Background and objective: The extended treatment with lamivudine in patients with chronic hepatitis B is associated with the emergence of resistances. Patients with resistance to lamivudine show a loss of biochemical and virological responses and a higher progression of their liver disease. Adefovir dipivoxil, an analogue of the nucleotides, is effective for the treatment of patients with resistance to lamivudine. The aim of this study was to evaluate the efficacy, safety and resistance of adefovir dipivoxil in patients with chronic hepatitis B refractory to treatment with lamivudine.
Patients and method: One hundred and twenty hepatits B virus patients refractory to lamivudine were treated with adefovir dipivoxil. Seventy-four patients were followed up during two years. In all cases, the hepatitis B virus-DNA was determined by polymerase chain reaction, and in those cases without response to treatment, the presence of resistances to adefovir and lavimudine were studied.
Results: At the second year of treatment, we observed a biological response of 54.1%, a biochemical response of 62.2%, while an elimination of hepatitis B e antigen was seen in 21% cases. 20% patients developed resistance to adefovir dipivoxil, and the most frequent detected mutations were: A181V, A181T and N236T. Drug safety was excellent; in fact, only one adverse effect related to the drug was detected.
Conclusions: Treatment with adefovir dipivoxil for 2 years in mono-therapy in patient who are previously non-responders to lavimudine is associated with a high biochemical and virologycal response with an excellent safety. At the second year of treatment, the adefovir dipivoxil resistance rate is 20%.