Control of influenza: when do I use amantadine?

Influenza causes significant morbidity and mortality in Canada yearly despite the availability of vaccine and the antiviral drug amantadine (Symmetrel®). Vaccine is prepared annually against specific subtypes of influenza A and B that are anticipated to predominate during the winter months. The vaccine should be given in early autumn to patients considered at high risk for the sequelae of influenza. Amantadine, which was first marketed for the treatment of influenza in the early 1960s, is effective in the prevention and early treatment of illness caused by influenza A and is ineffective against influenza B. The drug is available in oral form and should be used as an adjunct to immunization or as an alternative in those for whom immunization is contraindicated or ineffective.