Collaborative work employs complementary particle characterization tools for inhaler development

Helsinki University of Technology & Malvern Instruments present results at DDL20

At Drug Delivery to the Lungs 20 (DDL 20), which takes place from 9 to 11 December 2009, in Edinburgh, Scotland, specialists from Malvern Instruments will present the results of work undertaken in collaboration with the Helsinki University of Technology. Their study highlights the application of laser diffraction particle size analysis and morphological imaging in the development of dry powder inhalers, using the Malvern Spraytec and Morphologi G3 systems respectively. Researchers used the techniques in combination to assess the performance of coated powders in ‘carrier-free’ dry powder inhaler (DPI) formulations.

Many DPI formulations include a carrier to improve powder flow and dispersion. However, carrier-free alternatives can reduce the amount of material depositing in a patient’s mouth and throat during inhaler use. For the study, three test samples were produced by coating salbutamol sulphate with L-Leucine using a gas phase deposition technique. The research teams investigated both the morphology of the resulting particles and their performance in a passive DPI.

The Morphologi G3 is an automated particle characterization system that captures images of hundreds of thousands of particles in just a few minutes, giving statistically relevant information on both size and shape. Results from this study demonstrate that coating the salbutamol sulphate with L-leucine produces spherical particles with a rough surface structure. Increasing the proportion of coating material gives rise to more-elongated particles. These changes in surface structure are believed to enhance the emitted dose, behaviour that was studied further using the Spraytec particle size analyzer.

The wide dynamic range (0.1 – 2000 microns) and rapid data acquisition rate (in excess of 2.5 kHz) of the Spraytec enable real-time study of the particle size and concentration delivered by an inhaler. It was shown that while the spherical particles entrained more readily, the elongated particles exhibited a higher total emitted mass, thereby achieving greater powder emptying and dose delivery to the patient.

DDL is one of the premier conferences for the inhalation community. Malvern experts will be on hand throughout.

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