Safety Study of Tenapanor for the Treatment of Pediatric Patients (6 to Less Than 18 Years Old) With IBS-C

Inclusion Criteria: 1. ≥6 and \<18 years old at enrollment of either parent study 2. Patient completed the parent study immediately with adequate compliance with study procedures in the opinion of the Investigator 3. Females of child-bearing potential must have negative pregnancy test at the last visit of the parent study and confirm the use of appropriate contraception (including abstinence). 4. Subject is ambulatory 5. Written informed consent by parent/guardian/ Legally Authorized Representative (LAR) and a willingness of both subject and parent/guardian/LAR to participate in the study as it is described Exclusion Criteria: 1. Patient discontinued prematurely from the parent study. 2. Any surgery on the stomach, small intestine or colon, excluding appendectomy or cholecystectomy 3. Pregnant or lactating women 4. If, in the opinion of the Investigator, patient is unable or unwilling to fulfill the requirements of the protocol