MVIC Case studies

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MVIC Case Study No 1: Droplet Size Measurements

Problem: A customer asks MVIC to perform particle size measurements on a newly developed liquid inhaler.

Approach: MVIC has the capability to perform droplet size distribution measurements using an instrument based on laser diffraction methodology. The instrument, a Malvern Mastersizer, can capture the droplet size distribution of an evolving aerosol plume. This can be done either as an acquisition average over the total device actuation time or in incremental time steps over the actuation time. The shortest acquisition time is 2 ms and 100 individual acquisitions can be achieved with a total acquisition time of 200 ms.

Analysis and Results: In Figure 1 the time mean average of a liquid inhaler actuation is seen. The inhaler has two distributions peaks, one around 5 um and one above 200 um. It is important to understand if his is an artefact or not. To investigate this further an incremental time resolution of the actuation was performed.

The same liquid inhaler was assessed using repeated 50 ms time sequences with a total of 25 individual measurements of 50 ms, equalling a total of 1,25 seconds, Figure 2.

Conclusion: The inhaler seems to produce a fraction of droplets above 150 um and displays a tailing off phenomena where the droplet size increases at the end of the measurement e.g. above 1 second.

This methodology can be a useful tool in the development of inhalers and can increase the understanding of the evolving atomisation process for liquid inhalers or the release characteristics of powder inhalers. Likewise it can be used to understand the characteristics of an originator product when developing a generic equivalent product.

Figure 1 Plume Geometry

Figure 2 Spray Pattern

MVIC Case Study No 2: Aerosol Characterisation

Spray Pattern and Plume Geometry

Inhalation product development involves the analysis of the aerosol characteristics of the product. Aerosol generation of these products is achieved by using inhalation devices, typically metered dose inhalers (MDI), dry powder inhalers (DPI) or aqueous systems such as nasal sprays and nebulisers.

The preferred technology for characterisation is high-speed video imaging, where the plume geometry and spray pattern are accessed and documented. Typical information that can be assessed are length, width, angle, velocity or plume duration. Regulatory authorities also require these parameters to be documented1,2 in the filing of inhalation product development.

MVIC has the capability to perform high-speed video characterisation of aerosol plume geometry and spray pattern using LaVision imaging systems. This is done using single or dual camera systems, and the plume can be visualized using laser or conventional white light.

1 FDA Guidance for Industry, 2002. Nasal spray and inhalation solution, suspension, and spray drug products – CMC documentation.

2 FDA Guidance for Industry (draft), 2003 Bioavailability and bioequivalence studies for nasal aerosol and nasal sprays for local action.