This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Pharmacology
Drug useful in hepatic encephalopathy is: 
Select and explain. 
A. Magnesium sulphate, B. Lactulose, C. Bisacodyl, D. Biphosphonates
B: Lactulose
Answer: B: Lactulose 
Explanation: Ans. (B) Lactulose(Ref: KDT 8th/e p725)Lactulose is a laxative that acts by conversion to short chain fatty acids in the colon.These fatty acids result in decrease in pH of intestinal juice.At low pH, ammonia becomes ionized (NH4+ ) and thus cannot be absorbed.