Tenofovir
Tenofovir: instructions for use and reviews
- 1. Release form and composition
- 2. Pharmacological properties
- 3. Indications for use
- 4. Contraindications
- 5. Method of application and dosage
- 6. Side effects
- 7. Overdose
- 8. Special instructions
- 9. Application during pregnancy and lactation
- 10. Use in childhood
- 11. In case of impaired renal function
- 12. For violations of liver function
- 13. Use in the elderly
- 14. Drug interactions
- 15. Analogs
- 16. Terms and conditions of storage
- 17. Terms of dispensing from pharmacies
- 18. Reviews
- 19. Price in pharmacies
Latin name: Tenofovir
ATX code: J05AF07
Active ingredient: tenofovir (tenofovir)
Producer: "Pharmasintez" JSC (Russia), Hetero Labs Limited (India), "MAKIZ-PHARMA" LLC (Russia)
Description and photo updated: 2018-23-11
Prices in pharmacies: from 248 rubles.
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Tenofovir is an antiviral drug.
Release form and composition
Tenofovir is available in the form of film-coated tablets: dosage 300 mg - triangular with rounded ends, biconvex, engraved on each side: on one side - H, on the other - "123", light blue; dosage 150 mg (round) and dosage 300 mg (oval) - biconvex, from brown to light brown, the core is white with a yellow tinge or white (dosage 150 mg and 300 mg: 10 pcs. in blisters, in a cardboard box 3, 6 or 10 packs; 30, 60, 100, 500 or 1000 pcs. in polymer cans, in a cardboard box 1 can; dosage 300 mg: 30, 60, 100, 500 or 1000 pcs. in polymer bottles, in a cardboard box 1 bottle; 500 or 1000 pieces each in silicone bags, in a bag of aluminum foil 5, 10, 25, 30 or 50 silicone bags, in a plastic drum 1 bag).
1 brown or light brown film-coated tablet contains:
- active substance: tenofovir disoproxil fumarate - 150 mg or 300 mg;
- auxiliary components: lactose monohydrate, sodium carboxymethyl starch (primogel), croscarmellose sodium, aerosil A-300 (colloidal silicon dioxide), microcrystalline cellulose, magnesium stearate;
- shell composition: hypromellose (hydroxypropyl methylcellulose), macrogol 6000 (polyethylene glycol 6000), titanium dioxide, iron dye yellow oxide, iron dye red oxide, talc.
1 light blue film-coated tablet contains:
- active substance: tenofovir disoproxil fumarate - 300 mg;
- auxiliary components: lactose monohydrate, pregelatinized starch, croscarmellose sodium, magnesium stearate, microcrystalline cellulose;
- shell composition: triacetin (triacetin), hypromellose, filler - lactose monohydrate (lactose monohydrate), dye - Opadray II light blue.
Pharmacological properties
Pharmacodynamics
Tenofovir is an antiviral drug with specific activity against hepatitis B virus and human immunodeficiency virus (HIV) types 1 and 2. After oral administration, tenofovir disoproxil fumarate is converted to tenofovir, which is an analogue of the nucleoside monophosphate (nucleotide) of adenosine monophosphate, followed by biotransformation into the active metabolite, tenofovir diphosphate, a nucleotide inhibitor of reverse transcriptase.
The mechanism of action of the drug is due to the ability of tenofovir diphosphate to competitively inhibit HIV-1 reverse transcriptase, causing the termination of the synthesis of the DNA strand (deoxyribonucleic acid).
Being a weak inhibitor of DNA polymerases, at a concentration of 300 μmol / L, tenofovir in vitro does not affect mitochondrial DNA synthesis and the formation of lactic acid.
Antiviral activity of tenofovir in the effective concentration range of 0.04–8.5 µmol was evaluated against clinical and laboratory strains of HIV-1 on primary monocytes and macrophages, lymphoblastoid cell lines, and peripheral blood lymphocytes. Its antiviral effect at an effective concentration of 0.5–2.2 µmol has been established against subtypes A, B, C, D, E, F, G, O of HIV-1. At an effective concentration of 1.6–5.5 µmol, tenofovir has an inhibitory effect on certain strains of HIV-2.
Additive effects or synergism have been noted when combined with HIV protease inhibitors, nucleoside and non-nucleoside HIV-1 reverse transcriptase inhibitors.
Resistance to tenofovir disoproxil fumarate occurs in the presence of previous antiretroviral therapy as a result of K65R mutations.
Pharmacokinetics
After oral administration, tenofovir disoproxil fumarate is rapidly absorbed into tenofovir. When taking tablets on an empty stomach, its maximum concentration in serum is reached after 1 hour, when taken with meals - after 2 hours, and after a single dose is 0.213–0.375 mg / ml.
The bioavailability of tenofovir when taken before meals is approximately 25%, when the drug is taken with food, it increases.
In vitro binding of tenofovir to plasma proteins is up to 0.7%, with serum proteins - 7.2%.
Tenofovir is not a substrate of human cytochrome P450 isoenzymes; in vitro does not affect metabolic processes involving cytochrome P450 isoenzymes, including CYP2E1, CYP3A4, CYP2D6, CYP2C9. There was a slight but statistically significant decrease in the metabolism of the CYP1A1 and CYP1A2 substrates.
Through the kidneys, as a result of glomerular filtration and active tubular secretion, the main part of the tenofovir dose is excreted.
Dose (in the range from 75 to 600 mg), frequency of administration or gender of the patient does not affect the pharmacokinetics of tenofovir.
Indications for use
According to the instructions, Tenofovir is used as part of combination antiretroviral therapy for HIV-1 infection.
Contraindications
- renal failure with creatinine clearance (CC) less than 30 ml / min, including the need for hemodialysis;
- lactose intolerance, lactase deficiency, glucose-galactose malabsorption syndrome;
- combination with didanosine, adefovir, tenofovir-containing agents;
- breast-feeding;
- age up to 18 years;
- hypersensitivity to the components of the drug.
Tenofovir should be prescribed with caution in renal insufficiency with a CC of 30-50 ml / min, during pregnancy, in patients over the age of 65 years.
Instructions for the use of Tenofovir: method and dosage
The tablets are taken orally before meals or during meals.
Recommended dosage: 300 mg once a day. The doctor determines the duration of therapy individually, as a rule, antiretroviral therapy is indicated throughout life.
In case of mild renal dysfunction (CC 50–80 ml / min), correction of the usual dosage regimen is not required; treatment must be accompanied by constant monitoring of laboratory parameters of creatinine clearance and serum phosphate levels.
In case of impaired renal function with a CC of 30–49 ml / min, patients are usually prescribed to take the drug at a dose of 300 mg every other day.
In case of impaired liver function, dose adjustment of the drug is not required.
Side effects
- from the nervous system: headache, dizziness, depression;
- from the gastrointestinal tract: abdominal pain, diarrhea, flatulence, vomiting, nausea, bloating, pancreatitis, increased amylase activity;
- on the part of the hepatobiliary system: increased activity of liver enzymes (most often - alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase), hepatitis, fatty degeneration of the liver;
- from the immune system: allergic reactions, angioedema;
- from the respiratory system: shortness of breath;
- from the side of metabolism: hypokalemia, lactic acidosis, hypophosphatemia;
- from the urinary system: impaired renal function, including acute renal failure, interstitial nephritis, Fanconi syndrome, acute nephritis, proximal renal tubulopathy, acute renal tubulopathy, nephrogenic diabetes insipidus, proteinuria, polyuria, increased creatinine levels;
- from the musculoskeletal system: muscle weakness, rhabdomyolysis, myopathy, osteomalacia (bone pain, bone fractures);
- dermatological reactions: skin rash;
- others: increased fatigue, asthenia.
Overdose
Overdose symptoms have not been established, taking the drug in a daily dose of 600 mg for 28 days did not cause severe side effects.
In case of signs of toxicity, the use of standard maintenance therapy is recommended, if necessary, hemodialysis is prescribed. The effectiveness of peritoneal dialysis has not been established.
special instructions
When prescribing Tenofovir, the physician should inform patients about the need to use barrier methods of contraception, since taking pills does not prevent the transmission of HIV infection to a sexual partner.
The ability of the drug to cause varying degrees of severity of mitochondrial damage should be taken into account. Among the most typical manifestations of mitochondrial dysfunction are neutropenia, anemia, hyperlactatemia, lactic acidosis, increased plasma lipase activity, severe hepatomegaly with fatty degeneration.
There is a high risk of developing lactic acidosis, especially in overweight women, as well as in hepatomegaly, fatty liver disease, hepatitis, and the presence of risk factors for liver damage. Therefore, if undesirable phenomena appear in the form of general malaise, loss of appetite, abdominal pain, nausea, vomiting, respiratory and motor function disorders, muscle weakness, you should consult a doctor. In case of severe hepatotoxicity or in the case of a serum lactic acid level of more than 5 mmol / l, the drug should be temporarily discontinued.
Due to progressive HIV infection or long-term antiretroviral therapy, osteonecrosis is likely. Risk factors for the development of osteonecrosis include alcohol consumption, acute immunosuppression, glucocorticosteroid intake, and an increased body weight index of the patient. If difficulties in movement, lethargy, stiffness or pain in the joints appear during the treatment period, patients are advised to seek the advice of their doctor.
Treatment should be accompanied by regular monitoring of QC and serum phosphorus levels; more careful monitoring is required in patients with impaired renal function.
It is not recommended to use the drug in combination or after recent use of nephrotoxic drugs.
When prescribing a drug for the treatment of HIV infection, it is necessary to conduct a study to determine if a patient has hepatitis B or C. HIV-infected patients with hepatitis B or C are at a higher risk of hepatotoxic effect of the drug, therefore they are at increased risk of adverse effects on the liver with possible lethal outcome. Their treatment should take place under close clinical and laboratory supervision. After discontinuation of tenofovir in HIV-infected patients with hepatitis B, severe exacerbation of hepatitis is possible. Therefore, in severe liver diseases (cirrhosis), it is not recommended to discontinue treatment, since an exacerbation of hepatitis that occurs after discontinuation of the drug can cause decompensation of liver function.
If liver function is impaired, the use of tenofovir in combination antiretroviral therapy should be closely monitored. In the event of symptoms indicating a deterioration in the functional state of the liver, treatment should be canceled.
With triple nucleoside therapy, which involves the administration of tenofovir in combination with abacavir and lamivudine, the rate of virological response may decrease and resistance may develop at an early stage of therapy, when these agents are taken once a day. In this case, it is recommended to change the treatment regimen.
A triple therapy regimen using two nucleoside reverse transcriptase inhibitors in combination with a non-nucleoside reverse transcriptase inhibitor or HIV-1 protease inhibitor is considered to be more effective.
With HIV infection against the background of combination antiretroviral therapy, there is a possibility of developing immune reconstitution syndrome. The appearance of any symptoms of an inflammatory nature requires an assessment of the patient's condition by a specialist experienced in treating HIV infection, and the appointment of appropriate symptomatic therapy.
Influence on the ability to drive vehicles and complex mechanisms
Given the profile of side effects, during the entire period of treatment, care must be taken when driving vehicles and complex mechanisms, or abandon types of work that require a high speed of psychomotor reactions and increased concentration of attention.
Application during pregnancy and lactation
The use of tenofovir during gestation is acceptable, provided that the expected therapeutic effect for the mother outweighs the possible risk to the fetus.
It is contraindicated to take the drug while breastfeeding. If it is necessary to prescribe the drug to prevent the risk of postnatal HIV transmission, breastfeeding should be discontinued.
Pediatric use
Treatment of children under the age of 18 is contraindicated due to the lack of data on the efficacy and safety of Tenofovir.
With impaired renal function
The appointment of tenofovir is contraindicated in renal failure with CC less than 30 ml / min.
Caution should be exercised in renal failure with a CC of 30-50 ml / min.
For violations of liver function
In case of impaired liver function, dose adjustment of the drug is not required.
Use in the elderly
Patients over the age of 65 should take pills with caution.
Drug interactions
- didanosine: its systemic exposure increases by 40-60%, which leads to an increase in the risk of developing undesirable effects, including pancreatitis, lactic acidosis, including fatal ones, therefore, joint use with tenofovir is not recommended;
- darunavir: causes an increase in plasma concentration of tenofovir by 20-25%; the use of standard doses in combination therapy is indicated under close supervision for the detection of tenofovir nephrotoxicity;
- atazanavir: its pharmacokinetics changes, so the combination of atazanavir at a dose of 300 mg with tenofovir is possible only in combination with 100 mg of ritonavir;
- oral contraceptives, abacavir, efavirenz, lamivudine, indinavir, emtricitabine, ritonavir, lopinavir, nelfinavir, saquinavir, ribavirin: do not cause clinically significant drug interactions;
- ganciclovir, valganciclovir and cidofovir: are active competitors of tenofovir for renal tubular secretion, causing an increase in the concentration of tenofovir in the blood plasma and increasing the risk of developing its side effects;
- aminoglycosides, amphotericin B: increase the risk of nephrotoxicity, may increase serum creatinine levels, so it is recommended to avoid combining tenofovir with these drugs; when clinically necessary, a combination with aminoglycosides or amphotericin B requires careful monitoring of renal function;
- tacrolimus: causes an increased risk of nephrotoxicity.
Analogs
Analogs of Tenofovir are: Tenofovir Canon, Tenofovir VM, Tenofovir-TL, Viread, Tenoflek.
Terms and conditions of storage
Keep out of the reach of children.
Store at temperatures up to 25 ° C.
Shelf life is 2 years.
Terms of dispensing from pharmacies
Dispensed by prescription.
Reviews of Tenofovir
Patients who took the pill for three months in the reviews of Tenofovir report no viral load during this period. Stopping the drug triples the viral load, which requires resumption of therapy. According to patients, the assessment of the therapeutic efficacy of the drug can be carried out after one and a half years of regular pill intake.
Such negative side reactions of the drug as nausea, loss of appetite, headache are described.
The price of Tenofovir in pharmacies
The price of Tenofovir, film-coated tablets (300 mg), 30 pcs. in the package can be from 3559 to 8027 p.
Tenofovir: prices in online pharmacies
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Drug name Price Pharmacy |
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Tenofovir 300 mg film-coated tablets 30 pcs. 248 r Buy |
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Tenofovir 300 mg film-coated tablets 30 pcs. 407 r Buy |
Maria Kulkes Medical journalist About the author
Education: First Moscow State Medical University named after I. M. Sechenov, specialty "General Medicine".
Information about the drug is generalized, provided for informational purposes only and does not replace the official instructions. Self-medication is hazardous to health!
