In the wake of U.S. regulators' nod for Synergy Pharmaceuticals Inc.'s Trulance (plecanatide), buyout speculation buzzed while analysts differed on prospects for the drug as a "fast follower" going up against Linzess (linaclotide) from Ironwood Pharmaceuticals Inc. in chronic idiopathic constipation (CIC) and, soon, irritable bowel syndrome with constipation (IBS-C).