Oseltamivir phosphate-Lifting the restriction on its use to treat teenagers with influenza in Japan.

Abstract

In 2007, Ministry of Health, Labour and Welfare (MHLW) warned to refrain from prescribing oseltamivir for teenagers when two Japanese teenagers with influenza fell from a high-rise building after taking oseltamivir. Revisions of the warning texts of anti-influenza drugs were discussed by the Subcommittee of Pharmaceutical Affairs and Food Sanitation Council, MHLW, based on the studies and trends of anti-influenza medication over the last 10 years. The research group led by Dr Nobuhiko Okabe conducted nationwide survey since the 2007/2008 influenza season. The results of Japanese and foreign epidemiological and non-clinical studies of abnormal behaviors in influenza patients since 2009 were reviewed. Severe abnormal behaviors have been reported in influenza patients taking all types of anti-influenza drugs, as well as in untreated patients. There are some risks to patients whether treated with any anti-influenza drug, or non-treated though it is still not possible to rule out a potential causal relationship between abnormal behaviors and anti-influenza drugs. 70% of abnormal behaviors occurred within two days after the onset of fever. No difference was found between anti-influenza drugs treated and non-treated patients. In patients receiving oseltamivir and other anti-influenza drugs, the frequency of abnormal behaviors is not clearly different between teenagers and patients under 10 years old. The specific "boxed warning" and the restriction only for oseltamivir that should not be used for teenagers was lifted. Therefore, the labeling of all anti-influenza drugs carry a consistent warning about the potential for abnormal behaviors in Japan.