Validating AIM-Based Instrumentation and Associated Measurement Techniques - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 287

Abbreviated
ACI For
QC Data

Abbreviated
ACI For HRT
Pertinent Data

EPM/
FPM/
CPM

LPM/
SPM

Stage d 50 at
28.3 L/min
(

Size Bands
(

Full ACI ISM

µ m)

µ m)

I.P l.P. l.P.

stage 0
(as spacer)

9.0 >9.0

Stage 0

Stage 0

5.8
4.7
3.3
2.1
1.1
0.7
0.4

5.8 9.0

−

Stage 1

4.7 − 5.8

Stage 2 Stage 2

3.3 − 4.7

Stage 3

2.1 − 3.3

Stage 4

Stage 4

1.1 − 2.1

Stage 5 Stage 5

0.7 − 1.1

Stage 6

0.4 0.7

< 0.4

−

Stage 7

Filter

Filter Filter

Spacer
(empty
Stage)

ACI AIM-QC AIM-pHRT

Fig. 10.8 CI configurations used in the IPAC-RS AIM precision experiment; the additional
“spacer” stage used after filter stage for the AIM-QC system has no measurement function and
does not interfere with analysis ( From [ 26 ]— used with permission )

fine and coarse mass fractions, there may be a need to evaluate the portion of the
emitted dose from some OIPs, particularly pMDI solution formulations such as
Qvar™ and Alvesco ® in terms of extra-fine fraction < ca. 1 m, comprising a sub-

fraction of the fine particle mass. In such instances, a second impaction stage
provides added flexibility to the abbreviated impactor, with cut-off size exactly at
this limit or in the case of systems derived by removing stages from a full-resolution
nonviable ACI, retaining stage 5, whose cut-off size is 1.1

μ

m at 28.3 L/min. This
was the rationale underlying the development of the so-called potential-HRT con-
figuration, referred to from now onward as the “AIM-pHRT”-abbreviated impactor
that was evaluated in the IPAC-RS precision comparison study at Trudell Medical
International in 2009 [ 26 ]. This apparatus is included here for the sake of complete-
ness, as it formed one arm of the precision comparison study. However, the underly-
ing reasons for the development of AIM-pHRT configurations are explored in more
detail in Chap. 12 . Like the T-FSA described earlier, the “pHRT-FSA” configuration
had a non-operable stage 0 inserted prior to the first separation stage to give dead
space equivalence to the full-resolution impactor. The “pHRT-FSA” system was
evaluated together with a so-called AIM-QC configuration having a single stage
with cut-off size at 2.1

μ

m (stage 4 from the full-resolution ACI operated at
28.3 L/min) chosen to be close to the MMAD of the product used in the evaluation
(AIM-QC apparatus).
The two abbreviated configurations compared with that of the benchmark full-
resolution system are illustrated schematically in Fig. 10.8 . C1, C2, and C3 are the
configurations for the full-resolution nonviable ACI, AIM-QC, and AIM-pHRT

μ