Pharmacokinetics of anti-influenza prodrug oseltamivir in children aged 1-5 years

Eur J Clin Pharmacol. 2003 Sep;59(5-6):411-5. doi: 10.1007/s00228-003-0639-6. Epub 2003 Aug 9.


Objective: The prodrug oseltamivir has been shown to be efficacious and safe for the treatment of influenza for patients 1 year of age or older; however, pharmacokinetic information was lacking for children below 5 years of age. This study was conducted to assess the metabolic and excretory capacity of oseltamivir and its active carboxylate metabolite in young children.

Methods: Twelve healthy children aged 1-5 years received a single oral suspension dose of oseltamivir (45 mg for 3-5 years, 30 mg for 1-2 years). Plasma and urine concentrations of oseltamivir and the carboxylate were determined by means of liquid chromatography/tandem mass spectrometry.

Results: Mean peak plasma concentration and area under the plasma concentration-time curve values normalized to milligram per kilogram oseltamivir dose in the 1- to 2-year group are lower than those in the 3- to 5-year group. Mean body weight normalized oral clearance of oseltamivir and its carboxylate in younger subjects aged 1-2 years (259 ml/min/kg and 12.2 ml/min/kg) were, respectively, 52% and 30% higher than those in older subjects aged 3-5 years (170 ml/min/kg and 9.4 ml/min/kg).

Conclusion: The results demonstrate that infants as young as 1 year old can metabolize and excrete oseltamivir efficiently. The data derived from this study provide the starting dose of oseltamivir for further investigation in an efficacy study among influenza-infected infants less than 1 year of age.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetamides / administration & dosage
  • Acetamides / pharmacokinetics*
  • Administration, Oral
  • Age Factors
  • Antiviral Agents / administration & dosage
  • Antiviral Agents / pharmacokinetics*
  • Area Under Curve
  • Child, Preschool
  • Female
  • Half-Life
  • Humans
  • Infant
  • Influenza, Human / drug therapy
  • Male
  • Neuraminidase / antagonists & inhibitors*
  • Oseltamivir
  • Prodrugs / administration & dosage
  • Prodrugs / pharmacokinetics*


  • Acetamides
  • Antiviral Agents
  • Prodrugs
  • Oseltamivir
  • Neuraminidase