Why does hepatitis B virus become resistant to nucleoside/nucleotide analogues?
The major challenge associated with long-term therapy with NAs is the development of viral resistance to the NAs. This resistance results from a change (mutation) in the genetic material of the virus. • For lamivudine (Epivir-HBV, Heptovir, Heptodin), the incidence of resistance is 25% after one year and as high as 50% after three years of treatment. • With telbivudine (Tyzeka), resistance rates are 5% to 11% after one year. Therefore, some guidelines do not recommended lamivudine or telbivudine alone as the first treatment for chronic hepatitis B. For other NAs such as adefovir (Hepsera), resistance is less common after one year of therapy but rises to 30% after five years. Early results with entecavir (Baraclude) suggest that resistance may be uncommon with this agent. When resistance occurs, the viral load may rise or blood liver tests may become abnormal. Is there a preferred treatment for chronic hepatitis B? There are no clear guidelines to recommend which agent to use first in t
