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Legal classification of medication

POM

Oseltamivir can only be obtained in accordance with a prescription given by an appropriate prescriber and therefore the legal status of the medication is prescription only medicine (POM)

Formulations

Oseltamivir comes in two different formulations:

• Capsules. 30mg, 45mg, and 75mg strengths are available.
• Suspension. The standard strength available is 60mg/5ml but other strengths can also be obtained

Class of drug

Oseltamivir is a neuraminidase inhibitor.

Indications

Oseltamivir is indicated for the treatment and prevention of influenza.

How does it work?

Influenza viruses have a protein on their surface called neuraminidase which enables them to replicate in human cells and help the virus to pass through the entire respiratory tract. Oseltamivir inhibits the viral neuraminidase preventing newly formed viruses from escaping infected cells, therefore preventing the spread of infection between cells.

How is it taken?

Capsules and suspension are bioequivalent of oseltamivir, i.e. 75mg dose can be administered as either:

• One 75mg capsule
• One 30mg capsule and one 45mg capsule
• One 35mg capsule and 45mg dose of suspension

Treatment should be initiated as soon as possible within the first two days of onset of symptoms of influenza. The following are the dosages treatment for influenza:

• For adolescents (13 to 17 years of age) and adults. The recommended dose is 75mg twice daily for 5 days.
• For infants older than 1 year of age and for children 2 to 12 years of age. 30mg and 45mg and oral suspension are available. Twice daily.
• For infants below 12 months of age the dose depends on the weight of the child. The GP will be able to calculate this using weight adjusted dosing regimens.

The dosage of oseltamivir for the prevention of influenza is similar to treatment. Your GP will discuss the best dosage regimen required.

Oseltamivir can be taken before or after food. It is recommended to be taken after food to avoid any stomach upsets. Capsules of oseltamivir can be opened and contents mixed with small amounts of sweetened food, such as yoghurt, just before administration.

Pregnancy and Breast feeing

Based on observational data and animal studies, it is thought that there are no obvious harmful effects to the pregnant woman and the embryo/foetus. Oseltamivir can be used in women who are pregnant or breast feeding if the intended benefits outweigh the potential harm that could be caused by not treating a dangerous strain of influenza.

Side-effects

In adults, the most commonly reported side-effects were vomiting and nausea. The majority of these side-effects were reported on single occasion on either the first or second day of treatment and resolve spontaneously with in 1-2 days. In children the most common side-effect is vomiting.

Other side-effects include:

• Abdominal pain
• Diarrhoea
• Headache
• Conjunctivitis

Since the use of Oseltamivir, there have been reports, of confusion, hallucinations, anxiety, nightmares and delusions, though this was mainly noted in children. These symptoms were also reported in children not taking Oseltamivir who had influenza. It remains unclear from the data whether this was due to Oseltamivir, or due to the influenza illness it self.