Suppression by 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (virazole, ICN 1229) of influenza virus-induced infections in mice.

1-beta-d-Ribofuranosyl-1,2,4-triazole-3-carboxamide (Virazole) was found to possess significant antiviral activity against aerosol-induced or intranasally induced influenza A(0), A(2), and B virus infections in mice. Significant protection was achieved by both oral and intraperitoneal routes of administration. Depending upon the level of virus infection, antiviral activity was best observed at the daily dose of 75 mg/kg. The efficacy of the compound was evidenced by an increase in survivor number, prolongation of mean survival time, suppression of lung consolidation, or decrease in hemagglutinin titer in the infected lung samples. The therapeutic value of this synthetic triazole nucleoside was evident as noted by a significant increase in survivor number even if the treatment was started as late as 24 h after infection with an aerosol of influenza A(2) virus.