A Study to Evaluate the Safety and Efficacy of CR845 in Chronic Kidney Disease Patients With Moderate-to-Severe Pruritus

Inclusion Criteria: To be eligible for inclusion into the study, a patient must meet the following criteria: * CKD patients with stage III, IV, or V (ie, moderate renal impairment with estimated glomerular filtration rate (GFR) ≥30 and \<60 mL/min/1.73 m2 or severe renal impairment with estimated GFR \<30 mL/min/1.73 m2). * For severe CKD patients on hemodialysis, they must be receiving hemodialysis 3 times per week for at least 3 months prior to the start of screening; * Prior to randomization: 1. Has completed at least 4 Worst Itching Intensity NRS worksheets from the start of the 7-day Run-in Period; 2. Has a mean baseline Worst Itching Intensity NRS score ≥5, defined as the average of all non-missing scores reported from the start of the 7-day Run-in Period. Exclusion Criteria: A patient will be excluded from the study if any of the following criteria are met: * Patients not currently on dialysis who are likely to initiate routine dialysis during study participation; * Scheduled to receive a kidney transplant during the study; * New or change of treatment received for itch including antihistamines and corticosteroids (oral, intravenous \[IV\], or topical) within 14 days prior to screening; * Received another investigational drug within 30 days prior to the start of screening or is planning to participate in another clinical study while enrolled in this study; * Received ultraviolet B treatment within 30 days prior to the start of screening or anticipates receiving such treatment during the study; * Participated in a previous clinical study with CR845.