Used in the treatment of chronic hepatitis B virus (HBV) infection. It works by inhibiting the viral DNA polymerase enzyme, reducing viral replication. Helps lower HBV DNA levels in the blood and can improve liver function in infected patients. Taken orally, it is part of long-term antiviral therapy, especially in patients with active viral replication and liver damage. Not recommended for use in HIV co-infected patients without appropriate antiretroviral therapy due to risk of resistance.