Tamiflu is an antiviral drug active against influenza A and B influenza viruses. Tamiflu contains oseltamivir, a prodrug that is metabolized in the body to oseltamivir carboxylate. The active metabolite of oseltamivir competitively and selectively inhibits neurominidase of influenza viruses type B and A, which prevents the release of newly formed viruses from infected cells and their entry into healthy cells. Thus, Tamiflu prevents the development of the disease. Oseltamivir carboxylate inhibits the replication of the virus and reduces its pathogenicity.
Tamiflu is effective in the treatment and prevention of influenza in children older than 1 year and adults. When taking oseltamivir in the first 40 hours after the onset of symptoms, there is a reduction in the period of the disease, a reduction in the risk of complications of influenza, and a decrease in the severity of clinical manifestations of influenza infection. As a prophylactic, Tamiflu significantly (by 92%) reduces the incidence of influenza in people who have had contact with infected people.
Oseltamivir has no effect on the formation of antibodies to the influenza virus, including in patients undergoing vaccination inactivated by influenza vaccine. There is no evidence of resistance to the drug in post-exposure and seasonal flu prevention. With the help of phenotyping and genotyping, strains of influenza virus resistant to oseltamivir were detected (virus resistance was caused by mutation of neuraminidases N1 and N2).
After oral administration of oseltamivir, phosphate is well absorbed in the intestine. Under the action of hepatic esterases, a pharmacologically active form of oseltamivir carboxylate is formed, which is determined in the plasma after 30 minutes and reaches a peak 2-3 hours after taking Tamiflu. In the systemic circulation after oral administration, about 75% of oseltamivir in the form of carboxylate and about 5% of oseltamivir in the form of phosphate are determined. Bioavailability of Tamiflu does not depend on food intake. With plasma proteins, no more than 3% of oseltamivir is bound.
Excreted oseltamivir mainly kidneys by tubular secretion in the form of oseltamivir carboxylate. The half-life of the active metabolite reaches 6-10 hours. The intestine displays no more than 20% of oseltamivir.
In patients with impaired renal function of mild and moderate severity, there is no significant change in the pharmacokinetics of oseltamivir. In patients with severe renal failure (creatinine clearance less than 30 ml / min) there is a significant increase in the half-life of the active metabolite, which may require a dose adjustment for Tamiflu. In patients with impaired liver function, there is no significant change in the pharmacokinetic profile of oseltamivir.
Indications for use of Tamiflu
Tamiflu is used to treat and prevent infections caused by the influenza virus type A and B.
Tamiflu can be prescribed to treat influenza in children older than 1 year and adults. It is recommended to appoint Tamiflu at the first symptoms of the disease.
Tamiflu is used to treat children older than 6 months during an influenza pandemic.
As a prophylactic agent, Tamiflu is prescribed to patients who have been in contact with patients who have been clinically diagnosed with influenza during the circulation of the influenza virus.
Influenza-infested children over 1 year of age and adults Tamiflu may be prescribed in the event of a discrepancy between the circulating influenza virus and the virus against which the vaccination was conducted.
It is recommended that Tamiflu be administered only if there is reliable data on circulating viruses, since oseltamivir is effective only for influenza A and B viruses and is not a treatment for respiratory infections caused by other viruses.
Tamiflu mode of application
Powder for oral suspension of Tamiflu:
The finished suspension is intended for oral administration. To prepare the suspension, the closed vial should be shaken several times, after which 52 ml of drinking water is measured and added to a bottle of powder. After the addition of water, the vial is tightly closed with a lid and shaken for 15 seconds until an equilibrium slurry forms. After the suspension is ready to remove the protective cap and insert the adapter into the neck of the vial. Next, close the bottle tightly with the lid again, so that the adapter assumes the correct position. It is recommended to mark the date of suspension preparation on the vial label.
Before each use of Tamiflu, shake the bottle thoroughly. Dosage should be carried out using a measuring syringe included in the kit. To assemble the suspension into the syringe, it is necessary to move the piston to the tip of the syringe, open the vial, attach the tip of the syringe to the adapter, and turn the bottle upside down, collect the desired amount of suspension into the syringe. The suspension can be taken directly from the dispensing syringe. After each drug intake, disinfect the syringe in the running water.
The suspension is taken regardless of food intake. The dose of oseltamivir and the duration of therapy are determined by the doctor.
Doses recommended for adults:
To treat influenza, adults and adolescents are usually prescribed 75 mg of oseltamivir twice a day.
The maximum recommended daily dose of oseltamivir is 150 mg (note that with an increase in the daily dose, there is no increase in the effectiveness of the drug Tamiflu).
Adults and children with a body weight of more than 40 kg for postexposure prophylaxis of influenza are usually prescribed to take 75 mg of oseltamivir per day for 10 days.
Adults and children weighing more than 40 kg for seasonal prevention of influenza are usually prescribed 75 mg of oseltamivir per day for the entire epidemic period. The safety of taking Tamiflu for 6 weeks has been proven.
Doses recommended for children:
Children older than 1 year with a body weight of less than 15 kg, usually prescribed oseltamivir in a single dose of 30 mg.
Children older than 1 year with a body weight of 15 to 23 kg, usually prescribed oseltamivir in a single dose of 45 mg.
Children older than 1 year with a body weight of 23 to 40 kg, usually prescribed oseltamivir in a single dose of 60 mg.
To treat influenza, children are prescribed a single dose of Tamiflu twice a day.
Children with a body weight of more than 40 kg oseltamivir are prescribed in doses recommended for adults.
The duration of therapy is 5 days.
Children aged 6 to 12 months with an influenza pandemic are prescribed 3 mg of oseltamivir per 1 kg of body weight twice a day under the supervision of a doctor. Duration of therapy is 5 days.
For the prevention of influenza, children older than 1 year are usually prescribed a single dose of oseltamivir once a day. The duration of post-exposure prophylaxis is 10 days, the duration of seasonal prevention is calculated depending on the duration of the epidemic and can be up to 6 weeks.
Special cases of dosing:
Patients with impaired renal function and creatinine clearance greater than 30 mL / min dose adjustment for oseltamivir is not required.
Patients with impaired renal function and creatinine clearance from 10 to 30 ml / min are recommended to administer 50% of the standard dose of oseltamivir (the calculated daily dose is taken for 1 time).
Capsules Tamiflu:
The drug is taken orally. Capsule should be swallowed whole, with enough drinking water. Tamiflu is taken regardless of food intake. The dose of oseltamivir and the duration of therapy are determined by the doctor.
Recommended doses for adults:
Adults and children with a body weight of more than 40 kg for treatment of influenza are usually prescribed 75 mg of oseltamivir twice a day.
The duration of therapy is 5 days.
Adults and children with a body weight of more than 40 kg for prevention, usually prescribed to take 75 mg of oseltamivir per day.
The duration of post-exposure prophylaxis is 10 days, the duration of seasonal prophylaxis can be up to 6 weeks (the drug should be taken during the entire epidemic period).
Recommended doses for children:
Children older than 1 year with a body weight of less than 40 kg may receive capsules Tamiflu 30 and Tamiflu 45. If the child can not swallow the capsule, its contents are dissolved in a spoonful of drinking water or sweet tea.
A single dose for children weighing less than 15 kg is 30 mg of oseltamivir.
A single dose for children weighing 15 to 23 kg is 45 mg of oseltamivir.
A single dose for children with a body weight of 23 to 40 kg is 60 mg of oseltamivir.
For treatment, children are prescribed a single dose twice a day.
For prevention, children are prescribed a single dose once a day.
The duration of treatment is 5 days.
The duration of the course of post-exposure prophylaxis is 10 days, seasonal prophylaxis - during the whole epidemic period.
Special dosage regimens:
Patients with creatinine clearance greater than 30 ml / min dose adjustment for oseltamivir is not required.
Patients with a creatinine clearance of 10 to 30 ml / min, usually a dose of oseltamivir is reduced by half.
It should be noted that taking Tamiflu is not a substitute for vaccination against the flu. The prophylactic effect of oseltamivir lasts during the administration of Tamiflu.
Tamiflu side effects
During the period of therapy with Tamiflu, patients may develop vomiting and nausea; as a rule, these unwanted effects develop at the beginning of therapy, pass independently and do not require the abolition of oseltamivir.
In addition, in some cases, patients may develop such undesirable effects due to oseltamivir:
From the nervous system: hallucinations, headache, cramps, disturbance of sleep and wakefulness, dizziness, weakness. It is also possible to develop delirium and inadequate behavior, which can manifest as symptoms of encephalopathy without severe severe disease. Delirium, including mental disorders, inadequate behavior, hallucinations, agitation, bards and nightmares, can lead to accidental injuries and death, most often this condition was noted in children and adolescents (as a rule, these phenomena developed suddenly and quickly passed). It is noted that the development of delirium and seizures was registered in patients with influenza who did not receive Tamiflu, therefore, the association of these phenomena with oseltamivir is not proven.
On the part of the respiratory system: acute bronchitis, tracheitis, laryngitis, rhinorrhea, cough.
On the part of the digestive system: dyspeptic phenomena, pain in the epigastric region, stool disorders. In isolated cases, there was a development of gastrointestinal bleeding and hemorrhagic colitis.
From the hepatobiliary system: increased activity of hepatic enzymes, hepatitis, liver failure.
Allergic reactions: eczema, dermatitis, urticaria, bronchospasm, toxic epidermal necrolysis, Stevens-Johnson syndrome, anaphylactoid reactions.
Others: epistaxis, conjunctivitis, otitis media, lymphadenopathy, arrhythmia.
Tamiflu contraindications
Tamiflu is not used to treat patients with known hypersensitivity to oseltamivir phosphate and additional capsule or suspension components.
Tamiflu in the form of a suspension in pediatric practice can be used only for treatment of children older than 6 months, treatment of children from 6 to 12 months should be done with caution and only if the expected benefit exceeds possible risks.
Capsules Tamiflu in pediatric practice are used only for the treatment of children over 12 years of age or children weighing more than 40 kg (in young children, the use of Tamiflu capsules is allowed in the absence of suspension and with the mandatory dissolution of capsules, according to the recommendations for admission).
There is no data on the safety and efficacy of oseltamivir in patients with unstable severe illness (when mandatory hospitalization is indicated) and in immunocompromised patients.
The efficacy of Tamiflu has not been established in patients suffering from chronic heart and respiratory diseases.
Tamiflu is not prescribed for patients with terminal stage of renal failure.
It is advisable to use caution when driving a car and managing potentially unsafe mechanisms during oseltamivir therapy.
Tamiflu during pregnancy
Care should be taken when prescribing Tamiflu to pregnant women. Oseltamivir is administered to pregnant women taking into account the pathogenicity of the circulating strain of the virus and the condition of the woman. It is necessary to monitor the condition of the woman and the course of pregnancy during oseltamivir therapy. In animal studies, oseltamivir did not adversely affect the fetus and the newborn.
Some of the oseltamivir and the active metabolite penetrates into breast milk. When appointing Tamiflu during lactation, potential risks should be considered and the issue of possible interruption of breastfeeding should be addressed.
Tamiflu drug Interactions
Probenecid, when combined with Tamiflu, may slow the excretion of the active metabolite of oseltamivir by the kidneys, however, in patients with normal renal function, dose adjustment of oseltamivir is not required.
Caution should be exercised when combining oseltamivir with chlorpropamide, phenylbutazone and methotrexate, as these substances are excreted in the same way, and their simultaneous application may lead to a slowdown in excretion.
Tamiflu overdose
There is no evidence of an overdose of Tamiflu. When taking oseltamivir in doses much higher than recommended, you can expect the development of nausea and vomiting.
There is no specific antidote. With the development of an overdose Tamiflu drug is canceled. The decision on the possibility of further use of oseltamivir after an overdose is taken by a doctor.
Tamiflu form of issue
Capsules Tamiflu 10 pieces in a blister pack of polymeric materials and aluminum foil, in a cardboard bundle 1 blister pack.
Powder for the preparation of oral suspension Tamiflu 30 g in bottles of dark glass, in a cardboard bundle 1 bottle complete with a dosing device.
Tamiflu storage conditions
Powder for the preparation of oral suspension Tamiflu should be stored no more than 2 years after release in rooms with a temperature regime of 15 to 25 degrees Celsius.
A ready-made suspension of Tamiflu should be stored in rooms with a temperature of 2 to 8 degrees Celsius for no more than 17 days or in rooms with a temperature of 15 to 25 degrees Celsius for no more than 10 days.
Capsules Tamiflu should be stored no more than 5 years after release at a temperature regime of 15 to 25 degrees Celsius.
Tamiflu pharmacological group
Antimicrobial and antiparasitic agents
Antiviral medicines
Antiviral medicines of other groups
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