Clinical considerations in the use of inhalation delivery devices

Medications delivered through oral inhalation represent the cornerstone of pharmacotherapy for asthma and chronic obstructive pulmonary diseases. Several options exist as methods of delivering aerosols to the lung, including metered-dose inhalers, metered-dose inhalers attached to spacers or valved holding chambers, dry powder inhalers, and nebulizers. Delivery of aerosols to the lung is affected by numerous factors including characteristics of aerosol particles, patients' ventilatory patterns, and physical condition of the lung. It has become increasingly clear that the device used to deliver the medication is an important factor in the extent of deposition and the ultimate therapeutic effect. Further, the same therapeutic agent may exhibit differing effects depending on which delivery device is used. Each inhalation device has specific instructions for use, and the techniques for use vary significantly among the available products. In each case, patients should be instructed and observed to ensure that they have the proper technique of use to achieve an optimal effect.