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Tenvir
Medical expert of the article
Last reviewed: 03.07.2025
Tenvir is a drug that has activity against hepatitis type B and HIV infection.
ATC classification
Active ingredients
Pharmacological group
Pharmachologic effect
Indications Tenvira
It is used for therapy of HIV and AIDS. In addition, it is used in separate schemes of combined treatment of hepatitis type B. It must also be taken during antiretroviral treatment.
[ 1 ]
Release form
The drug is released in tablet form, 30 pieces inside a container equipped with bags containing silica gel. The pack contains 1 such container.
[ 2 ]
Pharmacodynamics
The substance tenofovir disoproxil after absorption is transformed into the active element tenofovir, which is an analogue of the monophosphate nucleotide. After this, the substance is transformed into the active decay product, tenofovir 2-phosphate (with the participation of constructively expressed cellular enzymes).
The intracellular half-life of tenofovir 2-phosphate is 10 hours in the active state and 50 hours when in a quiescent state within peripheral blood mononuclear cells.
This element inhibits HIV-1 reverse transcriptase and HBV polymerase by competitive direct synthesis with the element's natural substrate deoxyribonucleotide, thereby breaking the DNA chain after joining it.
Tenofovir 2-phosphate has a weak inhibitory effect on cellular polymerases α, β, and γ. In vitro tests show that tenofovir at levels up to 300 μmol/L also affects mitochondrial DNA binding or the process of lactic acid formation.
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Pharmacokinetics
Absorption.
There is evidence that when administered orally to patients with HIV infection, tenofovir fumarate disoproxil is rapidly absorbed, converting it to the moiety tenofovir. When multiple servings of tenofovir fumarate disoproxil were administered with food to individuals with HIV infection, mean tenofovir Cmax (326 (36.6%) ng/mL), AUC 0-∞ (3.324 (41.2%) ng h/mL), and Cmin (64.4 (39.4%) ng/mL) values were observed.
Peak serum concentrations of tenofovir are recorded after approximately 60 minutes when taken on an empty stomach, and approximately 120 minutes when taken with food. After oral administration of the drug on an empty stomach, the bioavailability level is approximately 25%. When taken with fatty foods, the bioavailability of the drug increased (in addition, the AUC (by approximately 40%) and Cmax (by approximately 14%) also increased).
When taking the first dose of the drug, which was administered after eating a fatty meal, the median serum Cmax values were approximately 213-375 ng/ml. At the same time, taking the drug with lighter meals did not have a noticeable effect on its pharmacokinetic profile.
Distribution processes.
It was noted that Tenvir taken orally is distributed within many tissues, with its highest values being noted within the liver with kidneys, as well as intestinal contents (preclinical tests). Synthesis with plasma or serum protein in in vitro tests was equal to less than 0.7%, and also 7.2%, respectively (with a range of drug indicators within 0.01-25 mcg/ml).
Exchange processes.
In vitro testing revealed that neither the active ingredient of the drug nor its metabolic products are substrates for CYP450 enzymes.
Excretion.
Tenofovir is excreted primarily via the kidneys, via filtration and via a tubular active transport system. The unchanged component is excreted in the urine (approximately 70-80% of the administered dose).
Total body clearance is approximately 230 ml/hour/kg (approximately 300 ml/minute). Renal clearance values are approximately 160 ml/hour/kg (approximately 210 ml/minute), which is higher than the glomerular filtration rate. This fact confirms the high importance of tubular secretion in the excretion of tenofovir.
When taken orally, the terminal half-life of tenofovir is 12-18 hours.
Dosing and administration
Tenvir is allowed to be taken only as part of antiretroviral treatment. If it is taken as monotherapy, without addition of other therapeutic agents, the desired effect will not develop, because tenofovir has a weak inhibitory effect.
The drug should be taken before or with meals, in the amount of 1 tablet, once a day. The interval between uses should not exceed 24 hours. If the required time for taking the drug is missed, it is necessary to take the medicine as soon as possible.
It is prohibited to increase the dosage. A maximum of 0.3 g of the medicine is allowed to be taken per day (at one time). In general, it is prohibited to independently increase or decrease the portion size, because this may increase the likelihood of an overdose or weaken the drug's effectiveness.
The tablets are taken whole, without prior crushing, and should be washed down with plenty of water.
Use Tenvira during pregnancy
The drug should be prescribed with caution to pregnant women. Since there is no information on how tenofovir affects fetal development, it is necessary to first assess the benefits to the woman from its use and the likelihood of risk to the fetus.
People undergoing treatment with Tenvir should use reliable contraception during this period.
Contraindications
Among the contraindications:
- people who, in addition to the main pathology, also suffer from polyneuropathy;
- severe renal dysfunction;
- the presence of hypersensitivity to the elements that make up the medication.
Caution is required when using in the following cases:
- renal failure, in which the level of CC is within 30-50 ml/minute;
- The patient requires hemodialysis sessions.
If the above factors are present, the drug should be taken under the supervision of a doctor. Medical supervision is also required when used by people over 65 years of age.
If it is necessary to take Tenvir in a lactating woman, breastfeeding should be discontinued for the duration of therapy.
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Side effects Tenvira
The use of the drug may cause certain side effects:
- disorders of systemic blood flow and lymph function: development of anemia or neutropenia;
- immune disorders: the appearance of signs of allergy;
- problems with metabolic processes: development of lactic acidosis, hyperglycemia, as well as hypophosphatemia or hypertriglyceridemia;
- mental disorders: the occurrence of insomnia or abnormal dreams;
- disorders in the functioning of the nervous system: the appearance of headaches, thoracic or respiratory disorders, as well as dizziness and difficulty breathing;
- disorders affecting digestive activity: development of vomiting, diarrhea, dyspeptic symptoms, nausea, pain in the epigastric region and pancreatitis. Also noted is an increase in the level of amylase (for example, in the pancreas), bloating and an increase in serum lipase values;
- lesions of the epidermis and subcutaneous layers: rash that has a pustular, vesicular or maculopapular form, change in the shade of the epidermis (increased pigmentation), itching and urticaria;
- problems with musculoskeletal activity and connective tissue function: increased creatine kinase values. Osteomalacia, rhabdomyolysis, as well as muscle weakness and myopathy may develop;
- urinary dysfunction: proteinuria, increased creatinine levels, renal failure (in the acute or chronic stage), tubulopathy in the kidney area, which is proximal in nature (this includes Fanconi syndrome), as well as acute tubular necrosis, etc.
Interactions with other drugs
It should be noted that combining the drug with most medications is prohibited. This is due to the fact that Tenvir is incompatible with many drugs. Therefore, when using drugs simultaneously, quite severe negative symptoms may develop, and the therapeutic effectiveness of Tenvir may be weakened or completely neutralized. The interactions of the drug with individual medications are presented below.
When combined with didanosine, its medicinal values increase. Therefore, such a combination is prohibited (only in isolated cases can the option of reducing the dose of didanosine be considered).
Combination with atazanavir causes a decrease in its indicators, as well as a parallel increase in tenofovir values. Such a drug combination is allowed only with additional potentiation of the effect of atazanavir with ritonavir.
Concomitant administration with ritonavir and lopinavir increases tenofovir levels, so this combination is prohibited.
Use with darunavir increases tenofovir values by approximately 20-25%. These drugs should be used in standard doses, while closely monitoring the nephrotoxic effect of tenofovir.
When Tenvir is combined with cidofovir, ganciclovir or valganciclovir, the levels of tenofovir or the drug taken simultaneously with it increase. Therefore, these medications should be used with caution, preventing the development of side effects. Nephrotoxic drugs can also increase the serum level of tenofovir.
If the patient has chronic pathologies that require regular use of medications, it is imperative to consult with your doctor regarding their compatibility with Tenvir.
Storage conditions
Tenvir should be kept in a place protected from moisture and sunlight, out of the reach of small children. The temperature level should be a maximum of 30°C.
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Shelf life
Tenvir can be used within 24 months from the date of release of the therapeutic drug.
Manufacturer
Attention!
To simplify the perception of information, this instruction for use of the drug "Tenvir" translated and presented in a special form on the basis of the official instructions for medical use of the drug. Before use read the annotation that came directly to medicines.
Description provided for informational purposes and is not a guide to self-healing. The need for this drug, the purpose of the treatment regimen, methods and dose of the drug is determined solely by the attending physician. Self-medication is dangerous for your health.