Olsalazine is a prodrug of 5-aminosalicylate that exhibits anti-inflammatory and chemopreventive activities. Olsalazine is used in both human and veterinary medicine and most commonly treats ulcerative colitis. Olsalazine acts as a non-steroidal anti-inflammatory drug (NSAID) that inhibits COX-1 and COX-2. In colonic epithelial cells, this compound prevents binding of IFN-γ to its receptor and, in other cellular models, inhibits activity of myeloperoxidase. In subjects with ulcerative colitis, olsalazine decreases risk of dysplasia and colorectal cancer.