Evaluation of Performance of Dry Powder Inhaler Formulations by Laser Diffraction

Cintia Veiga^1,3, Beatriz Fernandes² & Luis Sousa¹

¹Analytical Development, R&D, Hovione Hovione FarmaCiência SA, Lumiar, 1649-038, Portugal

²Inhalation and Advanced Drug Delivery, R&D, Hovione Hovione FarmaCiência SA, Lumiar, 1649-038, Portugal

³Biochemistry Department, University of Lisboa, Alameda da Universidade, 1649-004 Lisboa, Portugal

Summary

The work presented here describes an alternative approach to evaluate the inherent dispersibility of powders, by laser diffraction, to assess the performance of Dry Powder Inhaler (DPI) products and guide their formulation development at early stages. Laser diffraction has been previously used to characterize the dispersibility of respirable powders [1] and even to correlate the laser diffraction results with fine particle fraction obtained by cascade impaction [2]. However, the correlations that were found were greatly dependent on some method parameters, such as the dispersing pressure, and the most adequate parameters could not be selected prior to testing. This limitation constitutes a major drawback for implementing a tool to predict the aerodynamic performance of powder formulations. The laser diffraction approach presented here, involves analysing different DPI formulations, at different dispersing pressures, and determining the rate of de-agglomeration as a function of pressure. The parameters, obtained from this methodology, were then correlated with the emitted dose and fine particle fraction values obtained from cascade impaction testing.

Key Message

A novel laser diffraction methodology is presented here for the evaluation of the dispersibility of respirable powders based on the rate of de-agglomeration of particles as a function of dispersing pressure. The de-agglomeration parameters obtained from this new approach were correlated with the aerosolization performance results obtained from cascade impaction testing.