Lamivudine

3TC
2'-3'-dideoxy-3'-thiacytidine
Molecular Weight	229.26
Empiric Formula	C8H11N3O3S
ATC code	J05AF05
Metabolism	Renal elimination (ca.70%)
Pregnancy category	C (USA) B3 (Aus)

Lamivudine(2'-3'-dideoxy-3'-thiacytidine, 3TC) is a potent reverse transcriptase inhibitor. It can inhibit both types (1 and 2) of HIV reverse transcriptase and also the reverse transcriptase of hepatitis B. It needs to be phosphorylated to its triphosphate form before it is active. 3TC-triphosphate also inhibits cellular DNA polymerase.

Lamivudine is administered orally, and it is rapidly absorbed with a bio-availability of over 80%. Some researche suggests that lamivudine can cross the blood-brain barrier. Lamivudine is often given in combination with zidovudine, with which it is highly synergistic. Lamivudine treatment has been shown to restore zidovudine sensitivity of previously resistant HIV. Several mutagenicity tests show that lamivudine should not show mutagenic activity in therapeutical doses.

Lamivudine has been used for treatment of chronic hepatitis B at a lower dose that use in HIV. It improves the seroconversion of e-antigen positive hepatitis B and also improve histology staging of the liver. Long term use of lamivudine unfortunately leads to emergence of a resistant hepatitis B virus (YMDD) mutant. Despite this, lamivudine is still used widely as it is well tolerated.