An aerosol generator system for inhalation delivery of pharmacologic agents

Most commercially available aerosol generators widely used in medical applications produce aerosols characterized by a large mass median diameter in the 4-8 micron range and the particle size in the 0.1-10.0 microns range. The desirable size of therapeutic and diagnostic aerosols, however, is about 2-4 microns mass median diameter, and less than 2.0 geometric standard deviation; this size increases the reproducibility of inhalation tests and enhances drug efficacy. We combined the commercially available DeVilbiss Model 65 nebulizer with a dilution/mixing chamber developed in our laboratory. The characteristics of this aerosol generator system were examined over a range of operating conditions and concentrations of solutions of three bronchoconstrictive agents--histamine, carbachol, and methacholine. The aerosol generator system produced a polydispersed aerosol with a mass median diameter range of 1.7-2.4 microns and geometric standard deviation of 1.5. The reliable and reproducible operation of the aerosol generator system greatly increases the power of bronchial challenge tests with bronchoconstrictive drugs.