Class: Antiviral agent
- Powder, oral inhalation 5 mg
Inhibition of influenza virus neuraminidase, with the possibility of alteration of virus particle aggregation and release.
Approximately 4% to 17% of orally inhaled dose is systemically absorbed. C max is 17 to 142 ng/mL, and T max is 1 to 2 h following a 10 mg dose. The AUC is 111 to 1,364 ng•h/mL.
Less than 10% protein bound.
No metabolites were detected in humans.
Renally excreted as unchanged drug in urine. Serum half-life is 2.5 to 5.1 h. Total Cl is 2.5 to 10.9 L/h. Unabsorbed drug is excreted in feces.
Special PopulationsRenal Function Impairment
Renal Cl is decreased and the half-life is increased in patients with mild, moderate, or severe renal impairment. Safety and efficacy have not been documented in severe renal insufficiency.Hepatic Function Impairment
Pharmacokinetics have not been studied in patients with hepatic impairment.Elderly
Pharmacokinetics have not been studied in patients older than 65 y.Children
After a single dose of zanamivir 10 mg inhalation, 5 patients 6 to 12 y of age had undetectable zanamivir serum concentrations or low drug concentrations (8.32 to 10.38 ng/mL) that were not detectable after 1.5 hours, and 11 patients had C max median values of 43 ng/mL (range, 15 to 74 ng/mL) and AUC ∞ median values of 167 ng•h/mL (range, 58 to 279 ng/mL).Gender
No differences in plasma concentrations or pharmacokinetics were observed between men and women.Race
No differences in plasma concentrations or pharmacokinetics were observed based on race.Weight
No significant differences in serum concentrations and/or pharmacokinetic parameters were observed.
Indications and Usage
Treatment of uncomplicated acute illness caused by influenza A and B virus in adults and pediatric patients 7 y and older who have been symptomatic for no longer than 2 days; prophylaxis of influenza in adults and pediatric patients 5 y and older.
History of allergic reaction to any ingredient of zanamivir, including lactose (which contains milk proteins).
Dosage and AdministrationInfluenza Prophylaxis, Community Outbreak
Adults and Adolescents 12 to 16 y
Oral inhalation 2 inhalations (one 5 mg blister per inhalation) once daily for 28 days.Influenza Prophylaxis, Household Setting
Adults and Children 5 y and older
Oral inhalation 2 inhalations (one 5 mg blister per inhalation) once daily for 10 days.Influenza Treatment
Adults and Children 7 y and older
Oral inhalation 2 inhalations (one 5 mg blister per inhalation) twice daily for 5 days. Two doses should be taken on the first day of treatment whenever possible, provided there are at least 2 h between doses. On subsequent days, doses should be approximately 12 h apart at approximately the same time each day.
- For oral inhalation only with the Diskhaler provided. Not for intranasal inhalation.
- When treating influenza, initiate therapy within 48 h of onset of influenza symptoms.
- For the prophylaxis of influenza, there are no data on the effectiveness of prophylaxis with zanamivir in a household setting when initiated more than 1.5 days after the onset of signs or symptoms in the index case or more than 5 days after the outbreak was identified in the community.
- Administer doses at approximately the same time each day.
- Patients scheduled to use an inhaled bronchodilator at the same time as zanamivir should use their bronchodilator before taking zanamivir.
Store between 59° and 86°F. Do not puncture any blister until just before inhaling a dose.
Drug InteractionsLive, attenuated influenza vaccine
Administer more than 2 wk before or 48 h after zanamivir.
Arrhythmias, syncope, vasovagal-like episodes (postmarketing).
Headache (24%); fatigue/malaise (8%); dizziness (2%); delirium (including abnormal behavior, agitation, altered level of consciousness, anxiety, confusion, delusions, hallucinations, and nightmares), seizures (postmarketing).
Urticaria (less than 2%); facial edema, rash (including serious cutaneous reactions, such as erythema multiforme, Stevens-Johnson syndrome, TEN) (postmarketing).
Nasal signs and symptoms (20%); throat and tonsil discomfort and pain (19%); ear, nose, and throat infections (5%); nasal inflammation (1%).
Diarrhea, nausea (3%); vomiting (2%); abdominal pain (less than 2%).
Decreased or increased appetite and anorexia (4%).
Muscle pain (8%); musculoskeletal pain (6%); arthralgia and articular rheumatism (2%); arthralgia, myalgia (less than 2%).
Cough (17%); viral respiratory infection (13%); sinusitis (3%); bronchitis (2%); bronchospasm, dyspnea (postmarketing).
Fever and/or chills (9%); allergic or allergic-like reactions, including oropharyngeal edema (postmarketing).
Closely monitor for signs of abnormal behavior. If neuropsychiatric symptoms occur, evaluate the risks and benefits of continuing treatment for each patient. Closely monitor respiratory function in patients with underlying airway disease.
Category C .
Safety and efficacy not established in children younger than 7 y for the treatment of influenza; safety and efficacy not established in children younger than 5 y for influenza prophylaxis.
Elderly patients may need assistance with use of the device.
Allergic-like reactions, including oropharyngeal edema, serious skin rashes, and anaphylaxis, have been reported.
Consider the possibility of drug accumulation.
Special Risk Patients
Safety and efficacy not demonstrated in patients with underlying chronic pulmonary disease (severe COPD or asthma); use is not recommended. Safety and efficacy not demonstrated in patients with high-risk underlying medical conditions.
Zanamivir powder must not be made into an extemporaneous solution for administration by nebulization or mechanical ventilation. There have been reports of hospitalized patients, including a fatal case, where it was reported that the lactose in this formulation obstructed the proper functioning of the equipment.
Not established for prophylactic use to prevent complications from serious bacterial infections that may begin with influenza-like symptoms.
Serious cases of bronchospasm, including fatalities, have been reported. Discontinue use if this occurs.
Delirium and abnormal behavior leading to injury have been reported in postmarketing experience.
No reports of overdosage.
- Review and demonstrate proper use of the delivery system.
- Advise patients using an inhaled bronchodilator at the same time as zanamivir to use the inhaled bronchodilator before inhaling zanamivir.
- Remind patients to complete entire course of therapy, even if they are feeling better.
- Advise patients that medication does not reduce risk of transmission of flu virus to others, and to continue to take appropriate precautions to prevent spreading the infection.
- Advise patients that zanamivir is not a substitute for flu vaccination and to continue to obtain an annual flu vaccination.
- Advise patients to inform their health care provider if flu symptoms do not appear to be improving or are worsening, or if new symptoms develop during or after treatment.
- Advise patients of the risk of bronchospasm and instruct them to discontinue therapy and contact their health care provider immediately if they experience increased respiratory symptoms (eg, shortness of breath, worsening wheezing).
- Inform patients, particularly children and adolescents, that they may be at an increased risk of seizures, confusion, or abnormal behavior early in their illness. These reactions may occur after beginning zanamivir or when flu is not treated. These reactions are uncommon but may result in accidental injury to the patient. Therefore, observe patients for signs of unusual behavior and a health care provider should be contacted immediately if there are any signs of unusual behavior.
Copyright © 2009 Wolters Kluwer Health.
More Zanamivir resources
- Zanamivir Monograph (AHFS DI)
- zanamivir Inhalation, oral/nebulization Advanced Consumer (Micromedex) - Includes Dosage Information
- zanamivir MedFacts Consumer Leaflet (Wolters Kluwer)
- Relenza Prescribing Information (FDA)
- Relenza Consumer Overview