Population pharmacokinetic analysis and simulation of the time-concentration profile of etanercept in pediatric patients with juvenile rheumatoid arthritis

J Clin Pharmacol. 2005 Mar;45(3):246-56. doi: 10.1177/0091270004271945.


This study was performed to estimate the population pharmacokinetic (PK) parameters of etanercept in pediatric juvenile rheumatoid arthritis (JRA) patients and to compare the steady-state time-concentration profiles between etanercept 0.8-mg/kg once-weekly and 0.4-mg/kg twice-weekly subcutaneous (SC) regimens by clinical trial simulation. To this end, mixed-effect analysis (NONMEM, Version 5.1) was performed using the etanercept PK database consisting of 69 JRA patients (4-17 years). Based on the population PK parameters obtained herein, a Monte Carlo clinical trial simulation experiment was conducted to compare the PK profiles in 200 virtual JRA patients who randomly received either etanercept 0.4 mg/kg SC twice weekly or 0.8 mg/kg once weekly for 12 weeks. The following population PK model could adequately describe etanercept PK profiles for twice-weekly SC dosing of 0.4 mg/kg: CL/F (L/h)=0.0576 (female) or 0.0772 (male) x (body surface area in m2/1.071)1.41, V/F(L)=7.88 x (body weight in kg/30.8). The means +/- standard deviations of simulated trough concentrations for 0.8-mg/kg once-weekly and 0.4-mg/kg twice-weekly dosing regimens were 1.58 +/- 1.07 mg/L and 1.92 +/- 1.09 mg/L, respectively. Peaks during 0.8-mg/kg once-weekly dosing (2.92 +/- 1.41 mg/L) were only 11% higher than during 0.4 mg/kg twice-weekly dosing (2.62 +/- 1.23 mg/L). In conclusion, the clinical trial simulation confirmed that 0.8-mg/kg once-weekly and 0.4-mg/kg twice-weekly SC regimens of etanercept are expected to yield overlapping steady-state time-concentration profiles, leading to equivalent clinical outcomes. This has been the basis of the recent Food and Drug Administration approval of the 0.8-mg/kg once-weekly regimen in pediatric patients with JRA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Antirheumatic Agents / administration & dosage
  • Antirheumatic Agents / metabolism*
  • Arthritis, Juvenile / drug therapy
  • Arthritis, Juvenile / metabolism*
  • Child
  • Child, Preschool
  • Computer Simulation
  • Drug Approval
  • Etanercept
  • Female
  • Follow-Up Studies
  • Humans
  • Immunoglobulin G / administration & dosage
  • Immunoglobulin G / metabolism*
  • Male
  • Models, Biological*
  • Monte Carlo Method
  • Multicenter Studies as Topic
  • Pharmacokinetics
  • Randomized Controlled Trials as Topic
  • Receptors, Tumor Necrosis Factor / administration & dosage
  • Receptors, Tumor Necrosis Factor / metabolism*


  • Antirheumatic Agents
  • Immunoglobulin G
  • Receptors, Tumor Necrosis Factor
  • Etanercept