Ipratropium is an anticholinergic used in COPD. Which choice best describes its mechanism of action?

• A. Blocking muscarinic receptors and reducing secretions.
• B. Activating beta-adrenergic receptors to cause bronchodilation.
• C. Bronchodilation by blocking muscarinic receptors and reducing secretions.
• D. Inhibiting mucus production by non-anticholinergic pathways.

Answer: (D)

The key idea is that ipratropium is an anticholinergic, meaning it blocks muscarinic receptors in the airways. By blocking these receptors, it reduces vagal (acetylcholine-mediated) bronchoconstriction and also decreases glandular secretions in the airway, leading to bronchodilation and drier airways. This mechanism is distinct from beta-adrenergic activation (which causes bronchodilation via a different receptor system) and from non-anticholinergic pathways. Therefore, describing bronchodilation by blocking muscarinic receptors and reducing secretions best captures ipratropium’s action.