TECHNOLOGICAL PROPERTIES OF CRYSTALLINE AND AMORPHOUS ALPHA-CYCLODEXTRIN HYDRATES

In this study the technological properties of some crystalline and amo rphous modifications of alpha-cyclodextrin (alpha-Cd) were investigate d. The solid-state of alpha-Cd, as well as the amount and energy of cr ystal water and the presence of the alpha-Cd dehydrated form, play a r ole in the performance of the material as a pharmaceutical adjuvant. C ommon technological operations such as granulation, dehydration and re hydration, milling, compaction, etc. induce solid-state phase transfor mations of alpha-Cd which in turn influence the physical properties of the powder and of finished product (e.g. a tablet). The alpha-Cd soli d phases considered were the hexahydrate polymorph I in the pure state (both old batch recrystallized from water, B, and new batch, H), and also the hexahydrate polymorph I containing small amounts of dehydrate d alpha-Cd told batch, A), the nonstoichiometric hydrate with 7.57 mol of crystal water (alpha-Cd . 7.57H(2)O form III, C), two rehydrated s amples of dehydrated alpha-Cd (a new hydrated crystal form V, G, and a lpha-Cd . 6H(2)O form I, E) and two amorphous products (D, Fl. The tec hnological behaviour of each sample was evaluated in terms of flow pro perties, bulk and tapped density, compressibility and volume reduction for powders, and tensile strength, porosity and disintegration time f or compressed tablets (produced at five different force levels, from 5 0 to 300 kN). alpha-Cd . 7.57H(2)O, and both amorphous alpha-Cd sample s which all gave tablets whose characteristics were substantially inde pendent of the compression force displayed the most suitable technolog ical properties for a possible use as pharmaceutical adjuvants. (C) 19 98 Elsevier Science B.V. All rights reserved.