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16 June 2022 Inhalation Conclusion is article provides a short perspective on CFD simulations of nasal spray transport and use of CFD modeling to design nasal spray devices and analyze spray delivery performance. Overall, as illustrated in this article, in silico testing using CFD, guided with in vitro measurements, is a potentially valuable approach that can reduce the time and cost associ- ated with evaluating nasal spray delivery performance under variable usage conditions in realistic nasal air- way models. Funding and disclaimer Funding was provided by Contract HHSF2232 01810144C from the Department of Health and Human Services, US Food and Drug Administra- tion. Views expressed in this manuscript do not nec- essarily reflect the official policies of the US Food and Drug Administration, nor does any mention of trade names, commercial practices or organizations imply endorsement by the United States Government. References 1. Kolanjiyil AV, Hosseini S, Alfaifi A, Hindle M, Golshahi L and Longest PW: Importance of cloud motion and two-way momentum coupling in the transport of pharmaceutical nasal sprays. Journal of Aerosol Science 2021,156. 2. Kundoor V and Dalby R: Effect of formulation- and administration-related variables on deposition pattern of nasal spray pumps evaluated using a nasal cast. Pharmaceutical Research 2011,28:1895-1904. (Figure 3). Since the spray pump insertion axis with respect to the nasal valve was also found to affect the posterior nasal delivery, two pump insertion axes (the transverse and sagittal axes, shown in Figure 3) were considered in the study. Simulation results indicated that when the plume had the major axis in the trans- verse direction with the plume width decreased in the sagittal direction, the posterior delivery was similar to the circular spray nozzle, but with reduced drug distribution on the nasal surface. However, when the plume had the major axis in the sagittal direction with the width decreased in the transverse direction, there was marked improvement in the drug delivery to the posterior region, while maintaining high drug distri- bution on the nasal surface. erefore, an oval spray nozzle with the major plume axis aligned with the sagittal axis provided improved delivery to the pos- terior nasal region. To physically produce this device, a spray pump manufactured with an oval actuator body could ensure that spray pump insertion lines up with the nostril opening, while an oval spray noz- zle orthogonal to the actuator body would ensure an oval spray plume with alignment in the sagittal axis direction (Figure 3). e quantitative relationships identified here may be impacted by different insertion conditions includ- ing depth and angle; however, it is expected that the qualitative trends identified will remain unchanged under normal use conditions. Further analysis using different nasal airway models with different insertion conditions are required to complement the findings of this study. Figure 3 Spray nozzle designs and the related impact on nasal drug delivery. Also shown is an oval nozzle design for improved posterior delivery. Oval spray pump Ovality = 1 Ovality = 1.5 Transversal axis Ovality = 1.5 Sagittal axis Plane of observation Posterior delivery = 69% Posterior delivery = 70% Posterior delivery = 93%