Zanamivir

Zanamivir is a prescription medication used to treat and prevent influenza ("flu") in adults and children. Zanamivir belongs to a group of drugs called neuraminidase inhibitors, which stop the growth and spread of the flu virus in the body.

This medication comes in powder form to be inhaled by mouth. In people with the flu, zanamivir is inhaled twice daily for 5 days. For prevention of the flu, it is inhaled once daily for 10 to 28 days.

Some of the common side effects of zanamivir include headache, diarrhea, and nausea. 

Zanamivir is a prescription medicine for the treatment of influenza (flu, infection caused by influenza virus) and for reducing the chance of getting the flu in community and household settings. Zanamivir is for adults and children at least 7 years of age who have flu symptoms that appeared within the previous day or two. Typical symptoms of the flu include:

• sudden onset of fever
• cough
• headache
• fatigue
• muscular weakness
• sore throat

Zanamivir can also help reduce the chance of getting the flu in adults and children at least 5 years of age who have a higher chance of getting the flu because they spend time with someone who has the flu. Zanamivir can also reduce the chance of getting the flu if there is a flu outbreak in the community.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Zanamivir may be found in some form under the following brand names:

• Relenza

Some patients have had breathing problems while taking zanamivir. This can be very serious and need treatment right away. Most of the patients who had this problem had asthma or chronic obstructive pulmonary disease, but some did not. If you have trouble breathing or have wheezing after your dose of zanamivir, stop taking zanamivir and get medical attention.

In studies, the most common side effects with zanamivir have been:

• headaches;
• diarrhea;
• nausea;
• vomiting;
• nasal irritation;
• bronchitis;
• cough;
• sinusitis;
• ear, nose, and throat infections;
• and dizziness. 

Other side effects that have been reported, but were not as common, include rashes and allergic reactions, some of which were severe.

People with influenza (the flu), particularly children and adolescents, may be at an increased risk of seizures, confusion, or abnormal behavior early in their illness. These events may occur after beginning zanamivir or may occur when flu is not treated. These events are uncommon but may result in accidental injury to the patient. Therefore, patients should be observed for signs of unusual behavior and a healthcare professional should be contacted immediately if the patient shows any signs of unusual behavior.

If you are not feeling well when you take zanamivir, you may faint or become lightheaded after inhaling zanamivir. You should sit down in a relaxed position before inhaling the dose of zanamivir, and you should only hold your breath for as long as is comfortable after inhaling the dose.

If you are not feeling well, you are advised to have someone with you while you are inhaling the dose of zanamivir.

This list of side effects is not complete. Your healthcare provider or pharmacist can discuss with you a more complete list of possible side effects with zanamivir. Talk to your healthcare provider promptly about any side effects you have.

Tell your healthcare provider about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Let your healthcare provider know if you received live attenuated influenza vaccine (Flumist) intranasal in the past 2 weeks.

Some patients have had bronchospasm (wheezing) or serious breathing problems when they used zanamivir. Many but not all of these patients had previous asthma or chronic obstructive pulmonary disease. Zanamivir has not been shown to shorten the duration of influenza in people with these diseases. Because of the risk of side effects and because it has not been shown to help them, zanamivir is not recommended for people with chronic respiratory disease such as asthma or chronic obstructive pulmonary disease.

If you develop worsening respiratory symptoms such as wheezing or shortness of breath, stop using zanamivir and contact your healthcare provider right away.

If you have chronic respiratory disease such as asthma and chronic obstructive pulmonary disease and your healthcare provider has prescribed zanamivir, you should have a fast-acting, inhaled bronchodilator available for your use. If you are scheduled to use an inhaled bronchodilator at the same time as zanamivir, use the inhaled bronchodilator before using zanamivir.

You should not take zanamivir if you are allergic to zanamivir or any other ingredient of zanamivir. Also tell your healthcare provider if you have any type of chronic condition including lung or heart disease, if you are allergic to any other medicines, milk proteins or other food products, or if you are pregnant.

Zanamivir was not effective in reducing the chance of getting the flu in 2 studies in nursing home patients.

Zanamivir does not treat flu-like illness that is not caused by influenza virus.

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of zanamivir there are no specific foods that you must exclude from your diet when receiving zanamivir.

Tell your doctor if you are allergic to zanamivir or any other medicines.

Tell your doctor if you:

• are pregnant or breastfeeding.
• have asthma or other breathing problems
• have heart, kidney, or liver disease

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category C. In animal studies, pregnant animals were given this medication and had some babies born with problems. No well-controlled studies have been done in humans. Therefore, this medication may be used if the potential benefits to the mother outweigh the potential risks to the unborn child.

Tell your healthcare provider if you are breastfeeding or plan to breastfeed. It is not known if zanamivir excreted in human breast milk or if it will harm your nursing baby.

Zanamivir is packaged in medicine disks called ROTADISKS® and is inhaled by mouth using a delivery device called a DISKHALER®. Each ROTADISK contains 4 blisters. Each blister contains 5 mg of active drug and 20 mg of lactose powder (which contains milk proteins).

You should receive a demonstration on how to use zanamivir in the DISKHALER from a healthcare provider. Before taking zanamivir, read the “Patient Instructions for Use.” Make sure that you understand these instructions and talk to your healthcare provider if you have any questions. Children who use zanamivir should always be supervised by an adult who understands how to use zanamivir. Proper use of the DISKHALER to inhale the drug is necessary for safe and effective use of zanamivir.

If you have the flu the usual dose for treatment is 2 inhalations of zanamivir (1 blister per inhalation) twice daily (in the morning and evening) for 5 days. It is important that you begin your treatment with zanamivir as soon as possible from the first appearance of your flu symptoms. Take 2 doses on the first day of treatment whenever possible if there are at least 2 hours between doses.

To reduce the chance of getting the flu, the usual dose is 2 inhalations of zanamivir (1 blister per inhalation) once daily for 10 or 28 days as prescribed by your healthcare provider.

Never share zanamivir with anyone, even if they have the same symptoms. If you feel worse or develop new symptoms during treatment with zanamivir, or if your flu symptoms do not start to get better, stop using the medicine and contact your healthcare provider.

If you forget to take your medicine at any time, take the missed dose as soon as you remember, except if it is near the next dose (within 2 hours). Then continue to take zanamivir at the usual times. You do not need to take a double dose. If you have missed several doses, inform your healthcare provider and follow the advice given to you.

Treatment of Influenza

• The recommended dose of zanamivir for treatment of influenza in adults and children aged 7 years and older is 10 mg twice daily (approximately 12 hours apart) for 5 days.
• Two doses should be taken on the first day of treatment whenever possible provided there is at least 2 hours between doses.
• On subsequent days, doses should be about 12 hours apart (e.g., morning and evening) at approximately the same time each day.
• The safety and efficacy of repeated treatment courses have not been studied.

If you take too much zanamivir, call your local Poison Control Center or seek emergency medical attention right away.

• Zanamivir should be stored at room temperature below 77°F (25°C). 
• Zanamivir is not in a childproof container.
• Keep zanamivir out of the reach of children. Discard the Diskhaler after finishing your treatment.