GS-5816 is primarily used in the development of antiviral medications, particularly for the treatment of hepatitis C virus (HCV) infections. It functions as a potent inhibitor of the HCV NS5A protein, which is crucial for viral replication. By targeting this protein, GS-5816 effectively disrupts the virus's ability to multiply, thereby reducing the viral load in patients. It is often combined with other antiviral agents in combination therapies to enhance efficacy and reduce the risk of resistance. This compound has shown promise in clinical trials, contributing to the development of more effective and shorter-duration treatment regimens for HCV, improving patient outcomes and quality of life.