CROSS-LINKED CHONDROITIN SULFATE - CHARACTERIZATION FOR DRUG-DELIVERYPURPOSES

Chondroitin sulphate was cross-linked with 1,12-diaminododecane to giv e a series of cross-linked products with reduced water solubility. Sin ce the water solubility of the modified polymers is low, their chemica l characterization is complicated. A new method based on the adsorptio n of the cationic dye, methylene blue, on the cross-linked polymers wa s developed to characterize the degree of crosslinking. It was found t hat the values of the adsorptive capacity of the adsorbate, C-p(s), de creased with the extent of cross-linking. However, the values of the a dsorptive coefficient, K, and the free energy change of the adsorption reaction, Delta mu degrees, increased with cross-linking. The swellin g of films made of the cross-linked polymers was measured in water and an exponential-like dependency between the degree of swelling and ext ent of cross-linking could be defined. Indomethacin tablets made of tw o types of cross-linked polymers - very low water soluble and relative ly high water soluble - were made and analysed for their water uptake and drug release characteristics. Based on the physicochemical propert ies, an optimal product with a potential to serve as a colon-specific drug carrier was suggested.