US experts mull flu drugs, abnormal behavior link

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GAITHERSBURG, Md., Nov 27 (Reuters) The safety of influenza drugs is under scrutiny as advisers to the US Food and Drug Administration today analyzed abnormal psychiatric behavior seen in some patients, especially children.

Medical experts are reviewing cases of patients taking Roche Holding AG's Tamiflu and GlaxoSmithKline Plc's Relenza experiencing hallucinations, delirium and other abnormal behavior. In the case of Tamiflu, several cases resulted in erratic behavior, including jumping from buildings, resulting in death.

It's the third time health officials are publicly discussing flu drug safety, originally prompted by reports two years ago of a dozen deaths, including suicide, of children in Japan who had been taking Tamiflu.

Japan in March warned against prescribing Tamiflu to those ages 10 to 19 when more than 100 people, mostly young, showed signs of strange behavior after taking the drug. It also broadened its probe to other flu drugs, Relenza and amantadine, after additional reports of abnormal behavior.

FDA staffers are recommending a stronger label warning for Tamiflu to note patient deaths and suggest close monitoring children for behavioral changes. For Relenza, addition of a warning about hallucinations and delirium is recommended.

Although there is still no evidence of a direct link, the contribution of the drugs cannot be ruled out, FDA safety reviewer Dr. Adrienne Rothstein told the panel, which will vote later today on whether to beef up labeling warnings.

Known generically as oseltamivir, Tamiflu is a pill, while Relenza, generically known as zanamivir, is inhaled. Makers of both drugs have stood by their safety, citing no direct evidence of cause and effect.

Two earlier FDA panels found no evidence of a direct link between Tamiflu and the deaths, although the FDA did ultimately update Tamiflu's label to add a caution urging close monitoring of patients for abnormal behavior such as delirium or self- injury. Relenza's label has no such warnings.

About 48 million people have taken Tamiflu worldwide, including 21 million children, since approval in 1999, according to Roche. Relenza is much less widely used, by about 4 million people since its launch in 1999.

The Japanese have adopted the drug much more broadly than the United States, with a large majority of the worldwide use of Tamiflu occurring in Japan.

Tamiflu had lackluster sales as a drug to prevent and treat seasonal flu, but got a second life when it was the first drug to show real efficacy in fighting a strain of bird flu that raised fears of a human pandemic. Since then, Tamiflu has been stockpiled by governments preparing for a potential flu pandemic.

The influenza virus is a major cause of death and illness in the United States. Complications from the viral illness kills about 36,000 people a year in the country, a government expert told the panel. Children and seniors are especially at risk.

Four drugs are approved for influenza, but generics amantadine and rimantadine are no longer recommended for use as many strains of the virus are resistant to them.

Reuters AK VP0038

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