Entavir 0.5mg (Entecavir)
Entavir applicable in tablet form in the strength of 0.5mg used to treat hepatitis B viral infection
Entavir applicable in tablet form in the strength of 0.5mg used to treat hepatitis B viral infection, Entavir containing an active ingredient like Entecavir which is broadly used anti-viral agent, which produce admirable action while compared to previous medicines like lamivudine or Adefovir.
Entavir expose an anti-viral activity against hepatitis B viral infection by associating with inhibition of three stages of viral aggregation process. Entavir is a guanine analogue. A Entavir tablet is widely used in adolescent patient, and in pediatric with age of 2 years or older.
PHARMACOLOGY OF ENTAVIR 0.5MG
Entavir containing Entecavir exhibits its anti-viral activity by prohibiting three steps in viral production; Entavir is an anti-viral medicine, which is guanosine nucleoside analogue effective against HBV infection. Entavir is encounters with natural substrate deoxyguanosine triphosphate. Entavir interferes with three activities of HBV polymerase; Base priming from pregenomic messenger RNA, Reverse transcription of negative strand occurs Integration of positive strand of HBV DNA. A Entavir tablet has Entecavir, which is inserting into viral DNA has extreme effect of prohibiting the HBV polymerase activity.
Entavir tablet, after an oral administration it may undergo adme properties. The peak plasma concentration time of Entavir is occurs within 0.5 & 1.5 hours. The steady state of Entavir is reaches after 6 to 10 days of single dose administration. Entavir 0.5mg cmax value is 4.2ng/ml and trough plasma concentration is 0.3ng/ml
EFFECT OF FOOD
Oral administration of Entavir 0.5mg with high fat meal causes decreasing the absorption, depletes Cmax of 44 to 46%, decreases AUC of 18 to 20%.
The volume of distribution is exuberance of total body water; Entecavir is largely distributed into tissues. The binding of Entecavir with serum proteins occurs relatively 13%.
Entecavir should not be considering as cytochrome P450 enzymes substrate, inhibitor or inducers, which is adequately phosphorylated into an active triphosphate form.
Entavir tablets after metabolism get eliminated via kidneys, in an unchanged form with the range 62% to 73%. The plasma concentration of Entavir depletes in bi-exponential manner with the mean terminal half life period of relatively 128 to 148 hours and the phosphorylated metabolite half life is 15 hours.
ENTAVIR PROPHYLACTIC USE
The critical points take into consideration, while starting the therapy with Entavir tablets; Indication of Entavir is established by clinical trial data in nucleoside inhibitor-therapy naïve and lamivudine resistant patients with HBeAg positive and HBeAg negative HBV infection and compensated liver cirrhosis & decompensated cirrhosis. Entavir is used in pediatric patients with 2 years of age or older, with treatment naïve, lamivudine resistant with HBeAg positive HBV infection & compensated liver cirrhosis. Main indication: Entavir tablets are used to treat chronic hepatitis B viral infection commonly in adolescent patients with the sign of viral multiplication and other information of lasting elevation of serum aminotransferase or active disease.
ENTAVIR 0.5MG DOSING CONSIDERATION AND ITS USAGE
Entavir tablets should be taken on an empty stomach (partially 2 hours after a meal or two hours earlier to the next meal). The usual prescribed dosage of Entavir tablets;
IN COMPENSATED CIRRHOSIS
In adults In this condition, the prescribed dosage of Entavir is 0.5mg should be administered orally as a single dose for the chronic hepatitis B viral infected patients who have newly started with Cronivir. In past hepatitis B viremia, since taking lamivudine therapy or known lamivudine or telbivudine resistant alteration; the advised dosage of Entavir tablets is 0.5mg should be administered orally as a single dose.
The safety and efficacy of Entavir in children with the age of <2 years has not been established. In nucleoside naïve patients: 2 years or older with >30kg: 0.5mg of Entavir should be recommended as single dose. In lamivudine resistant patients: 2 years and older with >30kg: 0.5mg (2 tablet of 0.5mg Cronivir) of Entavir should be recommended as a single dose.
IN DECOMPENSATED LIVER CIRRHOSIS
In decompensated condition, the suggested dosage is 0.5mg of Entavir should be taken as once a day.
IN RENAL DAMAGED PATIENTS
If creatinine clearance decreased, then the apparent oral clearance of Entavir is also decreased. The dosage recommendation for the patients; With creatinine clearance of less than 50ml/min, Hemodialysis patients and For Continuous ambulatory peritoneal dialysis patients (CAPD) CrCl ≥50ml/min: 0.5mg of Entavir should be recommended; in lamivudine resistant or decompensated condition 0.5mg of Entavir is recommend. In 30 to <50ml/min: 0.5mg of Entavir is taken for every 48 hours; in lamivudine resistant or decompensated condition 0.5mg of Entavir as single dose or 0.5mg of Entavir taken for every 48 hours. In 10 to <30ml/min: 0.5mg of Entavir should be given for every 72 hours; in lamivudine resistant or decompensated condition 0.5mg of Entavir is recommended for every 72 hours. <10ml/min: & hemodialysis or CAPD: 0.5mg of Entavir is recommended for every 7 days; in lamivudine resistant or decompensated condition 0.5mg of Entavir should be given for every 7 days. In hepatic impairment patients, dosage adjustment of Entavir should not be recommended.
Some precautions should be taken while starting therapy with Cronivir
IN SEVERE ACUTE AGGRAVATION OF HEPATITIS B:
This adverse may occur after discontinuation of anti-hepatitis B therapy. In this condition patient should be monitored frequently with liver functions and other laboratory follow ups. Continue the anti-hepatitis B therapy, if required.
IN HBV/HIV-1 CO INFECTED PATIENTS
Entecavir has not assessed in HIV/HBV co infected patients who are not concurrently taking effective anti-retroviral therapy. Entavir tablet used for HBV infection in patients who are infected with HIV, produce resistant to HIV nucleoside reverse transcriptase inhibitors, not exist to treat. Entavir should not be suggested to HBV/HIV co infected patients, also not receiving HAART. To overcome this type of condition, patient should be examine with HIV antibody testing before the therapy.
IN LACTIC ACIDOSIS & HEPATOMEGALY WITH STEATOSIS
This condition may occur due to the combination of nucleoside analog with anti-retroviral agents, this may happen mostly in women. The major fatal cases of this condition is obesity and extended nucleoside exposure. Lactic acidosis frequently occurs in decompensated liver cirrhosis patients, the only way to reduce this adverse is discontinuing the treatment with Entavir .
ENTAVIR PRODUCES SOME UNDESIRABLE EFFECTS
The most common adverse reaction occurs during or after the treatment; Severe aggravation of hepatitis B infection Lactic acidosis Hepatomegaly with steatosis The common side effects like Dyspepsia Alopecia Rash Elevation of transaminase Headache Fatigue Anaphylactic reactions Dizziness Diarrhea Nausea Vomiting Somnolence Insomnia Hepatic failure Gastrointestinal hemorrhage Hepatocellular carcinoma
ENTAVIR INTERACTS WITH SOME DRUGS LIKE
Entavir is not a CYP 450 enzyme substrate, inhibitor or inducers. Since Entavir is majorly eliminated through kidneys, co administration of Entavir tablets with drugs which reduce the renal functions causes increasing the serum concentration of Entecavir and other combined drugs leads to adverse effects of Cronivir. Drug interaction may occur during combination of Entavir with the drugs which metabolized, inhibit or induce by CYP450 enzyme may have chance to alter pharmacokinetic properties of Entecavir. Co administration of Entavir with lamivudine, Adefovir or tenofovir disoproxil fumarate not expels any drug interaction.
RENAL AND HEPATIC IMPAIRMENT
Depending upon creatinine clearance, the dosage of Entecavir is suggested for patients who are having renal damage. They may follow the dosage adjustments. The safety and effectiveness of Entecavir in hepatic impaired patients has not been evaluated. If Entavir is necessary to take in hepatic impairment patients, who are already receiving Immuno suppressant like cyclosporine, Tacrolimus or sirolimus causes affecting the renal function. Patient must examine periodically before or after the therapy using with Cronivir
ENTAVIR OVER DOSAGE
If over dosage of Entecavir occurs, confirmation of toxicity should be taken and provide supportive measures. Following 0.5mg of Entecavir, nearly 13% of Entecavir dose should be eliminated by hemodialysis method.
PREGNANCY & LACTATION
The pregnancy category of Entavir tablets is C Entavir tablets should not be used in pregnancy condition. Entavir used in pregnancy for necessary condition, if risk and benefits are clearly known. In animal clinical studies reveals that Entecavir is excreted in human milk, but human data is not applicable. Breast feeding should be avoided, because most of the drugs are eliminated in human milk. To avoid problems related to Entecavir, it should be taken into consideration.
No contraindication is acquired in the therapy using with Entavir tablets. Any hypersensitivity reaction occurs, if patients who are contraindicated to the ingredients present in Entavir tablets.
PEDIATRIC AND GERIATRIC
In pediatric patient age of less than 2 years, the potency of Entavir has not been assured. Care should be taken while using in pediatric patients. In geriatric patient who have renal impairment, while taking Entavir caution should be taken because it is renal eliminated medicine. In elder patients renal functions are mostly decreased.
Entavir tablets should be stores at below 30°C Keep away from light, moisture and heat.
Entavir is used in chronic hepatitis B infection, if dose of Entecavir is fail to take by the patients, must consult with medical practitioner and take the dose within a time. On the other hand the missed dose is avoided and follows the regular schedule.
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