Evaluation of the Efficacy and Safety of ADL5945 for the Treatment of Opioid-induced Constipation in Adults Taking Opioid Therapy for Chronic Noncancer Pain

Key Inclusion Criteria * be a man or woman aged 18 to 75 years, inclusive, at the time of screening * have a body weight ≥45 kilograms (kg) and a body mass index (BMI) ≤40 kilograms per square meter (kg/m\^2) * be taking a stable daily dose of opioids of ≥30-milligrams (mg) morphine-equivalent total -daily dose for chronic noncancer pain for ≥30 days before screening * have opioid-induced constipation (OIC) by history. Additionally, based on the data collected during the 1-week screening period, participants must have \<3 spontaneous bowel movements (SBMs) per week and have experienced ≥1 other bowel movement (BM) symptom (that is, straining to pass a stool, lumpy hard stools or small pellets, or sense of incomplete evacuation after passing a stool) for ≥25% of the total BMs * be willing to discontinue use of all laxatives and stool softeners during the study period except as allowed by the protocol Key Exclusion Criteria * be pregnant, lactating, or planning to become pregnant during the study * have aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen, or serum creatinine results ≥ 2 times the upper limit of normal * have a recent history of myocardial infarction (MI) or unstable angina * have an active malignancy of any type * be taking opioids primarily for fibromyalgia * be taking methadone as a maintenance medication (participants taking methadone for pain may be enrolled) * be taking intrathecal opioids for the management of pain * be taking tramadol, tapentadol, or any mixed agonist/antagonist opioid analgesics as the sole opioid for analgesia * be taking any μ-opioid receptors (MOR) antagonist, including opioids in combination with naloxone, naltrexone, or methylnaltrexone bromide * be taking medical marijuana for pain * have gastrointestinal (GI) or pelvic disorders known to affect bowel transit, produce GI obstruction, or contribute to bowel dysfunction * have taken antispasmodics, antidiarrheals, or prokinetics within 7 days before the start of the screening week * be taking nonopioid medications known to cause constipation * be taking antidiarrheals and have an incidence or a history of intermittent diarrhea or loose stools * be unwilling to abstain from grapefruit and grapefruit-containing products * have a history of alcoholism or illicit drug dependence or abuse within 5 years before screening * have positive results on a urine drug screen (excluding opioids) that indicate illicit drug use