title: Population pharmacokinetics of valproate in Mexican children with epilepsy.
abstract: BACKGROUND
  The aim of this study was to determine the factors that influence valproate clearance (CL) in Mexican epileptic pediatric patients using a mixed-effect model and sparse data of serum concentrations of valproic acid (VPA) collected during routine clinical care of patients.
  
  
  METHODS
  The number of patients included in the study was 110. The population CL was calculated by using the NONMEM program. The following covariates were tested by their influence on CL: total body weight (TBW), height, age, body surface area, daily dose (DD), sex of the patient and comedication with phenobarbital (PB) or carbamazepine.
  
  
  RESULTS
  The final regression model for valproic CL found best to describe the data was: CL/F=(0.0466+0.00363 TBW+0.000282 DD)*(1+0.236 PB). This model allows a reduction of 50% of the interindividual variability and of 31% of the residual variability described by the basic model that does not include covariables.
  
  
  CONCLUSIONS
  Total body weight, daily dose of valproate and concomitant therapy with PB are factors that significantly influence VPA kinetic disposition and they should be considered in programming dosage regimens for this antiepileptic drug in the pediatric population. The validation of the model supports its acceptability for clinical purposes.
authors.affiliation: Pharmacy Department, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava No 6, San Luis Potosí, México.
authors.forename: Tania
authors.initials: T
authors.lastname: Correa
authors.forename: Ildefonso
authors.initials: I
authors.lastname: Rodríguez
authors.forename: Silvia
authors.initials: S
authors.lastname: Romano
mesh_terms: D000293:Adolescent; D000927:Anticonvulsants / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004827:Epilepsy / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D017058:Mexican Americans; D008954:Models, Biological; D012189:Retrospective Studies; D014635:Valproic Acid / Q000493:pharmacokinetics* / Q000627:therapeutic use*
chemical_list: D000927:Anticonvulsants; D014635:Valproic Acid