Nurses Compass
Drug Guide
Entecavir
Classification
Therapeutic: Antiviral agent, nucleoside analog, anti-hepatitis B virus
Pharmacological: Nucleoside analogue reverse transcriptase inhibitor
FDA Approved Indications
- Chronic hepatitis B virus infection
Mechanism of Action
Entecavir is a guanine nucleoside analogue that inhibits hepatitis B virus (HBV) DNA polymerase, leading to effective suppression of viral replication.
Dosage and Administration
Adult: 0.5 mg once daily on an empty stomach; can increase to 1 mg once daily for treatment-experienced patients with resistance or high viral load.
Pediatric: Not approved for children under 16 years old.
Geriatric: No specific dosage adjustment necessary; monitor renal function.
Renal Impairment: Dose adjustment required based on renal function, eGFR <50 mL/min: 0.5 mg every 48-72 hours.
Hepatic Impairment: No specific adjustment needed, but caution advised.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Extensively distributed in tissues.
Metabolism: Minimal hepatic metabolism.
Excretion: Primarily renal excretion.
Half Life: approximately 128-149 hours in plasma.
Contraindications
- Hypersensitivity to entecavir.
Precautions
- Renal impairment, lactic acidosis, risk of hepatic flares upon discontinuation, monitoring for resistance.
Adverse Reactions - Common
- Headache (Often)
- Nausea (Often)
- Fatigue (Often)
Adverse Reactions - Serious
- Lactic acidosis (Rare)
- Hepatic decompensation (Rare)
Drug-Drug Interactions
- Cobicistat, raltegravir (possible decrease in effectiveness)
Drug-Food Interactions
- No significant interactions noted.
Drug-Herb Interactions
- Limited data; consult current guidelines.
Nursing Implications
Assessment: Monitor hepatic function, renal function, and viral load periodically.
Diagnoses:
- Risk for hepatic flare after discontinuation.
- Impaired liver function related to HBV.
Implementation: Administer on an empty stomach, monitor labs regularly, educate patient about adherence and potential side effects.
Evaluation: Effectiveness assessed by reduction in HBV DNA levels, normalization of liver function tests.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report signs of lactic acidosis (e.g., muscle pain, weakness, unusual tiredness).
- Maintain regular follow-up appointments.
Special Considerations
Black Box Warnings:
- Risk of lactic acidosis and severe hepatomegaly with steatosis.
- Potential for resistance development; adherence is crucial.
Genetic Factors: No specific pharmacogenetic considerations identified.
Lab Test Interference: May cause transient elevations in liver enzymes.
Overdose Management
Signs/Symptoms: Nausea, vomiting, increased hepatic enzymes, lactic acidosis.
Treatment: Supportive care, hemodialysis in severe cases, no specific antidote.
Storage and Handling
Storage: Store at room temperature, away from moisture and light.
Stability: Stable in original container up to expiration date on package.