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 with 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/day 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 degrees 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 higher in patients who received oral plus topical treatment than in those who had 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, the mucosal concentrations of mesalazine were significantly higher in patients who had oral plus topical treatment than in those receiving oral treatment alone (46.6 ng/mg, range: 6-112.6 vs. 15.9 ng/mg, range: 2.3-42.4, respectively; P=0.01). CONCLUSIONS: Topical treatment of mesalazine significantly increases mucosal concentrations of mesalazine up to the splenic flexure, supporting the rationale to treat left-sided ulcerative colitis with topical formulations of mesalazine.