Tenvir

TDF desires initial diester hydrolysis for alteration of TDF into tenofovir Tenofovir is a parent compound, which is further phosphorylated into tenofovir diphosphate with the support of cellular enzymes. This active metabolite tenofovir diphosphate acts as chain dominator

Tenvir exhibits its activity by insertion of tenofovir diphosphate into viral DNA and prohibits the effect of HIV-1 & HBV reverse transcriptase against the natural substrate deoxyadenosine 5’-triphosphate after insertion

Tenvir dosage:

Tenvir is used as a single dose regimen

Tenvir tablets should be taken with or without food

Tenvir tablets recommended dosage in the conditions like HIV-1 & HBV infections; In adults & pediatric around the age of 12 years or weight of 35kg or more in hepatitis B infection and 2 years of age in HIV condition;

One Tenvir tablet 300mg should be administered orally as a single dose with or without food The dosage of Tenvir should be calculated on the basis of creatinine clearance value and body weight of the patients

In renal impairment patients, hemodialysis occurs weekly three sessions around 4 hours. Tenvir tablets should be taken only after conclusion of dialysis

Depending on body weight of pediatrics:

• 17 to <22kg: 150mg
• 22 to <28kg: 200mg
• 28 to <35: 250mg
• ≥35kg: 300mg

In adults:

Depending on creatine clearance:

≥50ml/min: 300mg of Tenvir should be given every 24 hours

30 to 49ml/min: 300mg should be recommended for every 48 hours

10 to 29 ml/min: 300mg recommended dosage for every 72 to 96 hours

In hemodialysis patients: Tenvir tablets should be taken every 7 days or after 12 hours of dialysis

Tenvir contraindicated to:

Tenvir tablet have no contraindication But some hypersensitivity reaction may occur if patients are contraindicated to the component of Tenvir tablet

Tenvir tablet produce some side effects;

Some undesirable effects occur during or after the therapy;

Immune restructuring syndrome

Serious acute aggravation of hepatitis B infection

New outbreak of renal impairment

Depletion of bone mineral density

Lactic acidosis or serious hepatomegaly with steatosis

Some common effects;

• Headache
• pain
• Fever
• Abdominal pain
• Back pain
• Asthenia
• Diarrhea
• Nausea
• Dyspepsia
• Vomiting
• Arthralgia
• Myalgia
• Depression
• Insomnia
• Dizziness
• Anxiety
• Lipodystrophy
• Pneumonia
• Rashes

Body works for Tenvir tablets as:

Tenofovir disoproxil fumarate is a prodrug which is converted into an active form tenofovir in-vivo.

The oral bioavailability of Tenvir tablet is reaches relatively at 25%

The peak serum concentration occurs within 1.0 hours ± 0.4 hours Binding of tenofovir with human plasma protein or serum proteins is occurred in-vitro as less than 0.7% & 7.2% respectively

The volume of distribution occurs at steady state 1.3±0.6L/kg The metabolism of Tenvir tablet occurs hepatically to form active tenofovir diphosphate which is pharmacologically active form with the help of cellular enzymes

The terminal half life period of Tenvir occurs nearly 17 hours The effect of food with Tenvir tablet on oral administration, with high fat meals increase the oral bioavailability at 40 to 50%

Tenvir precautions:

In lactic acidosis or serious hepatomegaly with steatosis: To avoid this problem, patient must discontinue the therapy or postpone Severity of hepatitis B infection after conclusion of therapy:

Patients who are discontinue the therapy, should be monitored frequently

Continue the therapy if required Aggravation of renal impairment

Mostly tenofovir is eliminated renally; creatinine clearance must be monitored periodically before starting the treatment

Serum phosphorus, renal protein, creatine clearance, urine glucose values should be monitored before begin the therapy Avoid concurrent use of Tenvir with drugs which reduce the renal function or nephrotoxic agents Care should be taken while using in patients who are co infected with HIV-1 & HBV

Major adverse effect is bone mineral density depletion, may leads to osteoporosis to avoid this condition calcium and vitamin D supplements should be provided Mineralization defects occurs

Tenvir drug interaction:

Tenvir containing active component tenofovir disoproxil fumarate interacts with some drugs and produce adverse effects

Tenvir tablet concomitant with Didanosine, while receiving these drug at same time may produce some adverse effects related to Didanosine to avoid this problem stop the Didanosine tablet immediately

While concurrent use of Tenvir with HIV 1 protease inhibitor, increases the concentration of tenofovir Tenvir is a substrate of P-gp & BCRP transporters, whereas co administration of Tenvir with P-gp inhibitors may increase the absorption

Tenvir with Lopinavir/ritonavir, ritonavir boosted atazanavir or ritonavir boosted darunavir should increase the tenofovir associated adverse effects

Tenvir co administered with hepatitis C anti-viral agents may have a chance to increase the tenofovir exposure, Tenvir is excreted through renal, if Tenvir tablet concomitant with drugs which decrease the renal function may elevates the serum concentration of tenofovir disoproxil fumarate. Some examples like acyclovir, cidofovir, valganciclovir, valaciclovir, amino glycosides

Tenvir storage:

Tenvir tablet container should be stored at room temperature at below 30oC

Tenvir should be kept in dry and cool place

Container should be keep away from moisture, heat and light

Pregnancy and lactation:

Tenvir tablets should be safe to use But in some patients placental transformation occurs, in that condition Tenvir should not be recommended

Generally HIV infected women not breast feed the child, to avoid spreading of infection to babies through human milk

Major adverse effect is bone mineral density depletion, may leads to osteoporosis to avoid this condition calcium and vitamin D supplements should be provided Mineralization defects occurs

Missed dose:

Tenvir tablet should be used only under the guidance of medical practitioner, if patient fail to take the dose of Tenvir tablet, must consult the physician and take the dose as soon as possible

Otherwise the missed dose should be discontinued and follow the regular dosing schedule Do not take over dose