Entecavir Hydrate

Entecavir-triphosphate is a highly potent inhibitor of wild-type HBV Pol and is 100- to 300-fold more potent than lamivudine-triphosphate against 3TC-resistant HBV Pol. Entecavir inhibits the replication of 3TC-resistant HBV, but 20- to 30-fold higher concentrations are required. ^[1] Entecavir results in an impressive reduction of serum viral DNA with covalently closed circular DNA and hepatitis B viral core antigen negativity in liver biopsy specimens. ^[2] Entecavir has potent activity (EC50, 0.1 nM) against HIV in a unique single-cycle, single-cell-based pseudovirus assay (24) with CD4+ lymphocytes using a green fluorescent protein reporter fluorescence-activated cell sorter assay as the endpoint. ^[3]

Entecavir causes a 4-log drop in serum DHBV DNA levels within 80 days and a slower 2- to 3-log drop in serum DHBV surface antigen (DHBsAg) levels within 120 days in ducks. Entecavir treatment reduces DHBV DNA replicative intermediates 70-fold in the liver, while the level of the stable, template form, covalently closed circular DNA decreases only 4-fold in ducks. Entecavir treatment reduces both the intensity of antigen staining and the percentage of antigen-positive hepatocytes in the liver, but the intensity of antigen staining in bile duct cells appeares not to be effected in ducks. ^[4]