The efficacy and safety of tenofovir disoproxil 245 mg (as fumarate) or tenofovir disoproxil 245 mg (as fumarate) plus 200 mg emtricitabine is being evaluated in a randomised, double-blind study (study GS-US-174-0106), in HBeAg positive and HBeAg negative patients who had persistent viraemia (HBV DNA ≥ 1,000 copies/ ml) while receiving adefovir dipivoxil 10 mg for more than 24 weeks.