['irritable bowel syndrome characterized by constipation']
['plecanatide', 'placebo']

        Inclusion Criteria:

        • Adult patients between the ages of 18 and 85 years (inclusive) with a diagnosis of IBS
        based on ROME III diagnostic criteria and meeting criteria for diagnosis of the
        constipation predominant subtype - IBS-C

        Exclusion Criteria:

          -  Refusal or inability to sign informed consent for the trial

          -  Refusal or inability to complete daily Episodic (real-time) BM / RM calls, End of Day
             daily Calls, and/or complete electronic questionnaires

          -  BMI ≥ 40 or < 18

          -  Women of child bearing potential who refuse to use an acceptable method of birth
             control for the duration of the trial

          -  Women who are pregnant or lactating

          -  Diagnosis of IBS-D or IBS-M

          -  Organic or obstructive disease of the small or large intestine

          -  Use of laxatives other than the study-supplied rescue medication (Dulcolax®,
             bisacodyl)

          -  Use of a prohibited concomitant medication within the time frame prior to screening
             outlined in the study protocol for that medication

          -  Unstable medical illness

          -  Bilirubin > 3X ULN in the absence of a conjugation defect

          -  Any laboratory value > 3X ULN unless discussed and approved by the study Medical
             Monitor
      