Preparation and evaluation of sustained release tablets prepared with .ALPHA.-starch.

A compressed tablet prepared from α-starch adsorbed water from the release medium and formed a gel, starting from the tablet surface. Theophylline was released slowly through the gelled layer. Release rates of theophylline from tablets prepared with α-starches from different sources were different. Release rates of theophylline from the tablets were faster in an acidic medium than in a neutral medium. The release rate of theophylline was faster in a medium containing α-amylase than in a medium without the enzyme.Salivary levels were lower but were sustained for longer following oral administration of an α-starch tablet than those after administration of a rapidly dissolving tablet.