Canada will adjust the mix of antiviral drugs in an emergency pandemic stockpile this year, a response to concerns over the vulnerability of the main drug in the arsenal, Tamiflu, to the development of viral resistance. Supplies of the drug zanamivir – sold as Relenza by GlaxoSmithKline – will be beefed up in the national emergency stockpile, (Snip) As well, some stocks of an older flu drug, amantadine, will be added to the mix as an inexpensive extra. Scientists are studying whether using Tamiflu in combination with amantadine or a sister drug, rimantadine, will lower the likelihood flu strains will develop resistance to the few drugs currently marketed to treat influenza.

“I think the general view is that from a scientific perspective, greater diversification (of stockpiles) would be desirable,” says King, director general of the public health agency’s centre for immunization and respiratory infectious diseases. “And as I’ve said, we’ve made that decision at a federal level.”

King says discussions are still underway with provincial and territorial partners about whether to diversify the holdings of another stockpile, known as the national antiviral stockpile, where the bulk of Canada’s pandemic flu drugs are held. The cost of building up and maintaining this stockpile is shared by the federal, provincial and territorial governments.

The national antiviral stockpile contains 55.7 million doses of drug, enough to treat nearly 5.6 million people. Tamiflu, which is sold by Hoffman-La Roche, makes up 90 per cent of the holdings. Relenza accounts for the remaining 10 per cent.