Cyclodextrins

Cyclodextrins are non-toxic cyclic polysaccharides. They form inclusion complexes with numerous organic molecules. The physical and chemical properties of the guest molecules change due to complex formation. Cyclodextrins (CDs) are chemically cyclic oligosaccharides which have been recognized as useful pharmaceutical excipients. Cyclodextrins are versatile pharmaceutical excipients used to enhance the solubility, stability, safety and bioavailability of drug. Besides, being used to reduce gastrointestinal drug irritation, convert liquid drug into microcrystalline or amorphous powder, and prevent drug-drug and drug-excipients interactions. The solubility of slightly soluble molecules may be increased by cyclodextrin inclusion complex. As a result of molecular complexation phenomena cyclodextrins are widely used in many industrial products, technologies and analytical methods.

This article deals with cyclodextrin (CD) based functional rotaxanes and polyrotaxanes for drug delivery. First, we present an overview of polyrotaxane preparations for biomaterials applications. Then we bring to light the studies and strategies implied for augmented drug delivery using CD-based polyrotaxanes. The concept for enhancing multivalent interaction of a ligand-mobile polyrotaxane with receptor proteins; which is significantly related to receptor-mediated drug delivery and the efficiency of ligand-conjugated polyrotaxanes is also demonstrated in the design of inhibitors which are recognized by intestinal transporters in mammalian tissues but neither absorbed into the tissue nor exhibiting any toxicity. This concept is of more practical applications, the studies on cytocleavable polyrotaxanes for gene delivery is the modern therapy. The dynamic motion of polyrotaxanes would contribute significantly to forming a polyplex with DNA to be delivered into target cells. Moreover, dissociating the polyrotaxane structure in intracellular environments is an effective way to release DNA for transfection at the nucleus. Furthermore, polyrotaxanes are also useful in manifestation of Niemann-pick type C disease. In present article, efforts have been taken with the intention to get thorough information of polyrotaxanes conjugation with drug/ligands along with a comprehensive review of diverse approaches adopted for drug delivery till date.