The AIM and EDA Concepts: Why They Are Needed and How They Fit Together - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 118

Metal TI
(GSK) throat

DPI Testing MDI Testing

inlet
cone

pre-separator
lid

Total
aerosol
collection
DPI or MDI

MDI - full apparatus

DPI - full apparatus

Simplified
method

Simplified
method

Stage X

Stage X

MDI MAMass kit

DPI MAMass kit

Fixed sampling
volume option

Impactor or impinger option

CI

pump

Plate
configuration

Dish configuration
(impinger option)

timer

Impactor plates

Flow diverter

Fig. 5.2 Abbreviated impactor measurement approach to DPI and MDI testing pioneered by Van
Oort and Roberts (adapted from ref [ 15 ]—used with permission)

thinking of the regulatory agencies, particularly in the USA. However, they did not
go further by recommending that a two-stage size fractionator might be used in
conjunction with a full-resolution CI system that could be used to verify that the
simplifi ed measurement system was sensitive to the changes in APSD of relevance
to a particular OIP.
Pioneering work by Van Oort and Roberts [ 15 ] in the mid-1990s pointed the way
forward in terms of setting out a hierarchy of reduced stack Andersen cascade
impactor (ACI) measurements, supported by the full-resolution eight-stage system
(Fig. 5.2 ). However, the regulatory approach at that time favored the inclusion of at
least fi ve stages with cut-point sizes between 0.5 and 5.0

m aerodynamic diameter,
and this requirement was a signifi cant contributor to the design of the NGI [ 16 ].
In the mid-2000s, the abbreviated impactor measurement (AIM) concept and
related effi cient data analysis (EDA) approach were simultaneously developed
out of the need to reduce method complexity. In addition, there was an increasing
recognition by stakeholders involved with the regulatory process for OIPs that

µ