Favipiravir is a potent and selective RNA-dependent RNA polymerase inhibitor for the treatment of influenza virus infections.

RdRP:341 nM.

The cytotoxicity of T-705 is evaluated by an assay with XTT. XTT is converted to aqueous formazan by an enzyme in MDCK cells, Vero cells, HEL cells, A549 cells, HeLa cells, and HEp-2 cells. The compounds are diluted to the appropriate concentrations (volume, 100 μl) with test medium (EMEM containing 10% FCS) in 96-well culture plates in which each well contains a concentration of 2 × 103 cells/100 μL. The test plates are incubated for 3 days at 37°C in 100% humidity and 5% CO2. After 3 days, 50 μl of the XTT reagent (1 mg/ml in FCS-free EMEM containing 5 mM phenazine methosulfate) is added, and the reaction product is assayed by measurement of the absorbance at 450 nm with a microplate reader. Cytotoxicity is expressed as the 50% cell-inhibitory concentration (CC50).(Only for Reference)