hbv has a template called cccdna inside liver cells genome and cannot be eradicated by immune system or drugs (it takes decades or all life)
so the drugs must be taken until hbsab antibody, which has complete control of hbv, appears (most cronic carriers will never have this antibody)
if you have problems you can use tenvir generic from cipla (tenofovir), cheaper, more potent and no resistance
check hbv forum for all info
http://www.medhelp.org/forums/Hepatitis-B