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
[{'content': 'All of the following drugs are used for the treatment of urinary incontinence except - \nSelect and explain. \nA. Oxybutynin, B. Ipratropium, C. Darifenacin, D. Tolterodine', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Ipratropium o In human urinary bladder, M2 and M. receptors are expressed predominantly with the M3 subtype mediating direct activation of contraction. M2 receptor acts indirectly by inhibiting relaxation by norepinephrine and epinephrine. o Drugs used for urinary incontinence ? Selective M3 antagonists - Oxybutynin, Darifenacin, solifenacin, Tolterodine. Nonselective antagonist - Trospium, Propiverine. Tricyclic antidepressant - Imipramine.", 'role': 'assistant'}]