Biochem/physiol Actions Lamivudine is a potent nucleoside analog reverse transcriptase inhibitor (nRTI). It is an analogue of cytidine, and can inhibit both types (1 and 2) of HIV reverse transcriptase as well as 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.