Voxilaprevir
Voxilaprevir is a Direct-Acting Antiviral (DAA) medication used as part of combination therapy to treat chronic Hepatitis C, an infectious liver disease caused by infection with Hepatitis C Virus (HCV). HCV is a single-stranded RNA virus that is categorized into nine distinct genotypes, with genotype 1 being the most common in the United States, and affecting 72% of all chronic HCV patients.   Voxilaprevir exerts its antiviral action by reversibly binding and inhibiting the NS3/4A serine protease of Hepatitis C Virus (HCV). Following viral replication of HCV genetic material and translation into a single polypeptide, Nonstructural Protein 3 (NS3) and its activating cofactor Nonstructural Protein 4A (NS4A) are responsible for cleaving genetic material into the following structural and nonstructural proteins required for assembly into mature virus: NS3, NS4A, NS4B, NS5A, and NS5B. By inhibiting viral protease NS3/4A, voxilaprevir therefore prevents viral replication and function. Treatment options for chronic Hepatitis C have advanced significantly since 2011, with the development of Direct Acting Antivirals (DAAs) such as voxilaprevir.   Voxilaprevir has been available since July 2017 in a fixed dose combination product with [sofosbuvir] and [velpatasvir] as the commercially available product Vosevi. Vosevi is approved for the treatment of adult patients with chronic HCV infection with genotype 1, 2, 3, 4, 5, or 6 infection. Notably, Vosevi is approved for use in patients with genotypes 1-6 who have been previously treated with an NS5A inhibitor, or patients with genotypes 1a or 3 infection and have previously been treated with an HCV regimen containing sofosbuvir without an NS5A inhibitor. Prior to Vosevi, there were no approved retreatment options for patients who have previously received, and failed, a regimen containing an NS5A inhibitor for treatment of chronic HCV infection.