ABSTRACT
The aims of our trial were to study the pharmacokinetics of tacrolimus in paediatric kidney transplant recipients. The study comprised 25 patients (median age 13 years, range 2-20 years) followed for 12 months; five pharmacokinetics profiles (within the first and second week and after 1 month, 6 months and 12 months) were obtained. Patients were divided into two groups: six children<6 years old and 19 older children. Tacrolimus was given at an initial dose of 0.15 mg/kg twice a day. Blood samples were drawn before and 1 h, 2 h, 3 h, 4 h, 6 h, 9 h and 12 h after drug administration. Patient and kidney survival rates were 100% at 1 year. At 6 months and 12 months creatinine clearance was 68.5+/-16.3 ml/min per 1.73 m2 and 64.0+/-15.2 ml/min per 1.73 m2 body surface area, respectively. Tacrolimus trough levels were 7.8+/-1.9 ng/ml and 7.3+/-2.5 ng/ml. The area under the concentration-time curve for 0 h to 12 h (AUC0-12) normalised to a dose of 0.15 mg/kg, increased with time from the kidney transplantation and stabilised after the 6th month post-transplantation. During the first month after transplantation the normalised tacrolimus concentration-time profiles were significantly greater in the older children (P<0.05); the actual doses were significantly greater in the younger children (P<0.05). In conclusion, initial doses of 0.15 mg/kg twice a day orally are safe and guarantee a satisfactory degree of immunosuppression, with our therapeutic regimen. Children<6 years old need to start with a 50% higher tacrolimus dose to achieve the same pharmacokinetic and immunosuppressive results.
