Using a representative powder blend containing ibuprofen, the applicability of coating with silica nanoparticles using a dry comilling process to effectively enhance flowability of formulated pharmaceutical powders was investigated. Using a shear cell, we systematically studied effects of process parameters, including the total number of comilling cycles, silica loading level, type of screen (mesh size), impeller speed, and impeller type, on the efficiency of the nanocoating process. Impact of silica coating on powder tabletability was also assessed using a compaction simulator. Results confirm that coating with silica nano particles significantly improves flowability of the formulated ibuprofen blend. The two most prominent factors that lead to flowability improvement are 1) repeated comilling cycles and 2) higher silica loading. In addition, we have observed that simple blending is effective in coating silica nanoparticles to improve flowability of the formulated ibuprofen powders, which is not very cohesive. This suggests the possibility of improving flowability of a sub-optimum formulation by prolonging the blending process in presence of colloidal silica. Moreover, silica coated ibuprofen blend exhibits improved tabletability and compactibility without significantly impacting compressibility. The simultaneous improvement in powder tabletability and flowability shows the potential of the nanocoating strategy in improving tablet manufacturability of pharmaceutical powders.
Bibliographical noteFunding Information:
This work was partially supported by a grant from Merck & Co. , Inc. SEM experiments were carried out at the Characterization Facility of University of Minnesota. We thank Dr. Yushi Feng for help in particle size analysis.
- Colloidal silica
- Powder flow
- Surface coating