β-Adrenoceptor responses of the airways: For better or worse?

• Published in: European journal of pharmacology Vol. 533; no. 1-3; pp. 15 - 27
• Main Author: Broadley, Kenneth J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 08-03-2006
• Subjects: Adrenergic beta-2 Receptor Agonists; Adrenergic beta-Agonists - adverse effects; Adrenergic beta-Agonists - pharmacology; Airway; Albuterol - adverse effects; Albuterol - pharmacology; Animals; Anti-Inflammatory Agents - adverse effects; Anti-Inflammatory Agents - pharmacology; Asthma - drug therapy; Asthma - metabolism; Bronchodilatation; Bronchodilator Agents - adverse effects; Bronchodilator Agents - pharmacology; Capillary Permeability; Drug Tolerance; Genetic polymorphism; Heparin - metabolism; Humans; Inflammation; Mucociliary Clearance; Polymorphism, Genetic; Pulmonary Disease, Chronic Obstructive - drug therapy; Pulmonary Disease, Chronic Obstructive - metabolism; Receptors, Adrenergic, beta-2 - genetics; Receptors, Adrenergic, beta-2 - metabolism; Respiratory System - blood supply; Respiratory System - drug effects; Respiratory System - metabolism; Stereoisomerism; Time Factors; β-adrenoceptor; Mucociliary clearance; Stereoisomerism; β-adrenoceptor; Genetic polymorphism; Bronchodilatation; Inflammation; Airway
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/j.ejphar.2005.12.060

β2-adrenoceptor agonists are the first-line treatment of asthma and chronic obstructive pulmonary disease (COPD), in which a short-acting β2-adrenoceptor agonist is used as required for relief of bronchoconstriction. A long-acting β2-adrenoceptor agonist may be added to an inhaled corticosteroid as step 3 in the management of chronic asthma. Long-acting β2-adrenoceptor agonists may also be added in treatment of COPD. This review examines the beneficial and detrimental effects of β2-adrenoceptor agonists. The beneficial effects of β2-adrenoceptor agonists are mainly derived from their bronchodilator activity which relieves the bronchiolar narrowing and improves air flow. The potential anti-inflammatory actions of stabilizing mast cell degranulation and release of inflammatory and bronchoconstrictor mediators, is considered. Other potential beneficial responses include improvements in mucociliary clearance and inhibition of extravasation of plasma proteins that is involved in oedema formation in asthma. The side effects of β2-adrenoceptor agonists are primarily related to β2-adrenoceptor-mediated responses at sites outside the airways. Of major concern has been the development of tolerance and this is discussed in relation to incidence of increased morbidity and mortality to asthma over the past three decades. A clinical aspect of β2-adrenoceptor pharmacology in recent years has been the recognition of genetic polymorphism of the receptor and how this affects responses to and tolerance to β2-adrenoceptor agonists. A controversial feature of β2-adrenoceptor agonists is their stereoisomerism and whether the inactive (S)-isomer of salbutamol had detrimental actions in the commercially used racemate. The consensus is that despite these adverse properties, β2-adrenoceptor agonist remains the most useful pharmacological agents in the management of asthma and COPD.