Paper II — 2024 June (Supplementary) (2019 Scheme) — Q1
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Paper II
2024 June (Supplementary) (2019 Scheme) · 100 marks · 180 min
Question
Enumerate Antiemetic drugs. Explain the Mechanism of action, uses and adverse effect of
any one group.
Briefly describe proton pump inhibitors (6+4+5)
Q115 marksEssays
Answer
Classification of antiemetics
Class
Examples
5-HT3 receptor antagonists
Ondansetron, Granisetron
D2 receptor antagonists
Metoclopramide, Domperidone
NK1 receptor antagonists
Aprepitant
Antihistaminics/anticholinergics
Promethazine, Hyoscine
Corticosteroids
Dexamethasone
Cannabinoids
Nabilone
One group — 5-HT3 receptor antagonistsMechanism: block serotonin receptors both peripherally (vagal afferents — enterochromaffin cells release serotonin after chemotherapy/radiation mucosal damage) and centrally at the chemoreceptor trigger zone. Uses: chemotherapy/radiotherapy-induced nausea and vomiting (first-line), post-operative nausea/vomiting. Adverse effects: headache, constipation, QT prolongation.
Proton pump inhibitors
Prodrugs that accumulate in the acidic parietal cell canaliculus, convert to their active sulfenamide form, and irreversibly bind H⁺/K⁺-ATPase, blocking the final common step of gastric acid secretion regardless of stimulating pathway. Uses: peptic ulcer disease, GERD, H. pylori eradication, Zollinger-Ellison syndrome. Adverse effects: generally well tolerated short-term; long-term use — hypomagnesemia, fracture risk, vitamin B12 deficiency, increased C. difficile risk.
