Zanamivir !

An inhaled neuraminidase inhibitor for influenza. It acts directly in the airways but can cause bronchospasm in asthma or COPD.

Updated 2026-11-01

Class: Anti-influenza agents
Enzyme: Influenza virus neuraminidase
ATC code: J05AH01

Influenza virus neuraminidaseZanamivir

The figure shows zanamivir in an influenza A (N1) neuraminidase carrying the H274Y change that makes the virus resistant to oseltamivir.

Target in 3D: Influenza virus neuraminidase. PDB structure 3CKZ (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Zanamivir is a sialic acid analogue that blocks the active site of the influenza neuraminidase. New virions cannot release themselves from the infected cell and clump together, so infection spreads less. It binds differently from oseltamivir and often still works against oseltamivir-resistant strains.

Inhaled into the airways
Binds the active site of the viral neuraminidase
New virions stay attached to the infected cell
Spread of influenza in the airway falls

Pharmacokinetics

Absorption: Inhaled powder that acts directly in the airways

Indications

Treatment of influenza in people with symptoms for less than 2 days Influenza (flu) →
Prevention of influenza after exposure or during community outbreaks Influenza (flu) →

Adverse effects

Common

Dizziness
Nose and throat irritation
Joint pain

Contraindications

Hypersensitivity to zanamivir
Asthma or chronic lung disease: risk of serious bronchospasm, so it is generally avoided

Key interactions

Live attenuated (intranasal) influenza vaccine: May reduce the vaccine's effect if given from 2 weeks before to 48 hours after zanamivir

What is monitored

Breathing, wheeze and oxygen saturation after inhalation in people with lung disease
Behaviour in children

Administration and safety

Inhaled only with its own device; the powder is not dissolved or nebulized
Patient is taught how to load and use the inhaler
A fast-acting bronchodilator is kept at hand in lung disease

Nursing care

Ask about asthma or COPD before the first dose
Teach to stop and seek help if wheezing or breathlessness appears
Demonstrate the inhaler technique
Ask families to report unusual behaviour

Pregnancy and breastfeeding

Data are limited; influenza itself is more dangerous in pregnancy, and the benefit and risk are weighed.

Test yourself

Think of the answer, then tap the question to see it.

How is zanamivir usually given?

As an inhaled powder through its own device.

Which patients should not usually receive inhaled zanamivir?

People with asthma or chronic obstructive lung disease, because of the risk of bronchospasm.

What class of drug is zanamivir?

A neuraminidase inhibitor, like oseltamivir.

Add to my cards (3)

Influenza (flu)

← Back to the class: Anti-influenza agents

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Zanamivir Oral Inhalation: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 62 (McGraw Hill, 2023).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.