Epinephrine is a hormone produced by the adrenal glands (located above the kidneys within the abdomen). The adrenal glands naturally release a very small amount of this substance that may bind to specialized ß2 (beta-2) receptors in the lungs. These receptors, in turn, are responsible for bronchodilation (relaxing of bronchial tube constriction). In addition, epinephrine also can stimulate the heart to beat faster and elevate the blood pressure.
If you are asthmatic, you may have a deficiency in the biochemistry of your ß2 receptors. Therefore the amount of natural epinephrine that you produce may be insufficient to promote adequate stimulation and bronchodilation. Sympathomimetic medications stimulate biochemical changes in the airway, which leads to quick relief of asthmatic symptoms as the airway opens. They are reliever medications.
Sympathomimetic medications include: