4 ~ I i ,lt ELSEVIER Journal of Electrostatics 40&41 (1997) 579-584 Journalof ELECTROSTATICS Control of Drug Aerosol in Human Airways Using Electrostatic Forces W. Balachandran, W. Machowski, E. Gaura, C. Hudson Department of Manufacturing and Engineering Systems Brunel University Uxbridge, Middlesex UB8 3PH, U.K. tel. no. (01895) 203297 fax (01895) 812556 1. ABSTRACT A computer model has been developed for analysing the deposition of inhaled electro- aerosols in human airways. The effect of electrostatic charges on the total aerosol deposition efficiency in the human respiratory tract has been investigated. Based on measured data, a computer prediction can be made of the site of deposition in human airways. 2. INTRODUCTION Accurate evaluation of aerosol effects requires knowledge of factors affecting the deposition of inhaled particles within the human lung. Electrical charge is a very important parameter of an artificially generated aerosol, as it may influence the particle behaviour in deposition. Due to the increased deposition of the aerosol in the human lungs, as a result of the inherent charge - acquired by the particles in the process of aerosol generation - both theoretical and experimental aspects of deliberately charged aerosols in humans were studied. The devices presently used for drug delivery into the human airways include nebulisers, metered-dose inhalers (MDI) and dry powder inhalers (DPI). The basic mechanisms involved in the deposition at specific sites are the same for all three methods of delivery. However, the overall efficiency of deposition will depend on the nature of the drug aerosol generated by the respective devices. The deposition of inhaled drug aerosol in the respiratory system is governed by inertial impaction, gravitational sedimentation, Brownian diffusion, interception and electrostatic forces. Various models have been developed for predicting the site of inhaled aerosol deposition in the human lungs. It has been shown that deposition is dominated by electrostatic forces particularly in the alveolar region. Many simplifying assumptions have been made in developing these models. We have re- examined these assumption and we have developed an integrated deposition model [1] based on Weibel's symmetrical model A for the lung [2], for the process of aerosol inhalation only. The model assumes the airways to be tubular, and does not include the alveolar sacs. The respiratory tract is viewed as a succession of 23 generations. Each airway generation is 0304-3886/97/$17.00 © Elsevier Science B.V. All rights reserved. Pll S0304-3886(97)00106-X