The purpose of this study was to determine the safety and anti-hepatitis B virus (-HBV) activity of ACH-126,443 in comparison to lamivudine or placebo in treatment-naive adults with chronic hepatitis B infection.

Evaluation of the safety and antiviral activity of 3 dose levels of ACH-126,443 versus lamivudine and placebo over 12 weeks of treatment in the population is described.

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.