title: A population pharmacokinetic model of remifentanil in pediatric patients using body-weight-dependent allometric exponents.
abstract: BACKGROUND
  Allometric exponents in population pharmacokinetic analysis are regularly used but the issue of fixing or estimating an allometric exponent remains controversial. The objective of the current analysis is to evaluate the performance of a body-weight-dependent allometric exponent (BDE) model of remifentanil.
  
  
  METHODS
  The study was conducted in 34 patients (neonates to 17 years and 2.5 to 97 kg body weight) following a single intravenous (IV) infusion of remifentanil (5 μg/kg). A population pharmacokinetic approach was taken to describe drug clearance by the following BDE equation: CL=CLpop(BW/14.6 kg)L×BW(-M). Three allometric models were used to explore the impact of allometric exponents on the total clearance of remifentanil.
  
  
  RESULTS
  All model-fitted structural, covariate, and statistical parameters were estimated with good to excellent precision (%RSE). However, on the basis of calculated Akaike weights (0.000 for model 1, 0.004 for model 2, and 0.996 for model 3), model 3 is the most robust model to describe individual clearance estimates.
  
  
  CONCLUSIONS
  The BDE model performed best for the estimation of remifentanil clearance and is realistic and of practical value. Further investigation should be conducted for such models.
authors.forename: Carl-Michael
authors.initials: CM
authors.lastname: Staschen
authors.forename: Iftekhar
authors.initials: I
authors.lastname: Mahmood
mesh_terms: D000293:Adolescent; D000375:Aging / Q000378:metabolism; D000465:Algorithms; D018686:Anesthetics, Intravenous / Q000493:pharmacokinetics*; D001835:Body Weight / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D004950:Esterases / Q000097:blood; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015233:Models, Statistical; D010880:Piperidines / Q000493:pharmacokinetics*; D011153:Population; D000077208:Remifentanil; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D004950:Esterases; D000077208:Remifentanil