Inhalation therapy for bronchial asthma: strategies and targets.

Bronchial asthma is associated with symptoms, reversible airflow obstruction, airway hyper-responsiveness and inflammation along large and small airways. Inhalation therapy with bronchodilators (relievers) and anti-inflammatory agents (controllers) forms the basis of treatment for most patients with asthma of different severities. Conventionally, therapeutic efficacy is assessed on the basis of improvements in symptoms and lung function. However, airway hyper-responsiveness as a primary outcome may change therapeutic strategies. There are problems associated with this concept which need to be addressed, such as the heterogeneity of airway inflammation in the asthmatic lung. The goals for inhalation therapy should be to determine the site of airway inflammation for each degree of asthma severity, to improve inhaler technology, ensuring that the drug can reach the site of inflammation, and to improve compliance. New inhalers need to do the following: contain appropriate therapeutic agents; have particle dimensions small enough to be deposited in distal airways; and minimize the effects of incorrect inhalation and low compliance.