Measurement of colonic mucosal concentrations of 5-aminosalicylic acid is useful for estimating its therapeutic efficacy in distal ulcerative colitis: Comparison of orally administered mesalamine and sulfasalazine

Objectives: Oral 5-aminosalicylic acid (5-ASA) preparations have been used frequently in the treatment of ulcerative colitis. However, there have been few reports investigating the relationship between colonic mucosal concent rations of 5-ASA and its clinical efficacy when oral sulfasalazine or 5-ASA compounds were administered. The aim of this study is to compare the mucos al concentrations of 5-ASA ensured by sulfasalazine or mesalamine, and to d efine the clinical significance of the measurement of 5-ASA concentrations in the treatment of distal ulcerative colitis. Materials and Methods: Biops ies were taken from the rectum and sigmoid colon of the oral sulfasalazine group (n = 13) and the slow-release 5-ASA (mesalamine) group with (n = 5) o r without (n = 11) rectal administration of 5-ASA. High-pressure liquid chr omatography was used to measure the tissue concentrations of 5-ASA and its metabolites. We compared the 5-ASA concentrations of the sulfasalazine, gro up with the mesalamine group. Further more, we analyzed the relationship be tween tissue 5-ASA concentrations and the Disease Activity Index (DAI). Res ults: The concentrations of 5-ASA and acetyl-5-ASA in the sulfasalazine gro up were higher than those in the group taking oral mesalamine alone (p < 0. 01). The concentration of 5-ASA was much higher in the patients who receive d oral and rectal mesalamine in an enema than in the patients who had oral mesalamine alone. There was a significant inverse correlation between the D AI and concentrations of 5-ASA in the rectum (r = 0.712, p < 0.001). Conclu sions: We demonstrated that the colonic mucosal concentration of 5-ASA was significantly higher in the sulfasalazine group than in the mesalamine grou p. Furthermore, the concentrations of mucosal 5-ASA may be a good marker fo r the estimation of its efficacy in the treatment of ulcerative colitis.