This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2017, Subject name: Pharmacology
Lubiprostone is a: 
Select and explain. 
A. Chloride channel activator, B. Chloride channel inhibitor, C. Sodium channel activator, D. Sodium channel inhibitor
A: Chloride channel activator
Answer: A: Chloride channel activator 
Explanation: Lubiprostone :- selectively stimulates type 2 chloride channels in epithelial cells thereby causing an efflux of chloride into the intestinal lumen. - The resultant fluid secretion into the gastrointestinal lumen provides a bolus effect that softens stool, increases intestinal transit, and improves symptoms of constipation. - Lubiprostone acts locally within the intestinal tract, is rapidly metabolized, and has very low systemic bioavailability.