USA. Roche Laboratories Inc, in consultation with US FDA, is advising healthcare professionals that oseltamivir (Tamiflu), indicated in the treatment of uncomplicated acute illness due to influenza, should not be used for either treatment or prophylaxis of influenza in children under one year of age. This warning is being issued because a single dose of 1000 mg/kg oseltamivir phosphate (about 250 times the recommended dose in children) in juvenile rats resulted in the death of 7-day old rats; the deaths were associated with levels of oseltamivir phosphate in the brain approximately 1500 times those seen in adult animals. It is likely that these high exposures were related to an immature blood-brain barrier. The clinical significance of these preclinical data to human infants is uncertain. Given the uncertainty in predicting the exposures in infants with immature blood-brain barriers, it is recommended that oseltamivir (Tamiflu) not be administered to children younger than one year of age. The company is in the process of updating the product monograph with the above information.

Reference:
‘Dear Healthcare Professional’ letter from Roche Laboratories Inc, December 2003. Available from URL: http://www.fda.gov/medwatch