Chemical Properties
White powder or crystal
Uses
A molecule used to solublize non-polar molecules such a cholesterol for use in cell culture.
Definition
ChEBI: Gamma-cyclodextrin is a cycloamylose composed of eight alpha-(1->4) linked D-glucopyranose units.
Production Methods
Cyclodextrins are manufactured by the enzymatic degradation of
starch using specialized bacteria. For example, β-cyclodextrin is
produced by the action of the enzyme cyclodextrin glucosyltransferase
upon starch or a starch hydrolysate. An organic solvent is
used to direct the reaction that produces β-cyclodextrin, and to
prevent the growth of microorganisms during the enzymatic
reaction. The insoluble complex of β-cyclodextrin and organic
solvent is separated from the noncyclic starch, and the organic
solvent is removed in vacuo so that less than 1 ppm of solvent
remains in the β-cyclodextrin. The β-cyclodextrin is then carbon
treated and crystallized from water, dried, and collected.
General Description
Cyclodextrins belongs to the family of cyclic α-1,4-glucans and is made of glucose units. This molecule has a shape of a hollow cone. It possesses a hydrophilic external and hydrophobic internal surface, because of which cyclodextrins can form inclusion complexes. γ-Cyclodextrin is extensively used in food and pharmaceutical industries. Cyclodextrins are obtained by the enzymatic conversion of starch/starch derivatives by cyclodextrin glycosyltransferase.
Flammability and Explosibility
Nonflammable
Pharmaceutical Applications
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. γ-cyclodextrin has the largest cavity and can be used to form inclusion complexes with large molecules;it has low toxicity and enhanced water solubility.
In parenteral formulations, cyclodextrins have been used to produce stable and soluble preparations of drugs that would otherwise have been formulated using a nonaqueous solvent.
In eye drop formulations, cyclodextrins form water-soluble complexes with lipophilic drugs such as corticosteroids. They have been shown to increase the water solubility of the drug; to enhance drug absorption into the eye; to improve aqueous stability; and to reduce local irritation.
Cyclodextrins have also been used in the formulation of solutions,suppositories, and cosmetics.
Safety
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, β-cyclodextrin
is not metabolized but accumulates in the kidneys as insoluble
cholesterol complexes, resulting in severe nephrotoxicity.
Cyclodextrin administered orally is metabolized by microflora in
the colon, forming the metabolites maltodextrin, maltose, and
glucose; these are themselves further metabolized before being
finally excreted as carbon dioxide and water. Although a study
published in 1957 suggested that orally administered cyclodextrins
were highly toxic, more recent animal toxicity studies in rats and
dogs have shown this not to be the case, and cyclodextrins are now
approved for use in food products and orally administered
pharmaceuticals in a number of countries.
Cyclodextrins are not irritant to the skin and eyes, or upon
inhalation. There is also no evidence to suggest that cyclodextrins
are mutagenic or teratogenic.
γ-Cyclodextrin
LD50 (rat, IP): 4.6 g/kg
LD50 (rat ,IV): 4.0 g/kg
LD50 (rat, oral): 8.0 g/kg
storage
Cyclodextrins should be stored in a tightly sealed container, in a
cool, dry place.Cyclodextrins are stable in the solid state if
protected from high humidity.
Regulatory Status
Included in the FDA Inactive Ingredients Database: α-cyclodextrin
(injection preparations); β-cyclodextrin (oral tablets, topical gels);
γ-cyclodextrin (IV injections).
Included in the Canadian List of Acceptable Non-medicinal
Ingredients (stabilizing agent; solubilizing agent ); and in oral and
rectal pharmaceutical formulations licensed in Europe, Japan, and
the USA.
