A 62-year-old man develops postoperative urinary retention after hip replacement. A cholinergic agonist that selectively stimulates muscarinic receptors, is resistant to acetylcholinesterase, and has negligible nicotinic action is chosen to stimulate detrusor contraction. Which drug fits this description?
- A Acetylcholine
- B Bethanechol ✓
- C Carbachol
- D Methacholine
Correct answer: B. Bethanechol
Explanation
Bethanechol is a muscarinic-selective agonist with a carbamate structure that makes it resistant to acetylcholinesterase, giving it a longer duration of action. It has virtually no nicotinic activity, so it contracts the detrusor without ganglionic or neuromuscular effects. Acetylcholine is destroyed rapidly and acts on all cholinoreceptors, carbachol has strong nicotinic activity, and methacholine is used mainly as a bronchial provocation agent in asthma testing.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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