepine sedation and does not treat postoperative nausea and vomiting. Ondansetron can prolong the QT interval, so relevant cardiac risk factors and interacting medicines should be considered.

Reference: hameln pharma ltd. Ondansetron 2 mg/ml solution for injection/infusion, Summary of Product Characteristics, sections 4.1, 4.2 and 5.1; text revised 2025. https://www.medicines.org.uk/emc/product/101465/smpc