Safety and Antiviral Activity Study of ACH-126,443 (Beta-L-Fd4C) in Treatment-naive Adults With Chronic Hepatitis B Virus Infection

Inclusion Criteria: Chronic hepatitis B virus (HBV) infection, known to be hepatitis B surface antigen positive ≥ 6 months. Plasma HBV deoxyribonucleic acid level ≥ 100,000 copies/milliliter. Hepatitis B e-antigen positive. Human immunodeficiency virus negative. Basic hematologic and chemistry parameters within acceptable limits (defined in protocol). No need for excluded medications. Participants of reproductive capability must have utilized 2 approved forms of birth control, one of which must have been barrier protection. Exclusion Criteria: Human immunodeficiency virus infection. Hepatitis C co-infection. Concurrent systemic antiviral treatment. Previous antiviral treatment for HBV infection within 6 months prior to randomization or treatment with lamivudine for more than 6 months at any time in the past. Previous therapy with agents with significant systemic myelosuppressive or cytotoxic potential within 3 months of study start or the expected need for such therapy at study start. Alcohol abuse. Pregnancy or breast-feeding. Inability to tolerate oral medication. Aspartate aminotransferase > 7.0 times the upper limit of normal. Alanine aminotransferase > 7.0 times the upper limit of normal. Any clinical condition or prior therapy that, in the Investigators opinion, would make the participant unsuitable for the study or unable to comply with the dosing requirements. Use of any investigational drug.