Performance testing system MDIs

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Overview
The aerodynamic particle size distribution (APSD) testing of Metered Dose Inhalers (MDIs) describes measurement approaches using cascade impactors and supporting accessories for reliable in vitro aerosol characterisation. The guidance addresses standard impactors, breath-actuated devices and the influence of add-on components such as spacers or valved holding chambers (VHCs).

Test conditions and key considerations

• Typical flow rates: 28.3 L/min for Andersen Cascade Impactor (ACI); 30 L/min for Next Generation Impactor (NGI).
• Breath-actuated MDIs (BAIs) require control of actuation timing; use a Breath Actuation Controller to generate an appropriate delay and trigger during flow.
• Add-on devices (spacers, VHCs) can substantially modify APSD and must be evaluated in representative configurations.
• Impactor configuration, induction port geometry and cup arrangement influence stage recovery and must be controlled and documented.

Impactors and measurement options

• Next Generation Impactor (NGI)
• Andersen Cascade Impactor (ACI)
• Multi Stage Liquid Impinger (MSLI)
• Glass Twin Impinger (GTI)

Ancillaries and featured items used with APSD systems

• Mouthpiece adapters and nosepiece variants to match device interfaces
• NGI induction port and NGI cup racks/tilting platforms for correct mounting and stage handling
• Breath Actuation Controller (BAC 100i) for BAIs to initiate flow and synchronised actuation
• Flow Rate Sensor (FRS) and calibrated flow meters for accurate flow measurement and control
• Low Capacity Vacuum Pump (LCP7) and High Capacity Pump options for required vacuum performance
• Inhalytix®+ APSD data analysis software for processing, analysis and reporting of impactor data

Automation and semi-automation (Vertus® systems)
The Vertus® III automated shake, fire and shot waste range offers integrated solutions for repeatable MDI testing. Key controllable parameters include:

• Speed, angle and duration of shaking prior to actuation
• Firing force and application/release speed
• Time delay between end of shaking and device actuation

Related applications and support
The APSD workflow is complemented by products and services to improve clinical relevance and reproducibility: realistic breathing profiles, throat/nasal models, sample preparation units, impactor cleaning systems, environmental control chambers and training/maintenance services to implement robust APSD and DDU test methods.

Technical characteristics / specifications

• Recommended flow rates: ACI 28.3 L/min; NGI 30 L/min
• Impactor options: NGI, ACI, MSLI, GTI
• Compatibility with Breath Actuation Controller for BAIs (BAC 100i) to synchronise actuation with flow
• Use of induction ports, cup racks and tilting platforms to support stage recovery and setup
• Ancillary options: mouthpiece adapters, NGI induction port, NGI cup rack, NGI carrying/washing rack, internal/external filter holders
• Pumping options: low capacity and high capacity vacuum pumps (e.g. LCP7, HCP7) for required vacuum/flow conditions
• Data analysis: integration with APSD data analysis software (Inhalytix®+)