Japanese Relenza Sales Could get a Boost from Tamiflu Warning

GlaxoSmithKline (GSK) could see a boost to sales for its antiviral treatment Relenza following reports of a Japanese Health Ministry recommendation against Tamiflu use in teenagers because of reports of abnormal behavior.

Although GSK would not comment on the Tamiflu (oseltamivir) recommendations and any subsequent sales expectations resulting from the health ministry's action, the company said its Relenza (zanamivir) labeling does not carry warnings for neuropsychiatric or behavioral adverse events.

GSK also noted that Relenza is indicated for prevention of influenza for children ages 5 and up, as well as for the reduction in the duration of influenza for children ages 7 and up. Relenza is an inhaled drug product while Tamiflu, distributed by Roche's Japanese subsidiary Chugai Pharmaceutical, is an oral treatment.

Roche said it "does not see this label change in Japan as an appropriate course of action." The firm said that the updates to Japanese labeling for Tamiflu will state that there is "no established causality between Tamiflu and these events."

In addition, Roche said the label will state that "influenza itself has been associated with such events" and that "abnormal behavior and delirium is observed in influenza patients regardless of the treatment with Tamiflu."