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 125

5.6 Selection of an AIM System

In practical terms, when selecting an appropriate technique, it is important to under-
stand that the AIM concept is not confi ned to one particular confi guration of impac-
tor (Fig. 5.7 ). Instead, many options exist, from potentially the Twin Impinger to
reduced versions of the Andersen cascade impactor (ACI), semiautomated ACI,
fast-screening impactor (FSI), and modifi ed versions of the NGI. 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 important operating variables,
in particular fl ow rate through the system.
The adoption of AIM together with EDA concepts by regulatory agencies and
eventually the pharmacopeial compendia will depend upon the assembly of both
experimental and theoretical evidence that can be developed in support of a para-
digm shift from multistage CI-based measurements.
Work continues to understand and characterize AIM and EDA approaches [ 29 ,
30 ]. AIM and EDA topics were presented and extensively discussed in a workshop
held by the USP in December 2011.
In Europe, the Inhalanda Committee that has oversight of the aerosol-based mono-
graphs of the European Pharmacopoeia took on the AIM concept as a new work item in
2011 and is seeking high-quality validated data sets with currently marketed OIPs to
support moving forward with this concept. In the long term, it is to be hoped that both

Fig. 5.7 Examples of the various options for AIM-based measurements [Courtesy of Copley
Scientifi c Ltd., Westech Instrument Services Ltd., MSP Corporation, and GSK plc (r-NGI)]