Pharmacokinetics of oseltamivir in infants under the age of 1 year

Area of Science:

• Pediatric Pharmacology
• Infectious Diseases
• Antiviral Therapeutics

Background:

• Oseltamivir is the recommended influenza antiviral for children over one year old.
• Limited pharmacokinetic data exists for oseltamivir in infants under one year.
• This study addresses the need for PK data in this vulnerable population.

Purpose of the Study:

• To evaluate the pharmacokinetics (PK) and safety of oseltamivir in infants under 12 months.
• To determine if standard dosing achieves therapeutic drug levels in infants.
• To assess viral clearance and adverse events associated with oseltamivir treatment in infants.

Main Methods:

• Prospective, uncontrolled, open-label study in infants (<12 months) diagnosed with influenza.
• Oseltamivir doses ranged from 2.35-3 mg/kg administered orally.
• Blood samples measured oseltamivir and its active metabolite (carboxylate) at multiple time points to calculate PK parameters (Cmax, Tmax, AUC).

Main Results:

• Four infants with influenza A received oseltamivir (2.35-3 mg/kg/dose).
• The administered doses achieved target oseltamivir carboxylate plasma concentrations, exceeding the proposed 12-h AUC of 3800 ng·h/mL.
• One infant experienced a gastrointestinal adverse event (dry retching); otherwise, oseltamivir was well tolerated.

Conclusions:

• Oseltamivir, at 2.35-3 mg/kg twice daily, is well-tolerated in infants under one year.
• These doses achieve target plasma exposure levels, supporting their use in this age group.
• The findings align with previous data and suggest oseltamivir is a viable treatment option for infants with influenza.