1. Previous participation in any trial involving AST-120

2. History of TIPS or surgically created portocaval shunt

3. Treatment for overt HE within the past 3 months

4. Use of lactulose, rifaximin, neomycin or other antibiotics in the past 7 days

5. Active alcohol abuse

6. Psychosis or organic brain syndromes due to alcohol or other causes

7. Use of interferon and sedating or cognition-altering drugs

8. Undergoing chemotherapy or radiotherapy for the treatment of cancer

9. Active GI bleeding within the past 3 months

10. Presence of an active infection

11. Presence of signs and symptoms of severe dehydration

12. Other major physical or major psychiatric illness within the past 6 months

13. Pregnant, breast feeding, or planning to become pregnant during the study

14. Using hormonal contraception as the only method of birth control

AST-120 Used to Treat Mild Hepatic Encephalopathy