Effect of operation conditions on coating of pharmaceutical pellets with a film of HPMC/PEG in a Wurster coater

Wurster coater was utilized for coating glass beads with HPMC/PEG. The effects of design and operating parameters on the coating process were evaluated.

It was found that the pressure drop decreases when spraying the coating solution into the bed, indicating that spraying prevents the particles from flowing easily in the draft tube. Moreover, it was observed that the minimum spouting velocity increases during the coating process.

The results indicated that increasing the entrainment zone height and decreasing the distributor hole pitch increase the coating yield, while the draft tube height did not have a significant influence on the coating yield. These findings were confirmed by thermogravimetric analysis (TGA). The degree of agglomeration intensifies when increasing the entrainment zone height, increasing draft tube height and decreasing the distributor hole pitch. Finally, scanning electron microscopy and energy dispersive X-ray spectroscopy analyses confirmed deposition of the coating material on the surface of particles. More on pellet coating