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
All of the following drugs are useful in detrussor instability EXCEPT: 
Select and explain. 
A. Solefenacin, B. Tolterodine, C. Flavoxate, D. Duloxetine
D: Duloxetine
Answer: D: Duloxetine 
Explanation: None