Use: For the flu (influenza A and B)
Relenza contains zanamivir and Tamiflu contains oseltamivir. These
anti-viral medicines work against an enzyme on the surface of the
influenza virus, called neuraminidase (new-ram-in-ee-daze). This
enzyme helps new pieces of virus leave the cells of the body that are
already infected by the virus, therefore these medicines reduce the
amount of virus in the breathing passages (e.g. throat).
The influenza viruses are different from the cold viruses and
therefore there is no benefit from taking Relenza or Tamiflu for a
cold, they only help the flu.
In studies, people with the flu who were given these anti-virals
had their symptoms last less time than people who did not use them,
e.g. they may have felt bad for 4 days if using Relenza instead of 5
days in people not using Relenza. This improvement seemed to be more
obvious for people who have high temperature (fever) with their flu.
These medicines may reduce time off work and also may reduce
complications from the flu such as bronchitis and pneumonia.
The main difference between Relenza and Tamiflu is how they are
taken. Relenza is inhaled from a diskhaler and Tamiflu comes in
capsules that are swallowed.
Relenza is inhaled from a device called a diskhaler. Two
inhalations are used twice a day for five days, and it is recommended
that treatment be started as soon as possible after symptoms have
occurred, preferably within two days. Follow the directions in the
pack, fitting the disk with four doses into the diskhaler, then
taking two doses at a time; change the disk when all doses on the
disk have been used.
One Tamiflu capsule is swallowed twice a day for five days,
starting on the first or second day of flu symptoms. Some people may
like to take it with food to help avoid stomach upset, but this is
not essential.
Cautions:
- Relenza disks contain zanamivir and lactose, and should not be
used in people with an allergy to either ingredient. Anyone with
an allergy to oseltamivir should not take Tamiflu.
- Take special care using Tamiflu in people with kidney
problems.
- Patients with asthma or other lung problems can very rarely
have a problem with tightening of airways when using Relenza. Keep
your reliever inhaler (beta-agonist, e.g. Ventolin) with you at
all times in case this could happen.
- Relenza and Tamiflu are not recommended for use during
pregnancy or breastfeeding unless the likely benefits outweigh the
possible risks.
Side effects:
- In studies, the side effects of Relenza were no greater than
in those using the pretend (placebo) disks instead of the
medicine.
- A very uncommon side effect of Relenza is tightening of
airways.
- Only very little Relenza leaves the airways and moves into the
bloodstream.
- Nausea and vomiting are possible side effects of Tamiflu.
- There may be other side effects, so if you have any unexpected
symptoms while taking this medicine, tell your doctor or
pharmacist.
Interactions:
Interactions are unlikely.
Patient information:
- Follow the instructions on the label of the medicine or as
directed by your doctor.
- Start to use the medicine as soon as possible after the flu
symptoms start to get the most benefit.
- Relenza and Tamiflu will not help with a cold.
- Complete the five-day course and don't miss any doses.
Differences between a cold and the flu
Some differences between colds and flus are:
- The flu is likely to keep you in bed feeling very exhausted,
while a cold makes you feel tired but you can usually get out of
bed.
- The flu is more likely to give you a high temperature and a
headache than a cold.
- Body aches and pains can be quite severe with the flu whereas
with a cold they are very minor or not at all.
- The flu occurs suddenly while a cold is usually more
gradual.
Editorial note:
These drugs are not funded by governments in New Zealand or the
UK. This means the patient has to meet the full cost.
Difficulties in using it are raised because it is hard to
distinguish influenza from other milder viruses without rapid
reliable tests which are not yet widely available.
The benefit in higher risk groups (e.g. the elderly and people
with respiratory problems) is not clearly known.
The current best strategy includes vaccination of high risk groups
to reduce the risk of complications and death from influenza.
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