Relenza

zanamivir

Relenza

Pharmacologic class: Neuraminidase inhibitor

Therapeutic class: Antiviral

Pregnancy risk category C

Action

Inhibits influenza virus neuraminidase, an enzyme essential for viral replication

Availability

Powder for inhalation: 5 mg/blister

⊘Indications and dosages

➣ Prevention of influenza

Adults and children ages 5 and older: Prophylaxis in the household setting, 2 inhalations (10 mg) once daily for 10 days. Prophylaxis during community outbreaks, 2 inhalations (10 mg) once daily for 28 days.

➣ Influenza virus A or B

Adults and children ages 7 and older: Two oral inhalations (5 mg/inhalation) b.i.d. for 5 days

Contraindications

• History of allergic reaction to components of drug, including lactose milk proteins

Precautions

Use cautiously in:
• chronic obstructive pulmonary disease, asthma, lactose intolerance
• concurrent use of live attenuated intranasal influenza vaccine (Don't administer until 48 hours after cessation of zanamivir and don't administer zanamivir until 2 weeks after administration of live attenuated influenza vaccine, unless medically indicated.)
• pregnant or breastfeeding patients
• children younger than age 7 (safety not established).

Administration

• Give two doses on day 1, spaced at least 2 hours apart. On subsequent days, space doses 12 hours apart, and give at approximately same time each day.

Adverse reactions

CNS: headache, dizziness

EENT: sinusitis, EENT infections

GI: nausea, vomiting, diarrhea

Respiratory: bronchitis, cough

Other: allergic reaction

Interactions

None significant

Patient monitoring

• Assess respiratory status. Watch closely for signs and symptoms of declining respiratory function.

Patient teaching

• Explain therapy to patient. Demonstrate how to use Diskhaler device.
• Tell patient to take drug exactly as prescribed for as long as directed, even if symptoms improve.
• If patient is also taking an inhaled bronchodilator, advise him to take bronchodilator before zanamivir.
• Emphasize that drug doesn't prevent spread of influenza to others.
• Instruct patient to immediately report worsening respiratory symptoms.
• As appropriate, review other significant adverse reactions.

zanamivir

(za-na-mi-veer) ,

Relenza

(trade name)

Classification

Therapeutic: antivirals
Pharmacologic: neuraminidase inhibitors

Pregnancy Category: C

Indications

Treatment of uncomplicated acute illness caused by influenza virus in patients ≥7 yr who have been symptomatic ≤2 days.Prevention of influenza in patients ≥5 yr.

Action

Inhibits the enzyme neuramidase, which may alter virus particle aggregation and release.

Therapeutic effects

Reduced duration or prevention of flu-related symptoms.

Pharmacokinetics

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

Distribution: Unknown.

Protein Binding: <10%.

Metabolism and 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

Contraindications/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); Obstetric / Lactation: Safety not established; Pediatric: Children <7 yr (for treatment) or <5 yr (for prophylaxis) (safety not established; may be at ↑ risk for neuropsychiatric events).

Adverse Reactions/Side Effects

Central nervous system

• seizures (life-threatening)
• abnormal behavior
• agitation
• delirium
• hallucinations
• nightmares

Respiratory

• bronchospasm

Miscellaneous

• allergic reactions

Interactions

Drug-Drug interaction

None noted.

Route/Dosage

Treatment

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

Prophylaxis

Inhalation (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

Nursing implications

Nursing 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.

Potential Nursing Diagnoses

Risk for infection (Indications)

Implementation

• Consider available information on influenza drug susceptibility patterns and treatment effects before using zanamivir for prophylaxis.
• Inhalation: 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 on subsequent days. Zanamivir is only for oral inhalation via DISKHALER; do not attempt via nebulization or mechanical ventilation.

Patient/Family Teaching

• Instruct patient to use zanamivir exactly as directed and to finish entire course, even if feeling better.
• 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. 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 patients to report behavioral changes (hallucinations, delirium, and abnormal behavior) to health care professional immediately.
• Inform patient that zanamivir does not replace flu shot. Flu shot should be taken according to instructions of health care professional.
• Advise female patient to avoid zanamivir if pregnant or breast feeding.

Evaluation/Desired Outcomes

• Reduced duration or prevention of flu-related symptoms.

Relenza

(rə-lĕn′zə)

A trademark for the drug zanamivir.

Relenza®

Zanamivir Infectious disease An neuraminidase inhibitor used to treat and prevent influenza A and B infection. See Influenza. Cf Amantadine, Rimantidine.