BALSALAZIDE DISODIUM, A PRODRUG THAT IS ENZYMATICALLY CLEAVED IN THE COLON TO PRODUCE MESALAMINE (5-AMINOSALICYLIC ACID), AN ANTI-INFLAMMATORY DRUG. THE MECHANISM OF ACTION OF 5-AMINOSALICYLIC ACID IS UNKNOWN, BUT APPEARS TO BE TOPICAL RATHER THAN SYSTEMIC. MUCOSAL PRODUCTION OF ARACHIDONIC ACID METABOLITES, BOTH THROUGH THE CYCLOOXYGENASE PATHWAYS, I.E., PROSTANOIDS, AND THROUGH THE LIPOXYGENASE PATHWAYS, I.E., LEUKOTRIENES AND HYDROXYEICOSATETRAENOIC ACIDS, IS INCREASED IN PATIENTS WITH CHRONIC INFLAMMATORY BOWEL DISEASE, AND IT IS POSSIBLE THAT 5-AMINOSALICYLIC ACID DIMINISHES INFLAMMATION BY BLOCKING PRODUCTION OF ARACHIDONIC ACID METABOLITES IN THE COLON.