Azathioprine and penicillamine in treatment of rheumatoid arthritis: a controlled trial.

Sixty-five patients, 33 receiving azathioprine and 32 receiving penicillamine, took part in a one-year, single-blind external-observer trial designed to compare the efficacy and toxicity of these two drugs in the treatment of rheumatoid arthritis. By six months there was a significantly greater rise in haemoglobin and fall in erythrocyte sedimentation rate among those receiving penicillamine, and by one year this difference remained only in the increase in haemoglobin levels. Fifteen patients, 10 on azathioprine and 5 on penicillamine, had to stop treatment because of side effects; 90 single side effects occurred, 48 in those on penicillamine and 42 in those on azathioprine. After one year both drugs were similar in efficacy and toxicity, but longer-term trials are needed. Both drugs were effective.