GS-5816 is used in the treatment of chronic hepatitis C virus (HCV) infection. It functions as an NS5A inhibitor, disrupting viral replication by targeting the NS5A protein, which is essential for the HCV life cycle. GS-5816 is typically administered in combination with other antiviral agents, such as sofosbuvir, to enhance efficacy across multiple HCV genotypes. This combination therapy has shown high cure rates, particularly in patients who have not responded to prior treatments. It is effective in both cirrhotic and non-cirrhotic individuals and is valued for its pan-genotypic activity, allowing for simplified treatment regimens without the need for genotype-specific therapies. The compound contributes to shorter treatment durations and improved tolerability compared to older interferon-based regimens.