<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>The 3-O-valine ester prodrug of the nucleoside analog 2'-C-methylcytidine with anti-hepatitis C virus (HCV) activity. Upon administration, valopicitabine is converted into 2'-C-methylcytidine; upon phosphorylation into its 5-triphosphate form, this metabolite inhibits viral RNA chain elongation and viral RNA-dependent RNA polymerase activity. This blocks viral production of HCV RNA and thus viral replication.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>