Which of the following GI medications has strong anticholinergic activity?

• A. Metoclopramide
• B. Mineral oil
• C. Atropine
• D. Esomeprazole

Answer: (C)

Anticholinergic activity means blocking muscarinic receptors for acetylcholine, which reduces secretions and slows or disrupts normal signaling in the gut and other organs. In older adults, strong anticholinergic effects increase the risk of delirium, confusion, constipation, urinary retention, and other adverse effects, so Beers Criteria flags drugs with high anticholinergic burden.

Among the options, atropine is a classic antimuscarinic agent; it directly blocks muscarinic acetylcholine receptors, producing strong anticholinergic effects. That direct receptor blockade explains why it has the strongest anticholinergic activity of the group.

The other medications act through different primary mechanisms. Metoclopramide is a dopamine D2 receptor antagonist with prokinetic and antiemetic effects, not a primary muscarinic blocker. Mineral oil is a plain lubricating laxative with no anticholinergic action. Esomeprazole is a proton pump inhibitor that reduces acid production, with no significant anticholinergic activity.