Background: The suitable dosage regime of mycophenolate mofetil (MMF) based on the pharmacokinetics of mycophenoric acid (MPA) for pediatric patients with idiopathic nephrotic syndrome (INS) is controversial. The pharmacokinetics of MPA is influenced by renal function, serum albumin concentration, and concomitant medications, especially calcineurin inhibitors. This study analyzed the pharmacokinetics of MPA in clinically stable children with INS receiving cyclosporine (CyA).
Methods: This retrospective study enrolled children with INS receiving MMF (Cellcept®) (30-40 mg/kg/day in two divided doses) combined with CyA (Neoral®) without relapse and renal dysfunction. Pharmacokinetic parameters, including the area under the concentration-time curve (AUC) calculated by the trapezoid method, were calculated from seven serial blood samples.
Results: Thirty-two patients (22 males) of median age 11.0 years were included; 32 pharmacokinetic studies were performed. The median MMF dose was 16.2 mg/kg/time or 470.4 mg/m2/time. The median AUC0-12 was 44.3 ng h/mL. AUC0-12 of all patients showed excellent correlations with C2 (r 2 = 0.6405, P < 0.0001), resulting in a regression formula of AUC0-12 = 21.971 + 2.6059 C2. Comparisons of dose/body weight-normalized AUC0-12 values among age groups showed a lower value in the youngest group (≤5 years).
Conclusion: In children with clinically stable INS receiving CyA, C2 monitoring was the most useful single parameter for estimating MPA pharmacokinetics. Younger children required higher MMF doses.
Keywords: Children; Cyclosporine; Mycophenolate mofetil; Mycophenolic acid; Nephrotic syndrome; Pharmacokinetics.