A new generation of starch products as excipient in pharmaceutical tablets. I. Preparation and binding properties of high surface area potato starch products

A new pharmaceutical excipient with a high binding capacity was prepared from potato starch by enzymatic degradation, followed by suitable dehydration of the precipitated and filtered retrograded starch to produce high specific surface area products. Thermal dehydration methods like drying at room or elevated temperature and spray-drying resulted in particulate solids with low specific surface area, as measured by nitrogen adsorption, and low compactibility. Both freeze-drying and chemical desiccation, like washing with ethanol or acetone, produced powders with strongly increased specific surface area and increased binding capacity. The compactibility of the final products showed a positive correlation with the specific surface area, changing at high surface areas into constant compactibility. Moreover, the binding capacity appeared to increase with the moisture content of the products.