Modified cyclodextrins and their application in drug delivery

Abstract

Cyclodextrins (CDs) are cyclic oligosaccharides containing intersaccharide α-1,4-glycosidic bonds. The most common CDs are those consisting of six, seven, and eight glucose units, which are called α-, β-, and γ-cyclodextrins. The native CDs have limited aqueous solubility therefore they have limited application in drug delivery system. Cyclodextrins could be modified through substituting various functional compounds on the primary and/or the secondary rim of the molecule. Through modification, the applications of cyclodextrins can be expanded. Modified cyclodextrins (MCDs) have much higher aqueous solubility compared to the parent and the property of molecular recognition of MCDs can be utilized for targeted drug delivery. In the pharmaceutical industry, MCDs have mainly been used as complexing agents to increase aqueous solubility of poorly soluble drugs and to increase their bioavailability and stability. Moreover, the future prospects of MCDs, especially mono-substituted CDs, are quite bright since they are single isomer and possess remarkably unique properties of forming inclusion complexes with drugs.