Biomedical Engineering Reference
In-Depth Information
Although many abbreviated CIs have a corresponding “parent”
full-resolution apparatus (e.g., the FSA and the ACI), some, in particu-
lar the FSI, do not. This restriction, however, need not be a limiting
factor in the choice of equipment like the FSI, as long as the necessary
due diligence is done to seek out potential sources of bias in method
development. However, it is important for the ACI-based systems to
use the correct abbreviated CI that relates to the parent impactor
(i.e., the FSA with the nonviable ACI and the FPD with the viable
ACI). This precaution is necessary, since the internal dead space of the
nonviable CI is signifi cantly smaller than its equivalent with the
viable design, due to the use of Petri dish-type collection surfaces in
place of near-to-fl at collection plates with the nonviable design.
Chapter 11 : AIM and EDA concepts have by now established a fi rm basis for their
adoption by stakeholders involved with OIP aerosol assessments.
However, consideration must now be given to the development of
processes based on sound scientifi c principles and supported by evi-
dence, for their adoption into the pharmacopeias and perhaps eventu-
ally into the regulatory guidance literature. This chapter provides an
outline of the pathways that both concepts will likely follow in order
to achieve this goal. The fact that these concepts are in harmony with
the Quality-by-Design principle should be advantageous to their
eventual acceptance by the regulatory agencies.
Chapter 12 : The application of an AIM-based approach, combined with improve-
ments to the architecture of the CI measurement system, in particular
the induction port, has been explored with the ultimate goal of making
improvements to the present less than satisfactory situation concern-
ing in vitro-in vivo relationships that exists with OIPs. Complete reso-
lution of the discrepancies between aerosol transport in impactors and
in the HRT cannot be attained, because, among many reasons, the
continuous reduction in fl ow velocity profi le along the length of the
HRT cannot be realized with current CI-based technology. However,
interfacing CIs (full resolution or abbreviated) with breathing simula-
tors is becoming more common, as more robust confi gurations for the
aerosol transport from inlet, where the fl ow rate is continuously varying,
to the CI, where it must be kept constant, are realized. These develop-
ments could avoid the need for parallel experiments, establishing TM
by fi lter collection and breathing simulation and later mass subfrac-
tions (i.e., CPF , FPF , and EPF ) by the CI method. The interface
between OIP and the measurement apparatus has to be considered
more carefully, in cases where the inhaler has a facemask instead of a
mouthpiece. Novel face models that simulate the skin and sub-skin
facial tissue resistance to an applied force in clinically realistic ways
when the facemask is fi tted are the way forward to the development of
more realistic testing conditions.
Search WWH ::




Custom Search