Entecavir is ring e acyl bird nucleoside analogues. Researching study showed that can effectively inhibit HBV DNA replication, curative effect is superior to lamivudine. Also study shows that to develop YMDD mutants will can effectively inhibit HBV DNA replication. Treatment in patients with early cure the incidence of drug resistance, The SFDA in China have also been approved for the treatment of chronic hepatitis b patients.

Entecavir is a cyclopentyl guanosine analog launched for the once-daily oral treatment of chronic hepatitis B virus (HBV) infection, and it is the third nucleoside or nucleotide analog to be marketed for this indication. Lamivudine, a deoxythiacytosine analog, and adefovir dipivoxil, a nucleotide analog, have been marketed since 1998 and 2002, respectively. Entecavir and adefovir are specifically indicated for HBV, whereas lamivudine is indicated for both HBV and HIV infections. In mammalian cells, entecavir is efficiently phosphorylated to the active triphosphate form, which competes with the natural substrate deoxyguanosine triphosphate and functionally inhibits all three activities of the HBV polymerase: (1) base priming, (2) reverse transcription of the negative strand from the pregenomic messenger RNA, and (3) synthesis of the positive strand of HBV DNA.The most common adverse events associated with the use of entecavir are similar to those typically seen with HBV therapy and include headache, abdominal pain, diarrhea, fatigue, and dizziness.