Abstract

Mutual azo prodrug of 5-aminosalicylic acid with histidine, was synthesized by coupling L-histidine with salicylic acid, for targeted drug delivery to the inflamed gut tissue, in inflammatory bowel disease. In vitro kinetic studies in HCl buffer (pH 1.2) showed negligible release of 5-aminosalicylic acid, whereas in phosphate buffer (pH 7.4), only 14% release was observed over a period of 6h. In rat fecal matter, the release of 5-aminosalicylic acid was almost complete (85.6%), with a half life of 163 min, following zero order kinetics. The azo conjugate was evaluated for its ulcerogenic potential by Rainsford's cold stress method. Therapeutic efficacy of the carrier system and the mitigating effect of the azo conjugate were evaluated in trinitrobenzenesulphonic acid- induced experimental colitis model. The synthesized prodrug was found to be equally effective in mitigating the colitis in rats, as that of sulfasalazine, without the ulcerogenicity of 5-aminosalicylic acid, and adverse effects of sulfasalazine.