title: Population pharmacokinetics of 25-hydroxyvitamin D in healthy young adults.
abstract: OBJECTIVE
  The aim of our study was to develop a population pharmacokinetic (PPK) model for 25-hydroxyvitamin D clearance in a healthy young adult population in Serbia.
  
  
  METHODS
  Study sample consisted of 70 healthy young students of the Faculty of Medical Science, University of Kragujevac, Serbia, with a mean age and body mass index of 22.39 ± 1.82 years and 21.31 ± 2.69 kgm-2, respectively. Non-linear mixed-effect modeling (NONMEM) software was used for data analysis. A validation set of 16 participants was used to estimate the predictive performance of the pharmacokinetic model.
  
  
  RESULTS
  In the base model (without covariates), we had parameter estimates of 0.01 L/h for apparent clearance, 0.25 L for apparent volume of distribution, while value of minimum objective function (MOF) was 383.468. The full regression model was established by estimating the effects of 12 covariates. Mean intake of vitamin D from foods (DD) and value of phosphate in serum (PHO) were covariates included in the final model, while others were excluded in this process. The estimated value in the final MOF model was 274.555. The final regression model formula was: clearance (CL) (L/h) = 0.0711 + 0.738 x DD + 0.618 x PHO.
  
  
  CONCLUSIONS
  The PPK model obtained determined clearance of 25-hydroxyvitamin D in a healthy young adult population in Serbia. Mean intake of vitamin D from foods and serum phosphate level are the most important covariates that influence value of 25-hydroxyvitamin D clearance in healthy young adults.
authors.forename: Olivera
authors.initials: O
authors.lastname: Milovanovic
authors.forename: Jasmina R
authors.initials: JR
authors.lastname: Milovanovic
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Djukic
authors.forename: Milovan
authors.initials: M
authors.lastname: Matovic
authors.forename: Aleksandra Tomic
authors.initials: AT
authors.lastname: Lucic
authors.forename: Nenad
authors.initials: N
authors.lastname: Glumbic
authors.forename: Ana
authors.initials: A
authors.lastname: Radovanovic
authors.forename: Slobodan M
authors.initials: SM
authors.lastname: Jankovic
mesh_terms: D004032:Diet; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D017711:Nonlinear Dynamics; D010710:Phosphates / Q000097:blood; D015203:Reproducibility of Results; D055771:Serbia; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D055815:Young Adult
chemical_list: D010710:Phosphates; D014807:Vitamin D; C104450:25-hydroxyvitamin D