Medications and Drugs
Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: zanamivir
BRAND NAME: Relenza
DRUG CLASS AND MECHANISM: Zanamivir is an inhaled medication used for treating and preventing influenza or the "flu." Zanamivir suppresses and 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.
GENERIC AVAILABLE: No
PRESCRIPTION: Yes
PREPARATIONS: Inhalation Powder: 5 mg
STORAGE: Zanamivir should be stored at room temperature, 15-30 C (59-86 F)
PRESCRIBED FOR: Zanamivir is used for the treatment of infection with the influenza viruses, including
H1N1, in individuals seven years of age or older with symptoms for no longer than two days. It also is used for preventing influenza in adults and children five years of age and older.
DOSING: 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.
DRUG INTERACTIONS: 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
within 2 weeks before or 48 hours after administration of zanamivir.
PREGNANCY: The Centers for Disease Control (CDC) states that
pregnancy is not
a contraindication for use of zanamivir in pregnant women because the benefits
outweigh the risks.
NURSING MOTHERS: It is not known whether zanamivir is excreted in
breast
milk. However, the CDC recommends that women who develop flu after child birth
should be treated with antiviral drugs.
SIDE EFFECTS: The most frequent side effects are
headaches, diarrhea, nausea,
cough, vomiting and dizziness.
Sinusitis,
ear, nose, and throat infections may
occur. Skin reactions, allergic reactions, bronchospasms, and behavioral
disturbances have been reported.
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.
REFERENCE:
Relenza FDA Prescribing Information
Centers for Disease Control. "H1N1flu recommendations." November 1, 2009.
Last Editorial Review: 11/9/2009
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.
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