zanamivir (Rx)

Brand and Other Names:Relenza
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

inhalation powder

  • 5mg (20 units per Rotadisk)

Influenza A & B, Prophylaxis

Household setting: 10 mg inhaled qDay for 10 days

Initiate within 36 hours of exposure

Community outbreaks: Begin within 5 days of outbreak; may administer for up to 28 days

Influenza A & B, Treatment

Start within 2 days of symptom onset; administer 2 doses on day 1, at least 2 hours apart

10 mg inhaled q12hr for 5 days; may consider longer treatment for patients severely ill after 5 days

Influenza H1N1 (Swine Flu) Prophylaxis (Off-label)

10 mg inhaled qDay for 10 days

Initiate within 7 days of exposure

Influenza H1N1 (Swine Flu) Treatment (Off-label)

Start within 2 days of symptom onset; administer 2 doses on day 1, at least 2 hours apart

10 mg inhaled q12hr for 5 days; may consider longer treatment for patients severely ill after 5 days

Dosage Forms & Strengths

inhalation powder

  • 5mg (20 units per Rotadisk)

Influenza A & B, Prophylaxis

Household setting, >5 years: 10 mg inhaled qDay for 10 days; initiate within 48 hours of exposure

Community outbreak, 12-16 years: 10 mg inhaled qDay for 28 days; initiate within 5 days of outbreak

Influenza A & B, Treatment

>7 years: 10 mg inhaled q12hr for 5 days

Start within 2 days of symptom onset; administer 2 doses on day 1, at least 2 hours apart

Influenza H1N1 (Swine Flu) Prophylaxis (Off-label)

Household setting, >5 years old: 10 mg inhaled qDay for 10 days; initiate within 48 hours of exposure

Community outbreak, 12-16 years old: 10 mg inhaled qDay for 28 days; initiate within 5 days of outbreak

Influenza H1N1 (Swine Flu) Treatment (Off-label)

>7 years old: 10 mg inhaled q12hr for 5 days

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Adverse Effects

>10%

Headache (13-24%)

Throat/tonsil pain (8-19%)

Cough ( 7-17%)

Viral infection (3-13%)

>1%

Dizziness (2%)

Nausea (3%)

Diarrhea (3% adults, 2% children)

Vomiting (1% adults, 2% children)

Sinusitis (3%)

Bronchitis (2%)

Infection (ear, nose, & throat; 2% adults, 5% children)

<1%

Malaise

Fatigue

Fever

Abdominal pain

Myalgia

Arthralgia

Urticaria

Postmarketing Reports

Allergic Reactions: Allergic or allergic-like reaction, including oropharyngeal edema

Psychiatric: Delirium, including symptoms such as altered level of consciousness, confusion, abnormal behavior, delusions, hallucinations, agitation, anxiety, nightmares

Cardiac: Arrhythmias, syncope.

Neurologic: Seizures, vasovagal-like episodes shortly after administration

Respiratory: Bronchospasm, dyspnea

Skin: Facial edema; rash, including serious cutaneous reactions (eg, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis); urticaria

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Warnings

Contraindications

Hypersensitivity to zanamivir or formulation, including milk proteins

Cautions

Administer only via the Diskhaler inhaler

Do not make into an extemporaneous solution for administration by nebulization or mechanical ventilation; fatality reports of hospitalized patients with influenza who received a solution made with Relenza Inhalation Powder administered by nebulization or mechanical ventilation; lactose in this formulation obstructs proper functioning of the equipment

Most effective when used within 24-48 hr of onset of symptoms

Not recommended for treatment or prophylaxis of influenza in individuals with underlying airway diseases (eg, asthma, COPD); serious cases of bronchospasm, including fatalities, have been reported during treatment

If use is considered for patient with underlying airway disease, carefully monitor respiratory function, closely observe patient, and have supportive therapy (ie, fast-acting bronchodilators) immediately available

Reports of abnormal behavior and delirium

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Pregnancy & Lactation

Pregnancy

Available data from published studies suggest that use during pregnancy is not associated with an increased risk of birth defects or adverse maternal or fetal outcomes; however, these studies are limited by their small sample sizes, which preclude a definitive assessment of the risk; there are risks to mother and fetus associated with influenza infection in pregnancy; in animal reproduction studies, no adverse developmental effects were observed with intravenous or subcutaneous administration of zanamivir at exposures 300 and 150 times, respectively, the systemic exposure at the maximum recommended human inhalation dose (MRHID) of 10 mg twice daily

Pregnant women are at higher risk of severe complications from influenza, which may lead to adverse pregnancy and/or fetal outcomes, including maternal death, stillbirths, birth defects, preterm delivery, low birth weight,and small for gestational age

Lactation

There are no data on presence of zanamivir in human milk or effects on milk production; there are data from adults that have shown low oral bioavailability of zanamivir; limited data from postmarketing case reports have not suggested a safety concern in infants exposed to breast milk of mothers receiving therapy; drug was present in milk of lactating rats without effect on nursing pups; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from drug or underlying maternal condition

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

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Pharmacology

Mechanism of Action

Inhibits viral neuraminidases; stops release of virus from cells & prevents virus from crossing mucous lining of respiratory tract

Pharmacokinetics

Absorption: Inhalation: 4-17%

Protein binding: <10%

Metabolism: None

Half-life: 2.5-5.1 hr

Excretion: Urine (as unchanged drug); feces (unabsorbed drug)

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Formulary

FormularyPatient Discounts

Adding plans allows you to compare formulary status to other drugs in the same class.

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The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

Tier Description
1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
NC NOT COVERED – Drugs that are not covered by the plan.
Code Definition
PA Prior Authorization
Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
QL Quantity Limits
Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
ST Step Therapy
Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
OR Other Restrictions
Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.