Epclusa is a combination medication, 400 milligrams of sofosbuvir and 100 milligrams of velpatasvir, for the treatment of chronic hepatitis C and is effective against hepatitis c genotypes 1, 2, 3, 4, 5, or 6. Sofosbuvir is considered to be a prodrug which is converted to a nucleotide analog polymerase inhibitor and is a direct-acting antiviral agent, which means it will help block the life cycle of the hepatitis C virus.