Limited sampling model for area-under-the-curve monitoring in pediatric patients receiving either Sandimmune or Neoral cyclosporin A oral formulations.

Several limited sampling equations were tested to predict the area under the curve (AUC) of cyclosporin A (CsA) at steady state in 10 children with end-stage renal disease receiving oral CsA 2.5 mg/kg b.i.d. as two different formulations, namely Sandimmune and Neoral, according to a randomized crossover design with a one-month washout period. AUC was significantly correlated with CsA concentration at 5 h. The equation derived from this single concentration time point was able to adequately predict the AUC for Sandimmune but not for Neoral. The equation derived from CsA concentration data, measured at 2 and 12 h, significantly improved predictive performance in terms of bias and precision, allowing adequate AUC predictions in both formulations. CsA concentration at 2 h was also able to predict Cmax, while the concentration at 12 h corresponded to the trough value in a b.i.d. dosing scheme. Therefore, it is concluded that a limited sampling model including concentration data at 2 and 12 h allows the estimation of AUC, Cmax and trough levels, yielding a complete profile in patients exposed to CsA as Sandimmune or Neoral. Hence, this model can be used for therapeutic monitoring of CsA levels in pediatric patients being switched from one formulation to another.