mepolizumab
Nucala (mepolizumab) is a monoclonal antibody from GlaxoSmithKline that neutralises interleukin-5, the key survival signal for eosinophils. It prevents attacks in severe eosinophilic asthma and treats chronic rhinosinusitis with nasal polyps.
This page is based on FDA prescribing information and the EMA medicine record for mepolizumab, cross-checked with DailyMed and the National Cancer Institute dictionary; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Eosinophils are inflammatory soldiers that need a daily ration order, IL-5, to stay deployed in the airways. Mepolizumab intercepts every ration order in the blood. Starved of the signal, the soldiers leave the tissue, and the swelling, mucus and attacks they were causing gradually subside.
In simple terms
Some people with severe asthma have too many eosinophils, a type of immune cell, inflaming their airways. These cells depend on a signal called IL-5 to survive. Mepolizumab is an antibody that binds IL-5 and removes it from circulation. Eosinophil numbers fall, airway inflammation decreases, and severe asthma attacks become much less frequent. The same action shrinks nasal polyps.
In depth
Mepolizumab is a humanised IgG1-kappa monoclonal antibody that binds soluble IL-5 with high affinity, preventing engagement of the IL-5 receptor alpha chain on eosinophils. This suppresses eosinophil production in bone marrow and survival in tissues, reducing blood and airway eosinophilia. Trials showed large reductions in asthma exacerbations and oral corticosteroid requirements, establishing anti-IL-5 therapy for severe eosinophilic asthma.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
Mepolizumab intercepts every ration order in the blood
- Some people with severe asthma have too many eosinophils, a type of immune cell, inflaming their airways.
- These cells depend on a signal called IL-5 to survive.
- Mepolizumab is an antibody that binds IL-5 and removes it from circulation.
- Eosinophil numbers fall, airway inflammation decreases, and severe asthma attacks become much less frequent.
Target: Interleukin-5 (IL-5)
The main cytokine that drives production, activation and survival of eosinophils; in eosinophilic disease these cells inflame airways and nasal tissue, so removing their survival signal calms the disease.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- Add-on maintenance treatment of adults and children 6 years and older with severe asthma and an eosinophilic phenotype
- Add-on maintenance treatment of chronic rhinosinusitis with nasal polyps in adults 18 years and older with an inadequate response to nasal corticosteroids
Approved uses in European Union
EMA- As add-on treatment for severe refractory eosinophilic asthma in adults, adolescents and children aged 6 years and older
- As add-on therapy with intranasal corticosteroids for chronic rhinosinusitis with nasal polyps in adults with inadequate response to intranasal corticosteroids
Official sources
The statements on this page trace back to these records.
- Nucala (mepolizumab) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- DailyMed: Nucala (mepolizumab) label
DailyMed, U.S. National Library of Medicine
- U.S. Food and Drug Administration: mepolizumab prescribing information
U.S. Food and Drug Administration
- National Cancer Institute: mepolizumab
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.