Direct Encapsulation Method for Controlled Release of (E)-3-[2-(thiazol-2-yl)hydrazinylidene]- chroman-2,4-dione as Promising Anticancer Substances in Calcium-linked Alginate Gels

In this paper, a direct encapsulation method for loading water-insoluble thiazolohydrazinylidene-chroman-dione in alginate gels for controlled drug delivery systems is presented. Calcium cross-linked alginate gels have been prepared and used as a controlled release system for the most promising anti-carcinogenic of a series of coumarin substances - (E)-3-[2-(thiazol-2-yl)hydrazinylidene]chroman-2,4- dione. Prolonged ultrasound treatment was used to prepare water solution of the active substance at concentrations of 1 mg/dl. These direct encapsulation method for loading an active substance within a gel matrix produces excellent homogenicity and 100% encapsulation efficiency of the substance in the gel. Due to the preparation of cylindrically shaped hydrogels, the system can be modeled using Korsmeyer-Pepas relation for Fikian diffusion of cylindrically shaped delivery systems. The time- dependent release kinetics shows a diffusion coefficient of 0.4 and a kinetic constant depends on cross-link ratio, alginate concentration and p H of the release medium. The gel matrix used in this research releases 30% to 50% of the active substance Within 4 hours of rehydration from completely dry form. The way the chroman is released points to molecular interactions between the alginate and the chroman that can be broken by diffusion of water inside the gel, thus releasing the active substance in a water-soluble molecular form. (author)