Opioid-induced Bowel Dysfunction Pivotal Assessment of Lubiprostone

Inclusion Criteria: * Consistent treatment for chronic, non-cancer-related pain with any full agonist opioid for at least 30 days prior to screening. * Diagnosis of opioid-induced bowel dysfunction as confirmed during the screening period. * If patient has a history of chronic constipation, condition must have been exacerbated by initiation of opioid treatment. * Use of prescribed or over-the-counter (OTC) medication that affects gastrointestinal motility (other than opioid therapy) must be discontinued during the study. * If treated for clinical depression with selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), or monoamine oxidase (MAO) inhibitors, treatment must have been at a stable dose for at least 30 days prior to screening. * Use of laxative and stool softeners (with the exception of approved rescue medications) must be discontinued while on study. Exclusion Criteria: * Opioid dose adjustment (+/- 30%), and/or change in opioid agent or route of administration within 30 days of screening. * Non-ambulatory patients, or those who are unable to eat/drink, take oral medications, or to hold down oral medications due to vomiting. * Treatment with opioid therapy for cancer-related pain, abdominal pain, scleroderma, and/or for the management of drug addiction. * Patient has been treated for cancer in the past 5 years (with the exception of localized basal cell, squamous cell skin cancer, or in situ cancer that has been resected). * Gastrointestinal or abdominal surgical procedures within 90 days prior to screening. * Female patients of childbearing potential who are unable/unwilling to use protocol-specified method(s) of birth control and/or are pregnant, nursing, or plan to become pregnant or nurse during the study.