Description: Dolcanatide (formerly SP-333; SP333; SP 333) is the second uroguanylin analog currently being developed for ulcerative colitis by Synergy Pharmaceuticals which is a biopharmaceutical company focused on the development and commercialization of novel gastrointestinal (GI) therapies. Analogs of uroguanylin, a naturally occurring human GI peptide, have the potential for the treatment of functional GI disorders and inflammatory bowel disease. Plecanatide (Trade name Trulance; formerly SP-304), a 16 amino acid peptide, is a drug approved by the FDA for the treatment of chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation. Plecanatide is an agonist of guanylate cyclase-C. It works as a laxative by drawing water into the gastrointestinal tract thereby softening stool and encouraging its natural passage. Plecanatide increases intestinal transit and fluid through a buildup of cGMP. As of January 2017, Plecanatide is approved in the United States for the treatment of chronic idiopathic constipation in adults. As of January 2017, Plecanatide is approved in the United States for the treatment of chronic idiopathic constipation in adults.