Researchers present work using Malvern Spraytec to model nebulisers

Researchers from the University of Tours INSERM-U618 in France are working with Malvern Instruments using the company’s Spraytec particle size analyzer to understand the dynamics of drug delivery from nebulisers. The first stage of that research, being carried out by Laurent Vecellio, was presented at the recent International Society for Aerosols in Medicine (ISAM) Congress held from 16th – 20th June 2007 in Tours.

Studying the dynamics of aerosol formation is an important aspect in understanding where drug deposition occurs during inhalation. Previous deposition models have assumed a constant aerosol concentration during inhalation. For nebulisers, however, this is often not the case, as the aerosol concentration delivered to the patient is related to the patient’s breathing pattern, along with the device design.

The research group at Tours is developing models to predict the concentration changes that occur during the operation of different nebulisers. The dynamic measurements possible using the Spraytec allow direct verification of these models, as both the droplet concentration and size can be monitored in real time during a simulated breathing manoeuvre. It is hoped that this work will allow for the development of new nebuliser systems that will provide more targeted deposition of the aerosol droplets within different regions of the respiratory system.

Malvern’s Spraytec system uses laser diffraction to measure particle size and is widely used in the pharmaceutical industry for the analysis of nasal sprays, nebulisers and inhalers. It delivers real-time, high-speed measurements that enable the complete characterization of both continuous and pulsed spray events.

Spraytec has a data acquisition rate of 10 kHz, which means a 100-microsecond time resolution, allowing extremely accurate analysis of the dynamics of spray atomization and dispersion. An extended size range from 0.1 to 2000 microns, using just two lens systems, enables the routine characterization of broad size distributions, with a dynamic range of more than 1000:1 covered by each lens. Malvern’s patented multiple scattering analysis ensures accurate measurements at high spray concentrations, where traditional laser diffraction systems would fail.

For use in regulated environments, full lifecycle documentation, following GAMP guidelines, provides complete design traceability; IQ/OQ documentation is provided for validation plans; and software provides technical compliance with the requirements of 21 CFR Part 11.