Biomedical Engineering Reference
In-Depth Information
“learnings” are summarized at the end of the chapter as guidance for those planning
on implementing an AIM-based method.
10.1
Introduction
The introduction of AIM-based apparatuses into the mainstream of OIP inhaler
performance testing is a highly desirable goal, as has been demonstrated in previous
chapters. Not only can the methodology for acquiring aerodynamic size-related
metrics be simplified, with the attendant prospect of reducing measurement vari-
ability, but the application of EDA principles may afford the prospect of better dis-
crimination in terms of product quality than is possible with current methods that
are based on grouped stages from full-resolution CI measurements or from a single
performance measure by itself, such as fine particle mass. Validation of the wide
variety of AIM-based apparatuses with all of the major OIP formats is a critical
component of this process.
Experimental studies were recognized from the outset as being of crucial value
to the development of the AIM concept, alongside detailed theoretical rationaliza-
tion. The following is a brief synopsis of key events. Following proof-of-concept
studies by Trudell Medical International with commercially available suspension
and solution formulated MDIs undertaken in 2007-2008, a comparative precision
experiment between abbreviated and full-resolution ACI systems was undertaken at
the same location by the CI Working Group of IPAC-RS the following year.
Subsequently, EPAG, through their Impactor sub-team, was responsible for initiat-
ing many follow-on investigations with a variety of inhaler types and abbreviated
impactor configurations. Since 2010, experimental work has also been undertaken
by several organizations outside these industry groups and is included in this chap-
ter in order to demonstrate that the AIM-EDA concept is of interest and is gaining
wider acceptance in the OIP manufacturing community. Included are studies carried
out using the following abbreviated impactor systems: the C-FSA (Copley Scientific
Ltd., Nottingham, UK); the FPD (Westech Instruments Services, Upper Stondon,
Beds., UK); other generic abbreviated Andersen CI stacks, in particular, the Trudell
(Medical) fast screening Andersen impactor (T-FSA); the FSI (MSP Corporation,
St. Paul, MN, USA); and differently modified versions of the NGI. In combination,
these initial results provide information to support use of the AIM concept with
each type of OIP (DPI, pMDI, and nebulizers).
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