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 127

Table 5.3 Applications for full-resolution and AIM-based CI measurements in the OIP product
life cycle: implementation
APSD measured for
Product characterization
and development

Product quality
control

In vitro assessment for
equivalence comparisons

Impactor
system
to use

Full-resolution CI for
initial screening
candidate formulations,
then AIM-QC on
short-listed candidates

AIM-QC, supported
by full-resolution
CI (e.g., in the
context of OOS
evaluation)

Full resolution
or AIM-pHRT
With an anatomically
correct or idealized
inlet possible

Proposed
metrics
to use

Initially, EPM , FPM , and
CPM with size ranges
related to likely
deposition in the HRT;
later, EDA metrics to
develop QC
specifi cation

EDA metrics, namely,
SPM and LPM
with boundary
near to MMAD :
LPM / SPM and
ISM ( SPM + LPM )

Full-profi le comparisons
or EPM , FPM , and
CPM with size ranges
related to likely
deposition in the
HRT

Statistical
approaches

A number of approaches
related to the APSD
characterization and
the development of the
product specifi cation

Tests to detect
signifi cant
changes in APSD

Generic statistical
equivalence testing

The following considerations also apply:

1. The full-resolution CI, ideally an apparatus of the same type as the abbreviated
system, is always present as the reference apparatus, in the event that discrepan-
cies between full- and AIM-based systems arise.
2. EDA is as applicable to full resolution as to abbreviated CI data.
3. The implementation of AIM or EDA approaches will be more likely to be suc-
cessful when discussed in advance with the appropriate regulatory agencies for
the OIP, and where a good correlation between AIM and full-resolution CI
results can be demonstrated.

Finally, the choice of AIM platform should ultimately depend on the familiarity
of the testing laboratory with the equipment and its limitations, the preference for
(semi)automation, as well as the nature of the product being evaluated (MDI with or
without add-on device, DPI, or nebulizing system), as the latter will dictate impor-
tant operating variables, in particular fl ow rate through the system.

References

1. Christopher D, Curry P, Doub W, Furnkranz K, Lavery M, Lin K, Lypapustina S, Mitchell J,
Rogers B, Strickland H, Tougas T, Tsong Y, Wyka B (2003) Considerations for the develop-
ment and practice of cascade impaction testing including a mass balance failure investigation
tree. J Aerosol Med 16(3):235-247