By licensing balsalazide from Salix Pharmaceuticals Ltd., Shire Pharmaceuticals Group plc now has two products to treat ulcerative colitis. SHP already owns U.S. rights to Pentasa as a result of its acquisition of Roberts Pharmaceutical Corp. last year. But the different territories where SHP has rights to the two drugs, as well as differences in their mechanisms of action, have led SHP to conclude that it can position