Relenza® | Relenza (Zanamivir) - 5mg (20 Rotacaps and Diskhaler)

How does Relenza (Zanamivir) work?

Relenza inhalation powder contains the active ingredient zanamivir, which is a type of medicine called a neuraminidase inhibitor. It is used to treat and prevent infection with the influenza virus (flu).

Flu is caused by a highly contagious virus that affects the respiratory system (lungs and airways). The virus is caught by inhaling microscopic airbourne droplets that are produced when an infected person talks, coughs or sneezes. The virus can also survive for a short-time on surfaces, so can be picked up if a person touches an infected surface and then rubs their nose or eyes. When the virus enters the body it invades cells in the airways, where it replicates to form lots of new copies of the virus.

These new copies of the virus leave the first cells and move on to infect adjoining cells, where the process is repeated. After a couple of days enough cells have been infected that the patient feels flu symptoms such as headache, fever and general aches and pains. These continue for about a week until the body's immune system kills the virus.

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.

In people who are otherwise healthy, zanamivir has been shown to reduce the duration of flu symptoms by approximately one to one and a half days. To treat the flu in adults, the medicine should be started within 48 hours of the symptoms starting. In children it should be started within 36 hours of the symptoms starting.

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.

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.

Relenza inhalation powder comes packed in blisters on circular foil disks that are used in a type of inhalation device called a diskhaler. The diskhaler pierces the blister when it is used and the powder is then inhaled through the mouthpiece. This deposits the medicine in the throat, airways and lungs, where it can attack the virus. Follow the instructions provided with the diskhaler and ask your doctor or pharmacist for advice if you have any problems.

What is Relenza (Zanamivir) used for?

• Treatment of flu (influenza type A or B) in adults and children aged five years and over, when the influenza virus is circulating in the community.
• Prevention of flu (influenza type A or B) in adults and children aged five years and over, who have been in contact with someone in their household who has been diagnosed with flu.
• Prevention of flu (influenza type A or B) in adults and children aged five years and over, in exceptional circumstances, such as during a pandemic, or in cases when flu vaccination doesn't provide protection against the strain of flu virus that is circulating.

Relenza (Zanamivir) Side Effects

• Narrowing of the airways
• Difficulty in breathing
• Throat tightness
• Rash
• Allergic reaction with swelling of the face or throat