Characterization and drug delivery behaviour of starch-based hydrogels prepared via isostatic ultrahigh pressure

The purpose of our study was to investigate the applicability of isostatic ultra high pressure (IUHP) for the aim of drug formulation. Aqueous suspensions of potato and maize starches containing theophylline as a model drug were subjected to IUHP. The changes in the structure and morphology of potato and maize starches were investigated. The release profile of theophylline from the pressurized samples was also studied. The aqueous suspensions subjected to IUHP turned into highly viscous gels. The crystalline structure of maize starch was changed, while PS pressurized in aqueous medium retained its original X-ray pattern. The sample containing potato starch as a gel-forming polymer exhibited faster drug dissolution compared to an aqueous theophylline suspension used as a reference, while the pressurization of maize starch resulted in a gel exhibiting sustained drug release. The results of the dissolution study can be explained with the changes in structure and morphology of the starches caused by IUHP processing and with the different pressure sensitivities of PS and MS.