Which pharmacologic agents slow gastric emptying?

• A. Cholinergic agonists
• B. Anticholinesterases
• C. Guanethidine
• D. Anticholinergics

Answer: (D)

Blocking acetylcholine’s action on the gut slows gastric emptying. The parasympathetic (vagal) system uses acetylcholine to stimulate smooth muscle contractions and propulsive movements in the stomach. When you block muscarinic receptors with an anticholinergic, you diminish that excitation, reducing peristalsis and delaying how quickly the stomach empties its contents.

Cholinergic agonists and anticholinesterases both boost acetylcholine signaling, which enhances GI motility and speeds gastric emptying. Guanethidine reduces sympathetic influence, which can indirectly increase parasympathetic activity and tends to promote motility rather than slow it. Anticholinergics, by contrast, dampen muscarinic signaling in the GI tract, making them the agents that slow gastric emptying.