Safety and Efficacy of AST-120 Compared to Lactulose in Patients With Hepatic Encephalopathy

Inclusion Criteria: * Patients with End Stage Liver Disease secondary to any cause (patients who have undergone portosystemic shunting (TIPS) procedure \> 3 months prior to randomization can be included) * Lactulose naïve patients or patients currently on an established dose of lactulose * MELD score ≤ 15 (MELD score up to 20 is allowable if it has remained stable for at least 3 months) * Meet the criteria for Stage 1-2 hepatic encephalopathy according to the Westhaven Scale * Patients must have discontinued rifaximin or other oral antibiotics for at least 48 hours prior to randomization * Able and willing to comply with all protocol procedures for the planned duration of the study * Able and willing to understand, sign and date an informed consent document, and authorize access to protected health information * Have a person (spouse, relative, or friend) willing to accompany the patient to the study visits (patients in this condition are not recommended to drive a vehicle) * Females must be postmenopausal, surgically incapable of bearing children, or practicing a reliable method of birth control (intrauterine devices, spermicide and barrier). Partner/spouse sterility may also qualify at the investigator's discretion. Females of child-bearing potential must have a negative urine pregnancy test at baseline. Note: Patients already on lactulose and randomized to AST-120 will stop taking lactulose on the day they begin taking AST-120. Exclusion Criteria: * Patients whose condition necessitates continuous administration of antibiotics (e.g. rifaximin, neomycin, metronidazole) * Patients undergoing chemotherapy for treatment of cancer (patients with hepatocellular carcinoma being treated by methods other than chemotherapy may be enrolled) * Patients who require continued treatment with narcotics or sedatives * Patients who have active GI bleeding * Patients who have an active infection * Patients who have signs and symptoms of severe dehydration * Poor tolerability of venipuncture or lack of adequate venous access for required blood sampling * Unable to attend all visits required by the protocol * Female patients must be EXCLUDED if they are pregnant, breast feeding, planning to become pregnant during the study or using hormonal contraception as their only method of birth control