Answer
Inhaled ipratropium bromide monohydrate acts locally on bronchial smooth muscle, blocking acetylcholine at muscarinic receptors and preventing the rise in intracellular calcium that causes airway constriction.
Sources for this answer
- Atrovent Inhaler CFC-FreeBoehringer Ingelheim Limited · emc · SmPC §5.1 Pharmacodynamic properties · Version 13Document updated
Sources checked