Velpatasvir-d 3 (GS-5816-d 3 ) is deuterium labeled Velpatasvir. Velpatasvir (VEL, GS-5816) is a novel pan-genotypic hepatitis C virus ( HCV ) nonstructural protein 5A (NS5A) inhibitor with activity against genotype 1 (GT1) to GT6 HCV replicons. Velpatasvir is also a SARS-CoV 3CL pro inhibitor with an IC 50 of 2.16 μM.