title: Once- or twice-daily dosing of nevirapine in HIV-infected adults: a population pharmacokinetics approach.
abstract: OBJECTIVE
  The aim of this study was to develop and validate a population pharmacokinetic model for nevirapine in a population of HIV-infected adults and to evaluate the influence of nevirapine dosing regimen and patient characteristics on nevirapine trough concentration.
  
  
  METHODS
  HIV-infected adults receiving oral nevirapine for at least 4 weeks were included. A concentration-time profile was obtained for each patient, and nevirapine concentrations in plasma were determined by HPLC. Pharmacokinetic parameters, inter-individual variability and residual error were estimated using non-linear mixed effects modelling. The influence of patient characteristics on the pharmacokinetics of nevirapine was explored, and the predictive performance of the final model was evaluated in an external data set of observations.
  
  
  RESULTS
  Totals of 40 and 18 Caucasian patients were included in two data sets for model building and model validation, respectively. A mono-compartmental model with first-order absorption and elimination best described the pharmacokinetics of nevirapine. Body weight influenced oral clearance (CL/F) and volume of distribution (V/F). The estimated population pharmacokinetic parameters (inter-individual variability) for an individual weighing 70 kg were CL/F 2.95 L/h (24%), V/F 95.2 L (30%) and k(a) 1.8 h(-1) (96%). The final model predicted nevirapine concentrations in the external model-validation data set with no systematic bias and adequate precision. Bayesian estimates of nevirapine trough concentrations were lower when nevirapine was administered once instead of twice daily, and nearly half of the patients weighing 90 kg had drug concentrations <3.0 mg/L when nevirapine was dosed once daily.
  
  
  CONCLUSIONS
  A population model to describe the pharmacokinetics of nevirapine was developed and validated in HIV-infected patients. Body weight influenced CL/F and V/F. Based on Bayesian estimates of individual nevirapine concentrations, twice- instead of once-daily administration of nevirapine would be more optimal in patients weighing >70 kg.
authors.affiliation: Lluita contra la SIDA Foundation, Hospital Universitari Germans Trias i Pujol, Badalona, Spain. jmolto@flsida.org
authors.forename: José
authors.initials: J
authors.lastname: Moltó
authors.forename: Marta
authors.initials: M
authors.lastname: Valle
authors.forename: Cristina
authors.initials: C
authors.lastname: Miranda
authors.forename: Samandhy
authors.initials: S
authors.lastname: Cedeño
authors.forename: José
authors.initials: J
authors.lastname: Miranda
authors.forename: José Ramón
authors.initials: JR
authors.lastname: Santos
authors.forename: Eugenia
authors.initials: E
authors.lastname: Negredo
authors.forename: Josep
authors.initials: J
authors.lastname: Vilaró
authors.forename: Joan
authors.initials: J
authors.lastname: Costa
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Clotet
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D019829:Nevirapine / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010949:Plasma / Q000737:chemistry; D044465:White People
chemical_list: D019380:Anti-HIV Agents; D019829:Nevirapine