This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
Which of the following drugs increases gastro- intestinal motility? 
Select and explain. 
A. Glycopyrrolate, B. Atropine, C. Neostigmine, D. Fentanyl
C: Neostigmine
Answer: C: Neostigmine 
Explanation: Ans. (C) Neostigmine(Ref: KDT 8th/e p130)Cholinergic drugs increase GI motility. Neostigmine is an inhibitor of the enzyme AChE (which is responsible for the breakdown of ACh). It thus acts like a cholinergic agent.Glycopyrrolate and atropine are anticholinergic drugs; thus reduce GI motility. Fentanyl is an opioid and can cause constipation.