Ipratropium bromide is preferred over atropine for bronchodilation in COPD because:

• A Ipratropium selectively blocks M3 muscarinic receptors whereas atropine blocks all subtypes including cardiac M2
• B Ipratropium has a longer duration of action than atropine due to irreversible receptor binding
• C Ipratropium is a quaternary ammonium compound with negligible systemic absorption and CNS penetration, producing bronchodilation without tachycardia or anticholinergic CNS effects ✓
• D Ipratropium undergoes active transport into bronchial smooth muscle via organic cation transporters

Explanation

Ipratropium bromide is a synthetic quaternary ammonium derivative of atropine. The quaternary ammonium charge prevents significant GI absorption and CNS penetration after inhalation, so its muscarinic blockade is largely confined to airway smooth muscle. This avoids the systemic anticholinergic effects of atropine (tachycardia, urinary retention, dry mouth, mydriasis, CNS stimulation). Both atropine and ipratropium block all muscarinic receptor subtypes non-selectively.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.