Pentasa and Canasa (mesalamine 5-ASA) do not have the same action as steroids. The designed effect of mesalamine is to reduce swelling and inflammation in the gut so as to treat inflammatory bowel disease, including ulcerative colitis. That is also what some steroids, such as Prednisone, are meant to do. Pentasa belongs to a separate class of medication known as aminosalicylates.