Particle Formation and Capture During Spray Drying of Inhalable Particles

• Published in: Pharmaceutical development and technology 2005-01, Vol.9 (4), p.409-417
• Main Authors: Mosén, Kristina, Bäckström, Kjell, Thalberg, Kyrre, Schaefer, Torben, Kristensen, Henning G., Axelsson, Anders
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Aerosols; Biological and medical sciences; Chemical Engineering; Chemistry, Pharmaceutical - methods; Chemistry, Physical - methods; Cyclone device efficiency; Droplet size; Drug Compounding - instrumentation; Drug Compounding - methods; Drug Compounding - standards; Drug Evaluation, Preclinical - methods; Engineering and Technology; General pharmacology; Inhalation; Kemiteknik; Mannitol; Mannitol - chemistry; Medical sciences; Particle Size; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Powders; Spray drying; Sweden; Teknik
• ISSN: 1083-7450; 1097-9867
• DOI: 10.1081/PDT-200035795

An investigation of the spray drying process is made in great detail regarding particle formation and capture efficiency with focus on the production of inhalable particles. Mannitol was spray dried as model substance and the spray-dried products were characterized. The resulting products consisted of smooth spheres with a volume median diameter of 2.2-5.5 µm, and narrow size distributions. The investigation was performed in pilot scale of sufficient size to draw general conclusions and make some recommendations. It has been shown that the size of particles is decreased when the feed concentration is decreased, the nozzle gas feed flow mass ratio increased, and the droplet size decreased. The collection efficiency of the cyclone device used in this study was shown to have a cut-off of 2 µm, i.e., 50% of the particles less than 2 µm are not captured. The data reported indicate that the majority of the single particles formed here, < 5 µm, arise from single droplets (of about 10 µm) and are solid, nonporous particles.