Which antiemetic is listed as having strong anticholinergic properties?

• A. Promethazine
• B. Metoclopramide
• C. Ondansetron
• D. Granisetron

Answer: (A)

Promethazine stands out because it is a first-generation antihistamine with strong muscarinic (anticholinergic) blockade. That anticholinergic activity explains many of its side effects—dry mouth, blurred vision, urinary retention, constipation, and possible confusion—reflecting a high anticholinergic burden. Metoclopramide acts mainly by blocking dopamine D2 receptors and enhancing gastric motility, so it doesn’t rely on anticholinergic effects. Ondansetron and granisetron block serotonin 5-HT3 receptors and their antiemetic action comes from serotonin pathway inhibition rather than muscarinic blockade, giving them little to no anticholinergic activity. Because of these mechanisms, promethazine is the antiemetic with strong anticholinergic properties.