A Case of Interstitial  Pneumonitis Caused by Leflunomide.

Lee, Jung Hwa; Cheon, Won Seok; Seo, Young Il; Eom, Kwang Seok; Jang, Seung Hun; Bahn, Joon Woo; Kim, Dong Gyu; Jung, Ki Suck

doi:2005.58.1.83

Tuberc Respir Dis > Volume 58(1); 2005 > Article

Case Report

Tuberculosis and Respiratory Diseases 2005;58(1):83-88.
DOI: https://doi.org/10.4046/trd.2005.58.1.83 Published online January 1, 2005.

A Case of Interstitial Pneumonitis Caused by Leflunomide.

Jung Hwa Lee, Won Seok Cheon, Young Il Seo, Kwang Seok Eom, Seung Hun Jang, Joon Woo Bahn, Dong Gyu Kim, Ki Suck Jung

Department of Internal Medicine, Hallym University College of Medicine, Korea. pulmoks@hallym.ac.kr

Abstract

Leflunomide is a new disease modifying anti rheumatic drug (DMARD) for the treatment of active rheumatoid arthritis. Its mechanism of action differs from other DMARDs in that it inhibits the de novo pyrimidine synthesis by inhibiting dihydroorotate dehydrogenase and therefore prevents the proliferation of activated lymphocytes. As it has been prescribed worldwide, there is a great deal of much concerns regarding its potential adverse effects. Because leflunomide has an active metabolite with a long elimination half life of approximately 2 weeks, serious adverse reactions may occur even after the leflunomide treatment has been stopped. The profile of serious reactions includes liver dysfunction, hematological disorders, severe skin reactions and respiratory dysfunction. Respiratory dysfunctions with leflunomide therapy are very rare and its incidence is lower than that of methotrexate therapy. However, there are reports in Japan showing that 5 patients died of interstitial pneumonitis and another 11 patients developed serious lung complications associated with leflunomide. This suggests the possibility of fatal respiratory toxicity of leflunomide. There are no reports of interstitial pneumonitis associated with leflunomide in Korea. We report a case of a 62-year old woman who developed interstitial pneumonitis, which might have been induced by leflunomide during the treatment of rheumatoid arthritis.

Key Words: Leflunomide, Interstitial pneumonitis, Rheumatoid arthritis, Methotrexate