Portosystemic Encephalopathy Medication

Updated: Sep 17, 2019
  • Author: Gagan K Sood, MD; Chief Editor: BS Anand, MD  more...
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Medication Summary

The mainstay of therapy is lactulose, a nonabsorbed disaccharide. The actions of this agent are multiple and culminate in reduced delivery of ammonia to the brain. Lactitol, another disaccharide, may be better tolerated, but it is used relatively infrequently. Oral antibiotics are not used as often, but they have a role in patients who are intolerant of lactulose. Flumazenil, bromocriptine, branched-chain amino acids (BCAAs), and L-ornithine have been investigated but cannot be considered as first-line therapy.


Nonabsorbed disaccharides

Class Summary

Promote acidification, sterilization, and ammonium ion trapping in colon lumen. Increased stool frequency occurs, and all mechanisms likely reduce ammonia delivery to the systemic circulation and the brain. Inexpensive and generally well tolerated.

Lactulose (Cephulac, Cholac, Constulose)

DOC; inhibits diffusion of NH3 into blood by producing an acidic pH that causes conversion of NH3 to NH4.


Nonabsorbed antibiotics

Class Summary

Used for gut sterilization.

Neomycin PO (Neo-Tabs)

Second-choice drug. Small percentage of neomycin may be absorbed with each dose. Chronic administration may lead to nephrotoxicity or ototoxicity.

Rifaximin (Xifaxan)

Oral antibiotic that reduces ammonia-producing enteric bacteria in patients with hepatic encephalopathy. In vitro, elicits broad-spectrum activity against gram-positive and gram-negative aerobic and anaerobic enteric bacteria. Minimal systemic absorption (< 0.4%); concentrated in GI tract; low risk for inducing bacterial resistance. Rifampin structural analog. Binds to beta-subunit of bacterial DNA-dependent RNA polymerase, thereby inhibiting RNA synthesis.