Which pharmacological property distinguishes tiotropium from ipratropium bromide?

• A Tiotropium dissociates slowly from M3 receptors giving bronchodilation lasting about 24 hours ✓
• B Tiotropium is a beta-2 agonist while ipratropium is a muscarinic antagonist
• C Tiotropium crosses the blood-brain barrier producing central anticholinergic effects
• D Tiotropium has significant systemic corticosteroid-sparing activity

Explanation

Both agents are quaternary ammonium muscarinic antagonists that do not cross the blood-brain barrier. Tiotropium binds M3 receptors kinetically slower than it binds M2 receptors, producing prolonged M3 blockade and bronchodilation lasting approximately 24 hours, allowing once-daily dosing. Ipratropium dissociates rapidly and acts for only about 6 hours, requiring multiple daily doses.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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