Comparative trial of remission prophylaxis in quiescent Crohn's disease with oral 4-aminosalicylic acid versus 5-aminosalicylic acid slow release tablets

4-Aminosalicylic acid (4-ASA) has been suggested to be effective in the treatment of active ulcerative colitis. Oral slow release tablets containing 4-ASA (1.5g/day) were compared with those containing 5-ASA (1.5g/day) in the maintenance treatment of Crohn's disease in a one-year double-blind, randomized study involving 60 patients with ileocolonic or colonic involvement. Patients were enrolled if in stable remission without active drugs for more than two months but less than one year. Total colonoscopy and ileoscopy were performed at enrollment and at the end of the study. The cumulative relapse rates at 12 months were 37% in the 4-ASA and 38% in the 5-ASA group. Clinical relapse, as defined by a rise in the Crohn's disease activity index (CDAI) of more than 100 points to values higher than 150, was accompanied by a statistically significant rise in serum concentrations of soluble interleukin-2 receptor and by an increased percentage of activated peripheral blood T cells. There were no statistical differences between the 4-ASA and the 5-ASA goup regarding relapse rates, the rise in CDAI during relapse or the increase of soluble interleukin-2 receptor concentrations. It is concluded that 4-ASA may be as effective as 5-ASA in the maintenance treatment of quiescent Crohns disease and that there were no differences in the severity of relapse between both treatment groups.