Report on chloroquine and dapsone in the treatment of rheumatoid arthritis: a 6-month comparative study.

A controlled study compared 6 months' treatment of 60 patients with rheumatoid arthritis (RA). Half were randomly allocated to treatment with chloroquine 250 mg daily, the other half dapsone 100 mg daily (50 mg/day for the first 7 days) following a one-month run-in assessment period. All patients had active or progressing disease. Both treatment groups showed significant improvement in morning stiffness, number of painful joints, pain scores, Ritchie index, and proximal interphalangeal joint size, and the chloroquine group alone in grip strength. Laboratory tests showed significant decreases in erythrocyte sedimentation rate, C-reactive protein, and total serum protein levels, with significant increase in serum albumin in the dapsone group, where there was a significant mean drop in haemoglobin (less than 1 g/dl) and a rise in serum bilirubin, associated with its haemolytic effect. X-ray erosion scores were not significantly affected. The clinical and laboratory responses became evident by the time of the 2-month assessment. Criteria for clinical and laboratory improvement were defined, according to which there were 21/26 improvers in the chloroquine group and 12/29 in the dapsone group. It is concluded that although both are effective preparations, chloroquine showed a significantly higher improvement rate and was certainly better tolerated. It is the preferred treatment for patients with active or progressive disease not controlled by nonsteroidal anti-inflammatory drugs, with dapsone as an alternative for patients who fail to respond to or cannot tolerate chloroquine.