Coating of Pharmaceutical Particles by Spouted Bed with a Draft Tube

Relationship between Coating Efficiency and Operating Conditions

Abstract

Although spouted bed with a draft tube is widely used in pharmaceutical particle coating to modify the release characteristics of various medicines, the coating condition and pharmaceutical formulation are determined based mostly on experiences and experiments. In the present work, we theoretically analyzed the coating process of a spouted bed with a draft tube by calculating particle trajectories in the draft tube and impaction efficiencies of sprayed mists onto a particle and obtained the coating efficiency. Furthermore, experiments were carried out to measure the coating efficiencies in a laboratory model of spouted bed. As a result, it was found that the number of seed particles in the draft tube was the most important parameter in determining the coating efficiency, suggesting that the coating efficiency can be raised by increasing the number concentration of seed particles.