Evaluation of renal function following treatment with 5-aminosalicylic acid derivatives in patients with ulcerative colitis

A number of cases of nephrotoxicity have been reported in patients with inflammatory bowel disease taking oral 5-aminosalicylic acid (5-ASA).To evaluate the effects of 9 months of therapy with mesalazine or olsalazine on renal function in patients with ulcerative colitis in remission.Forty patients with ulcerative colitis in complete remission for 6 months were randomized to either olsalazine (n=20) or mesalazine (n=20 for nine months). Thirty-six of the 40 patients were on prior salicylate therapy. Disease activity was the measure ofclinical efficacy and was assessed by the Harvey-Bradshaw Index (HBI). Laboratory efficacy measurements included glomerular filtration rate (GFR), microalbuminuria, urinary gluthathione S-transferase (GST) and serum C-reactive protein (CRP). Safety analysis consisted of documentation of adverse events and laboratory values.There was no significant reduction in the GFR overall on therapy. The levels of GFR adjusted for baseline were similar in the two treatment groups after 3, 6 and 9 months. A significantly higher percentage of mesalazine-treated patients experienced drug related adverse events, all of a minor nature. The incidence of adverse events causing early withdrawal was similar in the two treatment groups.Treatment with mesalazine or olsalazine for 9 months had no significant impact on GFR.