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
Lubiprostone is ? 
Select and explain. 
A. New anticholinergic antidiarrhoeal, B. Serotonin agonist, C. New drug to treat peptic ulcer, D. To treat irritable bowel syndrome
D: To treat irritable bowel syndrome
Answer: D: To treat irritable bowel syndrome 
Explanation: Ans. is 'd' i.e., To treat irritable bowel syndrome Lubiprostone is a PG analogue (EP4 receptor agonist), developed recently, represents a new strategy in the treatment of constipating-predominant IBS and chronic constipation. It acts by ? Stimulating CI- channel opening in the intestine. Increasing liquid secretion in gut. Decreasing transit time.