Optimum dose of sulphasalazine for maintenance treatment in ulcerative colitis.

Sulphasalazine is widely used in the maintenance treatment of ulcerative colitis but the optimum dose is not known. In the present study, 170 patients were allotted at random to three treatment groups, in which the daily dose was 1, 2 and 4 g respectively, and the trial period of treatment lasted for six months. A daily dose of 2 g was found to be much more efficacious than 1 g. A daily dose of 4 g was more efficacious than 2 g but at the price of fairly frequent symptomatic side-effects. Haematological abnormalities were observed at all dosage levels, but they occurred chiefly among the patients on 4 g daily. Both symptomatic and the haematological side-effects were usually associated with high concentrations of serum sulphapyridine and these high levels occurred chiefly among the slow acetylators. It is concluded that, for general use, a daily dose of 2 g sulphasalazine is satisfactory for the maintenance treatment of ulcerative colitis. If a patient does not do well on 2 g daily, it is worth trying a larger dose but in this case the patient's condition should be monitored by blood film, haemoglobin, MCV, and reticulocyte count.