Which direct-acting cholinergic drug is used to treat GI and urinary tract atony?

Which direct-acting cholinergic drug is used to treat GI and urinary tract atony?

• A. Pilocarpine
• B. Neostigmine
• C. Bethanechol
• D. Atropine

Answer: (C)

Direct-acting cholinergic drugs stimulate muscarinic receptors on smooth muscle, boosting motility and tone in the GI tract and bladder. Bethanechol specifically acts as a direct muscarinic agonist, focusing on these smooth muscles to increase intestinal contractions and detrusor (bladder) contraction. Because it’s a choline ester with minimal nicotinic effects and limited CNS penetration, it effectively treats nonobstructive ileus and urinary retention without broad neuromuscular stimulation or CNS issues. Pilocarpine also activates muscarinic receptors but is mainly used for glaucoma and xerostomia, not for GI/urinary atony. Neostigmine is indirect-acting (inhibits acetylcholinesterase), raising acetylcholine levels and stimulating both muscarinic and nicotinic receptors, which isn’t the direct-acting approach aimed for here. Atropine blocks muscarinic receptors and would worsen GI/urinary atony, not treat it.

Direct-acting cholinergic drugs stimulate muscarinic receptors on smooth muscle, boosting motility and tone in the GI tract and bladder. Bethanechol specifically acts as a direct muscarinic agonist, focusing on these smooth muscles to increase intestinal contractions and detrusor (bladder) contraction. Because it’s a choline ester with minimal nicotinic effects and limited CNS penetration, it effectively treats nonobstructive ileus and urinary retention without broad neuromuscular stimulation or CNS issues.

Pilocarpine also activates muscarinic receptors but is mainly used for glaucoma and xerostomia, not for GI/urinary atony. Neostigmine is indirect-acting (inhibits acetylcholinesterase), raising acetylcholine levels and stimulating both muscarinic and nicotinic receptors, which isn’t the direct-acting approach aimed for here. Atropine blocks muscarinic receptors and would worsen GI/urinary atony, not treat it.