Physical Causes of APSD Changes in Aerosols from OIPs and Their Impact on CI Measurements - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 59

Fig. 3.2 Regional particle deposition in an oral tidal-breathing adult ( Courtesy of Trudell Medical
International )

cystic fibrosis. There is also the potential for delivery of medication for systemic
rather than topical application via the lungs [ 17 ] because of the large surface area
for gas exchange to the blood circulation in the alveolar region.

3.3 Linking Aerosol Behavior to APSD Changes

3.3.1 Aerosol Formation from OIPs

This chapter has introduced the concepts that inhaled aerosols are useful for both
topical and systemic delivery of medication to the patient, using the HRT as the
portal of entry. However, aerosols are by their nature quasi-stable two-phase sys-
tems comprising either solid particles or liquid droplets (from now onwards referred
to collectively as particles) separated from each other by a supporting gas [ 18 ].

3.3.1.1 Dry Powder Inhalers

The aerosols produced by dry powder inhalers (DPIs) are the result of a combina-
tion of several factors that result in the de-aggregation of the bulk powder that is
stored either as a single-dose pre-metered unit (e.g., blister or capsule) until use or
as bulk powder within the inhaler. The physicochemistry of DPI formulations is