Ledipasvir (diacetone) is primarily used in the treatment of chronic hepatitis C virus (HCV) infection. It is a key component in combination therapies, often paired with sofosbuvir, to enhance antiviral efficacy. This combination targets specific genotypes of HCV, particularly genotype 1, which is the most common form of the virus, as well as genotypes 4, 5, and 6. The treatment works by inhibiting the NS5A protein, which is essential for viral replication and assembly. This leads to a significant reduction in viral load, improving liver function and reducing the risk of liver cirrhosis and hepatocellular carcinoma. Ledipasvir (diacetone) is known for its high cure rates and is often prescribed for patients who have not responded to previous treatments or those with compensated liver disease. Its use has revolutionized HCV therapy, offering a shorter treatment duration and fewer side effects compared to older regimens.