Study on the Safety and Efficacy of a Time-of-Day-Based Individualized Tacrolimus Dosing Regimen in Kidney Transplant Recipients

The goal of this clinical trial is to evaluate whether chronopharmacokinetic model-guided individualized unequal twice-daily tacrolimus dosing improves renal allograft function and reduces acute rejection in stable kidney transplant recipients. The main questions it aims to answer are: Does chrono-individualized tacrolimus dosing preserve graft renal function (eGFR) compared with conventional equal twice-daily dosing? Does chrono-individualized tacrolimus dosing lower the incidence of acute rejection in kidney transplant recipients? Researchers will compare recipients receiving chronopharmacokinetic-guided \"low morning, high evening\" individualized tacrolimus doses to recipients receiving conventional equal twice-daily tacrolimus doses to see if the chrono-individualized regimen improves renal function and reduces acute rejection risk. Participants will: Be randomly assigned to one of two tacrolimus dosing groups at a 1:1 ratio Receive routine immunosuppressive therapy and follow-up for 12 months Undergo blood sampling for tacrolimus concentration, calcineurin activity and multi-omics biomarker detection Complete regular clinical assessments of graft function, adverse events and rejection episodes