Common brand names

• Xolair

How it is administered

Omalizumab is administered as a subcutaneous (under the skin) injection. It is available in several forms, including prefilled syringes, autoinjectors, and vials containing a lyophilized powder that must be reconstituted by a healthcare provider.

The medication is given every 2 or 4 weeks, depending on the condition being treated, the patient's weight, and their baseline IgE levels. The injection can be administered in the thigh, abdomen (avoiding the area around the navel), or the outer area of the upper arms (if given by a caregiver or healthcare provider). For some patients, self-administration may be appropriate after initial doses are given in a healthcare setting.

How it works

Omalizumab is a monoclonal antibody that targets and binds to immunoglobulin E (IgE), a type of antibody involved in allergic reactions. By binding to IgE, omalizumab prevents it from attaching to receptors on the surface of mast cells and basophils—cells that play a key role in allergic responses and inflammation.

This action leads to a reduction in the amount of free IgE in the blood and causes a down-regulation of IgE receptors on these cells. As a result, the cells are less likely to release substances that cause inflammation and allergic symptoms. In conditions like asthma and chronic urticaria, this helps reduce symptoms and the frequency of flare-ups. While omalizumab is not specifically approved for systemic mastocytosis, its mechanism of reducing mast cell activation may be of interest in related allergic and mast cell-driven conditions.

Who should take it

Omalizumab is approved for:

• Moderate to severe persistent asthma in adults and children 6 years and older who have a positive skin test or in vitro reactivity to a perennial aeroallergen and whose symptoms are not well controlled with inhaled corticosteroids.
• Chronic rhinosinusitis with nasal polyps in adults who do not respond adequately to nasal corticosteroids.
• IgE-mediated food allergy in adults and children aged 1 year and older, to help reduce allergic reactions (including anaphylaxis) when accidental exposure to certain foods occurs. It is used alongside food allergen avoidance.
• Chronic spontaneous urticaria (hives) in adults and adolescents 12 years and older who remain symptomatic despite antihistamine treatment.

It is not indicated for the emergency treatment of allergic reactions or for acute asthma attacks.

Who should not take it

Omalizumab should not be used in patients who have had a severe hypersensitivity reaction (such as anaphylaxis) to omalizumab or any of its ingredients.

Caution is also advised in patients with a history of severe allergic reactions, as omalizumab itself can rarely cause anaphylaxis. It is not intended for the emergency treatment of allergic reactions or for acute asthma attacks. Patients with a known allergy to latex should avoid the prefilled syringe version, as the needle cap contains a latex derivative. The safety in patients with certain parasitic infections or those at high risk for these infections has not been fully established.

Commonly used with

Omalizumab is often used in combination with other medications, depending on the condition being treated. For asthma, it is typically used alongside inhaled corticosteroids and sometimes with other asthma controllers. For chronic urticaria, it is used when antihistamines alone are not effective.

In food allergy, it is used together with strict avoidance of the allergenic foods. For chronic rhinosinusitis with nasal polyps, it may be used with nasal corticosteroids.

Commonly tested with

Omalizumab has been tested in clinical trials with standard-of-care medications for asthma (such as inhaled corticosteroids and beta-agonists), antihistamines for urticaria, and nasal corticosteroids for nasal polyps.

It has also been studied in combination with food allergen avoidance strategies in patients with IgE-mediated food allergies. No formal drug interaction studies have been performed, and its use with immunosuppressive therapies or allergen immunotherapy has not been extensively studied.