Bronchial asthma and the role of beta 2-agonists

• Published in: Lung 1990-01, Vol.168 Suppl (S1), p.66-70
• Main Author: Cochrane, G M
• Format: Article
• Language: English
• Subjects: Adrenergic beta-Agonists - adverse effects; Adrenergic beta-Agonists - therapeutic use; Airway Resistance - drug effects; Asthma - drug therapy; Bronchial Provocation Tests; Humans; Mucociliary Clearance - drug effects; Receptors, Adrenergic, beta - drug effects
• ISSN: 0341-2040; 1432-1750
• DOI: 10.1007/BF02718115

Asthma is defined as reversible airflow obstruction; the mechanism for this airflow obstruction is considered to be caused by a combination of an inflammatory process leading to a thickened edematous airway lining and bronchial smooth muscle constriction. The identification of specific beta-receptors in the autonomic system led to the development in the early 1960s of selective beta 2-agonists with their precise effects on the bronchial smooth muscle without direct action on cardiac muscle. The early beta 2-agonists such as salbutamol have a comparatively short bronchodilator action but a rapid onset of action, making them useful as "rescue" bronchodilators. Regular beta 2-agonists alone may mask the underlying pathogenesis of asthma and may be associated with tachyphylaxis or rebound bronchial hyperreactivity. The observation that a thickened airway lining may lead to disproportionate increases in airways resistance with small changes in bronchial muscle shortening suggests beta 2-agonists should be given in conjunction with anti-inflammatory therapy. With their long duration of action but slow onset the new beta 2-agonists may have a role in prophylaxis of asthma rather than rescue bronchodilation.