The following extract from Wikipedia explains the 2 drugs that...

The following extract from Wikipedia explains the 2 drugs that are not effective. A law suit and subsequent inaction by Glaxo explains the lack of knowledge about relenza. It now seems that tamilflu has become the substitute word for 'anti-viral drugs'. I couldn't find a chemist in Perth who had ever stocked relenza, never mind one who could fill my script. Some had never heard of it and one thought it was just another name for tamilflu.

'Of the available antiviral treatments for influenza, the WHO stated that the viruses obtained from the human cases with swine influenza in the United States were sensitive to oseltamivir (Tamiflu)[164] and zanamivir (Relenza) but resistant to amantadine and rimantadine.[165] Tamiflu and Relenza also have a preventative effect against Influenzavirus A.[166] On April 27, the CDC recommended the use of Tamiflu and Relenza for both treatment and prevention of the new strain.[167] Roche and the U.S. government had already extended the shelf life of federally stockpiled Tamiflu from the original five years to seven years because studies indicated that the medication continues to maintain its effectiveness.[168]'