ABSTRACT
There are additional aerosol generation methodologies that have been known for many years but have gained relatively little popularity compared to jet nebulizers and metered dose inhalers (MDIs). Traditional ultrasonic nebulizers have been in commercial production since the early 1960s, and it is only recently that advanced uses in the form of vibrating plates, meshes, and membranes have emerged. The application of electrostatic forces for the production of aerosols has also been known for a long time, but has not yet gained acceptance as a commercially viable method. To some extent, this is due to the relative complexity and associated cost of the devices for use in routine patient care (1). It may also be due to the complexity of the theory and design of the devices, compared to the simple jet nebulizer. Further, application of these methods involves imparting considerable energy to the drug solutions, which, as will be seen, may cause degradation. However, as targeted delivery of medications to the respiratory tract increases, interest in these seemingly esoteric methods will continue. Ultimately, clinicians and patients will benefit from a wider variety of delivery systems.
