Which drug is used to stimulate GI motility after surgery?

• A. Bethanechol
• B. Pilocarpine
• C. Cevimeline hydrochloride
• D. Acetylcholine

Answer: (A)

Postoperative ileus occurs when the gut slows down after surgery, and restoring smooth muscle activity can help resume motility. Bethanechol is a direct-acting muscarinic agonist that targets the M receptors on GI smooth muscle, increasing tone and peristaltic activity. It’s resistant to acetylcholinesterase, so its effects on the GI tract are sustained, and it mainly drives muscarinic (not nicotinic) actions, which helps focus the effect on smooth muscle without much skeletal-muscle stimulation. Because of this targeted action, it’s used clinically to treat postoperative ileus and urinary retention.

The other agents don’t fit this clinical need as well. Pilocarpine and cevimeline are mainly used to stimulate secretions for dry mouth (and pilocarpine is also used in glaucoma); their primary clinical use isn’t to boost GI motility. Acetylcholine itself is rapidly broken down in the circulation and causes widespread muscarinic and nicotinic effects, making it impractical and unsafe for treating postoperative ileus.