Pharmacokinetics and pharmacodynamics of basiliximab in Japanese pediatric renal transplant patients

Objectives: This study was aimed at evaluating the pharmacokinetics and pharmacodynamics of basiliximab in Japanese pediatric renal transplant patients. Materials and methods: This study was carried out with the approval of the Institutional Review Board of our institution. Written consent was obtained from the legal representative of each patient, as also from the patients themselves where possible. Eligible patients were Japanese pediatric patients weighing less than 35 kg and younger than 15 years of age who were scheduled to undergo renal transplantation. Each patient was given intravenous basiliximab at the total dose of 20 mg administered in two divided doses of 10 mg each on the day of transplantation and on the fourth day after transplantation. Cyclosporine and corticosteroids were also administered as the basic concomitant maintenance immunosuppressive therapy. The time course of changes in the serum basiliximab concentrations and the percentage of CD25+ T-lymphocytes in the peripheral blood were determined up to 26 weeks after the transplantation to calculate the period of suppression of the CD25+ T-lymphocytes. Serum basiliximab was measured by an ELISA technique, and the percentage of CD25+ T-lymphocytes in the peripheral blood was determined by flow cytometry. Results: 6 Japanese pediatric patients weighing less than 35 kg and aged over 1 year and less than 15 years who were scheduled to undergo renal transplantation were enrolled in this study. In regard to the time course of changes of the serum basiliximab concentration, after the peak serum concentration was reached, basiliximab was gradually eliminated from the blood with a mean half-life of 7.06 days. CD25+ T-lymphocytes in the peripheral blood were suppressed completely when the serum concentration of basiliximab was over 0.2 mu g/ml, and the period of suppression of the CD25+ T cells was 40.3 - 51.7 days (mean +/- SD; 45.8 +/- 4.9). Conclusion: Changes in the serum concentration of basiliximab and the period of suppression of CD25+ peripheral blood T-lymphocytes in Japanese pediatric renal transplant patients were similar to those reported for non-Japanese pediatric transplant patients and Japanese adult renal transplant patients with a cyclosporine and corticosteroid regimen. This indicates that expected efficacy can be obtained in Japanese pediatric renal transplant patients using the recommended dosing regimens validated by non-Japanese studies.