zanamivir

Absorption: 4–17% of inhaled dose is systemically absorbed.

Distribution: Unknown.

Protein Binding: <10%.

Metabolism/Excretion: Mainly excreted by kidneys as unchanged drug; unabsorbed drug is excreted in feces.

Half-Life: 2.5–5.1 hr.

Time/Action Profile ⬆ ⬇

(blood levels)

ROUTE	ONSET	PEAK	DURATION
Inhalation	rapid	1–2 hr	12 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to zanamivir or lactose.

Use Cautiously in:

Chronic obstructive pulmonary disease or asthma (↑ risk of decreased lung function and/or bronchospasm);
OB: Safety not established;
Pedi: Children <7 yr (for treatment) or <5 yr (for prophylaxis) (safety not established; may be at ↑ risk for neuropsychiatric events).

Adv. Reactions/Side Effects ⬆ ⬇

Neuro: abnormal behavior, agitation, delirium, hallucinations, nightmares, SEIZURES

Resp: bronchospasm

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS AND ANGIOEDEMA)

Interactions ⬆ ⬇

Drug-drug:

May ↓ efficacy of live attenuated influenza vaccine; do not administer vaccine within 2 wk before or 48 hr after administration of zanamivir.

Route/Dosage ⬆ ⬇

Treatment of Influenza

Inhaln (Adults and Children ≥7 yr): 10 mg (given as 2 inhalations of 5 mg each) twice daily for 5 days.

Prophylaxis of Influenza

Inhaln (Adults and Children ≥5 yr): 10 mg (given as 2 inhalations of 5 mg each) daily for 10 days (for household setting) (28 days for community outbreaks).

Availability ⬆ ⬇

Powder for inhalation: 5 mg/blister

Assessment ⬆ ⬇

Assess patient for signs and symptoms of influenza (fever, headache, myalgia, cough, sore throat) before administration. Determine duration of symptoms. Indicated for patients who have been symptomatic for up to 2 days.
Determine if patient is lactose intolerant; may cause allergic reaction.
Monitor for signs and symptoms of neuropsychiatric events (altered level of consciousness, confusion, delusions, agitation, anxiety, nightmares, seizures, hallucinations, delirium, abnormal behavior) during therapy. If symptoms occur, weigh risks and benefits of continuing therapy. Children and adolescents may be at increased risk for symptoms.

Implementation ⬆ ⬇

Consider available information on influenza drug susceptibility patterns and treatment effects before using zanamivir for prophylaxis. In a household setting, administer within 1.5 days of onset of signs and symptoms of index case.
Inhaln: Each dose requires 2 inhalations. Administer 2 doses on the first day of treatment whenever possible; must have at least 2 hours between doses. Doses should be administered 12 hr apart at about the same time on subsequent days. Zanamivir is only for oral inhalation via DISKHALER; do not attempt via nebulization or mechanical ventilation. If a bronchodilator inhalation is scheduled at same time, administer bronchodilator first.

Patient/Family Teaching ⬆ ⬇

Instruct patient to use zanamivir exactly as directed and to finish entire course, even if feeling better. Take missed doses as soon as remembered up to 2 hr before next dose. If <2 hr before next dose, omit missed dose and take next dose as scheduled; do not double doses.
Instruct patient in the use of the DISKHALER. Patient should read the accompanying Patient Instructions for Use.
Advise patients that zanamivir is not a substitute for a flu shot and does not reduce risk of transmission of influenza to others. Patients should receive annual flu shot according to immunization guidelines.
Patients with a history of asthma should be advised to have a fast-acting inhaled bronchodilator available in case of bronchospasm following zanamivir administration. If using bronchodilator and zanamivir concurrently, administer bronchodilator first. Advise patient to notify health care professional promptly if increased respiratory symptoms (worsening wheezing, shortness of breath, signs or symptoms of bronchospasm) occur.
Advise patients to report behavioral changes (hallucinations, delirium, and abnormal behavior) to health care professional immediately.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding..

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇