Pharmacology · Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
Lamivudine !
A very well tolerated NRTI found in almost every HIV regimen. It also suppresses hepatitis B virus.
Updated 2026-11-01
Also called: 3TC
The figure shows lamivudine triphosphate, its active form, in the polymerase site of HIV-1 reverse transcriptase bound to DNA.
Mechanism of action
A cytidine analogue. Cellular kinases convert it to lamivudine triphosphate, which competes with dCTP; once incorporated into viral DNA it ends the chain. It acts the same way on the hepatitis B virus polymerase. The M184V mutation in reverse transcriptase removes its activity but makes the virus less fit to replicate.
- It is phosphorylated to lamivudine triphosphate in the cell
- It competes with dCTP at reverse transcriptase
- It is built into viral DNA and ends the chain
Pharmacokinetics
- Absorption
- Good oral absorption (bioavailability about 86% in adults)
- Elimination
- Mostly unchanged in urine, by active tubular secretion; it accumulates in kidney failure
- Half-life
- Plasma half-life about 5 to 7 hours
Indications
- HIV-1 infection, combined with other antiretrovirals HIV infection and AIDS →
- Chronic hepatitis B (with products made for that use) Viral hepatitis →
Adverse effects
Common
- Headache
- Nausea
- Tiredness
- Diarrhoea
Contraindications
- Previous hypersensitivity to lamivudine
Key interactions
- Emtricitabine
- Both are cytidine analogues selecting the same resistance (M184V): they are not combined
- Sorbitol (in syrups and solutions)
- Can lower lamivudine concentrations; chronic co-use is avoided
- Trimethoprim
- Competes for tubular secretion and slightly raises lamivudine, without clinical importance
What is monitored
- Hepatitis B serology before starting
- Liver tests for several months if stopped in hepatitis B co-infection
- Kidney function
- Viral load and CD4
Administration and safety
- By mouth, as a tablet or solution
- Hepatitis B products contain less drug: a person with HIV should only get HIV products, to avoid inducing resistance
- Check fixed-dose combinations: many already contain lamivudine
Nursing care
- Check hepatitis B status before starting or stopping
- Teach that it must not be stopped on one's own (risk of hepatitis B flare and resistance)
- Watch for abdominal pain in children (pancreatitis)
Pregnancy and breastfeeding
Antiretroviral treatment in pregnancy protects the mother and lowers HIV transmission to the baby; the treating team chooses the regimen.
Test yourself
Think of the answer, then tap the question to see it.
Besides HIV, which other virus does lamivudine suppress?
Hepatitis B virus; that is why stopping it in a co-infected person can trigger a severe hepatitis flare.
Why are lamivudine and emtricitabine not combined?
They are near-identical cytidine analogues: they compete for the same pathway and select the same M184V mutation, with no added benefit.
Why does lamivudine need adjustment in kidney failure?
It is mostly removed unchanged in urine by tubular secretion, so it builds up when the kidney fails.
Related drugs
Related conditions
← Back to the class: Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - LAMIVUDINE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Lamivudine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.