Issue link: https://www.e-digitaleditions.com/i/1469783
Inhalation June 2022 15 Use of CFD for improving nasal spray designs and optimizing drug delivery In addition to the use of CFD to assess existing and generic nasal spray products, CFD can also be used as a tool to optimize nasal spray delivery and develop new devices with improved targeting. In this study, simulations show the effect of changes in spray noz- zle design on the spray transport and its impact on drug deposition in the posterior nasal region. For nasal sprays, there is considerable delivery to the anterior part of the nasal cavity, which increases with spray cone angle and, consequently, the poste- rior delivery decreases. Because the intended site of action for most nasal sprays is the posterior region, it would be beneficial to have maximum delivery to this region and also have a wider distribution of drug on the posterior nasal surface for maximum absorption. With the objective of optimizing nasal spray delivery and considering that plume geometry has a pronounced impact on nasal delivery, different spray nozzle designs that produce sprays with dif- ferent plume ovality were tested using CFD. While CFD could be used to simulate different spray noz- zle designs and their effect on liquid atomization and droplet formation, for brevity, this study focused on envisioned outcomes of nozzle designs by simulating droplets injected from the designed nozzle surface. Two nozzle designs were considered that produced sprays with plume ovality ratios of either 1.0 or 1.5 Figure 2 shows the locations of the deposited spray droplets for each spray cone angle. It was observed that with an increase in cone angle, the spray cover- age increased and resulted in greater dispersed depo- sition along the direction of the spray projection. e momentum-jet developed due to the momentum transfer from the spray droplets to the air molecules (two-way coupling) is also plotted as sub-figure pan- els. e results indicate that with an increase in cone angle, the anterior deposition increases, while the posterior deposition decreases. Figure 2 also shows the parameter RD_PD plotted against the relative change in cone angle with respect to the baseline case and captures the influence of variability in spray cone angle on posterior deposition. e gradient of the RD_PD trend line indicates that small changes in spray cone angle will influence the nasal drug delivery profile. is procedure could also be used to compare the delivery efficiency of a generic spray to a reference spray by comparing the slope of the RD_PD trend line. e trend line provides a way to map differences in the in vitro metric to differences in expected pos- terior nasal drug delivery. For example, the generic sprayer may have a 30% relative difference in the spray cone angle compared with the reference listed product, which would result in a 30% x 0.73 = 21.9% relative difference in posterior nasal deposition.