Structure
2-Hydroxypropyl-β-cyclodextrins (HPβCDs) are synthesized by condensation between β-cyclo-dextrin (βCD) and propylene oxide. Structure of 2-hydroxypropyl-β-cyclodextrin (HPβCD) where R = H or CH2-CHOH-CH3 is shown below. There are 21 (red) hydroxyl groups on βCD, which are potential substitution sites for the condensation reaction with propylene oxide to yield various species of HPβCD with different degrees of substitution depending upon how many sites are substituted[3].
Chemical Properties
Hydroxypropyl betadex occurs as a white or almost white,
amorphous or crystalline powder.
Chemical Properties
White to slightly yellow powder
Uses
enteric coating, sustained release formulations, buccal and transdermal drug delivery
Uses
2-Hydroxypropyl-β-cyclodextrin can be used as selective estrogen receptor modulator for the prevention of osteoporosis
Uses
2-Hydroxypropyl-β-cyclodextrin (HBC) is a widely used modified cyclodextrin, the lipophilic cavity formed by 7 glucose units. Drug solubility in water is greatly enhanced by complexing with 2-Hydroxypropyl-β-cyclodextrin.
Production Methods
Hydroxypropyl betadex is prepared by the treatment of an alkaline
solution of b-cyclodextrin with propylene oxide. The substitution
pattern can be influenced by varying the pH. Formation of O-6 and
O-2 substituted products is favored by high and low alkali
concentration, respectively. The mixture of products produced
may be refined by preparative chromatography.
General Description
(2-Hydroxypropyl)-β-cyclodextrin, a hydroxyalkyl derivative, finds application as a formulation vehicle that is used to enhance the solubility of the drugs in aqueous solutions for the successful delivery of medical agents to biological systems. It is generally employed as a substitute for α-, β- and γ-cyclodextrins.
Pharmaceutical Applications
Hydroxypropyl betadex has been widely investigated in pharmaceutics
and has principally been used as a solubilizer for
hydrophobic molecules in oral liquids,oral solids, parenterals,
pressurized metered dose inhalers, dry powder inhalers,
and topical formulations. It has also been shown to act as a
stabilizer during processing and storage of formulations.
Hydroxypropyl betadex inclusion complexes have been reported
to show mechanical properties distinct from the pure materials.
The reported advantage of hydroxypropyl betadex over unsubstituted
b-cyclodextrin is its greater water solubility.
Biological Activity
Cell treatment with HPβCD results in the activation of the transcription factor EB, a master regulator of lysosomal function and autophagy, and in the enhancement of the cellular autophagic clearance capacity. HPβCD administration promotes transcription factor EB-mediated clearance of proteolipid aggregates that accumulate due to inefficient activity of the lysosome-autophagy system in cells derived from a patient with a lysosomal storage disorder. Interestingly, HPβCD-mediated activation of autophagy was found not to be associated with activation of apoptotic pathways[2].
Side effects
2-Hydroxypropyl-β-cyclodextrin (HP-beta-CD) has been shown to be well tolerated in humans, with the main adverse event being diarrhoea and there have been no adverse events on kidney function, documented to date[1].
Safety
The pharmaceutical toxicology of hydroxypropyl betadex has been
reviewed, and in general, the material was found to be of low
toxicity. It has been suggested that hydroxypropyl betadex may
have a synergistic toxic effect with, for example, carcinogens, by
increasing their solubility and thus bioavailability.
storage
Store in well-closed containers.
Regulatory Status
Included in oral and parenteral medicinal products. Included in an
injectable preparation licensed in the UK for intramuscular or
intravenous administration.
References
[1] Sarah Gould, Robert C. Scott. “2-Hydroxypropyl-β-cyclodextrin (HP-β-CD): A toxicology review.” Food and Chemical Toxicology 43 10 (2005): Pages 1451-1459.
[2] Wensi Song. “2-Hydroxypropyl-β-cyclodextrin promotes transcription factor EB-mediated activation of autophagy: implications for therapy.” The Journal of Biological Chemistry (2014): 10211–22.
[3] Alfred L Yergey. “Correction: Characterization of hydroxypropyl-beta-cyclodextrins used in the treatment of Niemann-Pick Disease type C1.” PLoS ONE (2018): e0192424.
