Product Life Cycle Approach to Cascade Impaction Measurements - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 134

were developed from the outset as AIM-based systems. Likewise, the twin impinger
(TI) was an abbreviated system from its inception.
It is not strictly necessary to choose an abbreviated impactor that has a parent
full-resolution system, since several groups have reported good results matching
data obtained by the FSI with the NGI, as can be seen from the data reviewed in
Chap. 10 . However, in some instances (e.g., when using the rNGI as the abbreviated
impactor confi guration), it may be more convenient in terms of the ability to use the
same components that have already been qualifi ed in terms of stage mensuration.
However, in this context, it is desirable, particularly in the case of DPI testing, to
match apparatus-specifi c variables, such as the magnitude of the internal volume
(also called dead volume ), between abbreviated and full-resolution CI when there is
no obvious parent system.

6.4 The Role of APSD in OIP Life Cycle Management

6.4.1 Overview

APSD testing is used for a variety of purposes during the life cycle of an OIP. In the
various stages of development, the sponsor studies safety and effi cacy of the prod-
uct and establishes the target APSD with associated metrics and specifi cations.
By contrast, in commercial production, QC testing is meant to confi rm whether
the APSD is the same as that of the clinical batches. Because the intent of QC test-
ing is not to repeat the extensive studies required for safety and effi cacy studies, the
most reasonable and practical goal of QC testing is to ascertain that the APSD is
within the specifi cations established for the product for release of the clinical
batches and during stability studies.
Developers of add-on devices for OIPs rely on the already established safety and
effi cacy profi les of the approved drug product. Therefore, their purpose of determin-
ing APSD-related data is related to the need to minimize the undesirable coarse
particle mass that deposits in the oropharyngeal region while maintaining the
amount of emitted fi ne particles ideally equivalent to that from the OIP device with-
out add-on [ 6 , 9 ]. Consequently, once the behavior of the add-on in this respect has
been established by full-resolution CI, there is no need to reestablish or retest the
entire detailed APSD profi le in future measurements of in vitro performance.

6.4.2 Management Strategy

It is highly desirable to have a defi ned strategy for optimizing the use of the different
variants of CI measurements throughout a product's life cycle. Figure 6.2 and the
following subsections of 6.4.2 contain the outline developed by Tougas et al. [ 4 ],
showing how such a management strategy might be developed where the need for