Current Approaches to APSD Measurements of OIPs Based on Inertial Impaction - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 40

1.00

AIM/Summed--
GSD

0.75

Fraction on First
Stage of AIM

0.50

0.25

0.00
1.00 1.50 2.00 2.50

GSD

Fig. 2.13 ACI system: mass fraction on first AIM collection stage or ratio of AIM system com-
pared with corresponding summed stages—GSD varied with MMAD fixed at 4.0 μ m ( From [ 43 ] ,

courtesy of D L Roberts and J P Mitchell )

the input aerosol by more than about 10%. However, it is believed that the potential
exists for larger discrepancies to arise if the incoming aerosol is more monodisperse
than those considered and also if it contains finer particles in the range of interest.
In summary, although bias from the assumption of ideal stage collection effi-
ciency behavior appears small with both systems, it can likely be ignored for the
NGI. However, account may need to be taken of this effect in the most accurate
work with the ACI and particularly when comparing data from abbreviated systems
developed from this CI design.

2.6 Overview of the Compendial Full-Resolution CI-Based

Methods for OIP Aerosol Characterization

Currently, the requirements for OIP in vitro performance assessment throughout the
product life cycle dictate the need for measurements by full-resolution multistage
CI, since this type of apparatus has good compatibility for the assessment of all
formats currently manufactured (Table 2.13 ).