A new class of medications called Immunoglobulin E (IgE) inhibitors is available
to treat allergy-related asthma. Omalizumab (Xolair) was the first approved
therapy to target the IgE molecule.
It is normal for your airways to tighten and become inflamed if you inhale
a dangerous substance. This reaction is an attempt by your body to prevent
the threat from traveling too far into your lungs. The airways open up again
when the threat has passed.
If you have allergy-induced asthma, however, your airways are overly responsive
to mild substances called allergens. Your body's response to these triggers
leads to blocked airways and the symptoms of asthma.
Most asthma drugs relieve symptoms by simply "blunting" the response to an
asthma trigger. In contrast, IgE blockers actually prevent the response from
occurring in the first place.
To understand this more fully, it helps to know what makes something an asthma
trigger. If you have an allergy to a substance like pollen, mold, or dust mites
(all called allergens), your body makes too many IgE antibodies to that substance.
These antibodies recognize and fight against the individual allergens. But,
having too many of the IgE antibodies can make the body too responsive to these
allergens, and lead to an allergic reaction like asthma.
Xolair binds to excess IgE antibodies in your bloodstream. This stops the
IgE antibodies from recognizing the asthma-provoking allergens. In other words,
omalizumab stops the body from overreacting to asthma triggers by making the
IgE antibodies ineffective. This interrupts the excessive inflammatory response
even before it starts. Xolair is given by injection every 2 - 4 weeks to prevent
asthma flare-ups. Xolair was approved by the FDA in 2003 for patients ages
12 and older with moderate-or severe persistent asthma. The most common side
effect is an injection-site rash.
IgE inhibitors also holds promise for the treatment of other forms of allergic
Note: In February 2007, the Food and Drug Administration requested the manufacturers
of omalizumab (Xolair) to include a “boxed warning” emphasizing
that this medicine may cause a severe and life-threatening allergic reaction
(anaphylaxis). Omalizumab is approved for patients who have moderate-to-severe
asthma related to allergies and whose symptoms are not controlled by inhaled
corticosteroids. It is given by injection in a doctor’s office every
2 - 4 weeks.
The warning indicates that patients may develop anaphylaxis after
any dose of omalizumab, even if they had no reaction to the initial shot. Health
care providers need to observe patients carefully for 2 hours after they receive
an omalizumab injection. However, because an allergic reaction can occur up
to 24 hours after the injection, patients need to know the signs and symptoms
of anaphylaxis and how to self-administer emergency treatment. Symptoms may
- Trouble breathing
- Chest tightness
- Itching and hives
- Swelling of the mouth and throat
Review Date: 5/16/2007
Reviewed By: Alan Greene, M.D., F.A.A.P., Department of Pediatrics, Packard Children's Hospital, Stanford University School of Medicine; Chief Medical Officer, A.D.A.M., Inc.
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