Tenofovir

General characteristics. Structure:

Active ingredient: 150 mg or 300 mg of a tenofovir.

Antiviral medicine, active against infection VICh-1.

Pharmacological properties:

Pharmacodynamics. Antiviral means, nucleotide inhibitor of the return transcriptase. Tenofovir of in vivo turns in тенофовир, an analog of a nukleozidmonofosfat (nucleotide) of adenosine of monophosphate. Tenofovir in the subsequent turns into an active metabolite - a tenofovir diphosphate which inhibits activity of the return VICh-1 transcriptase, being built in a molecule of virus DNA and breaking synthesis of a chain of DNA. Tenofivir is weak inhibitor of DNA polymerases α, β and a mitochondrial DNA polymerase γ mammals.

Pharmacokinetics. At reception on an empty stomach bioavailability of a tenofovir makes about 25% and to 40% (during food); improves at inclusion in food time, especially with the high content of fat. Meal does not exert clinically significant impact on efficiency of a tenofovir. After single intake in a dose of 300 mg of Cmax in blood serum is reached in 1±0.4 h. The pharmacokinetics of a tenofovir has dozozavisimy character. T1/2 from a cell> 60 h.

After a single dose in T1/2 of a tenofovir makes about 17 h. After multiple dose inside in a dose of 300 mg of 1 times/days (in the conditions of reception not on an empty stomach), 32±10% of the accepted dose are defined in urine during more than 24 h Tenofovir is brought by kidneys, by glomerular filtering and active canalicular secretion.

Indications to use:

Treatment of VICh-1 of an infection as a part of the combined anti-retrovirus therapy at adults.

Route of administration and doses:

Inside, irrespective of meal. The recommended dose - 300 mg of 1 times/days.

Patients with a renal failure at KK have 30-49 ml/min. - on 300 mg each 48 h; at KK of 10-29 ml/min. - on 300 mg each 72-96 h. The patients who are on a hemodialysis - to 300 mg have each 7 days after completion of a session of dialysis.

Features of use:

In need of use at pregnancy it is necessary to compare the expected advantage of therapy for mother and potential risk for a fruit. Due to the revealed changes of a bone tissue against the background of use of a tenofovir, and limited experience of use recommends to apply with care тенофовир at pregnancy.

Women of childbearing age during treatment have to use reliable methods of contraception. In need of use in the period of a lactation it is necessary to stop breastfeeding.

Use at renal failures. With care it is necessary to apply тенофовир at a renal failure with KK less than 50 ml/min., including the patients who are on a hemodialysis. At KK less than 30 ml/min. are not recommended to be applied тенофовир; in need of use it is necessary to control carefully function of kidneys and to correct an interval between administration of drug.

For the first time the arisen or progressing renal failure can lead to an acute renal failure and Fankoni's syndrome. Definition of KK before an initiation of treatment tenofoviry is necessary. Control of clearance of creatinine and phosphorus in blood serum at patients with the increased risk of development or progressing of a renal failure is necessary. It is necessary to avoid use of a tenofovir at the same time or after recent treatment by nefrotoksichny drugs.

With care it is necessary to apply тенофовир at a renal failure with KK less than 50 ml/min., including the patients who are on a hemodialysis. At KK less than 30 ml/min. are not recommended to be applied тенофовир; in need of use it is necessary to control carefully function of kidneys and to correct an interval between administration of drug.

For the first time the arisen or progressing renal failure can lead to an acute renal failure and Fankoni's syndrome. Definition of KK before an initiation of treatment tenofoviry is necessary. Control of clearance of creatinine and phosphorus in blood serum at patients with the increased risk of development or progressing of a renal failure is necessary. It is necessary to avoid use of a tenofovir at the same time or after recent treatment by nefrotoksichny drugs.

It is necessary to exclude use of a tenofovir along with the combined antiviral drugs which part is тенофовир and depivoksit an adefovir.

Tenofovir it is necessary to apply only as a part of the corresponding anti-retrovirus combination therapy at VICh-1 of the infected patients.

At use of a tenofovir development of a syndrome of Fankoni who is followed by a hypophosphatemia, a hypolithemia, a proteinuria, a normoglikemichesky glucosuria is possible; in certain cases the acute renal failure can develop. At early stages the current can be asymptomatic, or be followed by mialgiya; in most cases symptoms disappear at the termination of reception of a tenofovir. Treat the low body weight, existence of diseases of kidneys at the time of the beginning of therapy risk factors. Frequency of development of nefrotoksichny side effects extremely low at patients with initially normal function of kidneys.

Side effects:

From a metabolism: very often - a hypophosphatemia; seldom - лактацидоз; perhaps - a hypopotassemia.

From the alimentary system: very often - diarrhea, vomiting, nausea; often - a meteorism; seldom - pancreatitis, increase in activity of transaminases; very seldom - hepatitis; perhaps - a liver steatosis.

From a musculoskeletal system: perhaps - рабдомиолиз, osteomalacy, muscular weakness, a myopathy.

From an urinary system: seldom - an acute renal failure, a proximal renal tubulopatiya (including Fankoni's syndrome), a giperkreatininemiya; very seldom - an acute tubular necrosis; frequency is unknown - nephrite (including acute intersticial), a nephrogenic not diabetes mellitus.

Others: very often - dizziness; seldom - rash; very seldom - диспноэ, an adynamy.

Interaction with other medicines:

At simultaneous use of a tenofovir with didanoziny concentration of a didanozin in a blood plasma increases (this combination is not recommended; in need of a combination therapy the dose of a didanozin should be reduced).
At combined use to happen reduction of concentration in a blood plasma of an atazanavir and increase in concentration of a tenofovir. It is necessary to apply тенофовир with atazanaviry only with additional strengthening of action of the last ritonaviry.

At combined use of a combination lopinavir/ritonavir with tenofoviry concentration of a tenofovir in a blood plasma increases.

Darunavir increases concentration of a tenofovir by 20-25%. At this combination дарунавир and тенофовир it is necessary to apply in standard doses, at the same time it is necessary to monitorirovat nephrotoxic action of a tenofovir carefully. Tenofovir is generally brought from an organism by kidneys. At combined use of a tenofovir with drugs which reduce function of kidneys or suppress/stop active tubular secretion, increase serumal concentration of a tenofovir is possible and/or to increase concentration of other drugs which are removed by kidneys.
Gantsiklovir, валганцикловир and цидофовир compete with tenofoviry for active canalicular secretion by kidneys, as a result of it concentration of a tenofovir in a blood plasma increases (clinical observation is necessary for control of possible side effects).

Nefrotoksichny drugs are capable to increase concentration of a tenofovir in plasma.

Contraindications:

Hypersensitivity to a tenofovir.

Overdose:

 In case of overdose therapy symptomatic. Tenofovir is effectively brought by a hemodialysis, the coefficient of extraction makes about 54%.

Storage conditions:

To store at a temperature not above 25 °C in places, unavailable to children.

Issue conditions:

According to the recipe

Packaging:

10 pieces - planimetric strip packagings (3) - packs cardboard.
10 pieces - planimetric strip packagings (6) - packs cardboard.
10 pieces - planimetric strip packagings (10) - packs cardboard.
30 pieces - banks (1) - packs cardboard.
60 pieces - banks (1) - packs cardboard.
100 pieces - banks (1) - packs cardboard.
500 pieces - banks (1) - packs cardboard.
1000 pieces - banks (1) - packs cardboard.