Antiviral agents for treating influenza.

The new neuraminidase inhibitors zanamivir and oseltamivir are important additions to the treatment of influenza, being the first class of agents active against both influenza A and influenza B. The decision to use these agents rather than amantadine or rimantadine, which are effective only against influenza A, should be based on the age of the patient, antiviral activity, side effect profile, ease of administration, drug interactions, and cost. All of these agents are effective only when started within 24 to 48 hours of onset of symptoms. To avoid inappropriate use of these agents, treatment should be continued only in patients with a confirmed diagnosis of influenza. Although effective in decreasing symptoms, none of these agents prevent pneumonia or hospitalization secondary to influenza.