Antiviral — Hepatitis B (Nucleoside Analogue) Pregnancy: No adequate data in pregnant women; should not be used during pregnancy unless clearly necessary. Women of childbearing potential should use effective contraception. Breast-feeding should be discontinued during treatment.

Entecavir

Brand names: Baraclude

Entecavir is an oral nucleoside analogue antiviral used as first-line treatment for chronic hepatitis B infection in adults.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 0.5 mg once daily (nucleoside-naive); 1 mg once daily (lamivudine-refractory or decompensated liver disease)

Route: Oral

Frequency: Once daily

For chronic hepatitis B; therapy initiated by a physician experienced in its management. Compensated liver disease, nucleoside-naive: 0.5 mg once daily with or without food. Lamivudine-refractory (viraemia on lamivudine or lamivudine-resistance mutations): 1 mg once daily on an empty stomach (>2 hours before and >2 hours after a meal); in the presence of LVDr mutations, combination with a second non-cross-resistant antiviral is preferred over monotherapy. Decompensated liver disease: 1 mg once daily on an empty stomach. Optimal duration unknown; treatment cessation not recommended in decompensated liver disease or cirrhosis. Paediatric: patients >=32.6 kg may take one 0.5 mg tablet (or 10 ml oral solution) daily with or without food; oral solution should be used below 32.6 kg.

Dose adjustments

Renal

Dose adjustment recommended for creatinine clearance <50 ml/min (including haemodialysis or CAPD). Nucleoside-naive: 0.25 mg once daily OR 0.5 mg every 48 h (CrCl 30-49); 0.15 mg once daily OR 0.5 mg every 72 h (CrCl 10-29); 0.05 mg once daily OR 0.5 mg every 5-7 days (<10/HD/CAPD). Lamivudine-refractory or decompensated: 0.5 mg once daily (CrCl 30-49); 0.3 mg once daily OR 0.5 mg every 48 h (CrCl 10-29); 0.1 mg once daily OR 0.5 mg every 72 h (<10/HD/CAPD). For doses <0.5 mg use oral solution; on haemodialysis days give after dialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients, or to soya oil

Side effects

Headache
Fatigue
Dizziness; somnolence; insomnia
Nausea, vomiting, diarrhoea, dyspepsia
Increased transaminases (exacerbations of hepatitis); rare lactic acidosis

Interactions

Drugs that reduce renal function or compete for active tubular secretion: may increase serum concentrations of entecavir or the co-administered drug; monitor closely
No significant interaction with lamivudine, adefovir dipivoxil or tenofovir disoproxil fumarate

Clinical monograph

How it works

It is phosphorylated intracellularly to its active triphosphate form, which competitively inhibits hepatitis B viral polymerase (reverse transcriptase), suppressing viral DNA replication.

Prescribing in practice

Severe acute exacerbation of hepatitis B can occur on stopping treatment, so discontinuation requires careful specialist supervision with monitoring of liver function for several months afterwards.
It has a high genetic barrier to resistance but is not recommended as monotherapy in patients with lamivudine-resistant hepatitis B, where resistance emerges readily.
The dose interval should be extended in renal impairment, and it should be taken on an empty stomach as food reduces absorption.

Monitoring

Monitor liver function and hepatitis B viral load during treatment, and continue clinical and biochemical monitoring after stopping because of the risk of post-treatment flare.

Counselling the patient

Take on an empty stomach, well away from food, and do not stop the medicine without advice from your specialist.
Report any worsening tiredness, jaundice or dark urine, especially after the medicine is stopped.

Evidence & guidelines

NICE recommends nucleos(t)ide analogues including entecavir for the treatment of chronic hepatitis B.

Reference: EASL Clinical Practice Guidelines HBV 2017; Chang et al. NEJM 2006 (entecavir phase III); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways