Pirodavir demonstrates potent broad-spectrum activity against picornaviruses. It effectively inhibits 80 out of 100 tested human rhinovirus (HRV) strains at a concentration of 64 ng/mL. Additionally, Pirodavir shows effectiveness against 16 enteroviruses, with a mean IC80 of 1,300 ng/mL. Moreover, it inhibits enterovirus 71 replication with an IC50 of 5,420 nM and an IC90 exceeding 13,350 nM. Pirodavir also inhibits 56 laboratory strains of rhinovirus and three clinical isolates, encompassing 59% of the serotypes and isolates with IC50s of less than 100 nM ^[1].

Pirodavir concentrations of 16 and 4 μg/mL result in a reduction of cell growth by 66% (standard error of the mean [s.e.M.] 0.75) and 28% (s.e.M. 0.25), respectively. Lower concentrations (1 μg/mL) of Pirodavir do not exhibit inhibitory effects on cell growth. The 50% cytotoxic concentration of pirodavir for logarithmic cell growth at 37°C is determined to be 7 μg/mL. However, under the conditions of the antiviral assay (confluent HeLa cells at 33°C), the 50% cytotoxic concentration exceeds 50 μg/mL^[2].