A study of clofazimine in the rat.

1. Clofazimine, an anti-mycobacterial agent used in the treatment of leprosy, has been reported to be particularly effective in the treatment of acute erythema nodosum leprosum reactions.2. The present experiments were designed to study in the rat this apparent anti-inflammatory activity.3. In doses relatively non-toxic to the animals clofazimine inhibited both rat adjuvant arthritis and the inflammatory paw swelling following an adjuvant injection.4. Clofamizine failed to inhibit both the primary antibody response to sheep erythrocytes and the tuberculin skin response.5. It is concluded that clofazimine exhibits definite anti-inflammatory (but not immunosuppressive) activity, and that it should be tested in patients with rheumatoid arthritis.