Antivirals for the treatment of chronic hepatitis B: current and future options

Despite effective vaccination programmes, new hepatitis B virus (HBV) infections remain common and there are many millions of individuals already infected. Therapeutic agents are needed to reverse existing liver disease and prevent future disease progression. This article reviews recently published clinical data on the two currently available antivirals for the treatment of chronic hepatitis B infection, lamivudine and adefovir dipivoxil. Lamivudine, a nucleoside analogue, is currently the only licensed antiviral for the treatment of chronic hepatitis B in Asia. Extensive clinical trials have shown that lamivudine is effective and well tolerated in a wide range of patients. YMDD variants have been identified in some patients with reduced sensitivity to lamivudine after extended therapy. Adefovir dipivoxil, a nucleotide analogue, will soon be commercially available in Asia. Adefovir dipivoxil 10 mg is well tolerated and is as effective as lamivudine in reducing serum HBV DNA and alanine aminotransaminase levels and increasing seroconversion in patients with hepatitis B e antigen. No adefovir-resistant mutants have been reported during 48-week clinical trials. The addition of adefovir dipivoxil to ongoing lamivudine therapy, in patients with YMDD variants and a reduced response to lamivudine, leads to significant inhibition of viral replication and improvement in liver function after 1 year of therapy.