title: Ciclosporin kinetics in children after stem cell transplantation.
abstract: OBJECTIVE
  To develop a limited sampling strategy to determine ciclosporin systemic exposure [area-under-the-curve(AUC)]. This is meant to be the first step in a future study of the relationship between AUC and the biological effects of ciclosporin.
  
  
  METHODS
  The pharmacokinetics of ciclosporin was investigated prospectively following stem cell transplantation (SCT) in 17 children, aged 1.8-16.1 years. Ciclosporin was given twice daily, intravenously over a short infusion of 2 h duration during the early post-SCT period, or orally later on, when oral medication was well tolerated. Parameter estimation was performed using nonlinear mixed effect modelling as implemented in the NONMEM program. Individual empirical Bayes estimates of clearance and distribution volume were correlated with the demographic variables.
  
  
  RESULTS
  Pharmacokinetics was described adequately with a two-compartment model with lag time (population estimates: CL = 11.3 l h(-1); V(c) = 16.5 l; V(p) = 59.9 l; t(1/2) absorption = 0.78 h, t(lag) = 0.6 h). The AUCs, determined for the combination of trough level with one time point between 2 and 3 h after dosing, correlated very well with the reference AUC (r(2) = 0.97). No correlation was found between clearance and distribution volume, and the demographic patient variables length, body weight, age and glomerular filtration rate.
  
  
  CONCLUSIONS
  A two-point limited sampling strategy, in combination with a Bayesian fitting procedure using the pharmacokinetic population model described, can adequately determine the AUC of ciclosporin. Since no correlation between clearance and body weight was found, dosing ciclosporin per kg bodyweight is not supported by the results of this study. We suggest starting with a fixed dose, followed by AUC determination and dose adjustment.
authors.affiliation: Department of Paediatrics, Division of Immunology, Haematology, Oncology and Bone Marrow Transplantation and Autoimmune Diseases, Leiden University Medical Centre, Leiden, The Netherlands. a.j.willemze@lumc.nl
authors.forename: A J
authors.initials: AJ
authors.lastname: Willemze
authors.forename: S C
authors.initials: SC
authors.lastname: Cremers
authors.forename: R C
authors.initials: RC
authors.lastname: Schoemaker
authors.forename: A C
authors.initials: AC
authors.lastname: Lankester
authors.forename: J
authors.initials: J
authors.lastname: den Hartigh
authors.forename: J
authors.initials: J
authors.lastname: Burggraaf
authors.forename: J M
authors.initials: JM
authors.lastname: Vossen
mesh_terms: D000293:Adolescent; D019540:Area Under Curve; D001499:Bayes Theorem; D002648:Child; D002675:Child, Preschool; D016572:Cyclosporine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006086:Graft vs Host Disease / Q000188:drug therapy* / Q000517:prevention & control; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007223:Infant; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D012494:Sampling Studies; D033581:Stem Cell Transplantation / Q000009:adverse effects* / Q000379:methods; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D016572:Cyclosporine