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What is zanamivir, and how does it work (mechanism of action)?
Zanamivir is an inhaled drug that is used for treating and preventing influenza (the "flu"). Zanamivir decreases the spread of influenza A and B viruses, the viruses responsible for the flu. It does this by blocking the action of neuraminidase, an enzyme produced by the viruses that enables the viruses to spread from infected cells to healthy cells. By preventing the spread of virus from cell to cell, the symptoms and duration of influenza infection are reduced. On average, zanamivir reduces the duration of symptoms by one day if treatment is started within forty-eight hours after symptoms begin.
- The FDA approved zanamivir in July 1999.
- The brand name for Zanamivir is Relenza.
- Zanamivir is available over-the-counter (OTC).
What are the side effects of zanamivir?
The most frequent side effects are:
Other important side effects include:
- increase or decrease in appetite,
- sinusitis, and
- ear; nose; and throat infections,
- skin reactions,
- muscle or joint pain,
- allergic reactions,
- bronchospasm, and
- behavioral disturbances.
Patients with respiratory diseases may experience breathing problems when treated with zanamivir due to irritation of the breathing tubes by the particles from the inhaler. If breathing problems occur, zanamivir should be discontinued. Patients who have asthma or other breathing problems that make them sensitive to inhaled particles should have a fast acting, inhaled bronchodilator available to treat any breathing problem that may occur when zanamivir is used.
What is the dosage for zanamivir?
Zanamivir is administered by oral inhalation. The recommended dose is two inhalations (5 mg per inhalation) twice daily (approximately 12 hours apart) for five days. Two doses (separated by at least two hours) should be administered on the first day of treatment. For best results, treatment should begin as soon as symptoms develop. The recommended dose for prevention of influenza in a household setting is 10 mg once daily for 10 days. The recommended dose for preventing influenza in a community setting is 10 mg once daily for 28 days.
Which drugs or supplements interact with zanamivir?
Zanamivir potentially may interfere with the action of injections of live attenuated flu vaccine because zanamivir prevents viral replication. Therefore, live attenuated flu vaccine should not be administered from 2 weeks before to 48 hours after administration of zanamivir. Trivalent inactivated influenza vaccine can be administered while using zanamivir.
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Is zanamivir safe to take if I'm pregnant or breastfeeding?
What else should I know about zanamivir?
What preparations of zanamivir are available?
Inhalation Powder: 5 mg per inhalation
How should I keep zanamivir stored?
Zanamivir should be stored at room temperature, 15 C to 30 C (59 F to 86 F)
Zanamivir (Relenza) is a prescription inhaled medication used to treat and prevent the flu (influenza)including H1N1 (swine flu). Zanamivir (Relenza) decreases and suppresses the spread of influenza A and B viruses (to include H1N1 or swine flu. Side effects, drug interactions, warnings and precautions, and patient information should be reviewed prior to taking any medication.
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Related Disease Conditions
Influenza (flu) is a respiratory illness caused by a virus. Flu symptoms include fever, cough, sore throat, runny nose, headache, fatigue, and muscle aches. The flu may be prevented with an annual influenza vaccination.
Bird Flu (Avian Influenza, Avian Flu)
Bird flu (avian flu, avian influenza) infection in humans may result from contact with infected poultry. There is a vaccine to prevent human infection with the H5N1 strain of the avian flu virus.
Novel H1N1 influenza A virus infection (swine flu) is an infection that generally is transferred from an infected pig to a human, however there have been reported cases where infection has occured with no contact with infected pigs. Symptoms of swine flu are "flu-like" and include fever, cough, and sore throat. Treatment is generally with the antibiotics oseltamivir (Tamiflu) or zanamivir (Relenza).
Pregnancy: Swine Flu and the H1N1 Vaccine
Pregnant and women who are breastfeeding are encouraged to receive the seasonal flu shot as well as the 2009 H1N1 influenza (swine flu) vaccine. H1N1 flu is treated with the medications Tamiflu® (oseltamivir) or Relenza® (zanamivir). Pregnant women should not receive the H1N1 attenuated nasal spray vaccine. Possible side effects of the H1N1 flu vaccine include muscle aches, fever, nausea, tiredness, or headache.
Treating the Flu in People with Health Risks
Certain portions of the population are at an increased risk of suffering serious complications from the flu. Some of these indviduals at risk include: those with asthma, COPD, heart disease, liver or kidney disease, HIV, AIDs, elderly, women who are pregnant, and children under the age of two. Contact your physician if you have the flu immediately so that you receive the proper care to prevent serious complications.
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Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Relenza FDA Prescribing Information.
CDC.gov. What You Should Know About Flu Antiviral Drugs. September 17, 2013.