Relenza


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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)

ROUTEONSETPEAKDURATION
Inhalationrapid1–2 hr12 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.
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The firm said it expected further "significant orders" of the H1N1 vaccine and announced plans to triple the availability of its swine flu treatment Relenza to 190m doses per year by the end of 2009.
The Alabama Medicaid Agency, on April 29, took steps to ensure that Medicaid-eligible recipients can quickly gain access to two antiviral medications used to combat swine flu by extending the preferred status of Tamiflu and Relenza.
Summary: DUBAI -- The Ministry of Health has ordered for 100,000 packets of Relenza, one of the two drugs found effective in treating swine originated H1N1 influenza A that has spread to at least
21 countries.
Another pharmacy said that the Relenza vaccine is out of stock, as is the inhaler.