Classifications: antiviral agent; antiretroviral; nucleoside reverse transcriptase inhibitor (nrti);
Therapeutic: antiretroviral; nrti

Prototype: Lamivudine
Pregnancy Category: C


0.5 and 1 mg tablets; 0.05 mg/mL oral solution


Inhibits hepatitis B viral (HBV) DNA polymerase by inhibiting viral reverse transcriptase of messenger RNA that ultimately results in inhibiting the synthesis of HBV DNA.

Therapeutic Effect

The antiviral activity of entecavir inhibits HBV DNA synthesis.


Treatment of chronic hepatitis B infection in patients who have shown resistance to lamivudine or in nucleoside-treatment-na?ve patients.


Hypersensitivity to entecavir; pregnancy (category C), lactation; safety and effectiveness in children <16 y have not been established.

Cautious Use

Liver transplant patients; concurrent use of cyclosporine; renal impairment, ESRF, dialysis; labor and delivery.

Route & Dosage

Chronic Hepatitis B (nucleoside-treatment–na?ve patients)
Adult/Adolescent (≥16 y): PO 0.5 mg qd

Chronic Hepatitis B (lamivudine-resistant patients)
Adult/Adolescent (≥16 y): PO 1 mg qd

Renal Impairment
Clcr 30–49 mL/min: decrease dose by 50%; 10–29 mL/min: decrease dose by 70%; <10 mL/min: decrease dose by 90%


  • Give on an empty stomach (at least 2 h before/after a meal).
  • Administer after hemodialysis.
  • Dosage adjustment is recommended with Clcr <50 mL/min.
  • Store in a tightly closed container at 15°–30° C (59°–86° F)

Adverse Effects (≥1%)

CNS: Dizziness, fatigue, headache, insomnia, somnolence. GI: Diarrhea, dyspepsia, nausea, vomiting. Metabolic: Elevated liver enzymes (ALT, AST), hyperamylasemia, elevated lipase concentration, hyperbilirubinemia, fasting hyperglycemia, glycosuria, hematuria, lactic acidosis.


Drug: Use of entecavir with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of either drug. Food: High-fat meal reduces oral absorption.


Peak: 0.5–1 h. Distribution: 13% protein bound. Metabolism: Minimal. Elimination: Primarily in the urine. Half-Life: 128–149 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor closely for adverse reactions when drugs that are known to affect renal function are taken concurrently.
  • Lab tests: Periodic LFTs; monitor hepatic function for several months after drug is D/C; periodic fasting plasma glucose.
  • Monitor for S&S of lactic acidosis, including respiratory distress, tachycardia, and irregular HR.

Patient & Family Education

  • Follow directions for taking the drug (see ADMINISTRATION).
  • Do not discontinue medication without consent of physician.
  • Do not drive or engage in potentially hazardous activities until response to drug is known.
  • Inform physician if you are or plan to become pregnant.
  • Report any of the following to a health care provider: unexplained tiredness or weakness, unusual muscle pain, difficulty breathing, cold extremities, dizziness or light-headedness, irregular heartbeat, loss of appetite, stomach pain, nausea, vomiting, clay-colored stool, dark urine, or jaundice.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2023 medpill.info Last Updated On: 01/19/2023 (0.01)
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