This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Tiotropium is used for: 
Select and explain. 
A. Treating urinary retention, B. Treating ileus, C. Increasing salivation, D. Treating asthma
D: Treating asthma
Answer: D: Treating asthma 
Explanation: Tiotropium (Tiotropium Bromide) is a recently developed congener of Ipratropium bromide. It is an anticholinergic (antimuscaranic agents) used for the treatment of Asthma and COPD as it produces bronchodilation and relieves symptoms in such patients. It is poorly absorbed from the lungs and GIT and hence their systemic side effects are rare. Ref: KDT, 6th Edition, Pages 106, 110, 222;Basic and Clinical Pharmacology By Beram Katzung, 10th Edition, Page 114