Optimizing the use of metered-dose inhalers in chronic obstructive pulmonary disease and asthma.

The metered-dose inhaler (MDI) is a miracle of modern technology, but its use can be burdened with problems. Although it is a small, multidose, portable, safe, efficient, and cost-effective way to deliver inhaled medications, a majority of patients do not use the MDI correctly. The inability to coordinate actuation with inhalation and poor compliance, with both over- and under-use, are the most common problems. Understanding and dealing with the barriers to effective MDI use are essential to optimal care of patients with obstructive airways disease.