An Open-Label, Long-term Study to Assess the Immunogenicity of Linaclotide Administered Orally to Adult Patients With Irritable Bowel Syndrome With Constipation or Chronic Idiopathic Constipation

This study includes up to a 3-week Screening Period, followed by a 52-week treatment period.
Patients with CIC meeting the entry criteria will receive linaclotide 145-ug capsules,
orally, once daily and patients with IBS-C meeting the entry criteria will receive
linaclotide 290-ug capsules, orally, once daily.

Inclusion Criteria:

- Patients meet the Rome III criteria for IBS-C or CIC:

- IBS-C Criteria: the patient must meet the following 2 criteria (A and B)

- A. IBS Criteria: The patient must have abdominal pain or discomfort at least 3 days
per month in the 3 months before diagnosis (with symptom onset at least 6 months
before diagnosis) associated with 2 or more of the following:

1. Improvement with defecation

2. Onset associated with a change in frequency of stool

3. Onset associated with a change in form (appearance) of stool

- B. Stool Consistency Requirement: During the 3 months before diagnosis in the absence
of laxative or enema use, the patient has hard or lumpy stools (Bristol Stool Form
Scale [BSFS] score 1 or 2) with at least 25% of BMs and has loose or mushy stools
(BSFS 5 or 6) with <25% of BMs

- CIC Criteria: the patient must meet the following 3 criteria (A, B, and C):

- A. Patient meets 2 or more of the following criteria for 3 months before the diagnosis
with symptom onset at least 6 months before diagnosis:

1. Straining during at least 25% of defecations

2. Lumpy or hard stools in at least 25% of defecations

3. Sensation of incomplete evacuation for at least 25% of defecations

4. Sensation of anorectal obstruction/blockage for at least 25% of defecations

5. Manual maneuvers to facilitate at least 25% of defecations (eg, digital
evacuation, support of the pelvic floor)

6. Fewer than 3 defecations per week

- B. Loose stools are rarely present without the use of laxatives

- C. Insufficient criteria for irritable bowel syndrome. (The criteria for IBS are
provided in Point A under IBS Criteria, above)

- Patient meets the colonoscopy requirements, which are modified from the Summary of the
US-Multi-Society Task Force on Colorectal Cancer and other Colonoscopy Requirements

- Patient has successfully completed protocol procedures (with no clinically significant
findings)

Exclusion Criteria:

- At Day 1 visit, the patient reports having 6 or more spontaneous bowel movements
(SBMs) in the week prior to screening.

- At Day 1 visit, the patient reports having any SBMs that were watery (BSFS=7) or more
than 1 SBM that was mushy (BSFS=6) in the week prior to screening.

- Patient has a structural abnormality of the gastrointestinal (GI) tract or a disease
or condition that can affect GI motility.

- Patient has any protocol excluded or clinically significant medical or surgical
history that would limit the patient's ability to complete or participate in this
clinical trial or could confound the study assessments.

- Patient has ever received linaclotide as a treatment (including commercially-available
product) or has been randomized into any clinical study in which linaclotide was a
treatment. (Patients who enrolled into linaclotide clinical studies conducted prior or
during this study but failed to be randomized are eligible for the current study).

- Patient has ever received plecanatide, SP-333, or has participated in a plecanatide
clinical study.