When breathing becomes impaired, bronchodilators may relieve the symptoms of breathing difficulties. According to the Cleveland Clinic, bronchospasms result from narrowing of the bronchial airway caused by contraction of smooth muscle. Infections, allergens, stress and cold air will cause this contraction, resulting in bronchospasms. Bronchodilators affect these responses by preventing and treating the reaction. As a result, inflammation and mucus production can be avoided or minimized.
Sympathomimetic
Sympathomimetic drugs, named for their effect on the sympathetic nervous system, are bronchodilators used to prevent and treat bronchospasms. Also known as adrenergic bronchodilators, these drugs stimulate the sympathetic nervous fibers allowing the smooth muscles in the airway to relax. According to the Cleveland Clinic, sympathomimetics treat symptoms related to reversible airflow obstruction such as asthma, bronchitis, emphysema and bronchiectasis. Examples of sympathomimetic drugs include albuterol, pirbuterol, levalbuterol, salmeterol, formoterol and metaproterenol.
Xanthines
Xanthines are nitrogen-based compounds naturally found in human organs, blood and urine. This classification of drugs produces a bronchodilating affect. Physicians will prescribe xanthines to treat patients with asthma and chronic obstructive pulmonary disease, both stable and acute. These drugs directly affect the muscles lining the airway by causing them to relax. However, xanthines actually have a relatively weak bronchodilating effect when compared to sympathomimetics. According to the National Heart, Lung and Blood Institute, inhaled sympathomimetics are preferable over xanthines when available because the mechanism of action of these drugs in not fully understood. These drugs can also cause serious side effects, so patients should be closely monitored when taking xanthines. Examples of xanthines include theophylline and aminophylline.
Anticholinergics
Anticholinergic bronchodilators produce relaxation and widening of the bronchioles by blocking the action of acetylcholine, the neurotransmitter that causes bronchial muscle to contract. These medications, usually given metered dose inhaler or nebulizer, can block cholinergic-induced airway constriction. According to the U.S. National Library of Medicine, anticholinergics are most often prescribed in combination with sympathomimetics or xanthines. Examples of anticholinergics include tiotropium bromide, ipratropium bromide, and a drug combination of ipratropium bromide and albuterol called Combivent.
References
- Cleveland Clinic: COPD Medication Guidelines
- National Library of Medicine: Aminophylline (aminophylline) Injection, Solution
- U.S. National Library of Medicine, Daily Med, Current Medication Information: Albuterol
- U.S. National Library of Medicine, Daily Med, Current Medication Information: Atrovent (ipratropium bromide hfa)
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