Xynovir(Tenofovir Disoproxil Fumarate)

Therapeutic Group: Anti Viral

Presentation

Xynovir: Each tablet contains Tenofovir Disoproxil Fumarate INN 300 mg.

Description

Tenofovir Disoproxil Fumarate, an acyclic nucleotide analogue of adenosine monophosphate is a prodrug of Tenofovir. It shows activity against HBV polymerase and HIV reverse transcriptase after phosphorylation to the active diphosphate form. Tenofovir diphosphate inhibits viral polymerases (reverse transcriptase) by direct competing with the natural substrate deoxyribonucleotide and by causing DNA chain termination after its incorporation into viral DNA.

Indications

Tenofovir is indicated for the treatment of -

Chronic hepatitis B virus infection in adults

HIV-infected adults in combination with other antiretroviral agents

Dosage & Administration

The recommended dose of Tenofovir in chronic hepatitis B virus infection in adults 18 years of age and older with adequate renal function is 300 mg once daily with or without food.

Dose Adjustment in renal impairment: Tenofovir is eliminated by renal excretion, so the exposure to tenofovir increases in patients with renal dysfunction. Dosing interval should be adjusted in all patients with creatinine clearance <50 ml/min, as detailed below -

Dosing interval adjustment of Tenofovir in patients with renal impairment
Creatinine clearance(mL/min)>= 5030 to 4910 to 29Haemodialysis Patients
Recommended dose and dosing interval300 mg every 24 hours300 mg every 48 hours300 mg every 72 to 96 hoursEvery 7 days or after a total of approximately 12 hours of dialysis

Dose Adjustment in hepatic impairment: No dose adjustment is required in patients with hepatic impairment.
Pediatric Use: Safety and effectiveness of Tenofovir in pediatric patients below the age of 12 years have not been established.
Geriatric Use: Clinical studies of Tenofovir did not include sufficient numbers of elderly patients aged 65 years and over to determine whether they respond differently from younger subjects. But care should be taken in dose selection.

Side Effects

The most common side effects are nausea, vomiting, diarrhea and flatulence.

Precautions

Coadministration with other drugs: Tenofovir should not be administered concurrently with Emtricitabine & Tenofovir combination or Adefovir Dipivoxil.
Lactic Acidosis/Severe Hepatomegaly with Steatosis: Though the risk of occurrence of lactic acidosis is low for Tenofovir, treatment should be suspended in any patient who develops lactic acidosis or hepatotoxicity.
Exacerbation of Hepatitis after Discontinuation of Treatment: Discontinuation of Tenofovir therapy may be associated with severe acute exacerbations of hepatitis.

Use in Pregnancy & Lactation

In pregnancy: Pregnancy category B. It should be used during pregnancy only if clearly needed.
In lactation: It is not known whether it is excreted in human milk. Mothers should be instructed not to breast feed if they are taking Tenofovir.

Drug Interaction

Coadministration of Tenofovir with antiretroviral, entecavir, lamivudine, methadone, oral contraceptives, ribavirin and tacrolimus did not result in significant drug interactions. The effects of coadministration of Tenofovir with other drugs that are renally eliminated or are known to affect renal function have not been evaluated.

Over Dose

There is no experience of Tenofovir overdosage reported in patients.

Commercial Pack

Xynovir tablet: Each box contains 3 blister strips of 4 tablets.