Indication: first-line for treatment of hepatic encephalopathy
Mechanism: Lactulose is converted to lactic acid by intestinal flora → acidification in the gut → conversion of ammonia (NH3) to ammonium (NH4+) → ammonium is excreted in the feces → decreased blood ammonia concentration → decreased absorption of ammonia in the bowel → improved symptoms of hepatic encephalopathy
Rifaximin: a broad-spectrum, nonabsorbable oral antibiotic
Reduces the number of ammonia-producing intestinal bacteria
May be added to lactulose if a second episode occurs to prevent recurrent episodes of hepatic encephalopathy