A review of entecavir in the treatment of chronic hepatitis B infection.
BACKGROUND
Infection with the hepatitis B virus (HBV) affects two billion people worldwide, and an estimated 400 million people are chronically infected. Currently, FDA-approved regimens for the treatment of chronic HBV include interferon-alpha2b, peginterferon-alpha2a, lamivudine, adefovir dipivoxil, and recently, entecavir.


OBJECTIVE
The purpose of this review is to evaluate the pharmacokinetic and pharmacodynamic properties, and the clinical efficacy and safety of entecavir in the treatment of nucleoside-naĩve and nucleoside-resistant HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB). SEARCH METHODOLOGY: Computerized searches of PubMed and International Pharmaceutical Abstracts from 1985 to July 10, 2005, were performed with the search headings: entecavir, BMS-200475, and chronic hepatitis B.


RESULTS
Entecavir, a new deoxyguanosine analog, represents a third agent within the nucleoside/nucleotide HBV polymerase inhibitor class with distinct advantages over lamivudine and adefovir dipivoxil: it has a three-step mechanism of action, is the most potent inhibitor of HBV DNA polymerase, is not associated with any major adverse effects, and has a limited potential for resistance. In phase II and III clinical trials, entecavir was found to be superior to lamivudine for all primary endpoints evaluated in both nucleoside-naïve and lamivudine-resistant patients. Entecavir was effective in both HBeAg-positive and HBeAg-negative nucleoside-naïve patients. At this time, optimal duration of entecavir therapy is unknown.


CONCLUSIONS
Entecavir represents a new first- or second-line treatment option for patients chronically infected with HBV. Long-term efficacy and safety studies as well as studies of entecavir in combination with interferon products or other nucleoside/nucleotide analogs are eagerly awaited.
Rivkin
Anastasia
A
Arnold and Marie Schwartz College of Pharmacy and Health Sciences, Long Island University, Brooklyn, NY 11201, USA. anastasia.rivkin@liu.edu
D000818:Animals; D002986:Clinical Trials as Topic; D006147:Guanine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D006515:Hepatitis B virus / Q000378:metabolism; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use; D017410:Practice Guidelines as Topic; D016032:Randomized Controlled Trials as Topic; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use; D016896:Treatment Outcome
D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; C413685:entecavir; D006147:Guanine