(Adds details, shares)
Oct 1 (Reuters) - Ardelyx Inc said its experimental drug to treat constipation-related irritable bowel syndrome achieved the main goal of increasing bowel movement compared with a placebo in a mid-stage study involving 371 patients.
The company's shares were up 5.6 percent at $15.00 in pre-market trading on the Nasdaq on Wednesday.
Ardelyx said the trial met its main goal in 60.7 percent of patients taking the drug, tenapanor, compared with 33.7 percent in the placebo group.
Half the patients given the drug experienced at least a 30 percent reduction in abdominal pain, compared with 23.6 percent in the placebo group, the company added.
Ardelyx licensed the drug to AstraZeneca Plc in October 2012. The drug is also being tested as a potential treatment for chronic kidney disease and end-stage renal disease.
Constipation-related irritable bowel syndrome is a gastrointestinal disorder characterized by severe abdominal pain or discomfort due to constipation, significantly affecting health and quality of life.
Ardelyx estimates that about 4.4 million Americans suffer from the disorder. (Reporting by Amrutha Penumudi in Bangalore; Editing by Ted Kerr and Simon Jennings)