Optimizing aerosol delivery by pressurized metered-dose inhalers

The modern era of aerosol therapy began with the introduction of the Medihaler Epi in 1956, after a 13-year-old asthmatic told her father, an officer in the Riker company, that asthma medications should be as convenient to use as hair spray and she complained that the bulb atomizer leaked in her school bag. Since then, advances in technology have made aerosol delivery much more efficient, so that it is now the most widely used mode of medication delivery for chronic airways diseases. Today the pressurized metered-dose inhaler (pMDI) is a metal canister containing a mixture of propellants, surfactants, preservatives, and drug. However, pMDIs are underused in the United States. One barrier to use is the misconception related to pMDI effectiveness relative to small-volume nebulizers, especially among pediatricians. This is despite the strongest evidence of pMDI superiority, from well-controlled pediatric studies. In this manuscript we discuss ways to optimize the use of medications given via pMDI and examine recent changes in pMDI technology that will make drug delivery more efficient and consistent.