(T0930-09-50) Aerodynamic Performance of Inhalable Zinc Oxide Microparticles as Carriers for Dry Powder Inhalers

Purpose: The aim of this study was to utilize particle engineering to prepare zinc oxide microparticles with distinctive shapes and sizes, investigate how the characteristics of these microparticles influence inhalation patterns and efficiency, and evaluate the potential of zinc oxide as a carrier for dry powder inhalers (DPIs).

Methods: The inhalable zinc oxide microparticles were prepared via thermal precipitation. The preparation process included a reaction conducted in a drying oven at 100°C for approximately 1 hour. Each prepared zinc oxide microparticle was formulated by manual mixing with budesonide at a 1:1 weight ratio. The morphology of the particles was observed using scanning electron microscopy (SEM, Zeiss Group, Germany). Particle image velocimetry (PIV) was performed by inhaling the particles for 4 seconds at a flow rate of 60 L/min using a vacuum pump. An 8 mV laser sheet beam (specification: 532 nm) was generated parallel to the apparatus using a diode laser (LaserLab, Yongin, KR). Particle behavior images were captured at 8000 frames per second and 640 × 480 pixel resolution using a high-speed camera (HAS-D71M, DITECT Corporation, JP) positioned perpendicular to the laser sheet plane. The aerodynamic performance was evaluated using a next-generation impactor (NGI, Copley Scientific Limited, UK). The aerodynamic performance was evaluated through the emission rate (ED), fine particle fraction (FPF), mass median aerodynamic diameter (MMAD), and geometric standard deviation (GSD). Statistical analysis was performed using two-way ANOVA, followed by post hoc testing with Tukey's test. Statistical significance was set at p < 0.05. All data are expressed as the mean ± standard deviation (SD), with n ≥ 3.

Results: The different particle sizes and shapes of F1 to F3 were confirmed using SEM. Spherical F1 particles primarily exhibited streamlined dispersion rather than linear dispersion along the main flow path. Small star-shaped F2 particles demonstrated a combination of high-speed linear dispersion and dispersion with turbulences. Large star-shaped F3 particles displayed relatively narrow linear dispersion with turbulences. Among the inhalation efficiencies, there was no statistical difference in ED and GSD. However, FPF showed the most significant differences between F2 and F3. MMAD exhibited significant differences between F2 and F1, as well as between F2 and F3. The F2 particles, which display a complex dispersion pattern, are presumed to create various turbulent conditions, likely influencing inhalation efficiency.

Conclusion: The preparation of zinc oxide microparticles with controlled size and shape was investigated, and the impact of inhalation patterns on inhalation efficiency was evaluated. The engineering of zinc oxide microparticles confirmed their potential feasibility as carriers.

Acknowledgements: This research was supported by “Regional Innovation Strategy (RIS)” through the National Re-search Foundation of Korea (NRF) funded by the Ministry of Education (MOE) (2021RIS-001), grants funded by the Korean government (NRF-2021R1A2C4002746 and 2017R1A5A2015541), and a grant from the Korea Health Technology R&D Project through the Korea Health Industry De-velopment Institute (KHIDI) funded by the Ministry of Health and Welfare, Republic of Korea (HI14C1069).