Phase 2 Randomized, Double-Blind, Placebo-Controlled, Parallel Group Trial of Linaclotide Administered to Patients With Opioid-Induced Constipation Receiving Chronic Opioid Treatment for Non-Cancer Pain

Inclusion Criteria: * Patient has chronic non-cancer pain that has been present for a minimum of 3 months * Patient has been receiving a stable oral dose of a full-opioid agonist for at least 4 days per week during the 8 consecutive weeks * Patient meets protocol criteria for Opioid-Induced Constipation (OIC): \< 3 spontaneous bowel movements (SBMs) per week and reports one of the following symptoms for at least 4 weeks: 1. Straining during \> 25% of BMs 2. Lumpy or hard stools during \> 25% of BMs 3. Sensation of incomplete evacuation during \> 25% of BMs * Patient meets the colonoscopy requirements defined by the American Gastroenterological Association guidelines * Patient has successfully completed protocol procedures (with no clinically significant findings) * Patient is compliant with Interactive Voice Response System (IVRS) for daily diary reporting * Patient has a total of \< 6 SBMs in IVRS during the 14 days before and up to the time of Randomization * Patient has adequate relief and well-controlled pain with current dose of opioid Exclusion Criteria: * Patient has been using opioids for abdominal pain * Patient has symptoms of or been diagnosed with chronic constipation or chronic idiopathic constipation prior to initiation of opioid treatment * Patient has symptoms of or been diagnosed with Irritable Bowel Syndrome (IBS) prior to initiation of opioid treatment * Patient has a history of loose or watery stools for \> 25% of BMs during the 3 months before the Screening in the absence of laxatives, suppositories, or enemas * 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