EFFECT OF SOME PHYSICAL PARAMETERS ON THE SWELLING PROPERTIES OF CROSS-LINKED AMYLOSE MATRICES

The influence of compression force (CF) on initial tablet porosity and water uptake kinetics in cross-linked amylose (CLA) matrices was dete rmined by mercury intrusion and gravimetry, respectively. Major change s in tablet porosity and pore size distribution occurred in the CF ran ge of 1-5 T with little or no effect on the gelation properties of CLA matrices. Compression properties of CLA tablets were also characteriz ed by electron scanning microscopy. The presence of macrovoids within micro- or non-porous regions was observed. This may reflect a certain fragmentation taking place in addition to plastic deformation during c ompression, The effect of pH, ionic strength and osmolarity of the med ium on the uptake properties of CLA tablets was also evaluated. Althou gh the swelling profiles of CLA matrices were found to be independent of pH (1.4-8) and of medium osmolarity (0-0.1 M sucrose solutions), a significant drop in the swelling capacity of tablets was observed with increased NaCl concentration. This decrease-not related to ionic inte ractions-may be due to changes in the gelation properties of the polym er. (C) 1998 Published by Elsevier Science B.V. All rights reserved.