6. A history of hepatic impairment or abnormal liver function tests (defined as ALT, AST, alkaline phosphatase or bilirubin >1.5 times the upper limit of normal) with the exception that bilirubin elevations up to 2.0 times the upper limit of normal in the presence of normal liver enzymes will be permitted in patients with documented Gilbert's Disease. Subjects with Gilbert's disease not to be excluded.