Assessment of Responses of the Airways to Therapeutic Agents

I. Introduction Asthma is a chronic inflammatory disease of the airways, which is characterized by physiological abnormalities of variable airflow obstruction and airway hyperresponsiveness (AHR) to a wide variety of physical and inhaled chemical stimuli and the presence of symptoms, such as dyspnea, cough, chest tightness, and wheezing. Over the past 40 years, very effective medications have been developed to treat asthma, the most effective of which are inhaled b2-agonists for acute symptom relief and inhaled corticosteroids (ICS) for longterm management (1). Important insights into the optimal management of asthma were made in the early 1980s, when the central role of airway inflammation was identified to be important in asthma pathogenesis, even in very mild disease (2). This resulted in a change of focus from the relief of symptoms with frequent use of inhaled short-acting b2-agonists (such as salbutamol or terbutaline) to the prevention of symptoms and exacerbations by the regular use of ICS. This approach is extremely effective in the majority of asthmatic patients, and in those who remain symptomatic despite ICS treatment, the combination of ICS and a long-acting inhaled b2-agonists (such as formoterol or salmeterol) is generally sufficient to control asthma (3).