Clinical course of Case 2. Bosentan 125mg/day was started in July 2011; however, liver function abnormalities appeared after 3 weeks (August 2011). Bosentan was reduced to 62.5mg/day and ursodeoxycholic acid (300mg/day) was added simultaneously. Liver function abnormalities were normalized by September 2011. Bosentan was increased to the initial dose (125mg/day) concomitantly with increased ursodeoxycholic acid (600mg/day), and no liver function abnormalities appeared. Abbreviations: ALP, alkaline phosphatase; ALT, alanine aminotransferase; GGT, gamma-glutamyltransferase.