Role of Omalizumab (Xolair) in Treating Asthma
Omalizumab is an immunomodulator used as adjunctive therapy for patients 12 years of age and older with moderate to severe persistent allergic asthma who have sensitivity to relevant allergens and whose symptoms are inadequately controlled with inhaled corticosteroids. 1
Mechanism of Action and Indications
- Omalizumab is a humanized monoclonal antibody (anti-IgE) that specifically binds to free IgE, preventing it from binding to high-affinity receptors on basophils and mast cells 1, 2
- By blocking IgE binding, omalizumab prevents the allergic cascade and subsequent inflammatory effects in the airways that contribute to asthma symptoms 1, 2
- Indicated for patients aged 12 years and older with moderate to severe persistent asthma whose symptoms are inadequately controlled with inhaled corticosteroids (ICS) and who have demonstrated sensitivity to perennial aeroallergens via skin test or in vitro reactivity 1
- Recommended for use at steps 5 and 6 of asthma treatment (patients being treated with high-dose ICS plus a long-acting beta-agonist) 1
Dosing and Administration
- Dosage is determined by patient's body weight and pretreatment serum total IgE levels 2
- Administered subcutaneously every 2 or 4 weeks depending on the calculated dose 1, 2
- Patients typically receive 150 or 300 mg every 4 weeks, or 225,300, or 375 mg every 2 weeks 2
- Must be administered in a healthcare setting by healthcare providers prepared to identify and treat anaphylaxis 1, 3
Clinical Benefits
- Significantly reduces asthma exacerbations compared to placebo when added to standard therapy 4, 5
- Reduces hospitalizations due to asthma exacerbations 5
- Allows reduction or discontinuation of inhaled corticosteroids in many patients 2, 5
- Decreases rescue medication use 2, 5
- Improves asthma symptom scores and quality of life 2
Safety Considerations and Monitoring
- Risk of anaphylaxis (0.2% of patients) is the most serious concern, with reactions potentially occurring up to 4 days after administration 1, 3
- Patients should be observed for 30 minutes after each injection, extended to 2 hours for the first 3 injections 1
- Assessment of patient's current health status, including vital signs and lung function, should be performed before each injection 1
- Patients should be educated about signs and symptoms of anaphylaxis and prescribed an epinephrine autoinjector 1, 3
- Informed consent should be obtained after discussing risks, benefits, and alternatives 1
- Most common adverse events include injection site reactions, viral infections, upper respiratory tract infections, sinusitis, headache, and pharyngitis 2
Important Precautions
- Omalizumab should not be used for emergency treatment of asthma exacerbations or acute bronchospasm 3
- Patients should continue their other asthma medications unless instructed otherwise by their physician 3
- Clinicians administering omalizumab should be prepared and equipped to identify and treat anaphylaxis 1, 3
- The needle cover on the prefilled syringe contains latex, which may cause allergic reactions in latex-sensitive individuals 3
Special Considerations
- Most anaphylactic reactions occur within the first three doses, with the majority occurring within 30-60 minutes after administration 1
- The timing of reactions can vary, with some occurring up to 24 hours after administration 1
- While primarily indicated for allergic asthma, there have been case reports of effectiveness in patients with low IgE levels or without identifiable allergens 6
Omalizumab represents an important therapeutic option for patients with moderate to severe allergic asthma not adequately controlled with standard therapy, offering significant improvements in disease control and quality of life while potentially reducing the need for other medications.