Initial Relenza use in local areas cuts resistance risk*...

Initial Relenza use in local areas cuts resistance risk
* Strategy seen extending effectiveness of Tamiflu
* Roche and Glaxo drugs both stockpiled by governments
LONDON, May 1 (Reuters) - Using GlaxoSmithKline's less common drug Relenza early in local flu outbreaks should extend the effectiveness of Roche's Tamiflu, the drug most widely stockpiled against the risk of a pandemic.
Treating just 1 percent of the population in a local epidemic with Relenza rather than Tamiflu could substantially delay the emergence of resistance to Tamiflu, scientists said.
This would not only benefit local populations but also the wider world, since pandemic flu will be spread by air travel.
Governments in many countries are stockpiling antivirals to deal with a widely expected H1N1 swine flu pandemic, with most of the stocks comprising Tamiflu, known generically as oseltamivir.
The problem is flu viruses can quickly develop resistance to drugs and the widespread use of a single drug increases this risk. If that happens, the effectiveness of Tamiflu to treat infected patients and slow the spread of disease would be greatly reduced.
The researchers from Hong Kong, Britain and the United States used a detailed mathematical model to assess the implications of utilising different antivirals and published their results in the online journal PLoS Medicine.
"Our model predicts substantial potential benefits for populations that use a second antiviral (Relenza) early in their epidemic to limit the impact of the emergence of resistance," Joseph Wu of the University of Hong Kong and colleagues wrote.
Tamiflu, which is taken as a tablet, is more convenient than Relenza, or zanamivir, which must be inhaled. Tamiflu and Relenza are the only approved drugs to which the new H1N1 strain has been found to be susceptible.
Roche and Glaxo are both expected to enjoy windfall gains from sales of their medicines, and the two companies are racing to increase production capacity to keep up with demand.
The United States, Britain and Denmark have all announced this week that they plan to step up their stockpiling of antivirals to help fight the 2009 H1N1 virus, also known as swine flu, that has killed up to 176 people in Mexico. (Reporting by Ben Hirschler; Editing by Jon Loades-Carter)