The primary purpose of this study is to evaluate the efficacy and safety of lubiprostone administration in patients with Opioid-induced Bowel Dysfunction.

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 (OBD) 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 inhibitor (SSRIs), Serotonin-norepinephrine reuptake inhibitor (SNRIs), or Monoamine oxidase inhibitor (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:

• 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).
• Opioid dose adjustment (+/- 30%), and/or change in opioid agent or route of administration within 30 days of screening.
• Gastrointestinal or abdominal surgical procedures within 90 days prior to screening.
• Non-ambulatory patients, or those who are unable to eat/drink, take oral medications, or to hold down oral medications due to vomiting.
• 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.
• Prior use of Amitiza, lubiprostone, SPI-0211, or RU-0211.