Study to Assess the Efficacy and Safety of Rifaximin Soluble Solid Dispersion (SSD) Tablets Plus Lactulose for the Treatment of Overt Hepatic Encephalopathy (OHE).

The primary objective of this study is to assess the efficacy of rifaximin SSD plus lactulose versus placebo plus lactulose for the treatment of overt hepatic encephalopathy (OHE). The secondary objectives of this study are to assess the safety of rifaximin SSD in subjects with OHE and to assess the effects of treatment with rifaximin SSD on key secondary endpoints.

Inclusion Criteria:

• Male or female age 18 to 75 years of age (inclusive) at the time of screening.
• Females of childbearing potential, defined as a female who is fertile following menarche, must have a negative serum pregnancy test at screening and agree to use an acceptable method of contraception throughout their participation in the study.

Note: Female subjects who have been surgically sterilized (e.g., hysterectomy or bilateral tubal ligation) or who are postmenopausal (defined as total cessation of menses for > 1 year) will not be considered "female subjects of childbearing potential".

• Subject is hospitalized with liver cirrhosis and/or OHE and has a confirmed diagnosis of OHE at Baseline.
• Subject has a Grade 2 or Grade 3 HE episode according to the HE Grading Instrument (HEGI) following 8 to 12 hours of intravenous (IV) hydration and lactulose treatment.

Exclusion Criteria:

• Subject has an uncontrolled major psychiatric disorder including major depression or psychoses as determined by the investigator.
• Subject has been diagnosed with an infection for which they are currently taking oral or parenteral antibiotics, which cannot be discontinued at time of enrollment. Note: Subjects currently taking Rifaximin are not excluded
• Subject shows presence of intestinal obstruction or has inflammatory bowel disease.
• Subject has uncontrolled Type 1 or Type 2 diabetes. Note: Subjects with controlled diabetes may be enrolled if they are on stable doses of oral hypoglycemic drugs for at least 3 months prior to screening, and demonstrate clinically acceptable blood glucose control at Baseline, as determined by the investigator.
• Subject has an active malignancy (exceptions: non-melanoma skin cancers).

Blinding will be maintained in the QD SSD cohorts by administering placebo as the second daily dose.