Safety of long-term nucleos(t)ide treatment in chronic hepatitis B.

Currently, five nucleos(t)ide analogs (NAs) are approved for the treatment of chronic hepatitis B (CHB) infection. They are lamivudine, adefovir dipivoxil, telbivudine, entecavir (ETV) and tenofovir disoproxil fumarate (TDF). Two of them, ETV and TDF, are recommended as first-line treatment options. Their main advantages include excellent tolerability, antiviral potency and a high genetic barrier to resistance within medium duration treatment periods (2 - 6 years). In most patients, NAs need to be administered on a long-term basis. Several studies suggest that NAs long-term administration have been associated with low rates of serious adverse events (AEs), including lactic acidosis, renal function impairment, osteopenia and osteoporosis. Discontinuations due to AEs tended to be low in published randomized clinical trial and in the experience in clinical practice. NAs long-term use appears to be safe and effective; and in patients with advanced liver disease, despite preliminary concerning reports, their short-term use also appears to be safe and effective. Although major AEs are infrequent, they can be initially clinically silent yet lead to serious medical problems, therefore, a proactive surveillance and their prompt management is recommended.