Efficacy and Safety of Nalfurafine Hydrochloride ODT for Moderate-to-Severe Pruritus in Patients on Peritoneal Dialysis

Inclusion Criteria: At the time of signing informed consent: * Aged 18-85 years (inclusive), regardless of gender. * Chronic renal failure patients on regular peritoneal dialysis for ≥3 months, with no anticipated major treatment changes or rapid disease progression during the trial. * Able to understand and comply with study procedures, voluntarily participate, and provide written informed consent. At formal enrollment: * During the baseline period, ≥5 days with both morning and evening VAS scores recorded, and the average of the higher VAS values (morning/evening) ≥50 mm. * During the baseline period, ≥5 days with Xie-Kawashima itching severity assessed both morning and evening, including ≥2 days where the maximum itching score (morning/evening) was ≥3 (moderate). Exclusion Criteria: * Poor dialysis compliance, deemed by the investigator to affect efficacy/safety assessments. * Poor dialysis compliance, deemed by the investigator to affect efficacy/safety assessments. * Peritoneal dialysis regimen adjusted within 2 weeks prior to screening. * Currently on or planning hemodialysis within 2 months. * Planned kidney transplant or elective surgery during the study. * Peritonitis within 4 weeks prior to screening, unable to continue peritoneal dialysis. * ALT, AST, GGT, or total bilirubin \>2× upper limit of normal (ULN) during screening. * Pruritus not caused by chronic kidney disease (e.g., allergic, physical, infectious skin diseases, cholestatic liver disease). * Severe cardiovascular disease (NYHA Class III/IV, acute MI, unstable angina, large pericardial effusion, severe arrhythmia, or ECG abnormalities deemed unsafe for participation). * Active malignancy within 12 months prior to screening, or recent radiotherapy/chemotherapy/targeted/immunotherapy. * Uncontrolled or drug-treated fungal/bacterial/viral infections (e.g., active TB, HIV). * Uncontrolled hypertension (SBP ≥180 mmHg or DBP ≥110 mmHg). * Current systemic corticosteroids/immunosuppressants (topical excluded). * Psychiatric or cognitive disorders. * Initiated/adjusted restricted medications (antihistamines, systemic/local corticosteroids \[excluding ear/eye\], calcineurin inhibitors, gabapentin, pregabalin) within 7 days prior to screening, or anticipated changes during the study. * Initiated/adjusted medications affecting pruritus assessment (antipsychotics, hypnotics, SSRIs, anxiolytics, TCAs) within 2 weeks prior to screening, or anticipated changes during the study. * Opioid agonists/antagonists used within 2 weeks prior to screening. * Phototherapy for pruritus within 1 month prior to screening. * History of drug abuse, dependence, or alcoholism within 12 months prior to screening. * Allergy to opioids or trial drug excipients. * Participation in another clinical trial with investigational drugs/devices within 28 days prior to screening, or residual investigational drug within 5 half-lives. * Pregnant, breastfeeding, positive pregnancy test, or unwilling to use contraception during the study. * Other conditions deemed unsuitable by the investigator.