Validating CFD predictions of nasal spray deposition: Inclusion of cloud motion effects for two spray pump designs

Abstract

Momentum transfer from nasal spray droplets to the surrounding gas may create droplet cloud motion and influence nasal deposition patterns. The objective of this study was to develop a validated computational fluid dynamics (CFD) model of nasal spray deposition for two different spray-pump designs that includes cloud motion effects (i.e. two-way coupling) in a computationally efficient manner. Spray droplet transport and deposition were simulated in an average adult nasal airway model (that captures average drug delivery) using both two-way coupled and one-way coupled Euler-Lagrange frameworks. CFD model accuracy was established by comparing predictions of the two-way and one-way modeling frameworks with in vitro measurements. The two-way coupled simulation showed that momentum from the spray cloud resulted in displacement of surrounding gas, leading to an upward air velocity in the direction of the spray, which significantly increased the travel distance of smaller droplets with diameters equal to a median diameter of ∼70 µm and below. For the Flonase Sensimist spray pump, two-way coupling produced <10% relative error in posterior deposition fraction compared with the in vitro data, versus 47% relative error using one-way coupling. For the Flonase spray pump, two-way coupling did not improve posterior deposition agreement with both methods having a relative error of ∼30%; however, two-way coupling showed substantial increase in posterior deposition. As a result, two-way coupling is likely needed for the simulation of most nasal spray pumps and additional factors may be important to better capture final formulation distribution of the Flonase product, like post-deposition liquid motion.

Copyright © 2021 American Association for Aerosol Research

EDITOR:

• Yannis Drossinos

Acknowledgments

Views expressed in this article do not necessarily reflect the official policies of the U.S. Food and Drug Administration, nor does any mention of trade names, commercial practices, or organization imply endorsement by the United States Government. Laboratory assistance provided by Dr. Michele Dario Manniello is also gratefully acknowledged.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article.

Additional information

Funding

Funding was provided by Contract HHSF223201810144C, from the Department of Health and Human Services, U.S. Food and Drug Administration.