A postoperative patient has paralytic ileus and non-obstructive urinary retention. A direct-acting muscarinic agonist is prescribed to increase detrusor and gut smooth muscle tone. The chosen drug resists acetylcholinesterase because of its carbamate structure and shows negligible nicotinic activity. Which drug fits this description?

• A Pilocarpine
• B Methacholine
• C Carbachol
• D Bethanechol ✓

Explanation

Bethanechol is a muscarinic-selective agonist with a carbamate ester, making it resistant to acetylcholinesterase, so its action lasts longer than acetylcholine. It is given orally or subcutaneously for postoperative and postpartum urinary retention and neurogenic ileus. Carbachol also resists hydrolysis but has substantial nicotinic ganglionic activity, which bethanechol lacks, and methacholine is rapidly hydrolysed and used mainly as a bronchial provocation agent.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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