Rectal and colonic mesalazine concentration in ulcerative colitis: oral vs. oral plus topical treatment

Aim: To measure mucosal concentrations of mesalazine in ulcerative colitis patients treated with oral mesalazine alone, compared to patients treated w ith both topical and oral mesalazine. Methods: Twenty-two patients with mild to moderate ulcerative colitis were randomized to receive 2.4 g/day of oral mesalazine (11 patients) or 2.4 g/d ay oral plus 4 g/day of topical mesalazine (11 patients). After 2 weeks of treatment, endoscopic biopsies specimens were taken from the rectum and in descending colon just distal of the splenic flexure and stored to -80 degre es C for later assay (HPLC). Wilcoxon's rank sum test for unpaired data was used for the statistical analysis. Results: Mucosal levels of mesalazine in the rectum were significantly high er in patients who received oral plus topical treatment than in those who h ad oral treatment alone (52.1 ng/mg, range: 13.6-122.1 vs. 0.2 ng/mg, range : 0.2-9.7, respectively; P < 0.0001). Similarly, in the descending colon, t he mucosal concentrations of mesalazine were significantly higher in patien ts who had oral plus topical treatment than in those receiving oral treatme nt alone (46.6 ng/mg, range: 6-112.6 vs. 15.9 ng/mg, range: 2.3-42.4, respe ctively; P = 0.01). Conclusions: Topical treatment of mesalazine significantly increases mucosa l concentrations of mesalazine up to the splenic flexure, supporting the ra tionale to treat left-sided ulcerative colitis with topical formulations of mesalazine.