Cyclodextrins for drug delivery

Cyclodextrins (CDs) are macrocyclic oligosaccharides composed of α(1,4)-linked glucopyranose subunits. These molecules possess a cage-like supramolecular structure, comparable with the structures of crown ethers, cryptands, spherands, cyclophanes, or calixarenes. However, it took 50 years to establish the molecular structure of CDs. Owing to their capability to form inclusion complexes with a variety of guest molecules, CDs are considered as the most important supramolecular host family among all supramolecular structures mentioned above. They can form complexes with various types of molecules including inorganic, organic, or organometallic that can be radical, cationic, anionic, or neutral molecules. This phenomenon bears the name "molecular recognition," while the selectivity in the formation of complexes with enantiomeric species as guests is called "chiral recognition." In addition, the properties of the molecules forming the complexes with CDs can be modified significantly. As such, a large number of scientists have attempted to elaborate and evaluate various CD derivatives that are able to complex a variety of drugs, enhancing by this way their in vivo solubility and activity. Moreover, a large number of publications describe CD uses in other fields such as foods, textile, cosmetics, or agriculture. This review reports on the recent developments of CDs in drug delivery using various routes of administration.