About Ipratropium Bromide Anticholinergic, Muscarinic antagonist,Tropane derivative, Bronchodilator( Anti asthma) Mechanism of Action of Ipratropium Bromide Ipratropium bromide selectively acts on bronchial muscle without altering volume or consistency of respiratory secretions. It inhibits vagally mediated reflexes by antagonizing the actions of acetylcholine. It prevents the acetylcholine mediated increase in intracellular cyclic GMP concentration that results from interaction of acetylcholine with muscarinic receptor on bronchial smooth muscle. It does not depress the muco-ciliary clearance by bronchial epithelium. It blocks the cholinergic constrictor tone and acts primarily in the larger airways.