Study Comparing the Safety of Switching From Lamivudine to Adefovir Dipivoxil Versus Overlapping Lamivudine and Adefovir Before Adefovir Dipivoxil Monotherapy in Patients With Chronic Hepatitis B

In earlier clinical studies, when patients who have been on lamivudine (LAM) were switched to adefovir dipivoxil (ADV), some patients developed ALT flares with an elevation of ALT \> 10 x the upper limits of normal (ULN). There were no cases of hepatic decompensation with the flares, however. The transition methods were varied among physicians from no overlapping to overlapping for 1 to 3 months with LAM and ADV. There is still some uncertainty about the optimal approach to switching from LAM to ADV. This study will compare the safety of directly switching to ADV to a protocolled switch after a period of overlap of 12 weeks. This will facilitate pro-active switching in patients on LAM and will also highlight genotypic resistance ahead of phenotypic resistance as a reason to switch patients. Data to date have only been presented as part of a controlled study in patients with clinically evident LAM-resistance. This study will enroll patients who still have serum hepatitis B virus (HBV) DNA suppression whilst receiving LAM.