Medications for Allergy-Induced Asthma: Omalizumab / Xolair

Asthma is a condition where the air passages in the lungs go into spasm then swell. This, coupled with excess production of mucus in the lungs, makes it hard or even impossible to breathe. Triggers for asthma can be anything from air pollution to allergens to stress.

There are many types of drugs that treat or ease the symptoms of asthma. One of them is Omalizumab, or Xolair. Omalizumab is actually a type of antibody. It's used to treat allergies in people who are 12 years old and older and is usually administered after most other asthma medicines have proved ineffective. It works by binding to immunoglobulin E, which would bind to and stimulate basophils and mast cells in the body. Mast cells make histamine and other chemicals that create the symptoms of allergies. Basophils are white blood cells that also produce histamine and inflammatory chemicals. Omalizumab suppresses the severity of the patient's allergic reactions.

Omalizumab is injected beneath the skin. The usual dosage is between 150 and 375 mg every two weeks or every four weeks. Before the shots are given, the patient's levels of immunoglobulin E are measured. The dosage depends on these levels and the patient's weight. The immunoglobulin levels need to be tested before treatment because once treatment is started they'll remain high and stay high for up to a year.

If the dosage of Omalizumab needs to be more than 150 mg, the doctor uses more than one injection site. The usual injection sites are the thigh, the upper arm and the abdomen. Omalizumab is eventually cleared out of the body by the liver. It takes about 26 days for the body to eliminate half of it.

Side Effects

The possible side effects of Omalizumab include:

  • Headache
  • Dizziness
  • Fatigue
  • Dermatitis
  • Hair loss
  • Earache
  • Sinusitis
  • Sore throat
  • Thrombocytopenia. This is when the level of platelets in the blood is decreased, which can lead to increased bleeding. Thrombocytopenia also interferes with blood clotting.

Other side effects of Omalizumab are:

  • Infections of the upper respiratory tract
  • Joint pain, including pain in the leg and arm
  • Bone fractures

If the patient seems to be going into shock after taking Omalizumab, they should be taken to the emergency room right away. The symptoms of shock include difficulty in breathing, low blood pressure, fainting, hives and swelling of the tongue or the throat. Patients can experience this early or late in the treatment. Other patients might be at greater risk for cancers or parasitic infections.

Doctors should educate their patients about taking Omalizumab, especially when it comes to recognizing the signs of shock or side effects that need to be seen by a medical professional. They should also be taught which side effects are benign and should go away after a short time. This might include a reaction around the injection site.

When it comes to pregnancy, Omalizumab is in Category B. This means there aren't any studies on how the drug affects human pregnancy. There's a registry that follows pregnant women who have been exposed to Omalizumab from two weeks before conception onward.