Laser diffraction particle size analysis, already widely used in the characterization of a variety of OINDPs (orally inhaled and nasal drug products) is proving its value in the development of some of the newest drug delivery formulations - dry powder nasal sprays. This was the conclusion of a well-attended workshop on ‘Characterizing the Performance of Nasal Dry Powder Devices' presented by Dr Paul Kippax, from Malvern Instruments, and Dr Julie Suman, President of NextBreath LLC, during May's Respiratory Drug Delivery Europe 2011 (RDD 2011) conference in Berlin, Germany. 

"Over the past few years, there has been increased interest in the use of nasal dry powder delivery systems for a variety of therapies but to date there is no clear guidance on how these should be characterized," said Paul Kippax. "At Malvern we have considerable know-how and experience in characterizing standard nasal spray products, and our recent research with NextBreath has shown that techniques applied to liquid systems are appropriate for characterizing nasal dry powder devices."

The workshop considered whether the characterization techniques applied to liquid-based nasal spray formulations for in vitro bioequivalence and bioavailability assessments may also be used to understand the performance of dry powder devices. It focused on how measurements using laser diffraction and plume imaging provide a means of understanding powder dispersion and deposition behaviour. Malvern's Spraytec laser diffraction analyzer , for example, (www.malvern.com/spraytec_oindp) performs extremely rapid measurements and can be used to observe plume evolution and monitor the changes in concentration which occur as a device is actuated. 

Malvern, Malvern Instruments and Morphologi are registered trademarks of Malvern Instruments Ltd Spraytec is a trademark of Malvern Instruments Ltd

Attention was also paid to how emerging methods, such as combined automated image analysis and Raman spectroscopy (Morphologi G3-ID), can provide drug-specific metrics for device and formulation performance, and a more complete assessment of API dispersion. The Morphologi G3-ID enables the classification of particles based on size and shape parameters, followed by the acquisition of Raman spectra of targeted particles for further classification based on chemistry. www.malvern.com/morphologi