The Influenza Viruses

I-Adamantanamine (amantadine) causes a selective, reproducible, dose-related inhibition of influenza infections in tissue culture, chick embryos, and mice. The compound is not virucidal and appears to act by interfering with the penetration of the host cell by the virus. In influenza infections of mice, greatest efficacy occurs with treatment at the time of infection; however, there is significant antiviral activity with treatment delayed up to 72 hours after infection. Virus inhibition is not complete and survivors are immune to a challenge infection with the original infecting virus.