Bronchodilators And Their Role In Asthma Treatment
It seems there is a fair amount of interest in our community regarding the use of bronchodilators for people who have asthma. So, this post will review this class of asthma medications and talk about their important role in asthma treatment.
What is a bronchodilator?
To understand what this medication is and how it works, let's break down the medical term for it:
- Broncho = Airways
- Dilator = A substance that causes something to dilate or relax
So, a bronchodilator is simply a medicine that relaxes the muscles that surround your bronchial tubes, or airways. Sometimes, this happens immediately after using the medication. Other times, the effect is more long-lasting, or preventive, in nature.1
Why is this important in asthma?
When you have asthma, actions take place in the airways that can make it hard to breathe. Most often, this happens in reaction to coming into contact with an allergen, such as pollen, pet dander, dust, or mold. But it can also occur if you are sensitive to certain irritating substances in the environment, such as wood or tobacco smoke, chemical odors, perfumes, and air pollution.2
When an asthma attack occurs, your airway muscles tighten, causing the airways to narrow. In addition, the lining of your airways swells and may produce excess mucus. All of these effects make it harder to breathe, causing the hallmark symptoms of asthma:3
- Shortness of breath
- Chest tightness
So, anything that would prevent or counteract the effects of an asthma attack will lessen the symptoms of asthma.
Bronchodilators available for asthma treatment
There are two main categories of bronchodilator medicines used for asthma:1
- Short-acting. This type acts quickly (within minutes) to relieve or stop asthma symptoms that have already started. Short-acting bronchodilators are used via a hand-held device called an inhaler. They are commonly called "rescue" or "quick-relief" inhalers.
- Long-acting. This type of medicine helps prevent asthma attacks and symptoms by keeping the airways open for 12 to 24 hours at a time. Long-acting bronchodilators cannot be used to stop symptoms that have already started, however.
Short-acting medicines for asthma are all in the class of what are called beta-2-agonists. They stimulate beta-2 receptors on the smooth muscle cells in the lining of your airways. That makes the airway muscle cells relax and opens the airways. They act quickly, usually within 15 to 20 minutes, and last for about 4 to 6 hours. They can also be used 15 to 30 minutes before exercise to prevent symptoms in people with exercise-induced asthma. Needing to use a rescue inhaler more than two times a week is a sign that your asthma is not well-controlled. This should be discussed with your health care team.1,4
Examples of short-acting bronchodilators include:*
* Your rescue inhaler may be called by a brand name, rather than the generic names listed above.
Within the long-acting bronchodilator category are a number of sub-categories.1
- Beta-2 agonists. Similar to their short-acting cousins, these drugs maintain open airways, but must be used only in combination with an inhaled steroid. Examples are salmeterol and formoterol. Each of these drugs can be paired in a dry powder inhaler with an inhaled steroid, such as fluticasone, budesonide or mometasone.
- Anticholinergic drugs. This type of drug can increase bronchodilation in the airways for certain people with difficult-to-control asthma symptoms. It acts by blocking the effect of acetylcholine on your airways and nasal passages. Acetylcholine is a chemical in your body that helps nerves communicate with muscles. At this writing, there are only 2 available: ipratropium bromide or tiotropium bromide. The first one is used in either a metered-dose inhaler or in a nebulizer, 4 times a day. The second is used via a dry powder inhaler, only once a day, as the effects last for 24 hours.4
- Xanthine derivatives. This older type of medicine is used in pill or liquid form to prevent asthma attacks. It is generally only used for difficult-to-control or severe asthma. Experts aren't sure exactly how it works. But they do know that xanthines relax smooth muscles in your airway walls. Plus, they decrease the "overreaction" of your airways to allergens and irritants. The only xanthine in current use is theophylline. Frequent blood tests are needed with this drug to maintain the proper levels in your body. Certain antibiotics, seizure, and ulcer medicines can interfere with theophylline's effects. So can viral illnesses and even cigarette smoking.1,4
It's important to note that almost all bronchodilators in the U.S. are prescription medicines. Primatene mist is the one exception, and it is not recommended for long-term, or regular, use. There are no other over-the-counter, homeopathic, or herbal products that are approved by the FDA for treating asthma or considered effective by most doctors.
How do bronchodilators compare to inhaled steroids for asthma?
Inhaled steroids are the treatment of choice for asthma. This is because they treat the underlying inflammation that causes asthma in the first place. Bronchodilators, on the other hand, treat the symptoms of asthma. But they do nothing to inhibit the disease itself.5
Bronchodilators play an important role, though, in dealing with asthma symptoms that arise in response to exposure to allergens or irritants in the environment. While inhaled steroids are more of a preventive measure to help ensure ongoing asthma control, short-acting bronchodilators in particular help re-establish asthma control when it slips.
Sometimes, inhaled steroids alone are not enough to achieve consistent control of severe asthma. In those cases, the doctor may prescribe a combination controller medicine that includes both a steroid and a long-acting bronchodilator in the same inhaler (as noted above).
How do I know which one I should use?
Deciding on the best course of treatment is ideally a joint effort between both you and your health care team. At times, it may be a bit of a trial and error process. Most people with mild to moderate asthma respond well to inhaled steroids as controller medicines, with a short-acting bronchodilator inhaler to be used when symptoms still crop up. In cases where asthma proves harder to control, long-acting bronchodilators may be added to the mix.
Are there any risks?
As with most medications, there can be risks or side effects. They are usually due to a response from your sympathetic nervous system. These are the most common (and mostly non-worrisome) side effects of bronchodilators:5
- Sudden, noticeable heart palpitations
- Muscle cramps
- Dry mouth or constipation (anticholinergics)
More severe side effects could occur, though they are more common in high doses. Talk with your doctor or pharmacist or read the prescription insert to learn more about the possible side effects for your specific medication.
Have additional questions about bronchodilators? Ask in our forums or in the comments below!
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