Used primarily in the treatment of chronic hepatitis B virus (HBV) infection. It works by inhibiting the viral DNA polymerase, thereby reducing viral replication. Effective in patients with active liver disease and detectable HBeAg or those with lamivudine-resistant HBV. Administered orally, it allows long-term suppression of HBV DNA levels, helping to improve liver function and reduce the risk of disease progression. Requires careful monitoring due to potential nephrotoxicity, especially with prolonged use.