Mechanism of Enhancing Flowability and Tablet Hardness by Glidants in Pharmaceutical Powder Mixtures -Effects of Geometric Structure and Surface Wettability-

Abstract

This review deals with the effect of surface geometric structure and wettability of glidants on the flowability and com- pressibility of pharmaceutical powder mixture from microscopic aspects. For improving flowability, porous or fine non- porous structure is effective, independent of the surface wettability, and adhesion force between glidants and pharma- ceutical filler dominate flowability. Therefore, if glidants having the same particle diameter are added, porous structure is more effective to enhance the flowability, as porosity highly contributes to reduce the contact area and adhesion force due to rougher surface structure. As respect to compressibility, only porous and fine nonporous hydrophilic glidants can increase the tablet hardness when tabletted with lubricant. In particular, hydrophobic glidants have a deleterious effect and weaken tablet hardness. These trends indicate that microscopic structure and wettability are decisive factors to de- termine the macroscopic properties. This means that desired flowability and compressibility can be obtained by choos- ing the optimum microscopic structure and wettability of glidants.