An advisory panel of the FDA has recommended stronger warnings for the influenza drug zanamivir (Relenza, Glaxo-SmithKline). The panel wanted the label to mention the potential for abnormal psychiatric side effects, sometimes leading to death. The panel also recommended additional warnings for oseltamivir (Tamiflu drug, Roche).
The panel reviewed a small but rising number of cases, mostly in Japan. In the case of generic Tamiflu, erratic behavior, including jumping from buildings, resulted in deaths. The FDA described reports of approximately 700 cases of psychiatric adverse events for both drugs and 25 cases of pediatric deaths in patients taking (buy) Tamiflu. No fatalities were reported for Relenza.
The panel said that the labels for both drugs should mention that the psychotic reactions and hallucinations observed are rare and that the reactions might occur in patients with the flu who are not taking these drugs.
Both Roche and Glaxo told FDA advisers that their studies show no conclusive evidence that (order) Tamiflu and Relenza were causing psychiatric events and suggested that the flu itself might be responsible. The companies said that they opposed the label changes and cited data showing no causal link between the drugs and adverse events, noting the difficulty in differentiating “drug from disease.”
About 48 million people worldwide have taken Tamiflu since it was approved in 1999, according to Roche. Relenza has been used by about 4 million people since its launch in 1999.
(Sources: Reuters news, November 27, 2007