Ursodeoxycholic acid exacerbates peginterferon-induced interstitial pneumonia in a patient with hepatitis C.

Pegylated interferon alpha combined with ribavirin is currently the standard treatment for hepatitis C virus (HCV) infection. Ursodeoxycholic acid (UDCA) is used as a complementary treatment in patients who are non-responders or who develop severe side effects of this combined therapy. UDCA is generally considered to be a relatively safe drug. However, we recently encountered a patient with chronic hepatitis C in whom interferon-induced interstitial pneumonia was exacerbated by UDCA. This patient responded to initial antiviral therapy with non-pegylated interferon alpha-2b and ribavirin, but hepatitis recurred soon after the end of treatment. A second course of antiviral therapy using peginterferon alpha-2b and ribavirin achieved normalization of serum transaminases and HCV-RNA, but also caused interstitial pneumonia. After discontinuing peginterferon, this side effect was ameliorated. On the other hand, hepatitis relapsed four months later. UDCA treatment was started and serum transaminase levels decreased, but exacerbation of interstitial pneumonia occurred with marked elevation of the serum KL-6 level. To our knowledge, this is the first reported case of peginterferon-induced interstitial pneumonia showing exacerbation due to UDCA therapy.