Lamivudine

This nucleoside inhibitor of HIV reverse transcriptase is active in chronic HBV infection. Lamivudine has a longer intracellular half-life in HBV-infected cells than in HIV-infected cells and thus can be used in lower doses for hepatitis than for HIV infection. Used as monotherapy, lamivudine rapidly suppresses HBV replication and is remarkably nontoxic. This cytosine analog is an inhibitor of both hepatitis B virus (HBV) DNA polymerase and human immunodeficiency virus (HIV) reverse transcriptase. must be phosphorylated by host cellular enzymes to the triphosphate (active) form. This compound competitively inhibits HBV DNA polymerase at concentrations that have negligible effects on host DNA polymerase. As with many nucleotide analogs, the intracellular half-life of the triphosphate is many hours longer than its plasma half-life. Chronic treatment is associated with decreased plasma HBV DNA levels, improved biochemical markers, and reduced hepatic inflammation. Lamivudine is well absorbed orally and is widely distributed. Its plasma half-life is about 9 hours. Seventy percent is excreted unchanged in urine. Dose reductions are necessary when there is moderate renal insufficiency (creatinine clearance less than 50 mL/min). Lamivudine is well tolerated, with rare occurrences of headache and dizziness.