This is a multicenter, randomized, double-blind, placebo-controlled study to assess the potential of physical withdrawal from CR845 upon treatment discontinuation after 3 weeks of IV administration at a dose of 0.5 mcg/kg in hemodialysis patients. The purpose of this study is to determine whether hemodialysis patients who take CR845 develop physical dependence and experience withdrawal symptoms upon cessation, as exemplified by symptoms consistent with opioid withdrawal. The study will consist of a Screening Phase, a 3-week Open-label Phase, a 2-week randomized, placebo-controlled, Double-blind Phase and a Follow-up Visit.

Key Inclusion Criteria:

• Has ESRD and has been on hemodialysis 3 times per week for at least 3 months;
• Not currently taking opioid medication;
• If female, is not pregnant or nursing during any period of the study.

Key Exclusion Criteria:

• Has a concomitant disease or a history of any condition that, in the opinion of the Investigator, could pose undue risk to the patient, impede completion of the study procedures, or would compromise the validity of the study measurements; Past or present diseases, which as judged by the Investigator, may affect the outcome of this study.