Bird flu pandemic seen needing multiple drugs
Pastor Dale Morgan
*Bird flu pandemic seen needing multiple drugs*
14 May 2008 17:00:05 GMT
Source: Reuters
By Ben Hirschler
LONDON, May 14 (Reuters) - Governments need to stockpile different sorts
of flu drugs -- not just Roche Holding AG's Tamiflu -- to counter the
danger of resistance in a pandemic triggered by bird flu, British
experts said on Wednesday.
The warning could boost demand for GlaxoSmithKline Plc's <GSK.L> inhaled
medicine Relenza, which has been largely overlooked in favour of Roche's
<ROG.VX> more convenient pill.
Scientists analysing the structure of a key flu virus protein found that
both H5N1 and seasonal flu could develop resistance to Tamiflu, while
still remaining highly susceptible to Relenza.
"What this research shows is that stockpiling any one drug to prepare
for a potential H5N1 pandemic is unlikely to provide adequate cover,"
said Steve Gamblin of the National Institute for Medical Research in London.
"In order not to be outflanked by the virus, it will be necessary to
have stocks of both existing drugs."
There is a also "a huge imperative" to develop further drugs since the
best way to treat patients in the long term is likely to be a three- or
four-pronged approach, similar to the multi-drug cocktails used to fight
HIV and AIDS, Gamblin said.
A new influenza drug, peramivir, is being developed by Biocryst
Pharmaceuticals Inc <BCRX.O> but it must be injected and it has not
performed well in clinical trials. Two older flu drugs are available but
flu viruses have quickly developed resistance to them, although some
experts believe they may be useful in cocktails with newer drugs.
Both flu viruses and HIV have a high rate of mutation, which allows them
to adapt to the treatments devised to tackle them.
To date, H5N1 remains mainly a virus affecting birds, although it has
killed more than 200 people since 2003. But scientists say it is the
most likely source of the next deadly flu pandemic in humans, since it
may soon mutate into a form transmitted easily from person to person.
Tamiflu, known generically as oseltamivir, and Relenza, or zanamivir,
target the viral protein neuraminidase, which helps release newly made
viruses so that they can spread infection.
Using a technique called X-ray crystallography, Gamblin and colleagues
examined the exact mutation in protein structure that can make some flu
virus resistant to Tamiflu and showed the different nature of Relenza
meant it was still effective.
Their results were published in the journal Nature.
The main seasonal flu virus circulating this year in the United States
and Canada as well as parts of Europe has shown higher resistance to
Tamiflu. But cases of resistance remain relatively rare.