Using Computational Fluid Dynamics (CFD) to Improve the Bi-Directional Nasal Drug Delivery Concept

Nasal delivery is considered for an increasing number of existing and new drugs and vaccines, but current nasal delivery devices have major disadvantages. The Norwegian company OptiNose AS is developing a novel concept that challenges traditional delivery systems. The patended bi-directional delivery system improves drug and vaccine distribution to the nasal mucous membrane while at the same time preventing lung deposition. It takes advantage of the posterior connection between the nasal passages persisting when the velum automatically closes during oral exhalation. It is the exhalation into the delivery device that triggers the release of particles into an airflow, which enters one nostril via a sealing nozzle and exits through the other nostril.This paper describes how OptiNose is using Computational Fluid Dynamics (CFD) during the development process for their drug delivery concept. The simulations are used to visualize and demonstrate the basic features of the bi-directional technique and discuss how its design and function could be further optimized. CFD computations thus increase the efficiency of device development and reduce the need for expensive and time consuming laboratory experiments. To perform successful CFD calculations on the nose, construction of a proper surface grid of the nasal cavity is important. The process of building the surface grid is presented in the paper. The final surface grid was next imported into Tgrid, a volume grid generator, and finally the simulations were carried out by use of the commercial CFD code FLUENT. These steps are described in the paper. Testing of the cell quality, both during surface grid and volume grid generation, is mandatory. The testing procedures are briefly presented in the paper. Finally, to be able to rely on the CFD computations done, one needs thorough validation. This article presents some comparison of the CFD computation results against physical experiments. The comparison analysis shows promising results.