Prospective, Multicenter Clinical Study of Prolonged-release Tacrolimus in Stable Pediatric Liver Transplant Recipients

Inclusion Criteria: 1. Children (≤18 years old) who have undergone liver transplantation, with no gender limitations; 2. Able to completely swallow capsules; 3. Have been using immediate-release tacrolimus for at least three months prior to study enrollment; 4. Have normal blood count, liver and kidney function, coagulation function, and considered clinically stable by researchers; 5. Undergo a programmed liver biopsy; Exclusion Criteria: 1. Multi-organ combined transplantation or multiple liver transplantation; 2. Adjuvant liver transplantation or use of bioartificial liver therapy; 3. ABO incompatible children with liver transplantation; 4. Allergic to tacrolimus; 5. Participation in any other clinical study within 3 months prior to enrollment; 6. Use of tacrolimus sustained release capsules before enrollment; 7. Tacrolimus trough concentration lower than 3.5 ng/ml at the time of screening;