The drug "Tenofovir" is an antiviral drug that is prescribed for hepatitis and human immunodeficiency virus. What is this remedy? We will examine in more detail in this matter.
According to the instructions for use with Tenofovir, this medication is available in tablet form. The tablets are coated with a special film coating. At a dosage of 300 mg, the tablets have a triangular shape and rounded ends, light blue in color. At a dosage of 150 mg, they have a rounded shape, and at a dosage of 300 mg - oval. They are biconvex, light brown in color. Tablets of any dosage are packaged in blisters and cardboard packs of 3, 6 or 10 blisters, polymer cans of 1000, 500, 60, 30, as well as in bottles with the same number of tablets (500 and 1000 pcs. - when packed in silicone bags )
Structure
One Tenofovir tablet contains the main active ingredient, which is tenofovir disoproxyl fumarate. As auxiliary components in this medication are used:
- Lactose Monohydrate.
- Sodium carboxymethyl starch (primogel).
- Croscarmellose sodium.
- Microcrystalline cellulose.
- Aerosil A-300 (colloidal silicon dioxide).
- Magnesium stearate.
The film coat of brown tablets includes: titanium dioxide, hydroxypropyl methylcellulose, polyethylene glycol 6000, talc, iron oxide - dye yellow, iron oxide - dye red.
The price of Tenofovir will be listed below.
One light blue shade tablet contains the active substance tenofovir disoproxyl fumarate and additional components: lactose monohydrate, croscarmellose sodium, pregelatinized starch, magnesium stearate, microcrystalline cellulose. The composition of the shell includes triacetin, hypromellose, lactose monohydrate, a dye light blue. Reviews about "Tenofovir" are available in large numbers.
Pharmacological action of a drug
The drug is an antiviral agent with a specific effect against hepatitis B and HIV viruses of the first and second types. After oral administration of tenofovir disoproxil, the fumarate is converted to tenofovir, which is an analogue of adenosine monophosphate, nucleoside monophosphate (nucleotide) with biotransformation into the metabolite - tenofovir diphosphate, reverse transcriptase inhibitor.
The mechanism of action of Tenofovir is due to the properties of tenofovir diphosphate inhibition of HIV-1 reverse transcriptase in a competitive manner, provoking the termination of DNA chain synthesis. This basic substance does not affect the production of mitochondrial DNA and the formation of lactic acid.
Evaluation of the antiviral effect of the drug in the range of the most effective concentration was carried out in relation to laboratory and various clinical strains of HIV of the first type on primary macrophages and monocytes, peripheral blood lymphocytes and lymphoblastoid cells. Its antiviral effect is established in relation to A, O, D, B, C, F, E, G, HIV of the first type. In addition, tenofovir inhibits some strains of HIV of the second type.
The additive effect and synergism were also noted with concomitant use with HIV protease inhibitors, non-nucleoside and reverse transcriptase inhibitors. Susceptibility to tenofovir disoproxil fumarate occurs with antiretroviral therapy due to K65R mutations.
After oral administration, the active ingredient of the drug Tenofovir is rapidly absorbed. If you take tablets on an empty stomach, the maximum concentration of a substance in the blood is reached after an hour, with food - after two hours.
The bioavailability of a derivative of a substance before a meal is approximately 25%; when a drug is received with food, it increases slightly. Tenofovir is not considered a substrate of the cytochrome P450 isoenzyme; in vitro it does not affect the metabolic processes in which these isoenzymes participate. An insignificant but statistically significant decrease in the metabolism time of the substrate CYP1A2 and CYP1A1 was also noted.
Through the kidneys during tubular secretion, as well as glomerular filtration, the main part of the dosage of tenofovir is excreted. The dose, gender of the patient and the frequency of administration do not affect the pharmacokinetics of this derived substance.
Indications of the drug "Tenofovir" and contraindications
The drug is used as part of a comprehensive antiretroviral treatment for HIV-1.
This medical product has a certain list of contraindications, which must be taken into account by a specialist when prescribing therapy. These include:
- Renal failure with creatinine clearance less than 30 ml / min, and also if necessary, hemodialysis.
- Lactase deficiency, cases of lactose intolerance, as well as glucose-galactose malabsorption.
- In combination with adefovir, didanosine, as well as agents containing tenofovir.
- Breast-feeding.
- Age to 18 years.
- Cases of hypersensitivity to drug substances.
With special caution, a medication should be prescribed in case of kidney failure with creatinine clearance of 30-50 ml / min, as well as during pregnancy, for patients over 65 years of age.
This is confirmed by the instructions for use with Tenofovir.
Methods of use and dosage of medication
Tablets of this medication are taken orally before or during meals. Recommended dosages are 300 mg once daily. The duration of therapy is determined individually by a specialist, most often antiretroviral treatment is indicated throughout life.
In mild forms of impaired renal function, correction of normal dosing regimens is usually not required, and therapy should be accompanied by constant monitoring of laboratory levels of creatinine clearance and blood phosphate levels.
In case of impaired renal function with a clearance of 30-50 ml / min, patients are usually prescribed to take this medication every other day in a dosage of 300 mg Tenofovir. In case of impaired liver function, dosage dosage adjustment is also not required.
Adverse Reactions
According to reviews, Tenofovir can cause numerous side effects, including:
- Nervous system: cephalalgia, dizziness, signs of depression.
- Digestive tract: abdominal pain, upset stool, flatulence, dyspepsia, pancreatitis, increased amylase activity.
- Hepatobiliary system: an increase in the functionality of liver enzymes (in most cases, gamma-glutamyl transpeptidases, aspartate aminotransferase, alanine aminotransferase), fatty liver, hepatitis.
- Immune system: allergy, angioedema.
- Respiratory system: shortness of breath.
- Metabolism: lactic acidosis, hypokalemia, hypophosphatemia.
- Urinary system: impaired renal function, including acute renal failure, Fanconi syndrome, interstitial nephritis, nephritis, proximal renal tubulopathy, renal tubule necrosis, diabetes insipidus, proteinuria, polyuria, increased creatinine concentration.
- Musculoskeletal system: muscle weakness, rhabdomyolysis, osteomalacia (fractures, bone pain), myopathy.
- Dermatological phenomena: skin rashes.
- Other reactions: asthenia, excessive fatigue.
If such symptoms occur, the patient is urgently advised to inform the specialist and pass laboratory tests in order to monitor the general condition.
Symptoms of an overdose of a drug
Overdose phenomena have not been established, taking the drug in a daily dosage of 600 mg for 30 days of serious adverse reactions, as a rule, did not cause. In case of toxicity symptoms, the use of standard supportive treatment is recommended, and hemodialysis can be prescribed if necessary.
The effectiveness of the use of peritoneal dialysis has also not been established.
Special instructions for the use of the drug
When prescribing the drug "Tenofovir", the doctor should inform about the need to use barrier methods of contraception, since taking the drug does not prevent HIV transmission to the partner.
It is necessary to take into account the ability of the drug to cause damage to mitochondria, which contributes to the development of neutropenia, anemia, hyperlactatemia, lactic acidosis, an increase in lipase activity, severe hepatomegaly with fatty degeneration, and lactic acidosis.
With hepatotoxicity, the use of the medication should be temporarily discontinued. Due to progressive HIV or prolonged antiretroviral treatment, osteonecrosis is likely to develop. At the same time, risk factors include alcohol consumption, immunosuppression, the use of glucocorticosteroids, and a high weight index.
The use of the drug in combination with nephrotoxic drugs is not recommended.
HIV patients with hepatitis C or B are more likely to have hepatotoxic effects of this medication, so they are considered at risk of adverse effects on the liver with a potential fatal outcome. Their therapy should be under laboratory and clinical supervision.
Analogs of Tenofovir
Analogs of this drug include:
- "Tenofovir Canon";
- Tenofovir-TL;
- "Tenofovir VM";
- Tenoflek;
- Viread.
Only the attending physician should pick them up. Self-medication is unacceptable, as it can lead to severe side effects.
Cost of medication
The price of Tenofovir depends on the dosage and the number of tablets in the package, and averages from 3,500 to 8,100 rubles. This is also affected by the region.
Reviews
Patients who have been prescribed tablets for administration over a period of three months report that there was no viral load in the Tenofovir reviews. The cessation of taking her medicine, as a rule, triples her, which requires the resumption of treatment. According to patients, the evaluation of the drug efficacy of this medication can be carried out after about a year and a half of the systematic use of these tablets. Some negative side effects from taking the drug are also described, for example, nausea, lack of appetite, headaches. Reviews about Tenofovir are also available from doctors.
Reviews of specialists
Experts note that this medication is very specific and is not prescribed for every HIV patient, since it has very serious side effects and causes many complications. It is prescribed in most cases only when there is an urgent need, but at the same time careful monitoring of the patient's condition is carried out. In general, they indicate that the medicine is very effective. In addition, they avoid prescribing it to people with HIV who are suffering from kidney failure, as this has even more serious consequences than the underlying disease.