So it looks like that some farmers in China have been employing the antiviral drug amantadine to prevent the spread of H5N1. Unfortunately, this is a terrible idea as it has already been implicated in the spread of resistance to this drug. As amantadine is one of the main drugs that could be used to combat a pandemic, such resistance being introduced into the circulating avian flu strains could be devastating.
Amantadine was developed by Du Pont chemists more than 30 years ago and it was the first specific, effective antiviral drug developed. The drug itself works by targeting a specific structure on the surface of the influenza particle, the M2 porin. Once bound, it blocks this channel preventing the entry of protons into the viral particle. This stops the virus particle from uncoating once it has entered. Resistance to the drug is typically mediated by mutations that either prevent the drug from entering into the porin, or the drug cannot bind onto it at all in the first place.
Spreading resistance to the drugs that may potentially make up the first line of defence against influenza is not only irresponsible but potentially dangerous. China and other authorities should stamp down on these practices as quickly as possible before it is too late to go back.