Efficacy and Safety Study of TRK-820 to Treat Conventional-treatment-resistant Pruritus in Patients Receiving Hemodialysis

Inclusion Criteria: \[At the time of obtaining the consent form\] * Chronic renal failure patients who regularly receive hemodialysis three times a week and are not likely to have a serious treatment change or acute symptoms during the study period * Patients who received both of the drug pruritus treatments in section 1 and 2 below within one year before the day of singing consent form 1. Systemic therapy of more than two consecutive weeks depending on antihistamine or antiallergic drugs falling under "prescription drugs with indication of pruritus" (oral drugs, injections, etc.) 2. Local therapy depending on "prescription drugs with indication of pruritus" (ointment, etc.) or a moisturizer prescribed by a doctor (topical preparation, etc.) * Patients for whom all the conventional pruritus treatments in section (2) are not enough * Patients aged 20 years or older at time of signing the consent form \[At the time of enrollment\] * Patients whose VAS scores are measured both after breakfast and dinner for five days or more of the last 7 days of the predose observation period and whose mean of whichever the higher VAS scores after breakfast or dinner is ≥50 mm * Patients whose whichever the higher VAS score after breakfast or dinner for the last 7 days during the preliminary observation day (measured VAS score if one is missing) is more than ≥20 mm for five days or more * Patients who are judged to have pruritus both during the day and at night for more than two days based on the Shiratori's severity criteria assessed by the subject at days of fifth and sixth hemodialysis and the day of hemodialysis after the completion of the predose observation period, and whose whichever the higher pruritis score measured during the day or at night is 3 (moderate) for two days or more Exclusion Criteria: * Patients with malignant tumor * Patients with depression, schizophrenia or dementia as complications * Patients who currently have Child-pugh class B or C hepatic cirrhosis as complications * Patients with clinically significant hepatic or cardiovascular diseases which cannot be controlled by diet or drug therapy * Patients who currently have the following heart diseases: life-threatening arrhythmia; unstable angina or myocardiac infarction within 6 months; PCI or CABG within 6 months; NYHA class III or IV congestive heart failure * Patients with atopic dermatitis or chronic urticaria as complications * Patients who are allergic to opioid drugs * Patients with dependence on drug or alcohol * Patients who received phototherapy for pruritus within one month before signing the consent form * Patients who participated in the study of TRK-820 and received the study drug or who were already enrolled in this study * Patients who participated in other clinical studies (including the ones using artificial kidney and medical equipment), and received the study drug or treatment with clinical equipment within one month before signing the consent form * Pregnant women, lactating women and patients of childbearing potential who do not use contraceptive methods * Patients who cannot report VAS scores by their own for any reason at the principal investigator or study personnel's discretion * Patients whose complications or history can impact the results of this study at the principal investigator or subinvestisator's discretion * Other patients who are not proper to participate in this study at the principal investigator or study personnel's discretion