A 30-year-old woman on a long voyage develops severe motion sickness. Scopolamine (hyoscine) is prescribed as a transdermal patch. The antiemetic action of scopolamine is mediated by blockade of muscarinic receptors in which location?
- A Chemoreceptor trigger zone in area postrema
- B Gastrointestinal smooth muscle
- C Vestibular nuclei and vestibular-cerebellar pathway ✓
- D Vagal afferent nerve terminals
Correct answer: C. Vestibular nuclei and vestibular-cerebellar pathway
Explanation
Scopolamine is the drug of choice for motion sickness. It acts centrally by blocking muscarinic (M1/M3) receptors in the vestibular nuclei and the vestibulocerebellar pathway, reducing the mismatch signaling that triggers nausea. It does not work primarily on the CTZ (which has dopamine and serotonin receptors, not muscarinic as the dominant target) or on GI smooth muscle for this indication. Its central anticholinergic activity distinguishes it from peripheral antimuscarinics.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.