March 25, 2008
Scientists find flu virus that resists tamiflu, relenza. Some flu viruses appear to resist the antiviral flu drugs Tamiflu and Relenza, report Japanese researchers.
Hatakeyama and colleagues had previously noted cases of influenza type a resisted Tamiflu. Now, they note cases of influenza type B that show reduced sensitivity to Tamiflu and Relenza.
Researcher's team studied flu viruses from a Japanese epidemic of influenza type B from 2004 to 2005.
The flu specimens came from patients including 74 children who took Tamiflu for five days, 282 untreated children, and 66 untreated adults.
Building up tolerance
One of the children who took Tamiflu had influenza type B that resisted Tamiflu and Relenza, according to the researchers' lab tests.
Seven untreated patients had influenza type B that resisted Tamiflu and Relenza, the study shows.
The drug-resistant flu had the same symptoms and duration as normal flu. Drug-resistant flu likely spread through the community or among siblings, note the researchers.
Drug resistance in influenza type B seems to be rarer than drug resistance in influenza type a but requires "continued close monitoring".
Experts who wrote a journal editorial agree that drug-resistant flu should be watched closely.
The news about drug-resistant flu "is not good", states the editorial. But "an effective response to this news can help contend with the new challenges of influenza".
Tamiflu is made by Roche Laboratories. Relenza is made by GlaxoSmithKline. In the journal, the editorialists note financial ties to drug companies including Roche and GlaxoSmithKline. The Japanese researchers report ties to other drug companies, but not Roche or GlaxoSmithKline.
Source: webmd.com
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