Classify antiemetic drugs and describe their mechanism of action.

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College Answer

Antiemetics can be classified by their receptor actions including, dopamine antagonists,
serotonin antagonists, antihistamines, anticholinergics, antimotilinic etc or by their drug type
– butyrophenones, phenothiazines, benzamides etc. Marks were divided between each class,
and for “other/novel” antiemetics – such as, steroids, GABA agonists, alpha 2 agonists, mu
receptor antagonists, canabinoids, propofol and NK1 receptor antagonists.
Candidates were expected to mention the drug type, receptor interaction, the location of the
receptors and the pathways inhibited by the drug – central CTZ, vestibular nuclei, solitary
tract nucleus, vagal afferents or GIT motility and secretions. Most drugs work at one or more
of these sites and marks were awarded for mention of this. Commonest errors were omission
of adequate detail in each class. Antihistamines, anticholinergics and “others/novel” were
frequently omitted.
Syllabus - Q12e and Q2b2a
Reference: Chp 37 Goodman and Gillman