Used in combination with sofosbuvir for the treatment of chronic hepatitis C virus (HCV) infection, particularly genotypes 1 and 4. It acts as an NS5A inhibitor, blocking a key viral protein required for replication of HCV. This combination therapy offers high cure rates, typically administered orally over 8 to 12 weeks, with minimal side effects. It is effective in both treatment-naïve patients and those who have failed prior therapies, including patients with cirrhosis when combined with ribavirin. The drug plays a major role in modern direct-acting antiviral regimens, enabling interferon-free treatment protocols that improve patient tolerance and outcomes.