Validating AIM-Based Instrumentation and Associated Measurement Techniques - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 289

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line of
identity

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lmpactor Sized Mass (ISM)

40 41 42 43 44 45

Fig. 10.9 Relationship between IM versus ISM , showing measurements with a different symbol
for each of the six inhalers evaluated ( From [ 26 ]— used with permission )

three principal metrics related to the total mass of salbutamol emitted from the
inhaler, normalized on a per actuation basis:

1. Impactor mass ( IM ), defined as the total mass of API recovered from all compo-
nents of the measurement system downstream of the induction port (i.e., mass on
all stages including stage 0 for the full-resolution Andersen CI).
2. Ex-actuator mass ( Ex-ActM ), defined as the total mass of API recovered from all
components of the measurement system including the induction port.
3. Ex-metering valve mass ( Ex-MVM ), defined as the total mass of API recovered
from the measurement system together with that from the actuator mouthpiece
of the inhaler.

Values of the subfractions of the mass/actuation were subsequently established
and the relationship between IM (capable of being measured by all systems) and
impactor-sized mass ( ISM ), determined only by the AIM-QC and full-resolution
ACI, quantified (Fig. 10.9 ).
The consistent ca. 1

g/actuation offset between IM and ISM , representing a
fixed mass of API retained by stage 0 of the full-resolution ACI, enabled the
precision comparison to take place between the two abbreviated configurations
and the full-resolution CI, based on IM (Fig. 10.10 ).
On this basis, both abbreviated impactors had comparable precision with that of
the ACI (Table 10.5 ).

μ