Adefovir
Hepatitis B antivirals
Hepatitis B antiviralsPregnancy: avoid
Not used in pregnancy, and breastfeeding is avoided; other hepatitis B drugs are preferred.
An older oral nucleotide analogue for chronic hepatitis B. Kidney toxicity and resistance mean that entecavir or tenofovir are preferred today.
Also called: Adefovir dipivoxil
Quick facts
- Group
- Hepatitis B antivirals
- Target
- HBV polymerase (reverse transcriptase)
- Used for
- Chronic hepatitis B in adults
- Key effects
- Weakness · Headache · Diarrhoea
- Monitor
- Serum creatinine and phosphate · HBV DNA
- ATC
- J05AF08
No doses: the clinician sets them by the current guideline.
Mechanism of action
Adefovir dipivoxil is a prodrug that is de-esterified to adefovir, an acyclic phosphonate analogue of adenosine monophosphate. Cell enzymes add two phosphates; adefovir diphosphate competes with deoxyadenosine triphosphate at the HBV polymerase (a reverse transcriptase) and ends the viral DNA chain. Resistance builds up over years of use.
- The prodrug releases adefovir
- Cell kinases form adefovir diphosphate
- It competes with dATP at the HBV polymerase
- Viral DNA chain synthesis stops
Indications
- Chronic hepatitis B in adults and children twelve years and older (no longer a preferred agent) Viral hepatitis →
Adverse effects
Common
- Weakness
- Headache
- Diarrhoea, gas and indigestion
- Sore throat and runny nose
Contraindications
- Hypersensitivity to adefovir
- Use alone in untreated HIV infection (risk of HIV resistance)
Key interactions
- Nephrotoxic drugs (aminoglycosides, NSAIDs, ciclosporin, tacrolimus, vancomycin)
- Higher risk of kidney damage
- Drugs that compete for renal tubular secretion
- May raise adefovir levels
- Other nucleoside analogues
- Possible higher risk of lactic acidosis
What is monitored
- Serum creatinine and phosphate
- HBV DNA (resistance)
- Liver tests during and for months after stopping
- HIV test before starting
Administration and safety
- Oral, once daily, with or without food
- Doses are not missed and the drug is not stopped without the team
Pregnancy and breastfeeding
Not used in pregnancy, and breastfeeding is avoided; other hepatitis B drugs are preferred.
Nursing care
- Check HIV status and kidney function before starting
- Teach not to stop suddenly: hepatitis can flare
- Teach to report less urine, swelling, or yellow skin
- Ask about painkillers such as NSAIDs
Pharmacokinetics
- Absorption
- Oral prodrug, with or without food
- Metabolism
- Hydrolysed to adefovir by esterases in the gut, liver and blood
- Elimination
- Unchanged by the kidneys (filtration and tubular secretion via OAT1); adjusted in kidney disease
Test yourself
Think of the answer, then tap the question to see it.
Adefovir is an analogue of which nucleotide?
Adenosine monophosphate (an acyclic phosphonate).
What is the main toxicity of adefovir?
Kidney tubular damage, with raised creatinine and low phosphate.
Why is adefovir no longer preferred for hepatitis B?
Resistance develops over years and it is nephrotoxic; entecavir and tenofovir are better.
Connections
← Back to the class: Hepatitis B antivirals
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Adefovir: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.