daclatasvir + simeprevir + ribavirin

This is an oral, direct-acting antiviral **combination regimen** consisting of daclatasvir (a pan-genotypic NS5A inhibitor), simeprevir (an NS3/4A protease inhibitor), and ribavirin (a nucleoside analog antiviral). This combination is used in the treatment of chronic hepatitis C virus (HCV) infection, particularly in patients who are treatment-naive or have failed prior regimens, including those with genotype 1 and, less commonly, genotype 4 infection. The combination acts by targeting distinct steps in the HCV life cycle: daclatasvir inhibits NS5A protein to block viral replication and assembly; simeprevir inhibits the NS3/4A protease to prevent viral polyprotein processing; and ribavirin, though its precise anti-HCV mechanism is unclear, is thought to introduce mutations in the viral genome and enhance host immune response. Clinical studies demonstrate high rates of sustained virologic response (SVR), especially in genotype 1b patients, with variable results in other patient populations. The use of this regimen is supported for retreatment and difficult-to-treat cases, but it is not a fixed-dose combination and is considered off-label in some guidelines[1][2][3].