Nucleoside (acid) class antiviral drugs are effective in treating chronic hepatitis B. They are convenient to take orally and require only one tablet a day, with few side effects, but they take a long time to administer, usually at least 2 years or longer, and need to be observed regularly after stopping, and there is a risk of viral resistance with long-term use. 1.Lamivudine (Herceptin) The earliest nucleoside (acid) class of drugs used for anti-hepatitis B virus, marketed in China in 1999, is by far the most cumulative cases of oral anti-hepatitis B virus drugs. Lamivudine has a rapid onset of action, strong viral suppression, and is relatively inexpensive. Due to the very high incidence of lamivudine resistance, it is no longer recommended for first-line use. Treatment course: at least 2 years, midway mutation needs to be changed; Caution: due to long-term use is prone to mutation resistance, has been withdrawn from the first-line drugs; 1 year of clinical data: serum HBV-DNA conversion rate of 46%-70%, liver function in the ALT normalization rate of 41%-75%, e antigen seroconversion rate of 16%-21%. Drug resistance status: 20% at 1 year, 80% at 5 years. 2, Adefovir (Haverix, Daidin, Meizheng, Agmatine, Eugenol, Adesian) In 2005, Haverix was launched in China, its main feature is that its resistance site does not overlap with other nucleoside analogues at site 236, which is more suitable for patients with YMDD (site 204) variation. However, adefovir has weak antiviral ability, slow onset of action, and long-term use can harm the kidney, and is mainly used as a salvage therapy drug. Duration of treatment: at least 2 years Caution: Contraindicated in patients under 18 years of age, long-term use can damage the kidneys, mainly used as salvage therapy. Clinical data at 1 year: serum HBV-DNA conversion rate is 21%-51%, ALT normalization rate in liver function is 48%-72%, e antigen seroconversion rate is about 12%. Drug resistance: 0% at 1 year, 11% at 3 years, 29% at 5 years. 3, Entecavir (Boludin) Boludin was launched in China in 2005, with rapid onset of action, strong viral suppression, and very low viral mutation rate, and is recommended as the first-line drug of choice by the latest major domestic and international guidelines (2012 European Liver Institute, 2012 American College of Hepatology, 2012 Asia Pacific Liver Institute and China 2010 guidelines). The efficacy of the treatment has been widely recognized by doctors. Duration of treatment: at least 2 years; Caution: contraindicated in patients under 16 years of age, to be taken on an empty stomach. Clinical data at 1 year of use: serum HBV-DNA disappearance rate of 70-87%, liver function in the ALT normalization rate of 67%-78%, e antigen seroconversion rate of about 18%; drug resistance: initial nucleoside (acid) analogues of patients 2 years 0.4%, 3 years 1.1%, 6 years 1.2%. 4.Tibivudine (Sulbivir) has a strong viral inhibitory effect. The disadvantage is that the incidence of drug resistance is high. In addition, the safety performance of telbivudine is not satisfactory. The only point its a drug approved by the US FDA for pregnancy class B. Other nucleoside (acid) analogs are class C. Treatment duration: at least 2 years; Precautions: contraindicated in patients under 16 years of age; myotoxicity (elevated CK). Increased peripheral neuropathy in combination with interferon. Lack of data from long-term clinical studies Clinical data from 1 year of drug use: serum HBV-DNA disappearance conversion rate of 60%-88%, ALT normalization rate of 72%-74% in liver function, e antigen seroconversion rate of about 22%. Drug resistance: 5% in HBeAg-positive patients at 1 year, 22% at 2 years, and 8.6% in HBeAg-negative patients at 2 years.