A postoperative patient has paralytic ileus with abdominal distension and no flatus for 48 hours. A direct-acting cholinergic agonist that is resistant to acetylcholinesterase and acts selectively on muscarinic receptors is prescribed. Which drug matches this description?
- A Acetylcholine
- B Carbachol
- C Bethanechol ✓
- D Pilocarpine
Correct answer: C. Bethanechol
Explanation
Bethanechol is a direct muscarinic agonist with negligible nicotinic activity. Its carbamate structure makes it highly resistant to hydrolysis by acetylcholinesterase, giving it a longer duration of action than acetylcholine. It is used for postoperative and postpartum urinary retention and neurogenic ileus. Acetylcholine is destroyed within seconds by cholinesterase and also activates nicotinic receptors, while carbachol retains significant nicotinic activity, so neither fits the description.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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