There is a new study about antiviral resistance out today. The...

There is a new study about antiviral resistance out today. The essental paragraph that relates to Relenza is below.

The study shows that Relenza resistance is possible and we should not be complacent. However, Relenza again demonstrated it's relative superiority over Tamiflu.

Notice that the main guy involved in the study has strong links to Sankyo, and advocates strongly the development of new antivirals. Given Sankyo's compound is quite different to zanamivir, it would be interesting to discover it's resistance profile.

http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20070403/flu_resistance_070403/20070403?hub=Health
"There is urgent need to develop new kinds of antivirals,'' senior author Dr. Yoshihiro Kawaoka -- who splits his time between the University of Wisconsin-Madison and the University of Tokyo -- said in a release.

http://jama.ama-assn.org/cgi/content/full/297/13/1435#SEC3
When healthy children were given oseltamivir at 2 mg/kg of body weight, the mean peak plasma concentration of oseltamivir carboxylate, the active metabolite of the drug, was 630 nmol/L among children aged 3 to 5 years and 426 nmol/L among children aged 1 to 2 years.27 This indicates that the IC50 values for influenza B viruses tested against oseltamivir in our study were close to the plasma drug concentration, suggesting that this drug may not be as effective against influenza B virus as against influenza A virus. By contrast, the topical concentration of zanamivir in the human respiratory tract is estimated to be more than 10 000 nmol/L when healthy adults inhale 10 mg zanamivir,28 well above the influenza B virus IC50 values.