Azathioprine in 50 rheumatoid arthritic patients intolerant or unresponsive to gold or penicillamine

This is a retrospective review of 50 rheumatoid patients who had experienced side effects with gold and/or penicillamine and who were treated with azathioprine in routine clinical practice. The mean duration of the disease at commencement of azathioprine was 9.4 years; despite attempts to maintain the dose at 2.5 mg/kg.d because of minor side effects the average daily dose was 1.68 mg/kg.d. By one year, 11 (22%) had discontinued the drug due to side effects; 6 (12%) had not improved in any respect, 20 (40%) had a reduction in the total number of active joints with maintenance of function and in 13 (26%) the total number of active joints had been reduced by more than a half. During year 2 a further 4 discontinued therapy for adverse reactions. No further formal analysis has been performed though 31 patients were still on the drug with a mean duration of therapy for a period of 5 years. Ten of these had less than half their originally affected joints still active; this condition was usually associated with a fall in ESR and rise in haemoglobin but this was not invariable.