5-((4-((2-Carboxyethyl)carbamoyl)phenyl)diazenyl)-2-hydroxybenzoic acid

Balsalazide is a prodrug that has little or no pharmacologic activity until it is enzymatically cleaved in the colon to produce mesalamine (5-aminosalicylic acid), an anti inflammatory drug indicated for the treatment of mildly to moderately active ulcerative colitis. Balsalazide disodium is delivered intact to the colon where it is cleaved by bacterial azoreduction to release equimolar quantities of mesalamine, which is the therapeutically active portion of the molecule, and the intert 4-aminobenzoyl-(beta)-alanine. As a result, the spectrum of pharmacologic activity of balsalazide is similar to that of mesalamine.

The mechanism of action of 5-aminosalicylic acid is unknown, but appears to exert its anti-inflammatory effects locally (in the GI tract) rather than systemically. Mucosal production of arachidonic acid metabolites, both through the cyclooxygenase pathways (catalyzes the formation of prostaglandin precursors from arachidonic acid), and through the lipoxygenase pathways (catalyzes the formation of leukotrienes and hydroxyeicosatetraenoic acids from arachidonic acid and its metabolites), is increased in patients with chronic inflammatory bowel disease. Therefore, it is possible that 5-aminosalicylic acid diminishes inflammation by blocking production of arachidonic acid metabolites in the colon through both the inhibition of cyclooxygenase and lipoxygenase.

Low and variable, intact balsalazide is poorly absorbed systemically.

The products of the azoreduction of this compound, 5-ASA and 4-aminobenzoyl-ß-alanine, and their N-acetylated metabolites have been identified in plasma, urine and feces. Following single-dose administration of 2.25 g COLAZAL (three 750 mg capsules) under fasting conditions in healthy subjects, mean urinary recovery of balsalazide, 5-ASA, and N-Ac-5-ASA was 0.20%, 0.22% and 10.2%, respectively.