The Efficacy and Safety Study of CB-5945 for the Treatment of Opioid-Induced Constipation

Key Inclusion Criteria: * Is taking a stable daily dose of opioids of ≥ 30 mg morphine equivalent total daily dose (METDD) for chronic non-cancer pain * Has constipation that is caused by the chronic use of opioids * Is willing to use only the study provided laxative(s) and to discontinue use of all other laxatives, enemas, stool softeners, and other medications to treat constipation (e.g., lubiprostone) from Screening until the last study assessment Key Exclusion Criteria: * Has gastrointestinal (GI) or pelvic disorders known to affect bowel transit (for example \[e.g.\], obstruction) or contribute to bowel dysfunction * Has evidence of intestinal obstruction * Has a history of rectal bleeding not due to hemorrhoids or fissures within 6 months of screening * Has an active malignancy of any type (participants with a history of successfully treated malignancy \>5 years before the scheduled administration of study medication and participants with treated basal or squamous cell cancer may be enrolled) * Is taking antispasmodics (e.g., dicyclomine), antidiarrheals (e.g., loperamide), prokinetics (e.g., metoclopramide), or locally acting chloride channel activators (e.g., lubiprostone) * Is taking non-opioid medications known to cause constipation (e.g., iron sulfate therapy, tricyclic antidepressants)