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Entecavir INN // en-TEK-a-vir or en-te-ka-veer, abbreviated ETV, is an oral antiviral drug used in the treatment of hepatitis B virus (HBV) infection. Entecavir is a reverse transcriptase inhibitor. It prevents the hepatitis B virus from multiplying and reduces the amount of virus in the body.
Mechanism of Action
Entecavir is mainly used to treat chronic hepatitis B infection in adults and children 2 years and older with active viral replication and evidence of active disease. It is also used to prevent HBV reinfection after liver transplant and to treat HIV patients infected with HBV. Entecavir is weakly active against HIV, however it is not recommended for use in HIV-HBV co-infected patients without a fully suppressive anti-HIV regimen as it may select for resistance to lamivudine and emtricitabine in HIV.
Dosage forms and strengths
Tablet: 0.5 mg and 1 mg
Oral solution: 0.05 mg/mL
Entecavir should be taken on an empty stomach: at least 2 hours before a meal or 2 hours after a meal.
The most common adverse effects from entecavir include headache, fatigue, dizziness, and nausea. Others adverse effects include diarrhea, dyspepsia, vomiting, somnolence and insomnia. Laboratory abnormalities resulting from treatment include elevated alanine transaminase (ALT) and hematuria. Periodic monitoring of hepatic function and hematology are recommended.
Bristol-Myers Squibb is currently the drug patent holder for Baraclude®, the brand name of entecavir in the US and Canada. The drug patent expiration date for both Baraclude® 0.5 mg and 1 mg tablets is set for February 21, 2015. On August 26, 2014, TEVA Pharms USA gained FDA approval for generic equivalents of Baraclude® 0.5 mg and 1 mg tablets.
The clinical efficacy of entecavir has been studied in several randomized, double-blind, multicentre trials. Oral entecavir was an effective and generally well tolerated treatment.
- 1992: SQ-34676 at Squibb as part of anti-herpes virus program
- 1997: BMS 200475 developed at BMS pharmaceutical research institute as antiviral nucleoside analogue à Activity demonstrated against HBV, HSV-1, HCMV, VZV in cell lines & no or little activity against HIV or influenza
- Superior activity observed against HBV pushed research towards BMS 200475, its base analogues and its enantiomer against HBV in HepG2.2.15 cell line
- Comparison to other NAs, proven more selective potent inhibitor of HBV by virtue of being Guanine NA
- 1998: Inhibition of hepadnaviral polymerases was demonstrated in vitro in comparison to a number of NAs-TP
- Metabolic studies showed more efficient phosphorylation to triphosphate active form
- 3-year treatment of woodchuck model of CHB à sustained antiviral efficacy and prolonged life spans without detectable emergence of resistance
- Efficacy # LVD resistant HBV replication in vitro
- Superior activity compared to LVD in vivo for both HBeAg+ & HBeAg− patients
- Efficacy in LVD refractory CHB patients
- Entecavir was approved by the U.S. FDA in March 2005.
- “BARACLUDE® (entecavir) Tablets for Oral Use & Oral Solution. U.S. Full Prescribing Information.” Bristol-Myers Squibb Company, 2005. Revised December 2013. 
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- Levine, S., D. Hernandez, G. Yamanaka, S. Zhang, R. Rose, S. Weinheimer, and R. J. Colonno. Efficacies of entecavir against lamivudine-resistant hepatitis B virus replication and recombinant polymerases in vitro. Antimicrob. Agents Chemother. 2002.46:2525–2532
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