Astellas Pharma Inc. and Ironwood Pharmaceuticals Inc. reported that the phase 3 trial of linaclotide for chronic constipation, conducted in Japan, met its primary endpoint.

Linaclotide-treated patients showed statistically significant improvement in mean spontaneous bowel movement frequency compared to placebo-treated patients. The companies will use efficacy and safety data to pursue regulatory approval for the additional indication in Japan.

The drug is approved in Japan as prescription treatment for adults with irritable bowel syndrome with constipation. In the U.S., linaclotide is approved, and sold under the brand name Linzess, for the treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation.