Monitoring of CsA blood levels two h post-dose (C2) has shown a higher correlation to drug exposure than monitoring of trough levels (C0) at least in adults, but initial doses and target blood levels of CsA have yet to be established in pediatric transplant patients. The objectives of the study were to describe the pharmacokinetics of CsA administered by NGT in the first days after transplantation and the dose of Sandimmun Neoral required to achieve minimum therapeutic range blood levels. This study included 20 pediatric liver transplant recipients (mean age of 3.2 yr) treated with CsA administered by NGT from day one post-transplant until they were able to ingest oral medication. The study was continued until one yr of post-transplant follow-up. Eight h pharmacokinetic profiles were performed on days one, three, and five post-transplant to determine the minimum dose required to achieve the therapeutic range. All children received an initial dose of 15 mg/kg/day of CsA by NGT. Mean CsA doses administered on days one, three, and five were 16.8, 29.5, and 36.5 mg/kg/day, respectively. Mean C0 levels of 119, 310, and 337 ng/mL and mean C2 levels of 213, 753, and 888 ng/mL were obtained. No correlation was found between C0 and C2 levels and the AUC(0-8 h). Intravenous administration of CsA was required in 55% of patients. The biopsy-confirmed acute rejection rate was 45%, with graft and patient survival rates of 95 and 100%, respectively.
Conclusions: Poor absorption of CsA in small children requires a considerable increase in dose. CsA exposure cannot be estimated by single C0 or C2 determinations in the early post-transplant period.