The evolution of beta-agonists

Inhaled beta-agonists have become the mainstay of bronchodilator therapy for reactive airway diseases, either alone or in conjunction with other medications. The history of the development of beta-agonists is a fascinating one that spans more than 5000 years. Scientific investigation for the past several hundred years has elucidated the physiology of bronchoconstriction and bronchodilation. In the past decade, a wealth of knowledge has come forth since the discovery of the beta-adrenoceptor which, along with advances in pharmacology, have helped answer the questions of how beta-agonists work. From these advancements, three classes of beta-agonists have been developed: catecholamines, resorcinols, and saligenins. The chemical structures of the more commonly used agents in each class, their interaction with the beta-adrenoceptor, and their beneficial and adverse effects are discussed. Review of the duration of action of these agents may suggest a new way of classifying them into ultrashort-acting, short-acting, intermediate-acting, and long-acting.