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WASHINGTON, July 3 (Reuters) - Two rival flu drugs, Tamiflu and Relenza, work equally well to fight the symptoms of influenza in children, Japanese researchers reported on Thursday.
Doctors can feel free to choose either drug in treating children and may prefer Relenza, made by GlaxoSmithKline (GSK.L) (GSK.N) and known generically as zanamivir, for youths aged 10 to 19, they said.
They said their study was the first head-to-head comparison in children of the two drugs, in a class known as neuraminidase inhibitors.
The issue is important in Japan, where the drugs are heavily used and where doctors are still trying to determine if Roche's ROG.VX Tamiflu, known generically as oseltamivir, may have been linked with some suicides.
Dr. Norio Sugaya of Keiyu Hospital in Yokohama and colleagues studied nearly 350 children treated with either one of the drugs for influenza.
"More than 70 percent of the total amount of oseltamivir prescribed throughout the world each year is used in Japan," they wrote in the journal Clinical Infectious Diseases.
"Most patients in Japan with an influenza-like illness are now tested with rapid diagnostic tests; when results are positive, they are treated with a neuraminidase inhibitor, usually oseltamivir," they said.
But because of reports of psychiatric reactions, the Health, Labor, and Welfare Ministry of Japan suspended use of Tamiflu for patients aged 10 to 19.
"Accordingly, zanamivir will be prescribed widely for teenaged patients with influenza," the researchers wrote.
Both drugs can reduce the severity of illness if given soon enough and can cut a few days off how long a patient is ill.
Sugaya's team found almost no differences between the drugs when used to treat flu in children. Both drugs cut about two days off the time the children had fever, they found.
"Oseltamivir and zanamivir were equally effective in reducing the febrile period of children with influenza A (H1N1), influenza A (H3N2), and influenza B virus infection," they wrote.
Both drugs worked better against H3N2 flu than they did against either H1N1 or influenza B viruses, the researchers added.
Such comparisons may also be useful in planning for a pandemic of influenza. Many experts predict a pandemic is coming, with the current chief suspect the H5N1 avian influenza strain that has become entrenched in birds across much of Asia, Europe, the Middle East and Africa.
It rarely infects people now but has killed 243 out of 385 infected. Quick use of Tamiflu has been credited with saving some lives.
(Reporting by Maggie Fox; Editing by Will Dunham and Bill Trott)