5-Thiopyridoxine in rheumatoid arthritis: clinical and experimental studies.

Twelve patients with rheumatoid arthritis who had failed to respond to or developed side effects preventing further use of penicillamine were given 5-thiopyridoxine (5-TP). These patients were compared with 48 patients with similar indications randomly assigned to placebo or penicillamine. Both 5-TP and penicillamine were superior to placebo, and the effectiveness of the two active drugs was similar. Both produced a gradual amelioration of symptoms and signs of the disease accompanied by reduction in erythrocyte sedimentation rate, rheumatoid factor titer, and immunoglobulins. Nine patients on 5-TP were able to continue treatment with good control of the disease for at least 18 months. Toxic effects included rashes, proteinuria, loss of taste, and mouth ulcers. Patients who had developed a particular side effect with penicillamine did not necessarily do the same with 5-TP. This is the second mercaptan compound which has suppressive effects on the clinical and laboratory features of rheumatoid arthritis. Because of their similarities, 5-TP and penicillamine were studied in various experimental systems in an attempt to find some common biochemical or pharmacologic action. Among the properties studied were the effects on copper, vitamin B6 metabolism, dermal collagen, and mixed disulfide formation. Results with animal models of inflammation were also examined. The only common action was enhancement of the secondary lesions of adjuvant arthritis.