title: No role for patient body weight on renal function assessment for drug dosing.
abstract: To evaluate the ability of body-weight-driven renal function assessment (RFA) formulae to predict on-target elimination rate ranges for gentamicin in patients with varying degrees of renal function.
  
  
  
  A 6 year retrospective pharmacokinetic study was conducted at a university teaching hospital.
  
  
  
  A total of 85 patients met the inclusion criteria and 127 pharmacokinetic files were analysed from patients on medical-surgical wards (53%) and medical-surgical ICUs (13%) receiving intravenous gentamicin for treatment, as well as those for patients receiving it for surgical prophylaxis (34%). Each RFA formula was examined against standard dosing tables for gentamicin. A table of acceptable elimination rates was generated using a traditional peak of 8 mg/L and trough between 0.5 and 2 mg/L associated with each of the dosing interval extensions. The ability of each RFA formula to select on-target elimination rates was evaluated. The RFA formula assuming a normalized body weight of 72 kg and a modified creatinine reagent adjustment factor of 90% provided the most accurate on-target elimination rate selection. This method was superior to dosing interval selection based on the Modification in Diet Renal Disease (MDRD) formula, Sanford's guide method, as well as the Cockcroft-Gault formulae using total body weight, ideal body weight or lean body weight ( P  <   0.0001).
  
  
  
  Based on the use of gentamicin as a surrogate guide for renally adjusted drugs, these results support dosing interval selection based on a normalized body weight method and a formula reagent adjustment factor of 90% within the Cockcroft-Gault formula.
authors.affiliation: Department of Pharmacy, St Boniface General Hospital, 409 Tache Avenue, Winnipeg, Manitoba, Canada.|College of Pharmacy, University of Manitoba, Winnipeg, Canada.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ariano
authors.affiliation: Department of Pharmacy, St Boniface General Hospital, 409 Tache Avenue, Winnipeg, Manitoba, Canada.|College of Pharmacy, University of Manitoba, Winnipeg, Canada.
authors.forename: Sheryl A
authors.initials: SA
authors.lastname: Zelenitsky
authors.affiliation: Neepawa Health Centre, Neepawa, Manitoba, Canada.
authors.forename: Kristen R
authors.initials: KR
authors.lastname: Poncsak
authors.affiliation: Department of Pharmacy, St Boniface General Hospital, 409 Tache Avenue, Winnipeg, Manitoba, Canada.|College of Pharmacy, University of Manitoba, Winnipeg, Canada.|Manitoba Renal Program, Winnipeg, Canada.
authors.forename: J Christine
authors.initials: JC
authors.lastname: Davis
authors.affiliation: College of Pharmacy, University of Manitoba, Winnipeg, Canada.|Manitoba Renal Program, Winnipeg, Canada.
authors.forename: Lavern M
authors.initials: LM
authors.lastname: Vercaigne
mesh_terms: D061605:Administration, Intravenous; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D003404:Creatinine / Q000097:blood / Q000652:urine; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D005839:Gentamicins; D003404:Creatinine