A Study of Safety and Efficacy of HPN-100 in Subjects With Cirrhosis and Episodic Hepatic EncephalopathyHALT-HE

• Subjects aged 18 and over • Clinical diagnosis of cirrhosis of any cause • Potential to benefit from HE treatment • History of greater than or equal to 2 documented episodes of WH Grade 2 or more HE within the past 6 months, at least one of which occurred within the preceding 3 months • No change in other HE-specific medications within 1 week before randomization • Able to give informed consent and comply with study activities • Availability of at least one designated family member or caregiver who is capable of and willing to assume responsibility for facilitating subject compliance with study procedures • All females of childbearing age and all sexually active males must agree to use an acceptable method of contraception throughout the study.

• Use of any investigational drug within 30 days • Use of prohibited medications • Uncontrolled infection • Active GI bleeding or a history of GI bleeding requiring blood transfusion (> 2 units) within 3 months • Transjugular intrahepatic portosystemic shunt (TIPS) placement or revision within the past 90 days • Recreational drug use or alcohol consumption for subjects with a history of alcohol or drug abuse within 6 months • Lactating and/or pregnant females • Active malignancy • Clinically significant bowel disease, including obstruction, inflammatory bowel disease, or malabsorption • Expected to undergo transplantation within 6 months • Model for end-stage liver disease (MELD) score of > 25