VRT-127394

VRT-127394 is the **R-diastereomer metabolite of telaprevir**, a direct-acting antiviral agent used in the treatment of genotype 1 chronic hepatitis C virus (HCV) infection. Formed via epimerization of telaprevir at position 21 both in vitro and in vivo, VRT-127394 exhibits similar pharmacokinetics but is **approximately 30-fold less potent against HCV** compared to the parent S-diastereomer telaprevir. Like telaprevir, VRT-127394 inhibits the HCV NS3/4A protease, blocking cleavage of the viral polyprotein necessary for viral replication, though with reduced efficacy. VRT-127394 is a major circulating metabolite after oral administration of telaprevir and is excreted primarily via feces.