title: Review of commonly used age-based weight estimates for paediatric drug dosing in relation to the pharmacokinetic properties of resuscitation drugs.
abstract: OBJECTIVE
  To study which weight estimate calculation used in paediatric resuscitation results in optimal drug dosing; Advanced Paediatric and Life Support (APLS) or the UK Resuscitation Council age-based formula.
  
  
  METHODS
  Commonly used drugs used in paediatric resuscitation were selected and a literature search conducted for each drug's pharmacokinetic properties, concentrating on the volume of distribution (Vd). Hydrophobic drugs have a higher Vd than hydrophilic drugs as they distribute preferentially to fat mass (FM). The larger the Vd, the higher the initial dose required to achieve therapeutic plasma concentrations. Actual body weight (ABW) estimates are a good indicator of Vd for hydrophobic drugs as they correlate well with FM. Ideal body weight (IBW) estimates may be a better indicator of Vd for hydrophilic drugs, as they correlate better with lean body mass. This highlights potential variation between ABW and IBW, which may result in toxic or sub-therapeutic dosing.
  
  
  RESULTS
  The new APLS formulae give higher estimates of expected weight for a wider age range. This may be a more accurate reflection of ABW due to increasing prevalence of obesity in children. The UK Resuscitation Council's formula appears to result in a lower estimate of weight, which may relate more closely to IBW.
  
  
  CONCLUSIONS
  The main drugs used in paediatric resuscitation are hydrophilic, thus the APLS formulae may result in too much being given. Therefore the UK Resuscitation Council's single formula may be preferred. In addition, a single formula may minimize error in the context of a child of unknown weight requiring administration of emergency resuscitation drugs.
authors.affiliation: Accident and Emergency, Imperial College NHS Trust, London, UK.
authors.forename: Clare Francesca
authors.initials: CF
authors.lastname: Carasco
authors.affiliation: Pharmacy, Imperial College NHS Trust, London, UK.
authors.forename: Penny
authors.initials: P
authors.lastname: Fletcher
authors.affiliation: Accident and Emergency, Imperial College NHS Trust, London, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Maconochie
mesh_terms: D000367:Age Factors; D001823:Body Composition; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D054796:Drug Dosage Calculations; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000097:blood; D010599:Pharmacokinetics; D012151:Resuscitation / Q000379:methods*
chemical_list: D004364:Pharmaceutical Preparations
keywords: paediatric; pharmacokinetic; resuscitation; volume of distribution; weight