III. Contraindications

  1. Lamivudine resistant HBV

IV. Mechanism

  1. Nucleoside Reverse Transcriptase Inhibitor (nRTI) with Antiviral activity against Hepatitis B virus (HBV)
  2. Entecavir is a prodrug, activated in vivo to a 5-triphosphate metabolite
    1. Synthetic guanosine Nucleoside analog (to 2-deoxyguanosine)
  3. Competes with the the natural substrate deoxyguanosine triphosphate (dGTP), incorporating into viral DNA
    1. Reverse transcriptase inhibitor (viral RNA-dependent HBV DNA Polymerase)

V. Precautions

  1. Risk of severe HBV exacerbation on discontinuation
    1. Monitor for at least 2 months after discontinuation
  2. Risk of induced HIV resistance in undiagnosed HIV coinfection
    1. HIV Test before use
    2. Do NOT use in monotherapy in HBV/HIV infected patients

VI. Medications

  1. Tablets: 0.5 mg
  2. Oral Solution: 0.05 mg/ml

VII. Dosing: Chronic HBV

  1. General
    1. Take on an empty Stomach, separated at least 2 hours from mealtime (before or after)
    2. Reduce dose in eGFR <50 ml/min
      1. Dose after Hemodialysis
    3. Dosing assumes treatment naive patients
      1. Avoid in Lamivudine resistant HBV (previously treated with higher dose regimens)
  2. Adult (and child age >=16 years or weight >30 kg)
    1. Entecavir 0.5 mg once daily
  3. Child (age 2 years and older)
    1. Weight 10 to 11 kg: GIve 3 ml (0.15 mg) orally daily
    2. Weight 11 to 14 kg: GIve 4 ml (0.2 mg) orally daily
    3. Weight 14 to 17 kg: GIve 5 ml (0.25 mg) orally daily
    4. Weight 17 to 20 kg: GIve 6 ml (0.30 mg) orally daily
    5. Weight 20 to 23 kg: GIve 7 ml (0.35 mg) orally daily
    6. Weight 23 to 26 kg: GIve 8 ml (0.40 mg) orally daily
    7. Weight 26 to 30 kg: GIve 9 ml (0.45 mg) orally daily
    8. Weight >30 kg: GIve 10 ml (0.5 mg) orally daily (adult dosing)

VIII. Efficacy

  1. More effective than Lamivudine or Adefovir in HBV DNA level suppression

IX. Adverse Effects

  1. Well tolerated overall
  2. Headache
  3. Fatigue
  4. Dizziness
  5. Nausea
  6. Rash
  7. Fever
  8. Lactic Acidosis
  9. Hepatic Steatosis

X. Safety

  1. Pregnancy Category C, but overall unknown safety (pregnancy exposure registry exists)
  2. Unknown safety in Lactation

XI. Pharmacokinetics

  1. Elimination Half-Life: 128 to 149 hours

XIII. References

  1. Hamilton (2020) Tarascon Pocket Pharmacopoeia
  2. (2013) Med Lett Drugs Ther 11(127): 19-30 [PubMed]

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Related Studies

Cost: Medications

entecavir (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
ENTECAVIR 0.5 MG TABLET Generic $0.68 each
ENTECAVIR 1 MG TABLET Generic $0.74 each