Case Studies in the Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 301

Fig. 8.56 (continued)

8.4.8 Implications for Nasal Drug Delivery

The absorption of nasal drug formulations into the bloodstream occurs most effec-
tively in the main nasal passage (middle region) where curved turbinate structures
exist (Davis and Illum 2003). The benefits of targeted drug delivery are evident in
improving its efficacy while also reducing the bitter taste that users may experience
from swallowing, mucociliary action, or forced movement by further sniffing. Cur-
rent spray device designs administer drug formulations in a vertical position (Kublik
and Vidgren 1998). This contradicts the directional path of the nasal cavity which is
horizontal and often leads to high particle impaction at the top of the nostrils. This
can improved by spray atomizer designs that produce finer droplet sizes to reduce the
inertial propery of the particle, leading to less particles impacting early within the
nostrils. Furthermore this may also enhance the absorption of drugs since aqueous
drug solutions with small molecular size are more rapidly absorbed via the aqueous
path of the mucous membrane.
The results from the case study were aimed at gaining a greater insight into what
parameters are important in the design of nasal drug delivery devices. The results