Inhaled therapy in asthma: metered-dose inhaler experience.

Metered-dose inhalers are the most widely-used mode of administration of bronchodilators and anti-inflammatory agents in the treatment of asthma. However, their use is complex and about 50% of the patients do not use their metered-dose inhaler(s) properly. The most frequent errors include inadequate coordination between actuation and inspiration, rapid inspiration, absence of breathhold, and actuation of the aerosol on more than one occasion during the same inspiration. The misuse of metered-dose inhalers results in a loss of efficacy of the drug. It is, therefore, recommended that the patient be carefully trained in the proper use of metered-dose inhalers at the time of prescription. If a patient is unable to use a metered-dose inhaler properly, despite education, it may be advisable to employ a different inhalation system.