Validating AIM-Based Instrumentation and Associated Measurement Techniques - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 345

Table 10.18 Points to consider (PtC) when implementing an AIM-based CI method; “ √ ” important;

“ ≈ ” unimport ant

OIP class applicability
MDI PtC Description DPI Nebulizer/SMI

1 Select appropriate full-resolution CI

as benchmark method (Table 10.19 )

√

2 Eliminate particle bounce and re-entrainment √ ≈

3 Match pressure drop rise time of AIM system

to benchmark CI a

√

4 Chill AIM and benchmark CI ≈ √

5 Refer to benchmark CI data as first step

in resolving questionable AIM data

√

a In the case of DPI testing, adding a first impaction stage to match the full-resolution impactor will
not by itself be sufficient to mirror the volume and flow resistance of the full impactor. However,
in the case of the ACI, it would be a practical alternative to retain the redundant stages in the abbre-
viated impactor, but locate them beneath the filter stage (e.g., in the stage order: 0, 2, 5, Filter, 1, 2,
3, 5, 7) to achieve this goal

Table 10.19 Matching an AIM-based CI to a full-resolution benchmark CI
AIM system Suggested full-resolution CI

FSA, T-FSA variants Andersen 8-stage nonviable impactor (ACI)

FPD Andersen 8-stage viable impactor (ACVI)

rNGI variants Next Generation Pharmaceutical Impactor (NGI)

FSI No obvious matching full-resolution CI, therefore use with any CI

and evaluate need to match dead space for OIP being tested.
Using NGI as reference full-resolution CI with FSI could result
in some components (e.g., inlet and pre-separator housing) being
shared, allowing reduction in cost for additional equipment.
Furthermore, familiarity of test recovery procedures for these
components is very similar between FSI and NGI. Validation
work with appropriate benchmark CI needed with other systems

Other systems
including
abbreviated MSLI

Table 10.19 provides guidance concerning this matter. The interested reader is urged
to keep up-to-date with the continually developing literature concerning good AIM
practices, as newer approaches to resolving compatibility concerns are published.

References

1. European Pharmaceutical Aerosol Group (2010) Workshop on AIM-Based Techniques,
Edinburgh, UK. http://www.epag.co.uk/Library/Default2.asp . Accessed 12 Jan 2012
2. International Pharmaceutical Consortium on Regulation and Science (IPAC-RS) (2008)
IPAC-RS conference “Bringing value to the patient in a changing world”, Rockville, MD,
USA. http://www.ipacrs.com/ipac2008.html . Accessed 12 Jan 2012
3. International Pharmaceutical Consortium on Regulation and Science (IPAC-RS) (2010)
IPAC-RS conference “Bringing value to the patient in a changing world”, Rockville, MD,
USA. http://www.ipacrs.com/2011%20Conference.html . Accessed 12 Jan 2012