Betadex (beta-cyclodextrin)

• BPBetadex
• JPBetadex
• Ph. Eur.Betadex
• USP–NFBetadex

β-Cyclodextrin; beta-cycloamylose; betadexum; Cavamax W7; cycloheptaamylose; cyclomaltoheptaose; Kleptose; E459

Cyclo-α-(1→4)-heptakis(D-glucopyranose) · [7585-39-9]

UNII JV039JZZ3A · PubChem CID 444041

C42H70O35 · 1134.98

Solubilising agent

Typical concentrations: — · Dosage forms: Solid, Liquid

Used mainly to form inclusion complexes that improve the aqueous solubility, dissolution rate, chemical and physical stability or bioavailability of poorly soluble drugs, and to mask unpleasant tastes and odours or convert liquids and volatile substances into stable powders. It is used in oral tablets, capsules and topical products and as a direct-compression diluent; the amount is usually set by the molar ratio needed for complexation (often 1:1 or 1:2 drug:cyclodextrin).

A white or almost white, practically odourless, crystalline powder with a slightly sweet taste. It is a cyclic oligosaccharide of seven α-(1→4)-linked glucopyranose units, shaped like a truncated cone with a hydrophobic central cavity and a hydrophilic outer surface.

Cavity diameter

≈ 6.0–6.5 Å (seven glucose units)

Solubility

sparingly soluble in water (about 1.85 g per 100 mL at 25 °C, increasing with temperature); practically insoluble in ethanol and acetone

Water content

not more than about 14% w/w (it is a hydrate)

Specific rotation

≈ +160° to +164° (1% w/v in water)

Melting point

decomposes above about 255 °C without a sharp melting point

Stable in the solid state. It is resistant to alkaline hydrolysis but is slowly hydrolysed by strong acids, and it is degraded by some amylases. Store in a well-closed container in a cool, dry place.

Can complex and thereby reduce the activity of some preservatives (for example parabens and quaternary ammonium compounds) and flavours. It is incompatible with strong oxidising agents.

Produced by the action of the enzyme cyclodextrin glycosyltransferase, obtained from Bacillus species, on partially hydrolysed starch; betadex is separated from the other cyclodextrins by selective precipitation or crystallisation and purified.

Poorly absorbed after oral administration and largely digested by colonic bacteria, so oral use is regarded as safe; JECFA has set an ADI of 0–5 mg/kg body weight. It is nephrotoxic when given parenterally, because of its low solubility and accumulation in the kidney, and is therefore not used in injections.

Observe normal precautions for the quantity handled. Avoid dust generation; eye protection and a dust mask are recommended.

Accepted as a food additive in Europe (E459). Included in the FDA Inactive Ingredient Database (oral tablets and topical preparations) and in non-parenteral medicines licensed in Europe.

Alfadex (α-cyclodextrin); gammadex (γ-cyclodextrin); hydroxypropyl betadex; methyl-β-cyclodextrin; sulfobutyl ether β-cyclodextrin sodium.

Betadex has the lowest water solubility of the natural cyclodextrins, which limits the solubility gain it can provide; the more soluble hydroxypropyl and sulfobutyl ether derivatives are used when higher concentrations or parenteral use are needed. The size of its cavity suits many aromatic and heterocyclic drug molecules.