How do the influenza antiviral agents differ? Do they work against both influenza A and B?
• Amantadine (Symmetrel®) and rimantidine (Flumadine®) are chemically related antiviral drugs known as adamantanes. They have a known effect against influenza A viruses, but not influenza B viruses. During the 2005–2006 influenza season, the prevalent influenza strains in the United States were resistant to amantadine and rimantidine. The CDC updated recommendations for antiviral therapy for influenza in January 2006 due to this development. At that time, it was recommended to prescribe the influenza antiviral medications oseltamivir (Tamiflu®) or zanamivir (Relenza®). For details, see the January 14, 2006 CDC Health Alert Notice [HAN] at: http://www.cdc.gov/flu/han011406.htm* • The CDC Advisory Committee on Immunization Practices (acipacip) recommends that neither amantadine nor rimantidine be used for the treatment or chemoprophylaxis of influenza A in the United States because data from the past two flu seasons indicate widespread resistance of influenza virus to these medications.
