[Anti-influenza A viral drug--amantadine].

Amantadine, an inhibitor of M2 ion channel of influenza A virus, is an oral antiviral drug which specifically inhibits the uncoating and viral replication of the influenza A virus. Studies have shown that amantadine treatment within 48 hours of acute infection of influenza A reduces fever within 24 hours and shortens the course of illness. Amantadine has been found to have an efficacy of 50 to 90% prevention of illness. However amantadine-resistant viruses have been recovered approximately 30% patients treated with amantadine, as early as 2-3 days into treatment. Side effects of insomnia, decreased concentration and dizziness have been reported in 5 to 33% of amantadine recipients. Therefore amantadine should be only used for influenza A infected high risk persons.