A Trial of Linaclotide 290 μg in Patients With Irritable Bowel Syndrome With Constipation

12 week treatment period followed by 4-week Randomized Withdrawal (RW) Period.

Inclusion Criteria:

- Patient has no clinically significant findings on a physical examination and clinical
laboratory tests

- Female patients of childbearing potential must agree to use one of the following
methods of birth control:

1. Hormonal contraception

2. Double-barrier birth control

3. Maintenance of a monogamous relationship with a male partner who has been
surgically sterilized by vasectomy

- Patient meets protocol criteria for diagnosis of IBS-C

- Patient demonstrates continued IBS-C symptoms through Pretreatment Period

- Patient maintains a minimum level of compliance with daily diary

Exclusion Criteria:

- Patient has history of loose or watery stools

- Patient has symptoms of or been diagnosed with a medical condition that may contribute
to abdominal pain

- 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 could confound the study assessments