A study of the longterm efficacy and toxicity of cyclosporine A in rheumatoid arthritis.

We determined the longterm efficacy and toxicity of cyclosporine A in rheumatoid arthritis (RA) in an open clinical trial, at a single centre, outpatient rheumatology clinic. The initial dose was 5 mg/kg/day increased to 10 mg/kg/day with adjustments for toxicity and plasma cyclosporine A levels. We measured efficacy by the Ritchie articular index, pain and function on a 10 cm visual analog scale, C-reactive protein (CRP) and erythrocyte sedimentation rate. Toxicity was evaluated by patient reports, serum creatinine, cyclosporine A levels and liver function tests. Median treatment duration was 29 months (16.5-38). At 24 months median reduction in Ritchie articular index was 50% (9-79); pain: 49% (21-77), with a 50% (4-76) improvement in function; and CRP fell by 72.5% (22-87). The main side effect was a 40% (27-47) decline in estimated creatinine clearance. We conclude that cyclosporine A at doses below 5 mg/kg/day is associated with clinically significant improvements in indices of disease activity in RA. Renal dysfunction was the most frequent side effect.