Lamivudine, also known as 3TC, is a synthetic nucleoside analogue with antiviral activity against both HIV-1 and hepatitis B virus (HBV).
It is a dideoxynucleoside analogue that undergoes intracellular phosphorylation to its active metabolite, lamivudine triphosphate.
Lamivudine triphosphate metabolite inhibits viral reverse transcriptase by terminating the proviral DNA chain extension, thereby preventing viral replication.
In the context of HIV-1 infection, lamivudine is used in combination with other antiretroviral agents as part of highly active antiretroviral therapy (HAART).
It can be dosed once or twice daily due to its long intracellular half-life.
For chronic hepatitis B, lamivudine is used as monotherapy.
It inhibits HBV DNA synthesis by competitively inhibiting the viral reverse transcriptase and DNA polymerase stages of HBV replication.
Lamivudine effectively reduces serum HBV DNA levels, normalizes alanine aminotransferase (ALT) levels, and enhances hepatitis B e antigen (HBeAg) seroconversion.
Lamivudine’s most common adverse events are gastrointestinal disturbances, but it is generally well tolerated.
Resistance can develop, particularly with prolonged monotherapy, due to mutations in the YMDD motif of the viral polymerase.