['constipation predominant irritable bowel syndrome']
['tenapanor', 'placebo']

        Inclusion Criteria:

          -  18 to 75 years old

          -  Females must be of non-childbearing potential; If of child-bearing potential, must
             have negative pregnancy test and confirm the use of one of the appropriate means of
             contraception.

          -  Males must agree to use an appropriate method of barrier contraception or have
             documented surgical sterilization

          -  Subject meets definition of IBS-C using Rome III Criteria for the Diagnosis of IBS

          -  A colonoscopy based on AGA guidelines; every 10 years at ≥ 50 years old, or the
             occurrence of any warning signs

        Exclusion Criteria:

          -  Functional diarrhea as defined by Rome III criteria

          -  IBS with diarrhea (IBS-D), mixed IBS (IBS-M), or unsubtyped IBS as defined by Rome III
             criteria

          -  Diagnosis or treatment of any clinically symptomatic biochemical or structural
             abnormality of the GI tract within 6 months prior to screening, or active disease
             within 6 months prior to screening; including but not limited to cancer, inflammatory
             bowel disease, diverticulitis, duodenal ulcer, erosive esophagitis, gastric ulcer,
             pancreatitis (within 12 months of screening), cholelithiasis, amyloidosis, ileus,
             non-controlled GERD, gastrointestinal obstruction, ischemic colitis or carcinoid
             syndrome.

          -  Subject has a history or current evidence of laxative abuse (in the clinical judgment
             of the physician)

          -  Hepatic dysfunction (ALT [SGPT] or AST [SGOT] >2.5 times the upper limit of normal) or
             renal impairment (serum creatinine > 2mg/dL)

          -  Any evidence of or treatment of malignancy (other than localized basal cell, squamous
             cell skin cancer or cancer in situ that has been resected) within the previous year

          -  Any surgery on the stomach, small intestine or colon, excluding appendectomy or
             cholecystectomy (unless within 60 days of screening visit)
      