Mechanism of action:it combines two direct-acting antiviral agents with distinct mechanisms of action and non-overlapping resistance profiles to target hcv at multiple steps in the viral lifecycle.elbasvir is an inhibitor of hcv ns5a, which is essential for viral rna replication and virion assembly.grazoprevir is an inhibitor of the hcv ns3/4a protease which is necessary for the proteolytic cleavage of the hcv encoded polyprotein (into mature forms of the ns3, ns4a, ns4b, ns5a, and ns5b proteins) and is essential for viral replication. in a biochemical assay, grazoprevir inhibited the proteolytic activity of the recombinant ns3/4a protease enzymes from hcv genotypes 1a, 1b, 3 and 4a with ic50 values ranging from 4 to 690 pm.indications:it is indicated direct-acting antiviral for the treatment of chronic hepatitis c (chc) in adults .... for genotypes 1a, 1b & 4.dosage and administration:one tablet once daily with or without food.may be taken with ribavirin.