OLSALAZINE, ADMINISTERED ORALLY, IS A PRODRUG THAT IS CONVERTED TO MESALAMINE, WHICH IS THE ACTIVE MOIETY. BECAUSE THE ACTION OF MESALAMINE IS BELIEVED TO BE DUE TO ITS LOCAL EFFECTS, SIDE EFFECTS CAN BE MINIMIZED BY ADMINISTERING MESALAMINE IN THE FORM OF ITS PRODRUG OLSALAZINE.THE ANTIINFLAMMATORY MECHANISM OF MESALAMINE IS BELIEVED TO OCCUR, AT LEAST IN PART, THROUGH THE INHIBITION OF PROSTAGLANDIN PRODUCTION IN THE BOWEL MUCOSA BY INHIBITION OF CYCLOOXYGENASE. THIS EFFECTIVELY DIMINISHES THE PRODUCTION OF ARACHIDONIC ACID METABOLITES, THEREBY REDUCING COLONIC INFLAMMATION.