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
Longest acting drug among the following drugs for over reactive bladder: 
Select and explain. 
A. Oxybutynin, B. Trospium, C. Solifenacin, D. Flavoxate
C: Solifenacin
Answer: C: Solifenacin 
Explanation: Solefenacin is the longest acting drug from this group.
Gastro-intestinal tract

Anticholinergic drugs decrease the motility, tone and secretions in the gastrointestinal tract.

— Pirenzepine and telenzepine are selective M1 blockers useful in peptic ulcer disease.
— Hyoscine, dicyclomine, propantheline, oxyphenonium and clidinium are useful as anti-spasmodic agents for the treatment of intestinal colic.
— Darifenacin and solefenacin are selective M3 blockers useful for irritable bowel syndrome and overactive bladder.
Oxybutynin is shortest acting and solefenacin is longest acting drug from this group.
Mirabegron is a newer drug approved for overactive bladder. It acts by stimulating β3 receptors.