PREPARATION, CHARACTERIZATION AND PHARMACEUTICAL APPLICATION OF LINEAR DEXTRINS .5. STUDY ON THE BINDING-PROPERTIES OF AMYLODEXTRIN, METASTABLE AMYLODEXTRIN AND METASTABLE AMYLOSE

Abstract

Amylodextrin, metastable amylodextrins, Amylose V and metastable amylose were investigated on their dry binding properties. Amylose V showed poor binding properties. Both amylodextrin and metastable amylodextrin produced tablets showing crushing strengths comparable with microcrystalline cellulose, whereas tablets compressed from metastable amylose even showed crushing strengths which were more than 2-fold greater. Both amylodextrin and metastable amylose showed a granular structure composed of very small primary particles (mean diameter 1-2 mu m). During compression the granulates disaggregated into the primary particles. The latter deformed plastically followed by the formation of hydrogen bonds. Plastic deformation was confirmed by force-displacement curves and formation of hydrogen bonds was supported by the observation of increasing binding on increasing moisture content. Neither amylodextrin nor metastable amylose showed susceptibility for magnesium stearate, while Amylose V did show sensitivity for this lubricant. The difference is explained by the higher specific surface area and poorer flowing properties of amylodextrin and metastable amylose, as compared to Amylose V