title: Current therapy with nucleoside/nucleotide analogs for patients with chronic hepatitis B.
abstract: BACKGROUND
  Currently, more and more nucleos(t)ide analogs are appearing as therapeutic options in the treatment of chronic hepatitis B (CHB). Their efficacy and safety profile in hepatitis B virus (HBV) infection have already been studied in detail worldwide. This review summarizes the efficacy of lamivudine, adefovir, entecavir and newer antiviral agents such as emtricitabine, telbivudine and clevudine in the treatment of hepatitis B in different clinical situations.
  
  
  METHODS
  An English-language literature search using OVID and MEDLINE was performed and a total of 40 articles on the treatment of chronic hepatitis with nucleos(t)ide analogues were selected.
  
  
  RESULTS
  Nucleos(t)ide analogs such as lamivudine, adefovir and entecavir are well tolerated and induce a decrease in serum HBV-DNA levels associated with normalization of serum alanine aminotransferase (ALT) levels. But their sustained response with HBeAg to anti-HBe seroconversion is rarely obtained and HBsAg loss is exceptional. The response is maintained during therapy which needs to be continued indefinitely in the majority of patients since withdrawal of treatment is generally followed by a rapid reactivation of hepatitis B. However, drug resistant mutations can be induced in long-term treatment. Other newer antiviral agents such as emtricitabine, telbivudine and clevudine in the treatment of hepatitis B are still under phase II or III clinical trials.
  
  
  CONCLUSIONS
  Nucleos(t)ide analogs play an important role in the therapy of hepatitis B now and in the future. Lamivudine is limited by the frequent emergence of drug-resistant (HBV) mutants (YMDD). Adefovir and entecavir appear to be effective against both YMDD mutation and wild type. Therapeutic options against hepatitis B virus remain a major clinical challenge.
authors.affiliation: Department of Infectious Diseases, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310006, China.
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Xu
authors.forename: Ya-Gang
authors.initials: YG
authors.lastname: Chen
mesh_terms: D000998:Antiviral Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D004359:Drug Therapy, Combination; D005260:Female; D019694:Hepatitis B, Chronic / Q000150:complications / Q000188:drug therapy*; D006801:Humans; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy; D018894:Reverse Transcriptase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000998:Antiviral Agents; D018894:Reverse Transcriptase Inhibitors