ABSTRACT
A well-de†ned pharmacokinetic relationship exists between chemicals administered orally, dermally, or intravenously and the quantity of substance delivered to the speci†c target site. Certainly, some variability in dose exists due to interindividual differences in metabolism and transport kinetics, but it is relatively easy to de†ne the †nal delivery of an agent to the target site. In the case of aerosols, the understanding of this relationship is complicated for several reasons:
1. Aerosols are a complex medium consisting of particles in a very wide size range, with diameters ranging from nanometers to tens of micrometers (4-5 orders of magnitude).
