Calcium Chloride

Calcium chloride was applied as a cross‑linking agent to modify the structure of alginate microparticles produced by a one‑step spray drying technique. The goal of the study was to prolong the release of freely water‑soluble drugs from alginate‑based delivery systems, using metformin hydrochloride as a model compound. Cross‑linking of the alginate structure with calcium chloride reduced the swelling ratio of the particles and improved their mucoadhesive properties, which were evaluated on porcine stomach mucosa. Particles prepared from 2% alginate cross‑linked with 0.1% calcium chloride displayed a prolonged metformin release profile lasting up to 12 hours. The applied spray drying method simplified production, offering a fast, continuous, and scalable process that yielded products with low moisture content, high drug loading, and high production efficiency.

Fig. 1 Structure of non-modified (a) and CaCl2 cross-linked (b) ALG microparticles containing MF. (Szekalska M.; et al. 2018)

Calcium chloride is identified as the most suitable cross-linker for sodium alginate in the development of microsphere-based drug delivery systems. Alginate is a natural polysaccharide polymer valued for its biocompatibility, low toxicity, low cost, and ease of chemical modification. Research on calcium-alginate microspheres for delivering various therapeutic agents has covered in vitro drug release characteristics, biological activity, stability, and in vivo evaluations. The cross-linking function of calcium chloride is critical for controlling the release kinetics, timing, and site of action of the encapsulated drugs, thereby improving their overall efficacy and safety.

Fig. 2 Schematic structure of egg box calcium-alginate. (Amiruddin A.; et al. 2025)