Lamivudine is a synthetic nucleoside analogue reverse transcriptase inhibitor (NRTI) with potent activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV). It is phosphorylated intracellularly to its active 5'-triphosphate metabolite, lamivudine triphosphate, which inhibits viral DNA synthesis by terminating the nascent DNA chain. In India, it is a cornerstone of first-line antiretroviral therapy (ART) for HIV and a key component of HBV treatment, available as a low-cost generic medication.
Adult: HIV: 150 mg twice daily OR 300 mg once daily (as part of combination therapy). HBV: 100 mg once daily (Note: Indian brands commonly have 150mg; 100mg is the standard HBV dose, but 150mg is used in HIV/HBV co-infection as part of ART).
Note: Can be taken with or without food. For consistent absorption, take at the same time(s) each day. The tablet should be swallowed whole with water.
Lamivudine is a prodrug. After cellular uptake, it is phosphorylated by host cell kinases to lamivudine triphosphate (L-TP). L-TP competitively inhibits the reverse transcriptase (RT) enzymes of HIV-1, HIV-2, and HBV by incorporating into the growing viral DNA chain. This incorporation causes chain termination because lamivudine lacks the 3'-OH group required for phosphodiester bond formation.
Pregnancy: Pregnancy Category C. Lamivudine crosses the placenta. It is recommended for use in pregnancy as part of combination ART to prevent maternal-to-child transmission (PMTCT) of HIV. The benefit outweighs risk. Register with the Antiretroviral Pregnancy Registry.
Driving: Dizziness and fatigue have been reported; patients should be cautioned about driving or operating machinery if affected.
| Trimethoprim/Sulfamethoxazole (Cotrimoxazole) | Increases lamivudine AUC by ~40% due to competition for renal secretion. Clinical significance is minimal, but monitor for increased lamivudine side effects. | Moderate |
| Zidovudine (AZT) | Pharmacokinetic interaction is minimal. Used together as a foundational NRTI backbone in ART. Monitor for additive hematological toxicity (neutropenia, anemia). | Moderate |
| Ribavirin | Antagonistic antiviral effect in vitro; may reduce lamivudine efficacy. Use with caution in HIV/HCV co-infected patients. | Moderate |
| Other drugs excreted by active renal secretion (e.g., cimetidine) | Potential increase in lamivudine levels. Monitor. | Mild |
Same composition (Lamivudine (150mg)), different brands: