Biomedical Engineering Reference
In-Depth Information
Fig. 9.15 NGI stage deposition (mean ± SD) profi le in relation to LPM and SPM with bound size
at 2.30
μ
m aerodynamic diameter ( From [ 11 ] —used with permission )
9.5
Case Studies in Which EDA Has Been Successfully Applied
Perhaps the most signifi cant way in which to demonstrate the potential of the EDA
principle is through case studies with OIPs, based on real-life experience. The fi rst
such study was undertaken at Catalent Pharma Solutions and reported by Mao et al.
[ 11 ]. This group applied EDA to analyze three separate studies where the NGI had
been used to measure APSDs of aerosols emitted by a group of HFA-based solution
MDIs. These data were pooled for the analysis.
All NGI measurements were performed at 30 L/min on the same model solution
MDIs for each of the three separate series. The raw data expressed in terms of mass-
per-CI component were assessed in terms of grouped stages as follows:
1. Group 2 = sum of drug deposited on stages 1-3
2. Group 3 = sum of drug deposited on stages 4-6
3. Group 4 = sum of drug deposited on stage 7 to the MOC
Group 1, which was not part of the analysis, comprised the sum of the mass of API
collecting in the non-sizing components (i.e., induction port) upstream of the NGI.
MMAD values for the APSD were calculated using CITDAS ® (version 2.0,
Copley Scientifi c Ltd, Nottingham, UK) that interpolates the data points from the
cumulative mass-weighted APSD closest to the 50th mass percentile. LPM was cal-
culated as the sum of API mass deposited on each of the stages above and including
the stage at the d 50 value defi ning the bound between small and large particles (e.g.,
stage 3 with its d 50 size corresponding to 3.99
μ
m aerodynamic diameter associated
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