Preparation, characterization and application of linear dextrins. Part VI. General applicability and mechanism of programmed release from amylodextrin tablets

Abstract

This study reports the successful application of amylodextrin as a unique excipient in the design of programmed release systems. Physical mixtures of amylodextrin with the model compounds theophylline, paracetamol, methyl-PABA, prednisolone, atrazine, procaine HCl and potassium dichromate, respectively, were compressed into almost non-porous tablets and tested on their release profile, determined at pH 6.8 in the USP XXI paddle apparatus. All tablets did not disintegrate and showed almost constant release rates. Zero-order release of paracetamol was not affected by pH and ionic strength of the dissolution medium. Lubrication with magnesium stearate was found not to impair the release profile of potassium dichromate-amylodextrin tablets. Zero-order release from the amylodextrin tablets is explained by the mechanism of water penetration into the polymer associated with polymeric relaxations controlling the drug diffusional release. Immersion in phosphate buffer of tablets, compressed from a physical mixture of amylodextrin with neutral red, indeed demonstrated movement with an almost constant rate of a coloured front into the delivery system.