Omalizumab
Biologics for asthma
Biologics for asthma
An anti-IgE antibody injected under the skin for severe allergic asthma, nasal polyps, chronic hives and food allergy; it can cause anaphylaxis.
Quick facts
- Group
- Biologics for asthma
- Target
- Immunoglobulin E (Fc region)
- Used for
- Chronic rhinosinusitis with nasal polyps
- Key effects
- Injection-site pain · Headache · Joint and limb pain
- Monitor
- Asthma control and exacerbations
- ATC
- R03DX05
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows a single-chain fragment of omalizumab bound to the Fc region of human IgE.
Omalizumab is a humanised monoclonal antibody that binds the Cε3 domain of free IgE, the same part IgE uses to attach to its high-affinity receptor (FcεRI) on mast cells and basophils. With less free IgE, fewer IgE molecules sit on these cells, and the cells reduce their FcεRI. Allergen exposure then triggers less degranulation and less release of histamine and leukotrienes. It does not bind IgE already on cells, so it does not trigger degranulation itself.
- Omalizumab captures free IgE in the blood
- IgE can no longer load onto mast-cell FcεRI
- Mast cells and basophils lower their FcεRI
- Allergens trigger less mediator release
Indications
- Moderate to severe allergic asthma not controlled with inhaled corticosteroids Asthma →
- Chronic rhinosinusitis with nasal polyps Chronic rhinosinusitis and nasal polyps →
- Chronic spontaneous urticaria Urticaria and angioedema →
- Reduction of allergic reactions after accidental exposure in food allergy
Adverse effects
Common
- Injection-site pain, redness, swelling or bruising
- Headache, tiredness and dizziness
- Joint and limb pain
- Sore throat, runny nose
Contraindications
- Hypersensitivity to omalizumab
- Not for an acute asthma attack
- Caution with helminth (worm) infection or high risk of it
Key interactions
- Inhaled and oral corticosteroids
- Are not stopped suddenly when omalizumab starts; tapering is supervised
What is monitored
- Observation after injections for anaphylaxis, longer for the first doses
- Asthma control and exacerbations
- Total IgE and weight before starting (they guide the regimen)
Administration and safety
- Subcutaneous injection; the first doses are given in a healthcare setting with anaphylaxis treatment available
- Prefilled syringes are warmed to room temperature without heating and not shaken
- Patients allowed home injection are taught to recognise anaphylaxis and may carry epinephrine
Pregnancy and breastfeeding
IgG antibodies cross the placenta, especially late in pregnancy; registry data have not shown a clear increase in malformations, and use is decided with the specialist.
Nursing care
- Have epinephrine ready and observe the patient after each injection
- Teach signs of anaphylaxis: wheeze, throat tightness, faintness, hives
- Ask about worm infections and travel or living in endemic areas
- Remind that the rescue inhaler is still needed for attacks
Pharmacokinetics
- Absorption
- Slowly absorbed after subcutaneous injection
- Elimination
- Removed with IgE–antibody complexes through the reticuloendothelial system
- Onset and duration
- Benefit builds over weeks to months
Test yourself
Think of the answer, then tap the question to see it.
What does omalizumab bind?
Free IgE, at the site IgE uses to attach to its high-affinity receptor.
Why is the patient observed after omalizumab injections?
Anaphylaxis can occur after any dose.
What are two indications of omalizumab besides asthma?
Chronic spontaneous urticaria and nasal polyps (also food allergy).
Can omalizumab treat an acute asthma attack?
No; it reduces future exacerbations over weeks.
Connections
← Back to the class: Biologics for asthma
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Omalizumab Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.