Nuovi orizzonti in tema di terania dell'epatite B

To date, four different nucleoside/nucleotide analogues are available in the treatment of chronic hepatitis B (CHB): lamivudine, adefovir dipivoxil and entecavir; telbivudine, a deoxythymidine analogue that specifically inhibits polymerase-DNA of HBV, approved by the European Medicines Agency (EMEA), has recently become obtainable in Italy. Lamivudine, the first antiviral drug to be used in the treatment of chronic hepatitis B, shows an excellent bioavailability, a virtual absence of significant adverse drug reactions, and a high efficacy in reducing the viral load. Such good pharmacological features are not paralleled by a high genetic banter. Adefovir dipivoxil, a nucleotide analogue, is considered an effective alternative option to lamivudine, due to the better genetic barrier (almost 30% of resistant mutants after 5 years of treatment). However, at the therapeutic approved doses (10 mg/die), adefovir demonstrates sub-optimal efficacy in suppressing viral replication. By contrast, it has proved highly effective against viral strains resistant to lamivudine. Entecavir, the nucleoside analogue most recently introduced in Italy, exhibits a substantial inhibition of viral replication and a high genetic barrier both in naïve patients (