Drug profile of Tenvir 300mg
Tenvir 300mg tablets are containing Tenofovir disoproxil fumarate as an active substance which consisting anti-viral & anti-retroviral activity.
For HIV infection, Tenvir should be combined with other anti-retroviral medication for better activity. Tenvir tablets are not curable, but it has able to reduce the progression of disease state.
Tenvir is a analogue of nucleotide, which containing reverse transcriptase inhibitor effect; whereas reverse transcriptase enzyme is required for viral multiplication.
Tenvir is a prodrug which gets activated only after administrating the drug and gets converted in vivo as active moiety.
Brand name: Tenvir
Active substance: Tenofovir disoproxil fumarate
Pack: 30 tablets in a container
Category: Anti-viral & retroviral drug
Prescribing information of Tenvir 300mg
The most common clinical indication of Tenvir tablets are;
For HIV-1 infection:
The Tenvir 300mg tablets should be combined with other anti-retroviral medicines for therapy of HIV-1 infections.
The important point should be considered during HIV treatment is, Tenvir tablets should not be combined with Truvuda or Atripla (Tenofovir disoproxil fumarate with Emtricitabine).
For chronic hepatitis B infection:
The other indication of Tenvir tablets is to be used in advanced hepatitis B infection condition.
Before starting Tenvir therapy in hepatitis patients, the following points should be considered;
- The potency of Tenvir should not be evaluated in decompensated liver damaged condition.
- The efficacy rate should be too small in patients who are nucleoside experienced or lamivudine related variations.
- The usage of Tenofovir disoproxil fumarate is depends on data from one year of therpy in nucleoside treatment newly commenced adult patients with HBeAg positive & HBeAg negative hepatitis B infection with compensated liver cirrhosis.
Mechanism of Tenvir 300mg
Tenvir expels anti viral activity by fighting with natural substrates like deoxyadenosine 5’ triphosphate & insertion occurs into viral DNA, may causes inhibition of activity of HIV reverse transcriptase enzyme.
Due to inhibition of these enzymes causes viral production termination.
The major action of Tenofovir disoproxil fumarate is;
Nucleotide reverse transcriptase inhibitor, enzyme for viral assembly
For viral chain elongation, 3’ phosphodiester linkage is necessary; this formation should be reduced by preventing the conversion of 5’ to 3’phosphodiester. This is made by lacking of hydroxyl group on 3’ carbon of its deoxyribose sugar.
After insertion into developing DNA strand, tenofovir causes immature abolition of DNA transcription, this forbidding the viral proliferation.
Tenofovir disoproxil fumarate converted into tenofovir by undergoing diester hydrolysis.
Further conversion occurs due to phosphorylation, tenofovir into tenofovir diphosphate which act as chain terminator.
Tenvir is a prodrug, which is formulated as water soluble diester form of Tenofovir.
The mean oral bioavailability of Tenvir is nearly occurs by 25%.
The peak plasma concentration time is 1.0 ± 0.4 hours.
The Cmax & AUC of Tenvir is 0.30 ± 0.09ng/ml & 2.29 ± 0.69ng in hours/ml, relatively.
The volume of distribution of Tenvir is 1.3 ± 0.6L/kg.
Tenvir should be binding to human plasma protein occurs in vitro by range of less than 0.7 & 7.2%. Tenvir has very low binding capacity.
Cytochrome 450 enzymes are not involved in metabolism of Tenvir.
Nearly 32 ± 10% of dose is recovered in urine in an unchanged form of tenofovir within 72 hours of drug administration.
The terminal half life of Tenvir is relatively 17 hours.
Tenvir should be eliminated through glomerular filteration & active tubular secretion.
During administration of Tenvir with high fat meals, causes increasing bioavailability with an increase AUC0 -∞ of relatively 40% and increasing Cmax by 14%.
Tenvir with light meals causes no alteration in pharmacokinetic properties.
Food will delays the time to Cmax of tenofovir by 1 hour.
When to take the Tenvir 300mg
The dose of Tenvir should be administered as single dose without food.
Dosage regimens of Tenvir 300mg
The prescribed dose of Tenvir is one tablet should be taken as a once daily.
In chronic hepatitis B treatment, the maximum duration of therapy should not be detected.
The safety of Tenvir in hepatitis condition should not be evaluated in pediatric patients.
Dose alteration in renal impairment patients:
In moderate to severe renal impaired patients, have chance of increasing the exposure of Tenvir.
Based on creatinine clearance value, the dose should be suggested.
In mild renal damage: No dosage adjustment should be recommended and monitor the patient’s creatinine clearance & serum phosphorus level frequently.
CrCl 30 to 49ml/min: The prescribed dose is 300mg of Tenvir for every 48 hours.
CrCl 10 to 29ml/min: The prescribed dose is 300mg of Tenvir for every 72 to 96 hours.
CrCl ≥50ml/min: The prescribed dose is 300mg of Tenvir for every 24 hours
For hemodialysis patients: The prescribed dose is 300mg of Tenvir should be taken for every 7 days or relatively 12 hours of dialysis.
Tenvir 300mg caused side effects
The major adverse effects occurs during the treatment with Tenvir are;
Lactic acidosis or severe hepatomegaly with steatosis
Severe acute aggravation of hepatitis
New commencement of renal or worsening of renal damage
Reduction in bone mineral density
Immune reconstitution syndrome
The most common side effects;
Increased creatine kinase
Increased serum amylase
Increased AST & ALT
Drug- drug interaction
Didanosine combined with Tenvir tablets, causes increasing exposure of Didanosine leads to increase the adverse effects related to Didanosine.
To overcome the problems, the dose of Didanosine should be reduced.
During co administration of atazanavir with Tenvir, leads to produce increasing concentration of Tenvir content. This combination should be avoided, if patient may suspected with grade of toxicity of Tenvir.
The AUC & Cmin of atazanavir should be reduced by Tenvir during co administration. If patient requires this combination, then administer 300mg of atazanavir & 100mg of ritonavir.
Avoid combination of Lopinavir/ritonavir with Tenvir, because it may causes increasing the concentration of Tenvir leads to increase the adverse effects associated to Tenvir.
Tenvir content and its metabolites are majorly excreted through kidneys. If Tenvir combined with drugs which reduce the renal functions causes elevating the concentration of Tenvir.
Food drug interaction
Some minor food drug interaction will occurs, food increase the absorption & bioavailability of tenofovir, active moiety of tenofovir DF.
High fat meal elevates the maximum plasma concentration of tenofovir.
Food also postpones the time to acquire tenofovir Cmax by almost 1 hour.
It may consume without regard to meals.
No possible contraindications should be occurred.
Some hypersensitivity reactions should be present due to patients may contraindicated to the component of Tenvir.
Lactic acidosis or hepatomegaly with steatosis:
This reaction may cause some fatal effects.
This may occur due to combinational therapy of Tenvir with other anti-retroviral drugs.
This fatal effect majorly occurs in women; this may leads to obesity and extended exposure of nucleosides.
In case of this condition, patients should be suspended with Tenvir therapy.
Aggravation of hepatitis:
Monitor the hepatic function test.
This adverse occurs due to discontinuation of anti-HBV treatment.
Patient may cleanly observed after stoppage of therapy with Tenvir.
Restart the treatment with anti-HBV.
This condition is occurs due to combination of Tenvir with drugs reducing the renal functions.
Avoid this combination.
Patients with creatinine clearance <50ml/min should be monitored carefully.
Avoid some co administration; Tenvir should not be administered with Adefovir dipivoxil.
For patient with HIV-1 & HBV co infection, due to exposure of advancement of HIV-1 resistance, Tenvir should be used in HIV-1 & HBV co infections.
In this condition, HIV-1 antibody testing is performed.
Osteopenia is a major exposure of Tenvir; due to diminishing the bone mineral density which may causes fracture.
Fat redistribution: Accumulation of fat leads to cause obesity.
Immune reconstitution syndromes, this may occur in HIV-infected patients.
Pregnancy and lactation
Pregnancy category: B
The usage of Tenvir in pregnancy condition occurs very cautiously, after knowing the potential risk of therapy, the treatment should be continuing.
During treatment with Tenvir, the fetal events should be monitored frequently.
Breast feeding also recommend in safe manner.
Storage and handling
Tenvir tablet container should be stored at 25oC (77oC).
Keep the container away from moisture, heat & light.
If patient fail to take the dose of Tenvir, must be consult with physician and get advice and follow the instructions.
Patients acquiring with over dosage of Tenvir, should be monitored with confirmation of toxicity.
Provide the patient with supportive measures
Hemodialysis should be processed during the over dosage of Tenvir, with an extraction rate of 54%.
Following 4 hour hemodialysis leads to remove 10% of administered dose of Tenvir.