[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/) › Abacavir

[Pharmacology](https://durgical.com/en/pharmacology/) · [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/)

# Abacavir

An NRTI antiretroviral. Before use, patients are tested for HLA-B*5701, which predicts a severe, potentially fatal hypersensitivity reaction.

Updated 2026-11-01

- Class: [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/)
- Enzyme: HIV-1 reverse transcriptase
- ATC code: J05AF06
- WHO Model List of Essential Medicines

Also called: ABC

## Mechanism of action

A guanosine analogue. Inside the cell it becomes carbovir triphosphate, which competes with natural dGTP; reverse transcriptase incorporates it into viral DNA and the chain stops. Hypersensitivity happens because abacavir sits in the groove of the HLA-B*57:01 molecule and changes the peptides it presents, so T cells see them as foreign.

- Cellular kinases convert it to carbovir triphosphate
- It competes with dGTP at reverse transcriptase
- It is built into viral DNA and ends the chain

## Pharmacokinetics

**Absorption**
Good oral absorption (tablet bioavailability about 83%); food does not change it much

**Metabolism**
Liver, by alcohol dehydrogenase and glucuronidation; it barely uses cytochrome P450

**Elimination**
Inactive metabolites, mainly in urine

## Indications

- HIV-1 infection, combined with other antiretrovirals [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/)

## Adverse effects

### Common

- Nausea and vomiting
- Headache
- Tiredness
- Insomnia

### Serious (rare, important)

- Multi-organ hypersensitivity (fever, rash, gut or respiratory symptoms), potentially fatal
- Lactic acidosis and hepatomegaly with steatosis
- Possible higher risk of myocardial infarction

## Contraindications

- Carrier of the HLA-B*5701 allele
- Previous hypersensitivity to abacavir
- Moderate or severe hepatic impairment

## Key interactions

**Alcohol (ethanol)**
They share alcohol dehydrogenase: ethanol slows abacavir elimination and raises exposure

**Methadone**
Some patients may need a methadone adjustment

## What is monitored

- HLA-B*5701 test before starting
- Hypersensitivity symptoms, especially in the first weeks
- Viral load and CD4
- Cardiovascular risk

## Administration and safety

- Given by mouth, as a tablet or solution
- After a hypersensitivity reaction, no abacavir-containing product is ever restarted: the reaction can kill within hours
- Check whether the patient already gets abacavir inside a fixed-dose combination so it is not duplicated

## Nursing care

- Confirm the negative HLA-B*5701 result in the record before the first dose
- Teach the warning symptoms (fever, rash, nausea, abdominal pain, cough, shortness of breath) and to seek care at once
- Explain that it must not be stopped or restarted on the patient's own
- Hand over the product's warning card, if there is one

## Pregnancy and breastfeeding

Antiretroviral pregnancy registry data show no more birth defects than in the general population.

## Memory aid

'ABacavir: Always B*5701 before': test first, and after a reaction, never again.

## Test yourself

Think of the answer, then tap the question to see it.

## Which test is done before starting abacavir?

Testing for the HLA-B*5701 allele; carriers have a high risk of severe hypersensitivity and do not receive the drug.

## A patient stopped abacavir because of a probable hypersensitivity reaction. Can it be restarted?

No. Restarting it can cause a more severe reaction and death within hours.

## Why does alcohol raise abacavir levels?

Both are metabolised by alcohol dehydrogenase; ethanol competes and slows abacavir elimination.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/abacavir/)

## Related drugs

- [Lamivudine](https://durgical.com/en/pharmacology/lamivudine/)
- [Dolutegravir](https://durgical.com/en/pharmacology/dolutegravir/)

## Related conditions

- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

[← Back to the class: Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/)

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 - ABACAVIR tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5409c8ed-17c3-454f-bb88-d597ba8f84ec) (DailyMed (U.S. National Library of Medicine), 2026); [Abacavir: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a699012.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J05AF06) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/pharmacology/abacavir/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/abacavir/