New bird flu drug will provide new line of defence

Nov 28 2006

Flu experts say a new flu drug with the ability to kill deadly strains of bird flu promises to provide a much needed third option should a pandemic occur.

The antiviral agent Peramivir may well offer a vital new line of defence against the deadly the H5N1 avian strain which had killed 153 people since 2003 and infected 258 others.

Peramivir could totally transform global preparations for an influenza pandemic as it has been seen in studies to be more powerful and easier to deliver than either Tamiflu or Relenza, the two existing drugs for H5N1 flu.

Experts believe that should H5N1 acquire the ability to pass easily from person to person it could trigger a pandemic and the virus has recently shown signs possibly doing just that.

The World Health Organisation has said as many good antiviral drugs as possible are needed to fight bird flu and having multiple options with different antiviral spectra is very important.

Apparently where Peramivir has the advantage over the other therapies is that it is delivered as an injection while Tamiflu must be taken orally, and Relenza must be inhaled; both therapies are difficult when patients are unconscious.

Also because Peramivir is injected it enters the bloodstream in higher concentrations and remains active for longer.

Tests have also shown that peramivir is effective against every known variant of H5N1, and its greater potency means that the virus is less likely to acquire resistance.

Peramivir would also provide a valuable alternative if a pandemic strain were to evolve with a resistance to Tamiflu.

Tamiflu is currently the front-line treatment and has been stockpiled by many countries, but some H5N1 viruses have already shown resistance to it, and if such a strain became dominant, the drug would become useless.

Scientists have been warning governments for some time that to rely on Tamiflu exclusively would be foolhardy.

Peramivir is also simple to manufacture from synthetic raw materials that are readily available in bulk while Tamiflu production has been delayed by a shortage of star anise, the plant from which the active ingredient comes.

Peramivir was developed by BioCryst Pharmaceuticals in Alabama which says it already has the facilities to produce a billion doses a year if needed.

At present Roche is only able to produce 400 million doses of Tamiflu a year.

BioCryst also recently completed successful safety trials on human volunteers, and phase 2 trials will begin shortly to test peramivir’s effectiveness in more than 100 patients with seasonal flu, with another to follow in the new year.

Larger phase 3 trials should then take place during next winter’s flu season, and the drug could be marketed within two to three years.

In the event a flu pandemic were to happen before then, peramivir could be made available as an emergency measure, as it's safety record is good.