rev: October 1, 2004
Patent warning :We are not responsible any patent infringement with the use or derivation of any item. We strongly suggest you review the various patent issues covering the use of cyclodextrins especially in pharmaceutical applications. Purchase of these or any item does not grant any license under any issued or pending patent. patent law
DATA SHEET: Hydroxypropyl B Cyclodextrin ,Endotoxin controlled
replaces Encapsin(tm) brand which is no longer available
Catalog#: RDI-410200 $1875.00/kilogram
Data Sheet: Hydroxypropyl B Cyclodextrin, Endotoxin Controlled cat#RDI-82004HPB $1875.00/kilogram
-a high purity material with a higher degree of substitution $1750.00/kg 10+ bulk on quotation - Discontinued
not recommended for an invivo or cell culture applications)
cat#RDI-82005HPB $1250.00/1kg - Discontinued
(=spec range unique to that product)
|Sample Batch spec
|Degree Substitution||4.3(4.1-5.1)||7.6 (6.0-8.0)||5.2 (4.0-6.0)|
|ASH (0.5% max)||0.1%||0.1%||0.1%|
|Propylene Glycol (0.5% Max)||0.03%||0.3%||0.3% (1.5%)|
|Moisture (5% Max)||1.9%||3.1%||3.7% (8.0%)|
|specific rotation||+141 DEG (+138-+144)||+130 DEG (+120- +140)||+138 (+120 - +150)|
|pH(1% solution) 5.0-8.0||7.2||6.7||6.9|
|unmodified BCD||0.2% (1% Max)||0.1 (0.1% Max)||0.1% (1%max)|
|Aerobic Plate Count CFU/g||---||--||20CFU/g
|Appearance in solution (10%)||Clear||Clear||--|
|Total Viable Aerobic Bacteria
|Total Viable Fungi
|<<1CFU/g||<1 CFU/g||<20CFU (100CFU/g) Max|
|Heavy Metals 20ppm Max||<20ppm||<20ppm||<20ppm (20ppm max)|
-mfg in USA under GMP conditions (DMF Type IV on file)
-produced by chemical and enzymatic modification of corn starch
-no animal products involved in production or packaging process
-recommended storage: cool and dry -away from any odorous material
-expiration date: (longer terms currently being evaluated, at least 2 years from date of mfg before re-anlaysis-see label and certificate with each lot for mfg date )
-starting Jan 1, 2004 batches tested to Ph. Euro "Hydroxypropylbetadex" monograph)
DMF Type IV, TSCA, AICS, ELINCS, METI listed CN code 2940.00.6000
Stabilization of labile and reactive compounds*
*NOTE: Specific applications may be covered by prior patent law
-in USA suggest contacting National Institute of Health licensing office and or Janssen Pharmaceutical
Storage: Store in a cool dry place, off the ground and away from chemicals and odorous materials. Good ventilation should be provided. DEG C.
TSCA: THis product is listed on the TSCA Inventory
-no hazards identified to date
other legislation: AICS, ELINCS listed DMF 13081
CN Code 3505 10 10
Safety Dust is flammable and explosive
Precautions: For research Use Only.
It is the responsibility of the user to comply with all local/state and Federal rules in the use of this product. We are not responsible for any patent infringements that might result with the use of or derivation of this product.
MW= 1135 + (58)(DS)
specific rotation can be used as a measure of purity. The specific rotation is dependent upon the degree of substituion and decreases as the degree of substitution increases. The expected contaminants in HPBCD result from the synthesis. these are salt and propylene glycol.
Hydroxypropyl Beta Cyclodextrin (HPCD) (cas#94035-02-6) is a partially substituted poly(hydroxpropyl) ether of beta cyclodextrin (BCD). The empirical formula is: (C42 H70-n O35) . (C3 H7 O)n It contains not less than 10.0 percent and not more than 45.0 percent hydroxypropoxy(-OCH2CHOHCH3) groups. the structure is shown below where R represents either hydrogen or a hydroxypropoxy group.
R= CH2CH(OH)CH3 or H
The basic closed circular structure of BCD is maintained in HPBCD. The glycosidic oxygen forming the bond between the adjacent glucose monomers and the hydrogen atoms lining the cavity of the cyclodextrin impart an electron density and hydrophpbic character to the cavity. Organic compounds interact with the walls of the cavity to form inclusion complexes. The hydroxyl groups and the hydroxypropyl groups are on the exterior of the molecule and interact with water to provide the increased aqueous solubility of the hPCD and the complexes made with the HPCD.
The hydroxypropyl groups are randomly substituted onto the hydroxyl groups of the cyclodextrin and the amount of sub- stitution is reported as average Degree of Substitution or number of hydroxypropyl groups per cyclodextrin and is the perferred manner of describing the substitution. An alternate measurement is Molar Substitution or the average number of substitutions per anhydro gluycose unit in the ring of the cylcodextrin. Molar substitution is used with polymers whose molecular weight is not determined or contains a mixture of polymers of different degrees of polymerization. The cyclodextrin is a defined molecule. Molecular weight is calculated based upon the degree of substitution. Substitution is a distribution aroung the average degree of substitution of the number of hydroxypropyl groups per cyclodextrin with some molecules having more than the average and some less than the average degree of substitution. The result is a mixture of many molecular species with respect to the number and location of substitutions around the ring of the cyclodextrin. The reaction to produce HPBCD is highly controllable and repeatable so that the product produces is very consistent from batch to batch.
Substitution can have an effect on the binding of guests to the HPBCD. At low degrees of substitution, binding is very similar to that of the unmodified B-cyclodextrin. Increasing substitution can lead to weakened binding due to steric hindreance. The effect is dependent upon the particular guest and it is also possible to obtain increased binding due to an increase in surface area to which the guest can bind. With most guests, these differences in binding with degree of substitution are small if detectable.
Physical and Chemical Properties
HPBCD is very soluble in water. Substitution of the hydroxyl groups of the BCD disrupts the network of hydrogen bonding around the rim of the BCD. As a result of disruption of the hydrogen-bonding network, the hydroxyl groups interact much more strongly with water resulting in increased solubility compared to BCD. Solubilities of HPBCD are typically listed at >60% at amnbient temperature. As the concentraion becomes higher, viscosity begins to increase and solubility determinations become difficult to perform due to slow filtration rates and at very high solids levels, slow dissolution because of high viscosities making mixing difficult.
HPBCD is more soluble in solvents than BCD, but extensive work has not been done to characterize the solubility of HPBCD in solvents. The table below shows the solubility in selected alcohols.
|Ethanol Concentration (%)||DS 7.6|
Unlike BCD whose solubility is limited, solutions of HPBCD can become viscous. At concentrations normally used in applications the viscosity is not a concern. The table below shows the viscosity of HPBCD at different concentrations and temperatures.
Viscosity in mPa.s
Viscosity increases as the concentration increases and decreases as the temperature increases. The increase of viscosity with concentration is slow until a concentration of 55%, where the rate of increase of the viscosity becomes more rapid.
A thermogram obtained by differential scanning calorimetry is shown below. Energy is absorbed as water evaporates, peaking at about 100'C. A glass transition occurs in this thermogram from about 225 to 25-'C. The glass transition temperature varies with the degree of substitution. Thermal decomposition occurs at 308'C as determined by visual observation using a capillary-melting apparatus.
Strong acids, such as hydrochloric or sulfuric acids, hydrolyze HPBCD. The rate of hydrolysis is dependent upon the temperature and concentration of the acid. The higher the temperature or concentration of the acid, the more rapid is the rate of hydrolysis. Weak acids, such as organic acids do not hydrolyze HPBCD
HPBCD is stable in bases. HPBCD is synthesized under basic conditions without opening of the BCD ring.
Within the commonly used range of pH for most products and processes, HPBCD is stable as shown in the table below
Stability of HPBCD from pH 4.0 to 9.0
|Concentration HPBCD (ug/ml)|
|Initial||Day 5||% Hydrolysis|
HPBCD was incubated in buffers at 50'C for five days. The results indicated that little, if any hydrolysis occured.Variation in the assay could account for the differences found.
HPBCD is not hydrolyzed by B-amylase or glucoamylase. These enzymes require an end group in order to initiate attack. Since HPBCD has no end groups, no hydrolysis occurs with these enzymes.
BCD can be hydrolyzed by some alpha amylases,with fungal alpha amylases being more active than bacterial alpha amylases. The ability of these enzymes and cyclodextrintransglycosylases to hydrolyze HPBCD is limited. Substitution provides steric hindrance to the binding of the HPBCD to the active site of the enzyme and as a result, the amount of hydrolysis is reduces. The greater the degree of substitution, the less hydrolysis that occurs. Hydrolysis is probably largely limited to any unmodified BCD present.
Acute toxicity testing has not determined an LD(50) for HPBCD. 5000mg/kg have been administered orally to rats and no mortality was observed. (1)
C14 labeled HPBCD has bee administered orally to determine the metabolic fate of the HPBCD (2,3) . Most of the label was excreted in the feces. 3-6% of the label was absorbed and some label appeared in the blood about five minutes after administration indicating some absorption from the stomach. About 3% of the label appeared in the urine and another 3.25% in the exhaled CO2. The HPBCD preparation did contain some propylene glycol that was also labeled. The amount of label absorbed corresponded to the amount of proplyene glycol present (2)
Teratogenicty and embryotoxicity studies have been done in rats and rabbits at doses up to 5000 mg/Kg per day in rats and 1000mg/Kg per day in rabbits (1). No maternal toxicity, embryotoxicity or teratogenicity was found in rats. In rabbits, no teratatogenicity was observed, but slight maternal and embryotoxicity was observed at 1000 mg/Kg.
Chronic studies were done using both mice and rats. The study with mice was terminated after 104 weeks (4). The mice received 500mg/Kg HPBCD. No adverse histopathology was noted that could be attributed to HPBCD and the mice given HPBCD had a lower incidence of tumors than the controls. A two-year study was also done with rats with a dose of 500 mg/Kg per day (5) . No effects were observed that were attributed to HPBCD.
In an acute study with cynomologus monkeys, a dose of 10, 000 mg/Kg was not lethal (6)
HPBCD is quickly cleared after administration. After a single intravenous administration of (14)C labeled HPBCD, a half-life in the plasma of 0.4 hours and 0.8 hours was found for rats and dogs respectively (3). A plasma clearance of 512 and 188 ml/kg/h was calculated for rats and dogs.
The subchronic toxicity studies with rats (3), no adverse effects were found in rats treated intravenously with 50 mg/Kg HPBCD. At 100 mg/Kg HPBCD. At 100 mg/Kg some minimal histological changes were found in the epithelial cells of the urinary bladder, kidney tubular cells and in the liver. At 400 mg/Kg,there was a decreased body weight and food consumption, increased water consumption,decreased hematocrit, hemoglobin and erythrocyte levels, increased creatin- ine, total bilirubin and aspartate and alanine aminotransferase levels. Some organ weights also increase. Most of these changes were reversible after one month except for slightly elevated aspartate and alanine aminotransferase levels and histological changes in the lung and urinary tract that were only partially reversible.
In subchronic toxicity studies, no adverse effects were found in rats treated intravenously with 50mg/Kg or in dogs receiving 100 mg/KG HPBCD(1). At 400 mg/Kg in dogs therewere slight increases in serum alanine and aspartate aminotransferase and total bilirubin. Histological changes werefound in the lung and epithelial cells of the urinary bladder and renal pelvis. All of the changes were reversed within a month after treatment except for incomplete re- versibility of the swollen renal plevis epithelium.
Teratogenicity and embryotoxicity studies have been done in rats and rabbits at doses up to 400mg/Kg per day(1). Slight maternal toxicity was observed in rats at 400mg/Kg but there were no primary adverse effects in the offspring. No adverse effects were observed in the rabbits.
Dermal irritation studies were done with albino rabbits(7). No erythema, edema or other dermal effects were observed and the material was considered to be a nonirritant to the skin. A dermal sensitization study was done using guinea pigs(8). No irritation was detected upon the initial intradermal injection of HPBCD. Upon challenge of applying HPBCD to the surface of the skin, low incidences of very faint erythema were found in 30% of the animals at 48 hours and 10% of the animals at 72 hours.
HPBCD is nonmutagenic. Mutagenicity was tested using S. typhimurium and E. coli WP2 strains both with and without microsomal activation and found to be non-mutagenic(9). Testing with mammalian cell culture, with and without microsomal activation, also found HPBCD to be non-mutagenic(10).
A limit test using a single concentration was performed using Daphnia magna. Both the EC(50) and no-effect observed concentration (NOEC) are greater than 1084mg/L(11).
2. Fish-a limit test using a single concnetration was performed using Zebrafish (Brachydario rerio). Both the Ec50 and NOEC are greater than 1131mg/L. (12)
3. Algae-a limit test using a single concentration was perfromed using Selenastrum capricornutum. Both the EC50 and NOEC are greater than 1153mg/l.
Cyclodextrin inclusion is a molecular phenomenon in which usually only one molecule of guest interacts with the cavity of the cyclodextrin to become entrapped, unlike other encapsulation methods in which more than one molecule of guest is entrapped in the encapsulation matrix. In order to form a complex with HPBCD to form a stable assocication. A variety of non-covalent forces, such as van der Waal forces, hydrophobic interaction, dipole moment and other forces are responsible for formation of a stable complex.
In most cases, only one colecule is included in the cavity of HPBCD. In the case of some low molecular weight guests, more than one molecule of guest might fit into the cavity. In the case of some high molecular weight molecules, more than one molecule of cyclodextrin might bind to the guest. Only a portion of the molecule must fit into the cavity to form a complex. As a result, a one-to-one molar ratio is not always achieved, especially with high or low molecular weight guests and some prelimiary complex formation and analysis is needed to determine relative amounts of cyclodextrin and guest to be added for complexation.
Hydroxypropyl B-cyclodextrin is very soluble in water and is used to solubilize guest molecules (14). The guest associates with the cyclodextrin so that the hydrophobic portion of the guest interacts with the hydrophobic cavity of the cyclodextrin. This interaction is an equilibrium reaction.
[Guest] + [HPBCD] -----[Guest-HPBCD]
The direction of the equilibrium is dependent upon the guest. For some guests, the complex is predominant while for other guests, the free state might be preferred. In order to reduce the probability of free guest self-associating to form an insoluble precipitate, excess HPBCD is frequently used to increase the probability of the guest existing in the cavity of cyclodextrin and thus to be solubilized rather than associating with other molecules of the guest to form an insoluble mass.
Water is the perferred solvent for complexation. The quest, or portion of the quest which complexes with the cavity of the cyclodextrin is non-polar and perfers the non-polar environment of the cavity of the cyclodextrin rather than the polar aqueous environment. As a result, water provides a driving force for the complexation reaction in addition to dissolving or dispersing the cyclodextrin and guest.
Because of the high solubility of the hydroxypropyl beta cyclodextrin, complexes are also very soluble. Generally the solubility of the complex is not exceeded. If the solubility of the complex is exceeded, the precipitate is amorphous and has a tendency to remain suspended rather than to quickly settle. Addition of a small amount of water will dissolve the precipitate to give a clear solution.
Hydroxypropyl B-cyclodextrin is very soluble in water and heat is not needed to increase the solubility of the hydroxypropyl beta cyclodextrin. At very high concentration of hydroxypropyl B-cyclodextrin (60% and greater), increased temperature can be used to reduce the viscosity of the solution. Increased temperature can also be used to increase the solubility of the guest to increase the rate of complexation.
Heat can destabilize complexes and the temperature at which a complex is stabilized is dependent upon the guest.Temperature and holding time for complexation must be optimized for each guest.
Water is the preferred solvent for complexation. Water is very polar and the guest or portion of the guest which complexes with the cavity of the cyclodextrin is apolar and associates much more readily with the apolar cavity of the cyclodextrin than with water. As a result, the water provides a driving force for complexation.
Not all guests are sufficiently soluble in water making complexation either very slow or immpossible. Complete solubilization of the guest is not necessary. A small amount of guest must be soluble to form a complex. As the soluble guest is completed, more of the guest will dissolve to form more complex. Small amounts of water miscible solvents can be used to assist in dissolution of guests to make the complexation reaction proceed more rapidly. A polar solvent, such as acetone or diethyl ether, which does not complex with the cavity, is preferred in order to minimize competition for the cavity with the guest. Water miscible solvents can be added to the water to dissolve the guest, or the guest can be dissolved in a small amount of solvent and the solution added to the hydroxypropyl B-cyclodextrin solution.Upon addition of the dissolved guest to the solution of cyclodextrin, the guest may be solubilized or dispersed as a fine precipitate. In the latter case, a long stirring or complexation time might be needed, bu complexation occurs more rapidly than if the guest were still in the form of large crystals. Excessive amounts of solvent reduce the driving force for complexation by reducing the difference in polarity between the cavity of the cyclcodextrin and the bulk solution, which can result in good solubilization of the guest, but little or no complexation. Vacuum evaporation of the solvent might result in complexation occuring as the solvent is removed.
Because HPBCD is made up of a mixture of molecular species, there is no direct assay for HPBCD. Instead of assaying for HPBCD directly, assay of attributes and expected contaminants is performed.
Degree of Substitution is the average number of hydroxypropoxy groups per cyclodextrin. Some individual molecules in the mixture will have less than the average and some will have more substitutions than the average. The degree of substitution can be determined by TIR (Fourier Transform InfraRed Spectroscopy) or NMR (Nuclear Magnetic Resonance Spectroscopy). Molecular weight is calculated determining the degree of substitution. Molecular weight is equal to the molecular weight of BCD plus the product of the molecular weight of the hyddroxypropoxy group times the degree of substitution.
MW = 1135 + (58)(DS)
Specific rotation can be used as a measure of purity. The specific rotation is dependent upon the degree of substitution and decreases as the degree of substitution increases.
The expected contaminants in HPBCD result from the synthesis. These are salt and propylene glycol.
The load or amount of guest in a complex is in many cases is determined by measurement of the amount of materials added or by chemical analysis. For chemical analysis, the complex is usually dissolved. The amount of guest is determined by conventional means used for assay of the guest, such as light absorption or chromatography. For spectroscopic determination of the guest, appropriate controls should be used since complexation with HPBCD can cause the light absorption of some compounds to change by altering the ^max or intensity of absorption of light to change. The guest can also be extracted from an aqueous solution of the complex into an organic solvent and assayed using HPLC. Extraction is done at 60'C since the high temperature will assist in disrupting the complex. The amount of HPBCD can be determined using a total carbohydrate assay, such as the DuBois assay. Appropriate controls should also be used for these assays since the guest can effect the results.
Advantages compare to BCD
The main advantage of HPBCD is the increased solubility of the complexes compared to BCD. For most guest, the increase is somewhere between 10 and 100.
The ability of cyclodextrins to stabilize guest is retained in HPBCD. Due to the substitution, binding can be altered which can cause differences in the amount of stability obtained compared to BCD.
HPBCD is listed in TOSCA. The FDA has approved two pharmaceutical formulations that contain HPBCD. One is for oral use and the other for i.v. use. There is a USP monograph in the draft status. ELINCS registration has proceeded through the base set submission and Level 1 submission is in progress.
HPBCD is used for solubilization and stabilization of guests. By complexing with HPBCD, the guest interacts with cavity of the HPBCD to become entrapped. The outer surface of the HPBCD is very hydrophilic and interacts well with water to carry the guest into solution. Some examples are described below.
Itraconazole is used to treat fungal infections and is insoluble in water. It can be solubilized with HPBCD(15). Co-solvents have been used to solubilize itraconazole for oral dosage, but have not been completely successful because of irreversible precipitation which takes place in the stomach. Use of HPBCD prevents the precipitation from occuring. Itraconazole has a high molecular weight (some-where around 700). Propylene glycol is used as a co-solvent for dissolution of the itraconazole. It is compartible with the HPBCD.
Tolnafate is an antifungal drug that is not very soluble in water. HPBCD was used with a 8% or 3% substitution. Solubility increased 30 fold compared to solubilization with BCD(16). Solubility was greater using the lower degree of substitution. The stability constant for the lower degree of substitution was 1109 M-1, 1460 M-1 for the higher degree of substitution and 1860 M-1 for BCD. The complex in HPBCD had a faster dissolution rate than the BCD complex.
Some proteins can also be solubilized with HPBCD(17). Ovine growth hormone is a protein with a molecular weight of 20,000 and is not soluble in water at physiological pH. In water it is not solubilized until pH 11.5. Using HPBCD, the hormone could be solubilized at pH7.5 to pH8.5.
1. W. Cousssement,H. Van Cauteren,J. Vandenberghe, P.Vanparys,G. Teuns,A. Lampo and R. Marsboom (1990). Toxicological profile of hydroxypropyl B-cyclodextrin (HP B-CD) in laboratory animals. In D. Duchene (ed.) Minutes 5th International Symposium on Cyclodextrins. Editions de Sante pp. 552-524.'
2. A. Gerloczy,S.Amtal,I.Szatmari,R. Muller-Horvath and J.Szejtli (1990). Absorption, distribution and excretion of C-labelled hydroxypropyl B-cyclodextrin in rats following oral administration. In. In D.Duchene (ed.), Minutes 5th International Symposium on Cyclodextrins. Editions de Sante pp.507.513.
3. J. Monbaliu, L.van Beijsterveldt, W. Meuldermans, S. Szathmary, and J. Heykants (1990).Disposition of hydroxy- ropyl B-cyclodextrin in experimental animals. In D.Duchene (ed.).minutes 5th International Symposium on Cyclodextrins. Editions de Sante pp. 514-517.
4. J.J. Wallery, M.E.Shaw, J.T. Yarrington, M.S.Werley,T. M. Sullivan and A.W. Singer (1997). Effects of cage type, food type,and hydroxypropyl-B-cyclodrextrin on chronic toxicity/oral carcinogenicity study parameters in CD-1 mice. Bttelle. Poster presented at 1997 Annual SOT Meeting.
5. M.E. Shaw, D.M. Sells,T. Sullivan and A Singer (1997). Battelle,Poster presented at the 1997 Annual SOT Meeting. 6. M.E. Brewster.,K.S. Estes and N. Bodor (1990). An intravempis toxicity study of 2-hydroxypropyl-B-cyclodextrin,a useful drug sollubilizer in rats and monkeys. International Journal of Pharmaceutics 59: 231-243.7.
7.Primary Dermal Irritation Study in Albino Rabbits with Hydroxypropyl Beta Cyclodextrin (1993). Study report
8.Dermal Sensitization Study (Maximization Design in Guinea Pigs) with Hydroxypropyl Beta Cyclodextrin (1993). Study report
9-13 (research reports)
14 Solubilization of pharmaceuticals by HPCD is covered by patents such as US 4,727,064 "Pharmaceutical preparations containing cyclodextrin derivatives" and EP 0 149 197 "Pharmaceutical compositions containing drugs which are sparingly soluble in water or instable and methods for their preparations" and others.
15 US Patent 5, 707,975.
16 D. Peri, C.M. Wandt, R.W. Cleary, A.H. Hikal and A.B.Jones (1994). Complexes of tolnaftate with beta-cyclodextrin and hydroxypropyl beta-cyclodextrin. Drug Development and Industrial Pharmacy 20:1401-1410.
For In Vitro Research or Further Manufacturing Use Only (raw material, not a finished product)
Not responsible for any patent infringemnet with hte use, derivation or this or any product
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