The AIM and EDA Concepts: Why They Are Needed and How They Fit Together - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 124

Fig. 5.6 Nomenclature for a hypothetical abbreviated impactor system based on the Andersen CI
operated at 28.3 L/min for potential HRT application (AIM-pHRT system)

and total mass of API ex metering valve, in this example that is based on the evalu-
ation of a pMDI, where it is necessary to distinguish between the two quantities,
since an add-on device may be interposed between the inhaler mouthpiece and the
entry to the CI system. It is only necessary to defi ne the total mass ex inhaler mouth-
piece for other types of OIP.
In the so-called AIM-pHRT apparatus, the boundary size delineating fi ne from
coarse mass fractions is fi xed at 5 m aerodynamic diameter, in accordance with

monographs 2.9.18 and 2.9.44 of the Ph. Eur. [ 19 , 26 ] (Fig. 5.6 ). It is important to
note that the standard Ph. Eur./USP induction port may be replaced by an idealized
upper airway, such as that developed by Finlay and colleagues [ 27 ], or an anatomi-
cally accurate model airway cast to add further realism in terms of the fl uid dynam-
ics associated with aerosol entry from the inhaler into the measurement system [ 28 ].
The development of AIM-pHRT systems is described in Chap. 12 , where it will be
seen that prototype systems have been successfully evaluated side by side with a
full-resolution CI as the reference technique.

µ