Long-term safety study of iguratimod in patients with rheumatoid arthritis.

We conducted a 52-week clinical study of iguratimod in 394 Japanese patients with rheumatoid arthritis to evaluate the long-term safety of the drug. Iguratimod was administered orally at a daily dose of 25 mg for the first 4 weeks and 50 mg for the subsequent 48 weeks. Some of the patients continued the treatment for 100 weeks for their benefit. The cumulative incidence of adverse events for 100 weeks was 97.6%. The cumulative incidence of adverse reactions was 65.3%; unfavorable symptoms and signs (excluding abnormal laboratory data changes) accounted for 33.2% of the reactions, and abnormal laboratory data changes accounted for 50.4%. The continued treatment rate was 66.8% at week 28 and 53.6% at week 52. For reference, the American College of Rheumatology (ACR) 20 response rate was calculated for the patients who had assessable disease activity, who did not violate the study protocol, and who continued the study treatment at weeks 28 and 52. The rate was 46.9% at week 28 and 41.0% at week 52. To use iguratimod safely for a long time, patients should be observed closely for adverse reactions such as increased hepatic enzymes.