Beta-agonists are medications that serve as bronchodilators, helping to open the airways by relaxing the muscles that may constrict during an attack. These medications can be taken through inhalers or orally. They are termed "agonists" because they stimulate the beta-2 receptors located on the muscles surrounding the airways. When these receptors are activated, the muscles relax, allowing the airways to open up, which alleviates symptoms like shortness of breath. Beta-2 agonists have proven effective in easing breathing difficulties for many individuals with asthma and COPD. Their effects begin within minutes after inhalation and typically last around four hours. Due to their rapid action, beta-2 agonists are particularly useful for those experiencing sudden shortness of breath. However, because their effects are relatively short-lived, multiple doses throughout the day are often needed. Side effects can include anxiety, a rapid heart rate, and low blood pressure. Some examples of beta-2 agonists are albuterol (Ventolin, Proventil), metaproterenol (Alupent), pirbuterol (Maxair), terbutaline (Brethaire), isoetharine (Bronkosol), and levalbuterol (Xopenex). There are also beta-2 agonists like salmeterol xinafoate (Serevent), which have a slower onset but provide longer-lasting relief, with effects lasting up to twelve hours and requiring only twice-daily dosing.
