Bronchodilators are medications that relax the muscles that surround the airways in the lungs. This helps to open the airways, which makes breathing easier.
There are several different types of bronchodilators. They can be grouped by the length of their effects:
- Short-acting bronchodilators: short-acting bronchodilators are used on an as-needed basis. Their effects last for about four to six hours. Short-acting bronchodilators are usually used for less-severe lung disorders, such as mild asthma or mild chronic obstructive pulmonary disease.
- Long-acting bronchodilators: long-acting bronchodilators are taken daily. Their effects last for 12 hours or more. Long-acting bronchodilators are usually used for moderate or more severe lung disorders, such as moderate asthma or severe COPD.
Bronchodilators can also be grouped by the way they work. There are three types of bronchodilators. Each type works differently to relax the muscles around the airways:
- Beta-agonists: Beta-agonists activate tiny structures called beta-2 receptors on the muscles surrounding the airways in the lungs. Activation of the beta-2 receptors causes the muscles surrounding the lungs to relax. Beta-agonists begin working within a few minutes of administration. For this reason, they are especially helpful for patients who experience short periods of serious shortness of breath. The effects of beta-agonists last for around four hours, so multiple doses may be necessary each day.
- Anticholinergenics: Anticholinergenic drugs work by blocking the action of acetylcholine, a substance that transmits signals in the brain and to muscles throughout the body. By blocking acetylcholine, anticholinergenics prevent signals that tell muscles to contract from reaching the muscles surrounding the airways in the lungs. This keeps the airways open.
- Theophyllines/theofyllines: Theophyllines cause the muscles surrounding the airways to relax.
Many patients take more than one different bronchodilator. In fact, some patients take bronchodilators of every type. The type of bronchodilators a patient is prescribed depends on the severity of their disease and how well their symptoms are controlled.