Used in the treatment of chronic hepatitis C virus (HCV) infection, particularly genotypes 1, 3, and 4. It functions as an NS5A replication complex inhibitor, blocking viral RNA replication and assembly of new virus particles. Often combined with other antivirals like sofosbuvir to achieve high cure rates with shorter treatment durations. Effective in both treatment-naïve patients and those who have failed prior therapies. Also used in patients with liver cirrhosis and those co-infected with HIV, offering a pan-genotypic activity with high barrier to resistance.