抗病毒藥品 Treatment of chronic hepatitis B virus infection

Antihepadnaviral, Nucleoside Reverse Transcriptase Inhibitor (Anti-HBV)
Entecavir is intracellularly phosphorylated to guanosine triphosphate which competes with natural substrates to effectively inhibit hepatitis B viral polymerase; enzyme inhibition blocks reverse transcriptase activity thereby reducing viral DNA synthesis.

Absorption:
1. Delayed with food; Cmax decreased 44% to 46%, AUC decreased 18% to 20%
2. Time to peak, plasma: 0.5 to 1.5 hours
Distribution:
1. Extensive (Vd in excess of body water)
2. Protein binding: ~13%
Metabolism:
1. Minor hepatic glucuronide/sulfate conjugation
2. Half-life elimination: (Terminal) ~5 to 6 days; (accumulation) ~24 hours
Excretion:
Urine (60% to 73% as unchanged drug)

Hypersensitivity to entecavir or any component of the product

C

Avoided

Headache, fatigue, dizziness, nausea

Administration:
Be administered on an empty stomach (at least 2 hours after a meal or 2 hours before the next meal)
Dosage:
1. Nucleoside-treatment naive, compensated liver disease: 0.5 mg once daily
2. Decompensated liver disease: 1 mg once daily

1. ClCr 30-49 ml/min: the normal dose every 48 hrs
2. ClCr 10-29 ml/min: the normal dose every 72 hrs
3. ClCr <10 ml/min (including dialysis): the normal dose every 7 days; administer after hemodialysis

No dosage adjustment necessary.