Nucleoside (acid) class antiviral drugs for chronic hepatitis B is effective, convenient to take orally, only one a day, few side effects, but the medication time is long, usually need to use about 2 years or longer, after stopping the drug need to be regularly observed, long-term use are likely to occur virus resistance. 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, but has a high rate of viral mutation and rebound after discontinuation of the drug. Treatment course: at least 2 years, midway mutation needs to be changed; Treatment cost: one oral tablet a day, 14 yuan/tablet, 2 years cost about 10,087 yuan; Caution: due to long-term use is prone to mutation resistance, the existing trend of withdrawing from the first-line drugs; 1-year clinical data: serum HBV-DNA conversion rate of 46%-70%, liver function in ALT normalization rate of 41%-75%, e antigen seroconversion rate was 16%-21%. Drug resistance: 20% at 1 year, about 70% at 5 years. 2.Adefovir (Haverix, Daidin, Meizheng, Agmatine, Ugandine, Adesian) Adefovir was marketed in China in 2005. Its main feature is that it has low viral variation rate and no cross-resistance with lamivudine, which is more suitable for patients with lamivudine variation or YMDD variation. However, adefovir has a weaker antiviral ability, slower onset of action, and long-term use in individual patients can damage the kidneys. Treatment duration: At least 2 years, the effectiveness of the drug should be changed or combined with other drugs; Treatment cost: One oral tablet a day, 14 yuan/tablet, 2 years cost about 10,000 yuan; Precautions: Prohibited in patients under 18 years of age, long-term use in individual patients may cause kidney injury, regular review of kidney function after 1 year of use. Clinical data for 1 year of use: serum HBV-DNA conversion rate of 21%-51%, liver function ALT normalization rate of 48%-72%, e antigen seroconversion rate of about 12%. Drug resistance: 0% at 1 year, 5.9% at 3 years, 11% at 5 years. 3, Entecavir (Boludin) Entecavir was launched in China in December 2005. Entecavir has a rapid onset of action, strong viral inhibition and low viral mutation rate, but there is an increased chance of viral mutation in lamivudine-resistant patients, and it is more expensive. It is suitable for patients with good financial conditions, high viral titers, and severe disease who urgently need rapid viral suppression to alleviate the disease, and the treatment effect has been widely recognized by doctors. Treatment course: at least 2 years; Treatment cost: one tablet per day orally, 39 yuan/tablet, about 28080 yuan for 2 years; Precautions: contraindicated for patients under 16 years old, to be taken on an empty stomach. The clinical data of 1 year of medication: the rate of serum HBV-DNA disappearing and turning negative is 70-80%, the rate of ALT normalization in liver function is 60%-78%, the rate of e antigen seroconversion is about 18%; drug resistance: 0.4% in 2 years and 1.1% in 3 years for patients with initial nucleoside (acid) analogues, but 6% in 1 year, 14% in 2 years and 32% in 3 years for patients with lamivudine resistance. 4.Tebivudine (Sulbivir) was launched in China in April 2007, it is a moderately priced anti-hepatitis B virus drug with the dual advantages of potent, rapid viral suppression and high e antigen seroconversion rate. At the same time, tebivudine has a good safety profile and is approved by the US FDA as a pregnancy class B drug, while other nucleoside (acid) drugs are class C. Its antiviral rate is comparable to that of entecavir, with the only drawback being a moderate resistance rate. Treatment depends mainly on the effect achieved at six months of use, which can predict the effect of long-term use and drug resistance. Treatment course: at least 2 years; Treatment cost: one oral tablet a day, 24 yuan/tablet, 2 years at about 15,000 yuan; Precautions: contraindicated in patients under 16 years of age; Clinical data for 1 year of drug use: serum HBV-DNA disappearance rate of 60-88%, liver function ALT normalization rate of 72%-74%, e antigen seroconversion rate of about 32%. Drug resistance: HBeAg-positive patients treated for 1 year 5%, 2 years 21%, HBeAg-negative patients 2 years for 8.6%. 5, tenofovir (Viread) is expected next year may be marketed in China.