Which of the following laxatives lowers blood ammonia level in hepatic encephalopathy?: (A) Bisacodyl, (B) Liquid paraffin, (C) Lactulose, (D) Magnesium sulfate
Answer is C. (Ref: KDT 6/e p655) Lactulose is degraded to lactic acid that conves NH3 to NH4+. As ionic molecules cannot cross biological membranes, it is not absorbed and is thus excreted.