Cyclodextrins

Synonyms: Cyclodextrin Cavitron; cyclic oligosaccharide; cycloamylose; cycloglucan; Encapsin; Schardinger dextrin.
a-Cyclodextrin alfadexum; alpha-cycloamylose; alpha-cyclodextrin; alpha dextrin; Cavamax W6 Pharma; cyclohexaamylose; cyclomaltohexose.
b-Cyclodextrin beta-cycloamylose; beta-dextrin; betadexum; Cavamax W7 Pharma; cycloheptaamylose; cycloheptaglucan; cyclomaltoheptose; Kleptose.

Description: Cyclodextrins are cyclic oligosaccharides containing at least six D- (þ)-glucopyranose units attached by a(1 4) glucoside bonds. The three natural cyclodextrins, a, b, and g, differ in their ring size and solubility. They contain 6, 7, or 8 glucose units, respectively. Cyclodextrins occur as white, practically odorless, fine crystalline powders, having a slightly sweet taste. Some cyclodextrin derivatives occur as amorphous powders.

Chemical Name: a-Cyclodextrin

b-Cyclodextrin
g-Cyclodextrin

Solubilizing agent; stabilizing agent.

• Cyclodextrins are crystalline, nonhygroscopic, cyclic oligosaccharides derived from starch. Among the most commonly used forms are a-, b-, and g-cyclodextrin, which have respectively 6, 7, and 8 glucose units.

• Substituted cyclodextrin derivatives are also available.

• Cyclodextrins are ‘bucketlike’ or ‘conelike’ toroid molecules, with a rigid structure and a central cavity, the size of which varies according to the cyclodextrin type.

• The internal surface of the cavity is hydrophobic and the outside of the torus is hydrophilic; this is due to the arrangement of hydroxyl groups within the molecule.

• This arrangement permits the cyclodextrin to accommodate a guest molecule within the cavity, forming an inclusion complex.

• Cyclodextrins may be used to form inclusion complexes with a variety of drug molecules, resulting primarily in improvements to dissolution and bioavailability owing to enhanced solubility and improved chemical and physical stability.

• Cyclodextrin inclusion complexes have also been used to mask the unpleasant taste of active materials and to convert a liquid substance into a solid material. b-Cyclodextrin is the most commonly used cyclodextrin, although it is the least soluble.

• It is the least expensive cyclodextrin; is commercially available from a number of sources; and is able to form inclusion complexes with a number of molecules of pharmaceutical interest.

• However, b-cyclodextrin is nephrotoxic and should not be used in parenteral formulations.

• b-Cyclodextrin is primarily used in tablet and capsule formulations.

The activity of some antimicrobial preservatives in aqueous solution can be reduced in the presence of hydroxypropyl-b- cyclodextrin

Cyclodextrins are starch derivatives and are mainly used in oral and parenteral pharmaceutical formulations. They are also used in topical and ophthalmic formulations. Cyclodextrins are also used in cosmetics and food products, and are generally regarded as essentially nontoxic and nonirritant materials. However, when administered parenterally, b-cyclodextrin is not metabolized but accumulates in the kidneys as insoluble cholesterol complexes, resulting in severe nephrotoxicity

Observe normal precautions appropriate to the circumstances and quantity of material handled. Cyclodextrins are fine organic powders and should be handled in a well-ventilated environment. Efforts should be made to limit the generation of dust, which can be explosive

Dimethyl-b-cyclodextrin; 2-hydroxyethyl-b-cyclodextrin; hydroxypropyl betadex; sulfobutylether b-cyclodextrin; trimethyl-b-cyclodextrin.