4-Week, Multi-center Dose-Ranging Study for the IBS-C in Pts. 6 to <12 Yrs

Inclusion Criteria:

1. ≥6 and <12 years old at the Screening visit (Visit 1)

2. Confirmation of negative pregnancy test and use of appropriate contraceptive (including abstinence) in female subjects that have experienced menarche and are ofchild-bearing potential.

3. Meet the Modified Diagnostic Rome IV criteria for child/adolescent diagnosis ofIBS-C

4. Patient is willing to discontinue any laxatives used in favor of theprotocol-permitted rescue medicine (which will only be allowed after 72 hours withno bowel movement)

5. Meet the entry criteria assessed during the 2-week Screening period

6. Ability of both the patient and parent/guardian/LAR to communicate with theInvestigator and to comply with the requirements of the entire study, including anunderstanding of the assessments in the eDiary and how to use the eDiary device

7. Patient must provide verbal assent and the parent/guardian/LAR must provide writteninformed consent before the initiation of any study-specific procedures

Exclusion Criteria:

1. Functional diarrhea as defined by Modified Rome IV child/adolescent criteria

2. IBS with diarrhea (IBS-D), mixed IBS (IBS-M), or unsubtyped IBS as defined byModified Rome IV child/adolescent criteria

3. History of non-retentive fecal incontinence;

4. Required manual disimpaction any time prior to randomization (after consent)

5. Currently has both unexplained and clinically significant alarm symptoms (lowergastrointestinal [GI] bleeding [rectal bleeding or heme-positive stool],iron-deficiency anemia, or any unexplained anemia, or weight loss) and systemicsigns of infection or colitis, or any neoplastic process.

6. Patient has any of the following conditions:

7. Celiac disease, or positive serological test for celiac disease and thecondition has not been ruled out by endoscopic biopsy;

8. Cystic fibrosis;

9. Hypothyroidism that is untreated or treated with thyroid hormone at a dose thathas not been stable for at least 3 months prior to the Screening Visit;

10. Down's syndrome or any other chromosomal disorder;

11. Active anal fissure (Note: History of anal fissure is not an exclusion);

12. Anatomic malformations (eg, imperforate anus, anal stenosis, anterior displacedanus);

13. Intestinal nerve or muscle disorders (eg, Hirschprung disease, visceralmyopathies, visceral neuropathies);

14. Neuropathic conditions (eg, spinal cord abnormalities, neurofibromatosis,tethered cord, spinal cord trauma);

15. Lead toxicity, hypercalcemia;

16. Neurodevelopmental disabilities

17. Inflammatory bowel disease

18. Childhood functional abdominal pain syndrome

19. Childhood functional abdominal pain

20. Poorly treated or poorly controlled psychiatric disorders that might influencehis or her ability to participate in the study;

21. Lactose intolerance that is associated with abdominal pain or discomfort andcould confound the assessments in this study

22. History of cancer other than treated basal cell carcinoma of the skin;

23. History of diabetic neuropathy.

24. Use of medications that are known to affect stool consistency (ProhibitedMedications), including fiber supplements, anti-diarrheals, cathartics, antacids,opiates, prokinetic drugs, laxatives, enemas, antibiotics during the Screeningperiod; unless specified as rescue medication, and used accordingly as directed bythe Investigator.

25. Patient has had surgery that meets any of the following criteria:

26. Surgery to remove a segment of the GI tract at any time before the ScreeningVisit;

27. Surgery of the abdomen, pelvis, or retroperitoneal structures during the 6months before the Screening Visit;

28. An appendectomy or cholecystectomy during the 60 days before the ScreeningVisit;

29. Other major surgery during the 30 days before the Screening Visit

30. History of alcohol or substance abuse

31. Participation in other clinical trials within 1 month prior to Screening

32. Patient and/or parent/guardian/LAR is involved in the conduct and/or administrationof this trial as an investigator, sub-investigator, trial coordinator, or otherstaff member, or the patient is a first-degree family member, significant other, orrelative residing with one of the above persons involved in the trial

33. If, in the opinion of the Investigator, the patient is unable or unwilling tofulfill the requirements of the protocol or has a condition, which would render theresults uninterpretable