Monday, January 14, 2008
When you have allergic asthma, your immune system mistakenly identifies certain things in the environment, like pollen, animal dander, mold or dust mites, as threats. These are called allergens. Your immune system tries to eliminate the environmental threats called allergens through a complex biochemical process that leaves you wheezing and short of breath. The biochemical process is called inflammation, and it is the underlying problem needing treatment in asthmatics.
How Allergens Cause Asthma
Allergens, the specific substances to which you are allergic or sensitive, cause your body to produce antibodies, also called immunoglobulins, which attach to them and help eliminate them. These antibodies are known as immunoglobulin E, or IgE for short, and without them you are not allergic.
The Role of Antibodies
The problem with IgE is that it attaches itself to the surface of a certain kind of blood cell, known as a mast cell, which is just loaded with the chemicals, such as histamine, leukotrienes and prostaglandins, that cause asthma symptoms.
When a person with allergic asthma comes into contact with a specific allergen, it combines with the IgE on the mast cell, which causes the cell to disintegrate, releasing its chemicals.
This in turn leads to inflammation and narrowing of the airways in the lungs, making it difficult to breathe.
The first step in treating allergic asthma is to avoid attacks by avoiding your specific allergic triggers, but it’s not always possible to do this. So when an acute attack strikes, you'll need to take fast-acting medication, which is usually an inhaled bronchodilator such as albuterol, the effects of which wear off fairly quickly.
If the asthma attack persists after this "rescue" treatment, you may need to go to an urgent care center to get more intensive treatment, such as epinephrine (adrenaline) injections, and possibly oxygen.
Bronchodilators for Chronic Asthma
If your asthma is chronic, your doctor may recommend that you take medication daily whether you are having symptoms or not. Medications for chronic asthma fall into two main categories – long-acting bronchodilators and anti-inflammatory drugs – and they are often used in combinations.
The long-acting bronchodilators include beta-2 agonists and methylxanthines, which work to relax the tense muscles surrounding the bronchi that cause bronchoconstriction, wheezing and difficulty breathing.
Anti-inflammatory Drugs for Chronic Asthma
Because inflammation is a complex process involving many steps, there are different anti-inflammatory drugs that act at different points along the way. These drugs are often used in combination in order to alter the process in multiple ways. Once you've found the right combination to suppress your inflammatory process, you shouldn't stop taking them or your symptoms will return.
Anti-inflammatory drugs range from nonspecific to highly specific or targeted. They include:
- Inhaled steroids, which are nonspecific but highly effective
- Cromolyn (Intal and Tilade), leukotriene antagonists (montelukast [Singulair], zafirlukast [Accolate], zileuton [Leutrol, Zyflo]) and antihistamines. These drugs all act on the mast cells or on chemicals released by the mast cells that cause inflammation
- Xolair (omalizumab), an IgE blocker and the most highly targeted asthma anti-inflammatory, which works by blocking IgE from attaching to the mast cell, thus preventing the mast cell from releasing its noxious chemicals
For more information about asthma treatments that will work best for you, contact your doctor.