Antiviral properties, metabolism, and pharmacokinetics of a novel azolo-1,2,4-triazine-derived inhibitor of influenza A and B virus replication

Influenza viruses of types A and B cause periodic pandemics in the human population. The Antiviral drugs approved to combat Influenza Virus infections are currently limited. We have investigated an effective novel inhibitor of human influenza A and B viruses, triazavirine [2-methylthio-6-nitro-1,2,4-triazolo[5,1-c]-1,2,4-triazine-7(4I)-one] (TZV). TZV suppressed the replication of Influenza Virus in Cell Culture and in chicken chorioallantoic membranes, and it protected mice from death caused by type A and B influenza viruses. TZV was also effective against a rimantadine-resistant Influenza Virus strain and against avian influenza A virus H5N1 strains. The pharmacokinetic parameters and bioavailability of TZV were calculated after the administration of TZV to rabbits. The TZV metabolite AMTZV [2-methylthio-6-amino-1,2,4-triazolo[5,1-s]-1,2,4-triazin(e)-7(4I)-one] was discovered in IAK 293T and Huh7 cell cultures, a liver homogenate, and rabbit blood after intragastric administration of TZV. AMTZV was nontoxic and inactive as an inhibitor of Influenza Virus in Cell Culture. Most likely, this metabolite is a product of TZV elimination.