FDA approves Tamiflu use for children aged younger than 1 year

The FDA recently expanded the approved use of oseltamivir phosphate to treat children older than 2 weeks who have exhibited symptoms of influenza for no longer than 2 days.

Oseltamivir (Tamiflu, Roche) has not been approved for prevention of influenza infection in this population, however, and the safety and efficacy to treat influenza infection has not been established in children younger than 2 weeks old.

Oseltamivir was approved in 1999 to treat adults infected with influenza who demonstrated symptoms for no longer than 2 days. It has since been approved to treat influenza in children aged 1 year and older who have exhibited symptoms of influenza for no longer than 2 days, and to prevent flu in adults and children aged 1 year and older.

Although there is a fixed dosing regimen for patients aged 1 year and older according to weight categories, the dosing for younger children must be calculated individually based on their exact weight. Children should receive 3 mg per kg twice daily for 5 days, a dosage that will require a different dispenser than that currently co-packaged with oseltamivir.

Edward Cox, MD, MPH

“Pharmacists must provide the proper dispenser when filling a prescription so parents can measure and administer the correct dose to their children,” Edward Cox, MD, MPH, director of the Office of Antimicrobial Products in the FDA’s Center for Drug Evaluation and Research said in a press release. “Parents and pediatricians must make sure children receive only the amount of Tamiflu appropriate for their weight.”

The FDA extended the approved use of Tamiflu in children aged younger than 1 year based on extrapolation of data from previous study results in adults and older children, as well as supporting safety and pharmacokinetic studies sponsored by the National Institutes of Health and the drug’s manufacturer.

Pharmacokinetic data show a dose of 3 mg/kg twice daily provided concentrations of oseltamivir similar to those observed in older children and adults, and is projected to provide similar efficacy in this younger age group.

Almost all of the 135 pediatric patients enrolled in the two safety studies had confirmed influenza. Results from these studies showed the safety profile in children younger than 1 year was consistent with the established safety profile of adults and older children.

The most commonly reported side effects with oseltamivir use in this age group included vomiting and diarrhea. Although not observed in the new studies, infrequent cases of skin reactions, severe rash, delirium, hallucinations and abnormal behavior were previously reported.