particle surface as well as the diffusivity into the particle. Because of the low water vapor concentration and adsorption rate, water uptake by humidified air will be extremely slow compared to that in an aqueous solution. Therefore, water uptake into a particle deposited on a thin fluid film can be assumed to occur only from the submersion liquid. To model this situation appropriately, water uptake in the r and q-directions needs to be solved.
             Inhalation of aerosolized drugs holds promise as a means to treat localized disease states within the respiratory tract and may also represent an ideal method for drug delivery to the systemic circulation. The respiratory tract offers a more favorable environment compared to the low pH and high protease levels associated with oral delivery. The lung is an attractive route for drug delivery owing to its enormous surface area for absorption (~100-140 m2) and highly permeable epithelium compared with the gastrointestinal tract (1,2). In addition, this non-invasive route is often much more acceptable to patients than an injection.
             The design and use of controlled release polymeric systems is an approach that may improve the duration and effectiveness of drugs delivered to the respiratory tract (3,4). Micron-sized polymeric systems can be used to deliver precise amounts of drugs, including proteins and genes, over prolonged periods to local tissues or the systemic circulation (3,5,6). In particular, the use of biodegradable polymeric microparticles has shown considerable promise for achieving sustained drug delivery in the lung with the ability for repeat administrations without polymer buildup in the lung. We have been working on the development of exceptionally large (~ 5-15 µm) and light (< 0.1 g/cc) polymer-based aerosol carriers for controlled drug delivery via the lung. Large and light polymer aerosols may improve the duration and effectiveness of drugs delivered via the lung due to the...