Good Cascade Impactor Practices - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 108

Table 4.4 Metrics in common use with APSDs from OIPs

Related to particle deposition
in HRT Related to OIP QC

Metric Full resolution AIM Full resolution a AIM

EPM or EPF Ye s Ye s

FPM or FPF Ye s Ye s

CPM or CPF Ye s Ye s

LPM or LPF Ye s Ye s
SPM or LPF Ye s Ye s
ISM Ye s Ye s
IM b Ye s Ye s
TEM c Ye s Ye s Ye s Ye s
MB d Ye s Ye s Ye s Ye s
a EPM or FPM or CPM can be established from groupings of stages. In the case of FPM, the group-
ing may be defined with both an upper and lower bound (i.e., from 1.1 to 4.7 μm aerodynamic
diameter from stages 3 to 5 of the ACI operated at 28.3 L/min), or just with the upper bound
defined (i.e., <4.7 μm aerodynamic diameter from stages 3 to the backup filter in the example
quoted beforehand)
b IM includes the mass collected in the first stage of the CI where the upper bound size is undefined
(e.g., stage 0 in the ACI configuration for use at 28.3 L/min)
c TEM includes all non-sizing components of the CI system (i.e., the induction port, pre-separator
(if used), and the first stage of the CI)
d MB includes IM + the mass retained by the OIP and is only included to identify the need for a
system suitability test in CI-based determinations of OIP performance

version 3.10), data from the NGI operated at 15 L/min can be interpreted, thereby
making this software useful for those testing nebulizing systems in accordance with
compendial guidance to operate the CI at this relatively low low rate, as well as with
MDIs and DPIs. In addition to plotting the raw mass/component data, CITDAS
reports the cumulative mass-weighted APSD and associated descriptive statistics (i.e.,
MMAD, GSD). An interesting new feature is the ability to specify up to five different
interpretations of subfraction mass, defined either by impactor stage locations or in
terms of aerodynamic particle diameter range. Therefore, in addition to reporting
FPM, the reported delivered mass ex OIP can be subdivided into as many as this num-
ber of discrete subpopulations. CITDAS determines the profile of each subpopulation
by interpolation, which means that it is possible for users to process multimodal par-
ticle size distributions as a series of lognormal subpopulations.
CITDAS has certain features that make it attractive to those who need to use CI
data but do not want to get deeply involved in understanding all the complexities
associated with good data analysis practice. For instance, it carries out the following
data integrity checks:

1. Limit of detection (LOD) is reported for measures of FPD and FPF if the follow-
ing criteria are met:

(a) Values are associated with a cumulative drug mass <2% of the total mass.
(b) The cumulative mass on fewer than three stages is greater than 1% of the
total mass.