Size Distributions and Lung Deposition of Submicrometer Particles from Metered Dose Inhalers

Abstract

The size distributions of the submicrometer particles generated from ten metered dose inhalers (MDIs) were determined by a high resolution particle sizer, which could measure the particles in the size range of 0. 01μm to 1 μm. The particle sizer contains a differential mobility analyzer(TSI 3071) and a condensation particle counter (TSI 3022). The median diameters ranged from 0.06-0.10μm with a geometric standard deviation of 2. In addition, the surface median diameters and volume median diameters were found to be 0.30 μm and 0.45 μm, respectively. Moreover, none of the size distribrtions of the generated submicrometer particles fits log-normal distributions. The deposition probabilities of the submicrometer particles in the airways were evaluated. It was observed that the average deposition percentages of the particles in the alveolar, tracheobronchial, and wxtrathoracic regions are 32%, 4%, and 4%, respectively. Understanding the deposition of submicrometer particles from MDIs should benefit the clinical practice in inhalation therapy.#b0294013