AstraZeneca ($AZN) and Ironwood Pharmaceuticals ($IRWD) say their Phase III study for linaclotide, conducted primarily in China among patients with irritable bowel syndrome with constipation, came through on all primary and secondary endpoints. The successful late-stage study sets the stage for a regulatory filing in China next year as the developers target a market of some 13 million patients. The drug is already approved in the U.S. Release