Pediatric Irritable Bowel Syndrome With Constipation (IBS-C)

This study consists of 2-week screening period followed by 12 week randomized treatment period (RTP). At the beginning of the 2-week Screening period, patients who provide written assent will be fully assessed for eligibility into the study and will be asked to self-report daily information about the status of their IBS symptoms via an electronic diary (eDiary) device. Patient compliance with the eDiary will be monitored actively by the site staff and will be reviewed to determine eligibility at the end of screening. Eligible patients will be randomized to receive one of the study medications: tenapanor 25 mg BID, tenapanor 50 mg BID, or placebo. During the 12-week double-blind RTP, patients will continue recording daily assessments via the eDiary system as instructed and compliance with eDiary entries will be monitored on an ongoing basis. Patients will return for study visit every two or four weeks (Visits 3-6) and will undergo safety assessments at these visits.