Pharmacokinetics of cyclosporine after renal transplant in children.

The pharmacokinetics of cyclosporine and the relationship between blood levels and average drug concentration were prospectively evaluated in 18 children I month after renal transplantation. All children had normal renal function and no hepatic or gastrointestinal dysfunction. Cyclosporine was administered after an overnight fast, and serial blood samples were drawn over a 24-hour period. Analysis of cyclosporine levels was performed by means of monoclonal radio immunoassay on whole blood. Children were divided into three age groups for comparison : 2-5 years, 5-10 years, and >10 years. There were no differences between age groups in serum protein, serum lipids, or hemoglobin levels, or in the pharmacokinetic parameters of cyclosporine except as follows : significant differences were noted in cyclosporine dose based on body weight, apparent steady-state volume of distribution, and apparent blood clearance, with the youngest children (2-5) requiring higher doses, a relative greater distribution, and exhibiting more rapid drug clearance than those >10 years of age. In addition, we observed diurnal variation in trough levels, with morning levels (0 hr) significantly higher than those obtained in the evening (12 hours after administration of cyclosporine). Trough levels demonstrated a fair correlation with area under the concentration-time curve (AUC) and average concentration (C av ), but an abbreviated kinetic profile using cyclosporine levels 1 and 3.5 hours after administration accurately predicted AUC.