This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
Which of the following is not a serotonin-norepinephrine reuptake inhibitor? 
Select and explain. 
A. Venlafaxine, B. Duloxetine, C. Milnacipran, D. Tianeptin
D: Tianeptin
Answer: D: Tianeptin 
Explanation: Ref: KDT 8th ed *Tianeptin enhances the reuptake of serotonin rather than inhibiting it whereas the other drugs mentioned in the options inhibit the reuptake of serotonin and nor-epinephrine.