Novel instrument to measure water uptake, dissolution and hygroscopic growth of an individual levitated aerosol particle in an environment identical to the lung (relative humidity >99.5%)

Dry powder inhalers (DPIs) are commonly used devices for delivering inhalable pharmaceuticals. The overall efficacy of any inhalable pharmaceutical is a function of total and regional dose, and the bioavailability of the active pharmaceutical ingredient upon deposition in the lung. Thus, a detailed understanding of the dissolution dynamics of particles from a DPI from the point of generation through to deposition in the lung may shed additional insights into the interpretation of the pharmacokinetic effects, resulting in the design of improved formulations. We present the design and benchmarking of a novel technology that directly measures the dissolution dynamics of dry aerosol particles in situ, where the relative humidity and temperature are directly comparable to the highly humid conditions within the lungs. The rate of water uptake (mass) as well as changes in the physical structure of the particle are directly measured using a combination of electrodynamics and laser light scatter. This technique offers unique insights into the dissolution dynamics of DPI starting formulations.