Spray Drying of Aqueous Salbutamol Sulfate Solutions Using the Nano Spray Dryer B-90—The Impact of Process Parameters on Particle Size

Abstract

In order to prepare spherical salbutamol sulfate particles of adjustable size, a Nano Spray Dryer B-90 was employed. A 3³ full-factorial design was used to investigate the influence of process parameters (mesh size, feed concentration, and drying air temperature) on particle size (median size and width of the particle size distribution), amount of product produced per time, and product yield. The median particle size was significantly influenced by all three factors of the statistical design. Within the design space studied, particle sizes of 1.0 to 6.4 µm were obtained. The width of the particle size distribution (span) increased with increasing mesh sizes. All particles with a particle size greater than 2.4 µm showed a bimodal particle size distribution. Generally, larger mesh sizes as well as higher concentrations led to an increase in the amount of product prepared per time. The corresponding values observed were from 0.4 to 75.8 mg/min. The product yield was independent of the process parameters studied. All products were amorphous after spray drying and were stable up to a relative humidity of 60% at a temperature of 25°C.

Keywords:

• Dry powder inhaler (DPI)
• Nano spray dryer B-90
• Particles size
• Product produced per time
• Product yield
• Salbutamol sulfate
• Span
• Spray drying

ACKNOWLEDGMENTS

The authors thank the German Research Foundation (DFG) for financial support within the priority program SPP 1423 “Prozess-Spray” and Hartmuth Schroettner (Austrian Centre for Electron Microscopy and Nanoanalysis, Graz University of Technology) for his help with SEM.

Notes

E. M. Littringer and S. Zellnitz contributed equally to this work.