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CTZ-Targeted Antiemetic for Hypercalcaemia Nausea — SCE Palliative Medicine MCQ

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ModerateNausea & VomitingCTZ-Targeted Antiemetic for Hypercalcaemia NauseaSCE Palliative Medicine

A 72‑year‑old woman with advanced cancer has severe nausea from hypercalcaemia (corrected calcium 3.8 mmol/L). She has been rehydrated with intravenous saline and given zoledronic acid. While awaiting the bisphosphonate to take effect (48–72 hours), which short‑term anti‑emetic is most appropriate?

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Correct answer: C — Haloperidol 1.5 mg SC/oral once daily — targets dopamine receptors in the chemoreceptor trigger zone (CTZ), the pathway stimulated by metabolic causes such as hypercalcaemia

Hypercalcaemia causes nausea via stimulation of dopamine receptors in the chemoreceptor trigger zone (CTZ). UK palliative care guidelines (Scottish and North‑West Coast) recommend haloperidol as first‑line for CTZ‑mediated/metabolic nausea, delivered via oral, subcutaneous, or syringe‑pump routes and titrated to effect. Ondansetron targets 5‑HT3 receptors and is appropriate for chemotherapy or serotonin‑mediated nausea, not metabolic causes. Cyclizine acts on vestibular pathways or raised intracranial pressure, inappropriate here. Dexamethasone is reserved for multifactorial or raised intracranial pressure nausea and not first‑line for hypercalcaemia. Metoclopramide is a prokinetic for gastric stasis, not CTZ‑stimulated metabolic nausea.

Reference: North‑West Coast Palliative Care Clinical Practice Summary (2025), Scottish Palliative Care Guidelines: Nausea and Vomiting (2025), https://www.rightdecisions.scot.nhs.uk/scottish-palliative-care-guidelines/symptom-management/nausea-and-vomiting/