Complexes of Fat-Soluble Vitamins with Cyclodextrins

Vitamins are chemical compounds, or a group of closely related compounds known as vitamers, which are crucial for an organism's metabolic functions. Vitamins are categorized as either water-soluble or fat-soluble, with this second group composed of vitamins A, D, E, and K. The low aqueous solubility of these compounds often necessitates the use of pharmaceutical excipients to benefit from their medicinal efficiency. A successful example of this is the formation of the inclusion complexes with cyclodextrins (CDs), a group of cyclic oligosaccharides, composed of glucose subunits forming a macrocyclic ring. CD complexes with fat-soluble vitamins have been consistently utilized to accomplish diverse objectives, with CDs predominantly employed as solubilizers and absorption enhancers. This article examines studies detailing the synthesis and the biological, physicochemical, and structural characteristics of the inclusion complexes formed between fat-soluble vitamins and different cyclodextrins. This research demonstrates that although the fat-soluble vitamins form stable complexes with various CDs, the kind of CDs employed significantly influences the resultant properties of the complex formed.