Zanamivir

Zanamivir is a prescription medication used for the prophylaxis  and treatment of influenza A and B. 

• Zanamivir is available under various brand names: Relenza

Common side effects of Zanamivir include:

• trouble breathing,
• headache,
• dizziness,
• chest pain or discomfort,
• nausea, and
• flushing (warmth, redness, or tingly feeling)

Serious side effects of Zanamivir include:

• severe dizziness,
• fast heartbeats,
• warmth or tingly feeling,
• wheezing,
• chest tightness,
• trouble breathing,
• chest pain or pressure,
• pain spreading to the jaw or shoulder,
• seizure,
• lightheadedness,
• severe headache,
• pounding in the neck or ears,
• sudden numbness or weakness (especially on side of the body),
• slurred speech, and
• balance problems

Rare side effects of Zanamivir include:

• none

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
• Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult and pediatric dosage

Inhalation powder

• 5 mg (20 units per Rotadisk)

Influenza A & B, Prophylaxis

Adult dosage

• Household setting: 10 mg inhaled once daily for 10 days
• Initiate within 36 hours of exposure
• Community outbreaks: Begin within 5 days of the outbreak; may administer for up to 28 days

Pediatric dosage

• Household setting, above 5 years: 10 mg inhaled once daily for 10 days; initiate within 48 hours of exposure
• Community outbreak, 12-16 years: 10 mg inhaled once daily for 28 days; initiate within 5 days of outbreak

Influenza A & B, Treatment

Adult dosage

• Start within 2 days of symptom onset; administer 2 doses on day 1, at least 2 hours apart
• 10 mg inhaled every 12 hours for 5 days; may consider longer treatment for patients severely ill after 5 days

Pediatric dosage

• Aged above 7 years: 10 mg inhaled every 12 hours for 5 days
• Start within 2 days of symptom onset; administer 2 doses on day 1, at least 2 hours apart

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Zanamivir has no noted severe interactions with any other drugs.
• Zanamivir has no noted serious interactions with any other drugs.
• Zanamivir has no noted moderate interactions with any other drugs.
• Zanamivir has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

Contraindications

• Hypersensitivity to zanamivir or formulation, including milk proteins

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Zanamivir?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Zanamivir?”

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 the 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 a patient with underlying airway disease, carefully monitor respiratory function, closely observe the patient, and have supportive therapy (i.e., fast-acting bronchodilators) immediately available
• Reports of abnormal behavior and delirium

Pregnancy & Lactation

• 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 the presence of zanamivir in human milk or its 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; the drug was present in the 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 the breastfed child from the drug or underlying maternal condition