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

Amylodextrin, metastable amylodextrins, Amylose V and metastable amylo se were investigated on their dry binding properties. Amylose V showed poor binding properties. Both amylodextrin and metastable amylodextri n produced tablets showing crushing strengths comparable with microcry stalline cellulose, whereas tablets compressed from metastable amylose even showed crushing strengths which were more than 2-fold greater. B oth amylodextrin and metastable amylose showed a granular structure co mposed of very small primary particles (mean diameter 1-2 mu m). Durin g 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 i ncreasing 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 differenc e is explained by the higher specific surface area and poorer flowing properties of amylodextrin and metastable amylose, as compared to Amyl ose V.