The purpose of this study is to assess the safety and tolerability of RDC-1036 (ALKS 37) in adults with opioid-induced constipation (OIC) following repeat dose administration

Approximately 60 subjects will be enrolled in 1 of 2 cohorts. Following a review of Cohort 1 safety and tolerability data, subjects will then be enrolled into Cohort 2, to explore additional doses. Dose escalation will occur in both cohorts. There will be 18 visits over a 6-week period.

Inclusion Criteria:

• 18 to 70 years of age
• Body mass index (BMI) of 19 to 35 kg/m2 at screening
• Receiving prescribed opioid medication for the management of chronic, non-cancer, pain
• Diagnosis of opioid-induced constipation (OIC)
• Willingness to stop all laxatives and other bowel regimens from the first study visit following screening until the end of the study. The use of constipation rescue medication will be allowed during the study.

Exclusion Criteria:

• Pregnancy and/or currently breastfeeding
• Clinically significant medical condition or illness (other than the condition for which the pain medication is being prescribed)
• Receiving treatment with opioid therapy for cancer-related pain, abdominal pain, scleroderma, and/or for the management of drug addiction
• Any gastrointestinal (GI) or pelvic disorder known to affect bowel transit, produce a GI obstruction, or contribute to bowel dysfunction other than opioid-induced constipation (eg, diverticulitis, other intestinal strictures, bezoars)
• Use of medical devices such as pacemakers, infusion pumps, or insulin pumps
• Use of naloxone, Subutex or Suboxone, Revia, Relistor, or Entereg starting 15 days before the first study visit following screening until the end of the study
• Participation in a clinical trial of a pharmacological agent within 30 days before screening