Tamiflu is a medicine that contains the active substance oseltamivir. It is available as capsules (yellow: 30 mg; grey: 45 mg; yellow and grey: 75 mg) and as a powder that is made up into an oral suspension (12 mg/ml).
|Table of Contents|
|What is it used for?|
|How is it used?|
|How does it work?|
|How has it been studied?|
|What benefits has it shown during the studies?|
|What is the risk associated?|
|Why has it been approved?|
Tamiflu is used to treat or prevent influenza (flu) in patients above one year of age:
in the treatment of flu, it can be used in patients who have the symptoms of flu, when the flu virus is known to be circulating in the community
in the prevention of flu, it can be used in patients who have been in contact with someone who has flu. This is generally done on a case-by-case basis. Tamiflu can also be used as preventative treatment in exceptional cases, for instance when the seasonal flu vaccine may not provide sufficient protection and when there is a pandemic a global epidemic of flu.
During a flu pandemic, Tamiflu can also be used to treat or prevent flu in babies below one year of age. Doctors should make decisions on whether to use Tamiflu in babies of this age based on the severity of the disease caused by the flu virus and the baby?s state of health, to ensure that the baby is likely to benefit from the medicine.
Tamiflu cannot replace flu vaccination, and its use should be based on official recommendations.
The medicine can only be obtained with a prescription.
In the treatment of flu, Tamiflu must be started within two days of the onset of symptoms. It is given as one dose twice a day for five days.
In the prevention of flu, Tamiflu must be started within two days of contact with someone who has flu. It is given as one dose once a day for at least 10 days after contact with an infected person. When Tamiflu is used during a flu epidemic, this dose can be given for up to six weeks.
The dose of Tamiflu is 75 mg in patients aged 13 years and over, and in children aged between one and 12 years who weigh more than 40 kg. For children who weigh less than 40 kg, the dose is adjusted according to their weight using the lower-dose capsules (30 or 45 mg).
Patients above one year of age who cannot swallow capsules may receive the appropriate dose of the oral suspension.
If the powder for oral suspension is not available, the pharmacist can make up a solution using the contents of the capsules, or the contents of the capsules can be mixed into sweetened food at home. For babies aged less than one year the solution made up by a pharmacist is preferable to a home preparation as a pharmacist can measure the dose more accurately. The dose to use in premature babies has not been determined.
The doses may need to be lower in patients who have kidney problems. See the package leaflet for full details.
The active substance in Tamiflu, oseltamivir, acts specifically on the flu virus, blocking some of the enzymes on its surface known as neuramidases. When the neuramidases are blocked, the virus cannot spread. Oseltamivir works on the neuramidases of both influenza A (the most common type) and influenza B viruses.
Tamiflu has been compared with placebo (a dummy treatment) in studies of the treatment of flu (2,413 patients aged 13 years or over, 741 elderly patients aged 65 years or over and 1,033 children aged between one and 12 years). The effectiveness was measured using a score card to record symptoms (feeling feverish, muscle pain, headache, sore throat, cough, overall discomfort and runny nose).
In the prevention of flu, Tamiflu was studied in patients who had been exposed to the disease when one of their family members contracted flu (962 cases) or during an epidemic (1,562 people aged between 16 and 65 years, and 548 elderly people in nursing homes). The studies measured the number of cases of flu, proven by laboratory tests. A study also looked at using Tamiflu in a family setting (277 families) for both the treatment of the person with flu, and the treatment or prevention of flu in those in contact with him or her.
A small study has been carried out to show that the recommended doses of Tamiflu in babies between one month and one year of age produce similar levels of the medicine in the blood as the effective doses for older patients. Tamiflu has not been studied in babies less than one month of age, but the recommendations on its use in this age group are based on the results seen in older babies.
In the treatment studies in adults (aged 18 years or over), Tamiflu reduced the duration of the illness from an average of 5.2 days for patients taking placebo, to 4.2 days for patients taking Tamiflu. The average reduction in the duration of the disease in children aged one to six years was 1.5 days.
In the prevention studies, Tamiflu reduced the incidence of flu among the people in contact with a flu patient. In the study carried out during an epidemic, 1% of the people taking Tamiflu developed flu after contact, compared with 5% of those taking placebo. In families with one flu patient, 7% of the family members in the household developed flu when receiving Tamiflu, compared with 20% of those receiving no preventative treatment.
The most common side effects with Tamiflu in patients aged 13 years and over (seen in more than 1 patient in 10) are headache and nausea (feeling sick). In children aged between one and 12 years, the most common side effects (seen in more than 1 patient in 10) are vomiting and diarrhoea - similar side effects are seen in babies below one year of age. For the full list of all side effects reported with Tamiflu, see the package leaflet.
Tamiflu should not be used in patients who may be hypersensitive (allergic) to oseltamivir or to any of the other ingredients.