A 26-Wk Study to Assess Safety & Efficacy of Tenapanor for T/t of Chronic Idiopathic Constipation in Adults

Inclusion Criteria:

1. Patients ≥18 to ≤80 years old at the Screening visit (Visit 1).

2. Meet the Rome IV Diagnostic Criteria for functional constipation.

3. Females of non-childbearing potential, or agree to the use of an acceptable means ofcontraception for up to 30 days following the last dose of study medication.

4. Males must agree to use an appropriate method of barrier contraception or havedocumented surgical sterilization.

5. Meets the entry criteria assessed during the Screening period.

6. Ability to understand and provide input on the assessments in the eDiary.

7. Provide written informed consent before the initiation of any study-specificprocedures.

8. Must agree to have daily access to eDiary via a computer, tablet or smart phone

Exclusion Criteria:

1. Loose or watery stool in the absence of any medication that is known to affect stoolconsistency for >25% of bowel movements (BMs) during the 3 months prior to theScreening visit

2. Fecal impaction within 6 months prior to the Screening visit

3. Unexplained and clinically significant alarm symptoms.

4. Functional diarrhea as defined by Rome IV criteria

5. IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), mixed IBS (IBS-M), orunsubtyped IBS as defined by Rome IV criteria

6. Diagnosis or treatment of any clinically symptomatic abnormality of the GI tract oractive disease within 6 months prior to the Screening visit

7. Patient with central nervous system disorder

8. Use of prohibited medications defined by protocol

9. Patient has a history or current evidence of laxative abuse

10. Hepatic dysfunction

11. Positive HIV, hepatitis B or hepatitis C test at screening

12. Positive urinary drug test at Screening, with the exception of cannabis andcannabidiol (CBD)

13. Any evidence of or treatment of malignancy within 1 year prior to the Screeningvisit

14. Any surgery on the stomach, small intestine or colon; appendectomy orcholecystectomy are not excluded unless within 60 days prior to the Screening visit

15. Pregnant women or women planning to become pregnant during trial participation

16. A major psychiatric disorder that has required hospitalization in the last yearprior to the Screening visit.

17. Alcohol or substance abuse within 1 year prior to the Screening visit

18. Participation in other clinical trials within 1 month prior to the Screening visit

19. Clinical evidence of significant disease that may interfere with the patient'ssuccessful completion of the trial