Omalizumab

How it works

It binds free immunoglobulin E and prevents it from attaching to high-affinity receptors on mast cells and basophils, reducing allergen-triggered mediator release and inflammation.

Prescribing in practice

• Anaphylaxis can occur, sometimes with delayed onset, so doses are given under supervision with resuscitation facilities and patients are observed afterwards.
• It is an add-on preventer for severe allergic asthma and does not treat acute exacerbations; usual asthma therapy must continue.
• Dosing is determined by baseline IgE level and body weight, and treatment is initiated in specialist services per NICE guidance.

Monitoring

Monitor asthma control and exacerbation frequency, and observe each patient after injection for hypersensitivity and anaphylactic reactions.

Counselling the patient

• This injection prevents attacks over time and is not a rescue treatment.
• Carry on with your usual inhalers and reliever.
• Seek immediate help if you develop rash, swelling, dizziness or breathing difficulty after a dose.

Evidence & guidelines

NICE technology appraisal guidance recommends omalizumab as add-on therapy for severe persistent allergic asthma in defined patient groups.