Entecavir (entecavir)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Entecavir, a synthetic purine nucleoside analog derived from guanine, is an antiviral agent that is active against human hepatitis B virus (HBV).
Entecavir, a synthetic purine nucleoside analog derived from guanine, is an antiviral agent that is selectively active against human hepatitis B virus (HBV). The drug undergoes phosphorylation by cellular enzymes to form its active metabolite, entecavir triphosphate, which has an intracellular half-life of 15 hours. By competing with the natural substrate deoxyguanosine triphosphate, entecavir triphosphate inhibits all 3 activities of HBV DNA polymerase (reverse transcriptase): base priming, reverse transcription of the negative strand from the pregenomic messenger RNA, and synthesis of the positive strand of HBV DNA.
Following oral administration, peak plasma concentrations of entecavir are attained within 0.5-1.5 hours. Steady-state concentrations are achieved after 6-10 days of once-daily administration with approximately 2-fold accumulation. Commercially available entecavir tablets and oral solution are bioequivalent and may be used interchangeably.
Food delays absorption, decreases peak plasma concentrations, and decreases the area under the plasma concentration-time curve (AUC) of entecavir.
Entecavir is extensively distributed into tissues, and is approximately 13% bound to serum proteins in vitro. Following oral administration, entecavir undergoes phosphorylation by cellular enzymes to form the active metabolite, entecavir triphosphate. Entecavir is partially metabolized to glucuronide and sulfate conjugates.
Entecavir is not a substrate for and does not inhibit or induce cytochrome P-450 (CYP) isoenzymes.
Entecavir is excreted principally in urine via by both glomerular filtration and tubular secretion. Approximately 62-73% of an oral dose is eliminated unchanged in urine. Hemodialysis removes approximately 13% of a dose in 4 hours; continuous ambulatory peritoneal dialysis removes approximately 0.3% of a dose over 7 days.
The terminal elimination half-life of entecavir is approximately 128-149 hours. There are no significant gender or racial differences in the pharmacokinetics of entecavir.
USES: See also Warning section. Entecavir is used to treat long-term hepatitis B infection. Hepatitis B is an infection of the liver caused by the hepatitis B virus.
Long-term infection can cause liver damage, rarely liver cancer, and liver failure. Entecavir helps to decrease the amount of hepatitis B virus in your body. It is unknown if this medication lowers your chance of getting liver cancer or liver damage.
Entecavir is an antiviral that belongs to a class of drugs known as hepatitis B virus nucleoside reverse transcriptase inhibitors. Entecavir is not a cure for hepatitis B. It does not prevent the spread of the virus to others through sexual contact or blood/body fluid contamination (such as sharing used needles).
Generic name: entecavir
Pronunciation: (en-TEK-a-vir)
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
Today’s intelligence on Entecavir
Indications
The following indications are listed for Entecavir:
- Chronic Hepatitis B
- Lamivudine-Refractory Chronic Hepatitis B
Also known as: Chronic Hepatitis B Virus Infection, Chronic Hepatitis Due To Hbv.
Dosing
No dosing information is available for this tab.
Entecavir is administered orally (as tablets or oral solution).
Because the presence of food in the GI tract may decrease the rate and extent of absorption, entecavir should be administered on an empty stomach at least 2 hours before or 2 hours after meals.
Administer the oral solution using the supplied oral dosing spoon according to the patient instructions provided by the manufacturer. The oral solution contains 0.05 mg of entecavir per mL; do not dilute or mix the solution with water or any other liquid. Refer to the full prescribing information for specific instructions for administration of the oral solution.
Store entecavir tablets and oral solution at 25oC (excursions permitted between 15-30oC); the tablets should be stored in a tightly-closed container. Store both the tablets and the oral solution in the outer carton to protect from light. After opening, the oral solution can be used up to the expiration date on the bottle.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
There is no enhanced messaging for this drug.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
None.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
The most common adverse effects (>=3%, all severity grades) in adults were headache, fatigue, dizziness, and nausea. Adverse effects observed in pediatric patients were consistent with those observed in adults.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
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Safety and efficacy of were evaluated in clinical trials of pediatric patients >=2 years of age with HBeAg-positive chronic HBV infection and compensated liver disease.
Steady-state pharmacokinetics of entecavir were evaluated in pediatric patients 2 to <18 years of age with compensated liver disease. Entecavir exposures in nucleoside inhibitor-naive children receiving the oral solution in a dosage of 0.015 mg/kg (<=0.5 mg) once daily were similar to exposures observed in adults receiving a 0.5-mg tablet once daily. Exposures in lamivudine-experienced children receiving the oral solution in a dosage of 0.03 mg/kg (<=1 mg) once daily were similar to exposures observed in adults receiving a 1-mg tablet once daily.
There are limited data available on the use of entecavir in lamivudine-experienced pediatric patients; use entecavir in these patients only if potential benefits justify potential risks. Since some pediatric patients may require long-term or lifetime management of chronic active HBV infection, consider the impact of entecavir use on future treatment options.
Safety and efficacy of entecavir have not been established in pediatric patients <2 years of age; entecavir has not been evaluated in these patients since treatment of HBV is rarely required in this age group.
A pregnancy exposure registry (the Antiretroviral Pregnancy Registry (APR)) monitors maternal-fetal outcomes of pregnant women exposed to entecavir; clinicians are encouraged to enroll patients in the registry by calling 800-258-4263.
Prospective data from the APR are insufficient to adequately evaluate the risk of birth defects, miscarriage, or adverse maternal or fetal outcomes. The limited number of entecavir exposures reported to the APR is not sufficient to inform a risk assessment in comparison to a reference population. The rate of miscarriage is not reported in the APR.
In animal reproduction studies, there was no evidence of developmental toxicities in rats or rabbits at systemic entecavir exposures approximately 28 or 212 times, respectively, human exposures achieved at the maximum recommended human dose (MRHD) of 1 mg daily. In a pre/postnatal development study, no adverse effects on the offspring were observed when entecavir (<=30 mg/kg per day) was administered orally to pregnant rats from gestation day 6 to lactation/post-partum day 20, resulting in exposures >94 times those in humans at the MRHD.
It is not known whether entecavir is distributed into human milk, affects human milk production, or has effects on the breastfed infant. Entecavir was present in milk when administered to lactating rats.
Consider the benefits of breastfeeding and the importance of entecavir to the mother along with the potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition.
Select dosage of entecavir for geriatric patients with caution due to possible age-related decreases in renal function; monitoring renal function also may be helpful.
Clinical studies did not include sufficient numbers of patients >=65 years of age to determine whether they respond differently to entecavir than younger adults.
Entecavir is substantially excreted by the kidneys, and the risk of entecavir-induced toxicity may be increased in patients with impaired renal function. The area under the plasma concentration-time curve (AUC) of entecavir is increased compared with younger adults, possibly as the result of age-related changes in renal function. Since geriatric patients may be more likely to have decreased renal function, select dosage with caution; it also may be useful to monitor renal function in geriatric patients.
ICD codes
No ICD codes are available for this drug.
Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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