Ledipasvir hepatitis C drug molecule. Computer model showing the structure of a molecule of the protease inhibitor drug ledipasvir. Atoms are colour-coded: carbon (light blue), hydrogen (white), fluorine (green), nitrogen (dark blue) and oxygen (red). Ledipasvir is an antiviral used to treat hepatitis C virus (HCV) infection. It works by inhibiting the action of the HCV NS5A protein, which is vital for RNA (ribonucleic acid) replication. Atoms are colour-coded spheres: carbon (light blue), hydrogen (white), oxygen (red), nitrogen (dark blue), fluorine (green).