Abstract:
 A dry powder inhaler is a drug delivery device widely used to treat respiratory diseases. But the efficiency of drug delivery can be affected by a number of factors. At present, due to the large population of patients with respiratory diseases and the wide age span of patients, there are great differences between children and adults in the geometric structure of the respiratory tract and the way of using the inhalation drug delivery device. Therefore, a comparative study on the deposition mechanism of inhaled drug particles in the respiratory tract of children and adults is of great significance for improving the inhalation drug delivery device and improving the deposition efficiency of drug particles.
In this paper, based on CT images collected during the real administration of children and adults, a real oral model of children and adults under the condition of administration was constructed. Meanwhile, the geometric model of the drug delivery device Breezhaler^® was reconstructed. Using computational fluid dynamics (CFD) -discrete phase method (DPM), the simulation and comparison experiments of 1 ~ 30mm particle deposition were carried out under different air flow rates (30, 60, 90 L/min), aiming at the combined model of real oral cavity and inhalation device for 3 groups of adults and children. It is concluded that the vertical distance (L_D) from the nozzle outlet of the suction device to the tongue surface has a significant effect on the deposition of particles, and the smaller the L_D, the larger the deposition of particles on the tongue surface. Oropharyngeal diameter (R_D) also has an effect on the deposition of particles, and the larger R_D, the smaller the deposition of particles in the oral area. R_D in children is generally smaller than in adults, so the deposition of particles in the oral site is generally higher than in adults. This study provides relevant basis for the improvement of inhalation devices and the optimization of the use of inhalation devices in children and adults.

Key words: CFD, oral inhalation preparations, dry powder inhalers, upper respiratory tract in children and adults, numerical simulation, particle deposition mechanism
 

Key words: CFD, oral inhalation preparations, dry powder inhalers, upper respiratory tract in children and adults, numerical simulation, particle deposition mechanism