The Regulatory and Compendial Pathways to Acceptance for AIM and EDA Concepts - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 363

11.5 Concluding Observations

There are many AIM apparatus confi gurations available and several reasons why
one may choose to use an AIM-based technique, as have been explained in earlier
chapters. It is evident that incorporation of AIM (and possibly EDA) into the
pharmacopeial monographs related to OIP testing will be a key component in
gaining acceptance by the regulatory agencies. Given this situation, it will be a chal-
lenge to describe each AIM apparatus confi guration, even though currently several
full-resolution CI apparatuses are described within the pharmacopeias. However,
such a process may not be necessary, as a description of AIM and EDA as concepts
associated with narrative comprising minimum apparatus requirements may be a
suitable alternate approach.
In the short term, stakeholders within the inhaled pharmaceutical industry
involved in OIP assessments, and desirous of seeing AIM and EDA become accepted
as routine processes, need to work collaboratively to achieve the following goals:

(a) To establish precisely where AIM and EDA have utility and, perhaps more
importantly, where they are not applicable
(b) To demonstrate unambiguously that AIM and, preferably, EDA as well are “fi t
for purpose”
(c) To assist in helping the working groups of the USP and Ph. Eur. develop appro-
priate methods for the compendia

Once these goals have been met, then all that remains to be achieved is that these
concepts become recognized within relevant regulatory guidance as these documents
are revised. Under the current mode of operation, this would give pharmaceutical
industry stakeholders confi dence in the application of the techniques, and it would
indicate that many (all) of the general and specifi c concerns that the various regula-
tory agencies have about AIM and EDA had been addressed. Put in other words, at
this mature stage the concepts would no longer be regarded as “new technology.”
As a fi nal thought, as regulatory guidance moves towards a QbD approach, it
could be anticipated that specifi c techniques may not be mentioned in detail, as,
from the user's perspective, the selection process should be based more on the suit-
ability of the underlying science and not just because a given method is a listed
technique. In other words AIM and EDA may or may not always be the most appro-
priate (quality) assessment tools to be used in the OIP life cycle, and the sponsoring
company will need to assess the situation at each stage and justify their use to a
regulatory agency with appropriate science-based arguments.

References

1. Newman SP (1998) How well do in vitro particle size measurements predict drug delivery
in vivo? J Aerosol Med 11S1:S97-S104
2. Mitchell JP, Newman SP, Chan H K (2007) In vitro and in vivo aspects of cascade impactor
tests and inhaler performance: a review. AAPS PharmSciTech 8(4):Article 110. http://www.
aapspharmscitech.org/articles/pt0804/pt0804110/pt0804110.pdf . Accessed 20 Jan 2012