Laxative used in hepatic encephalopathy

Ref: Goodman & Gillman 13th ed. P 928, 940USES OF LACTULOSE* Constipation caused by opioids* Idiopathic chronic constipation* Lactulose also used to treat hepatic encephalopathyLACTULOSE IN HEPATIC ENCEPHALOPATHY* Impaired liver function/severe liver disease are unable to detoxify the ammonia coming from colon which is produced by colonic bacterial metabolism of fecal urea.* The drop in luminal pH that accompanies hydrolysis to short-chain fatty acids in the colon results in "trapping" of the ammonia by its conversion to the polar ammonium ion.* Combined with the increase in colonic transit, this therapy significantly lowers circulating ammonia levels. The therapeutic goal in this condition is to give sufficient amounts of lactulose (usually 20-30g three to four times per day) to produce two to three soft stools a day with a pH of 5-5.5.