NRTI in hepatitis B
Lamivudine (also named 3TC) is a drug with nucleoside reverse transcriptase inhibitor (NRTI)-like properties. It needs to be phosphorylated to its triphosphate form to become active. 3TC-triphosphate also inhibits cellular DNA polymerase. This drug (1) competes for reverse transcriptase activity with the normal substrate and (2) terminates chain elongation when incorporated into the viral DNA. This effect has been shown to have inhibitory activity against hepatitis B. Although structurally related to the NRTI zalcitabine, lamivudine has lower cellular cytotoxicity and doesn't cause peripheral neuropathy. The most frequently reported adverse effects are headache, fatigue, nausea, and insomnia. Dosages should be adjusted in patients with decreased renal function.
Adefovir, another NRTI acting by blocking reverse transcriptase, an enzyme that is crucial for the hepatitis B virus (HBV) to reproduce in the body. It is approved for the treatment of chronic hepatitis B in adults with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (primarily ALT) or histologically active disease. The main benefit of adefovir over lamivudine (the first NRTI approved for the treatment of hepatitis B) is that it takes a much longer period of time before the virus develops resistance to it.
NRTIs such as lamivudine and adefovir are used to treat hepatitis B which does not respond to (pegylated) interferons.
Lamivudine is commonly used in combination with interferons for the treatment of hepatitis B.
Patients typically receive lamivudine instead of interferon therapy when the patient:
Extra info: Lamivudine is indicated for patients with compensated liver disease and evidence of active viral replication and liver inflammation. Patients with decompensated liver disease often have leukopenia and thrombocytopenia, which limits the amount of interferon that can be administered to patients.