About tiotropiumanticholinergic(muscarinic antagonist) bronchodilator, thiophene, antiasthma,in copd.mechanism of action tiotropium selectively acts on bronchial muscle by binding very tightly to bronchial m1/m3 muscarinic receptors and produces long lasting bronchodilatation. 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.indications 1. chronic obstructive pulmonary diseases 2. bronchospasm 3. chronic bronchitis 4. emphysema.typical dosage for tiotropiuminhalation: contents of one rotacap (18mcg) once daily- inhaled with the rotahaler device