Steady-State Pharmacokinetics of Rifaximin 550 mg Tablets in Healthy and Hepatically Impaired Subjects

The primary objective of this study is to characterize the steady state plasma PK of
rifaximin (550 mg BID) in subjects with severe hepatic impairment (MELD 19 to 25 and MELD
>25), as well as healthy subjects with normal hepatic function.

Inclusion Criteria:

- Hepatically impaired subjects will be ≥18 years of age, have a diagnosis of liver
cirrhosis and a MELD score of ≥19 at Screening. Note: At least 6 of the hepatically
impaired subjects will have a MELD score of >25.

Exclusion Criteria:

- Subject has known allergy to rifaximin, rifampin, or other rifamycins, excipients
and/or vehicles used in the formulation, or any other clinically significant
allergies.

- Subject has participated in an investigational drug or device study within 30 days
prior to Day 1 (Baseline).

- Subject has any concurrent illness (other than liver cirrhosis), disability or
circumstance that may affect the interpretation of clinical data, could cause
noncompliance with treatment or visits or otherwise contraindicates participation in
this study in the opinion of the investigator.