Medical Aerosol Inhalers: Past, Present, and Future

The need to deliver pharmaceutical molecules to the respiratory tract has lead to the development of three major types of medical aerosol inhalers: The nebulizer, invented around the turn of the century, which uses aqueous solutions as its atomization substrate; the pressurized metered dose inhaler, invented in the mid-1950s, which uses a finely divided drug in a chlorofluorocarbon propellant suspension; and the dry powder inhaler, first commercialized in the early 1960s, which uses a powdered drug form. In general, these dosage forms have served the medical and patient community well, but recent advances in protein chemistry and the ozone depletion issues related to CFC propellants have lead to a renewed interest in the development of more efficient non-CFC inhalers. This article discusses the history of medical inhaler device technology and highlights the new technologies which may replace some of the existing delivery systems.