Lactulose enemas in the treatment of hepatic encephalopathy. Do we help or harm?

The administration of lactulose enemas instead of or in combination with oral lactulose is common practice in patients with hepatic encephalopathy. Lactulose is a non-absorbable disaccharide that is catabolized by the bacterial flora to short chain fatty acids (e.g., lactic acid and acetic acid) which lower the colonic pH. This pH favors the formation of non-absorbable NH4+ from NH3, trapping NH4+ in the colon and thus reducing plasma ammonia concentrations. Lactulose therapy is considered as a first-line treatment and can be administered both orally and rectally.