Tamiflu® (oseltamavir) is an
antiviral agent that is indicated for prophylaxis of influenza and treatment of acute illness caused
by influenza A or B viral infection with symptom onset within 48 hours. As of December 21, 2012 the FDA has expanded the
indication of Tamiflu for treatment of influenza infection to include pediatric patients of ages 2
weeks to 1 year. When the product was originally
approved in 1999, it was not indicated for the treatment of children less than 1 year of age, and it
is still not indicated for influenza prophylaxis in children less than 1 year of age. The decision
to expand the indication was based on data extrapolated from previous studies done in adults and
children and two additional, safety and pharmacokinetic studies. 1-3
Two open label trials evaluated the
safety and pharmacokinetics of oseltamivir and oseltamivir carboxylate in influenza infected
pediatric patients 2 weeks to less than 1 year of age (including premature infants at least 36 weeks
post conceptional age). Subjects received oseltamavir at doses ranging from 2 to 3.5 mg/kg twice
daily for 5 days depending on subject age. These clinical trials were not designed to evaluate
clinical efficacy or virologic response. The trials provided adequate safety data to support the
recommended dose selection for the treatment of acute illness in children 2 weeks to 1 year of age
of 3 mg/kg twice daily.2-3
Of the 136 subjects under the age
of 1 year enrolled and dosed in the trials, the majority of the subjects were male (55%), white
(79%), non-Hispanic (74%), full term (76%) and infected with influenza A (80%). Pharmacokinetic data
indicated that a dose of 3 mg/kg twice daily in pediatric subjects 2 weeks to less than 1 year of
age provided oseltamavir concentrations similar to or higher than those observed in older pediatric
subjects and adults receiving the approved dose and, by extrapolation to earlier study results, the
FDA has concluded that is expected to provide similar efficacy. 2-3
Current dosing recommendation for
the treatment of flu in adults and children older than 2 years of age or those with body weight
>40 kg is 75 mg twice daily for 5 days. The treatment
dosing recommendation for oseltamivir for children aged ≥1 year who weigh ≤15 kg is 30 mg
twice a day. For children who weigh >15 kg and up to 23 kg, the dose is 45 mg twice a day. For
children who weigh >23 kg and up to 40 kg, the dose is 60 mg twice a day. For children less than
1 year of age, dosing is weight based at 3 mg/kg twice daily.4
In conclusion, Tamiflu is indicated
for the treatment of flu in children as young as 2 weeks old when time since symptom onset is less
than 48 hours. However, it has not been approved for prophylaxis of flu in children less than one
year old. Children under the age of 2 years are among those in the highest risk category for
developing complications related to influenza infection. As of January 5 2013, The Center for
Disease Control (CDC) reports the death of 20 pediatric patients from this season’s flu
outbreak.5 This new expanded indication of oseltamivir can
become an important part of preventing deaths of pediatric patients.
1. FDA News Releases. FDA expands Tamiflu’s use to treat children
younger than 1 year. Cited on Jan 8, 2013 at fda.gov.
2. Tamiflu (oseltamivir phosphate) capsules and oral suspension package
insert. Roche Laboratories Inc. Jan 2008.
3. Kimberlin D, Acosta E, Prichard M, Sanchez P, Ampofo K, et al.
Oseltamivir Pharmacokinetics, Dosing and Resistance in Children From Birth to Two Years of Age with
Influenza. Journal of Infectious Diseases.
4. Seasonal Influenza. Guidance on the Use of Influenza Antiviral Agents.
Centers for Disease Control and Prevention. Cited on Jan 9, 2013. Available at CDC.gov.
5. Seasonal Influenza. Flu Activity and Surveillance. Center for Disease
Control and Prevention. Cited on Jan 14, 2013. Available