How does Relenza (Zanamivir) work:

Relenza (Zanamivir) is a medicine used to treat Influenza which is caused by a virus infection (or flu). Relenza inhalation powder contains the active ingredient zanamivir, which is a type of medicine called a neuraminidase inhibitor. In order to leave one cell and infect another, the influenza virus uses a chemical helper that is found on its surface. This substance is an enzyme called neuraminidase. Without it, newly formed copies of the virus can't leave the infected cells to infect other cells.

Zanamivir works by binding to the neuraminidase on the surface of the virus and stopping it from working. This prevents the flu virus from spreading and infecting other cells and so confines the infection to a smaller area. This makes the symptoms of the infection less severe and also makes it is easier for the body's immune system to kill the virus.

Relenza (Zanamivir) can also be used to prevent flu in people who have been in contact with someone with the virus. In this case the medicine should be started within 36 hours of being in contact with the infected person.

Dosage & Administration:

You should start taking Relenza as soon as possible, preferably within 2 days, after developing symptoms to get the best effect. You should breathe in the contents of 2 blisters, twice a day (usually morning and evening), for five days. If you forget to take a dose take it as soon as you remember, then go back to taking it as you would normally. If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to. Never take a double dose to make up for the dose that you missed.

If there is something you do not understand, contact your physician or pharmacist.

Side Effects:

• Narrowing of the airways
• Difficulty in breathing
• Throat tightness
• Rash
• Swelling of the face or throat

Precautions:

Do not take Relenza if you have ever had an allergic reaction to zanamivir or lactose. Do not take Relenza if you are breastfeeding, pregnant or trying to become pregnant, unless your physician says you should. You should discuss any concerns you have with your physician. If you suffer from asthma, you should discuss the use of Relenza with your physician. Also, tell your physician if you are allergic to any foods or medicines or if you are taking any other medicines.

Further Information:

The National Institute of Clinical Excellence (NICE) has recommended that zanamavir should not be prescribed to people who have flu but are otherwise healthy. They recommend that it is only used to treat people who are at risk of developing complications from flu. These people are those aged over 65 years; and those with chronic lung disease, eg asthma or COPD, significant heart disease, long-term kidney disease, diabetes, or a poorly functioning immune system. In addition, they recommend it should only be used in these people if they can start treatment within two days of the onset of symptoms, and if the influenza virus is known to be circulating in the community.