Tacrolimus C:D Ratio Measured in Renal Transplant Recipients Treated With Once-daily Prolonged-release Drugs

Inclusion Criteria: 1. Signed and dated written informed consent 2. Adult (≥18 years old) male or female 3. Renal insufficiency necessitating kidney transplantation and approved to receive a first or second kidney allograft from a living or deceased organ donor 4. ABO blood type compatible with the donor kidney 5. Able to swallow an oral formulation of tacrolimus in tablet or capsule form Exclusion Criteria: 1. Multi-organ transplantation 2. Any previous solid organ transplantation (other than a first kidney allograft) 3. For recipients of a second kidney transplant: loss of first kidney transplant within 2 years after transplantation owing to immunological reasons or recurrence of the underlying renal disease 4. Patient and/or donor is positive for HCV, HBV or HIV 5. History of any malignancy that could not be curatively treated 6. Ongoing abuse of drugs or alcohol 7. Signs of advanced liver disease or any signs of liver decompensation 8. Ongoing uncontrolled systemic infection 9. Severe diarrhoea, vomiting, active peptic ulcer, previous bariatric surgery, or any other gastrointestinal disorder that may affect absorption of tacrolimus 10. Planned or foreseeable use of cyclosporine, belatacept or any tacrolimus preparation other than Envarsus® or Advagraf™ 11. Known contraindication or hypersensitivity to tacrolimus, and/or to any of the excipients listed in section 6.1 of the Summary of Product Characteristics (SmPC) of both Envarsus® and Advagraf™, and/or to any other macrolides 12. Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive hCG laboratory test 13. Women of child-bearing potential (WOCBP), defined as all women physiologically capable of becoming pregnant, unless using a highly-effective method of contraception 14. Participation in another interventional clinical trial in the time period starting from 4 weeks prior to randomisation and throughout the entire trial period 15. Any condition or factor which, in the judgement of the investigator, would place the subject at undue risk, invalidate communication with the investigator or study team, or hamper compliance with the trial protocol or follow-up schedule 16. Inability to freely give informed consent (e.g. individuals under legal guardianship)