Seasonal influenza is an acute respiratory illness caused by influenza A or B viruses. Influenza occurs in outbreaks and epidemics worldwide, mainly during the winter season. Although acutely debilitating, influenza is usually a self-limited infection. However, it is associated with increased morbidity and mortality in certain high-risk populations.
Two classes of antiviral drugs are available for the treatment and prevention of influenza [1,2]:
●The neuraminidase inhibitors, zanamivir and oseltamivir, which are active against both influenza A and B
●The adamantanes, amantadine and rimantadine, which are only active against influenza A. Due to a marked increase in resistant isolates, the Advisory Committee on Immunization Practices (ACIP) recommends that adamantanes not be used in the United States for the treatment of influenza, except in selected circumstances . (See 'Choice of antiviral drug' below.)
The role of these drugs in the treatment of seasonal influenza will be reviewed here. Their role in the prevention of seasonal influenza, treatment and prevention of 2009 pandemic H1N1 influenza and avian influenza, and treatment and prevention of influenza in children are discussed separately; the pharmacologic characteristics of the antiviral drugs used for influenza are also presented elsewhere. (See "Prevention of seasonal influenza in adults" and "Treatment and prevention of pandemic H1N1 influenza ('swine influenza')" and "Treatment and prevention of avian influenza" and "Seasonal influenza in children: Prevention and treatment with antiviral drugs" and "Avian influenza A H7N9: Treatment and prevention", section on 'Postexposure prophylaxis' and "Pharmacology of antiviral drugs for influenza".)