Validating AIM-Based Instrumentation and Associated Measurement Techniques - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 334

Fig. 10.63 Modified FSI insert used by Tservistas et al. for nebulizer aerosol measurements at
15 L/min ( From [ 52 ]— courtesy of M. Tservistas )

Table 10.17 Comparative times for 6-replicate abbreviated and full-resolution impactor
measurements compared with laser diffractometry reported by Tservistas et al . in the context of
nebulizer aerosol assessment ( From [ 52 ]— courtesy of M. Tservistas )

Time allocation (h)
Measurement

Assessment method API analysis Data processing Total

LD 1.5 N/A 1.0 2.5

FSI (cooled) 7.0 6.5 1.0 14.5

FSI (ambient) 5.0 6.5 1.0 12.5

NGI 8.0 18.0 2.0 28.0

associated with nebulizer-generated aqueous droplet size measurements, as the
result of less pronounced heat transfer-related evaporative bias.
Comparative data for time savings provided by Tservistas et al . (Table 10.17 ) add
further evidence of approximately 50% gain in productivity with the cooled FSI
compared with the NGI.
As might be expected, LD was by far the most rapid technique; however, this
measurement method is not directly related to mass of API and is therefore limited
to the assessment of solutions, rather than more complex formulations (i.e., sus-
pensions, emulsions, liposomal forms, etc.) that may be encountered with this class
of OIP [ 58 ].

10.8 Assessing the Performance of AIM Systems

Based on the NGI

Since the NGI in its standard design does not have movable stages [ 14 ], the devel-
opment of an abbreviated system based on NGI geometry at first sight seems to be
unattractive and possibly a difficult process. However, this CI has a horizontal