Design and evaluation of polypseudorotaxanes of pegylated insulin with cyclodextrins as sustained release system

Supramolecular assemblies have attracted a great attention, due to their intriguing topologies and their application in various fields such as nanodevices, sensors, molecular switches, and drug delivery systems. In this study, we prepared the monosubstituted insulin with poly(ethylene glycol) (PEG, MW about 2200) and its cyclodextrin (CyD) polypseudorotaxanes. The pegylated insulin formed polypseudorotaxanes with alpha- and gamma-CyDs, by inserting one PEG chain in the alpha-CyD cavity and two PEG chains in the gamma-CyD cavity. The pegylated insulin/alpha- and gamma-CyD polypseudorotaxanes were less soluble in water and the release rate of the drug decreased in the order of drug alone>the gamma-CyD polypseudorotaxane>the alpha-CyD polypseudorotaxane. The plasma levels of the pegylated insulin after subcutaneous administration of the gamma-CyD polypseudorotaxane to rats were significantly prolonged, accompanying an increase in the area under plasma concentration-time curve, which was clearly reflected in the prolonged hypoglycemic effect. The results indicated that the pegylated insulin/CyD polypseudorotaxanes can work as a sustained drug release system, and the polypseudorotaxane formation with CyDs may be useful as a sustained drug delivery technique for other pegylated proteins and peptides.

Polypseudorotaxanes of pegylated insulin with cyclodextrins: Application to sustained release system

The monosubstituted insulin with poly(ethylene glycol) (PEG, MW about 2200) formed polypseudorotaxanes with alpha- and gamma-cyclodextrins (CyDs), by inserting one PEG chain of the pegylated insulin in the alpha-CyD cavity and two PEG chains in the gamma-CyD cavity. The pegylated insulin/alpha- and gamma-CyD polypseudorotaxanes were less soluble in water and the release rate of the drug decreased in the order of drug alone > the gamma-CyD polypseudorotaxane > the alpha-CyD polypseudorotaxane. The subcutaneous administration of the pegylated insulin/gamma-CyD polypseudorotaxane in rats significantly sustained plasma glucose levels with an enhanced hypoglycemic effect. The results indicated that the pegylated insulin/CyD polypseudorotaxanes can work as a sustained drug release system and the polypseudorotaxane formation may be useful as a sustained drug delivery technique for pegylated proteins and peptides.

Evaluation of polyamidoamine dendrimer/alpha-cyclodextrin conjugate (generation 3, G3) as a novel carrier for small interfering RNA (siRNA)

As the first step toward an evaluation of the potential use of the PAMAM dendrimer (G3) conjugate with alpha-cyclodextrin (alpha-CDE) for a small interfering RNA (siRNA) carrier, the ternary complexes of alpha-CDE or the transfection reagents such as Lipofactamine 2000 (L2), TransFast (TF) and Lipofectin (LF) with plasmid DNA (pDNA) and siRNA were prepared, and their RNAi effects, cytotoxicity, physicochemical properties and intracellular distribution were compared. Here the pGL2 control vector (pGL2) and pGL3 control vector (pGL3) encoding the firefly luciferase gene and the two corresponding siRNAs (siGL2 and siGL3) were used. The ternary complexes of pGL3/siGL3/alpha-CDE showed the potent RNAi effects with negligible cytotoxicity compared to those of the transfection reagents in various cells. alpha-CDE strongly interacted with both pDNA and siRNA, and suppressed siRNA degradation by serum, compared to those of the transfection reagents. alpha-CDE allowed fluorescent labeled siRNA to distribute in cytoplasm, whereas the transfection reagents resided in both nucleus and cytoplasm in NIH3T3 cells. Furthermore, the binary complex of siRNA/alpha-CDE provided the significant RNAi effect in NIH3T3 cells transiently and stably expressing luciferase gene. These results suggest that alpha-CDE may be utilized as a novel carrier for siRNA.

Effects of Cyclodextrins on Chemically and Thermally Induced Unfolding and Aggregation of Lysozyme and Basic Fibroblast Growth Factor

Effects of cyclodextrin (CyDs) on unfolding and aggregation of lysozyme and basic fibroblast growth factor (bFGF) were investigated. CyDs inhibited the chemically induced aggregation and its inhibition was generally in the order of gamma-CyDs < alpha-CyDs < beta-CyDs. Among these CyDs, branched beta-CyDs and dimethyl-beta-CyD (DM-beta-CyD) significantly reduced the aggregation of lysozyme. Hydrophilic CyDs reduced the thermally induced unfolding of lysozyme as shown by a decrease in the thermal unfolding temperature (T(m)) value of lysozyme, suggesting that CyDs destabilize native lysozyme or stabilize the unfolded state of lysozyme. In the case of bFGF, branched beta-CyDs showed greater effects on inhibition of the chemically and thermally induced denaturation. Interestingly, sulfobutyl ether beta-CyD (SBE-beta-CyD), which was not effective in case of lysozyme, provided the inhibitory effect for bFGF on the chemically, thermally and acid-induced denaturation, suggesting that both the inclusion and electrostatic interaction may be operative in the inhibition of aggregation of the positively charged protein. The results indicated that the use of CyDs for protein stabilization is dependent not only on the structure and property of CyDs but also on the nature of the denaturing stimuli, and the most appropriate CyD should be used for the stabilization of each protein.

Enhancement of antitumor effect of doxorubicin by its complexation with gamma-cyclodextrin in pegylated liposomes

In the present study, we examined tissue distribution and the antitumor effect of doxorubicin (DOX) after intravenous injection of the pegylated liposomes entrapping the DOX complex with gamma-cyclodextrin (gamma-CyD) (complex-in-liposome) in BALB/c mice bearing colon-26 tumor cells, compared with those of DOX solution, pegylated liposomes entrapping DOX alone (DOX-in-liposome), pegylated liposomes entrapping gamma-CyD (CyD-in-liposome) and the binary system of DOX-in-liposome and CyD-in-liposome. When injected to the mice, complex-in-liposome provided the high DOX levels in plasma and solid tumors, compared with the other preparations. Reflecting the result, complex-in-liposome elicited the retardation of tumor growth and the improvement of survival rate without suppression of increase in the body weight of mice. These results suggest the potential use of pegylated liposomes entrapping the DOX complex with gamma-CyD for a promising carrier for improvement of antitumor effects of DOX.

Enhancement of gene transfer activity mediated by mannosylated dendrimer/α-cyclodextrin conjugate (generation 3, G3)

To enhance gene transfer activity of dendrimers, we prepared its conjugate (generation 3, G3) with alpha-cyclodextrin bearing mannose (Man-alpha-CDE conjugates) with various degrees of substitution of the mannose moiety (DSM5, 10, 13, 20) and compared their cytotoxicity and gene transfer activity, and elucidated the enhancing mechanism for the activity. Of the various carriers used here, Man-alpha-CDE conjugate (G3, DSM10) provided the highest gene transfer activity in NR8383, A549, NIH3T3 and HepG2 cells, being independent of the expression of mannose receptors. Gene transfer activity of Man-alpha-CDE conjugate (G3, DSM10) was not decreased by the addition of 10% serum in A549 cells. Cytotoxicity of the polyplex with Man-alpha-CDE conjugates (G3, DSM10) was not observed in A549 and NIH3T3 cells up to the charge ratio of 200/1 (carrier/pDNA). The gel mobility and particle size of polyplex with Man-alpha-CDE conjugate (G3, DSM10) were relevant to those with alpha-CDE conjugate (G3), but zeta-potential, DNase I stability, pDNA condensation of the former polyplex were somewhat different from those of the latter one. Cellular association of polyplex with Man-alpha-CDE conjugate (G3, DSM10) was almost comparable to that with dendrimer (G3) complex and alpha-CDE conjugate (G3). The addition of mannan and mannose attenuated gene transfer activity of Man-alpha-CDE conjugate (G3, DSM10) in A549 cells. Alexa-pDNA complex with TRITC-Man-alpha-CDE conjugate (G3, DSM10), but not the complex with TRITC-alpha-CDE conjugate (G3), was found to translocate to nucleus at 24 h after incubation in A549 cells. HVJ-E vector including mannan, but neither the vector alone nor the vector including dextran, suppressed the nuclear localization of TRITC-Man-alpha-CDE conjugate (G3, DSM10) to a striking degree after 24 h incubation in A549 cells. These results suggest that Man-alpha-CDE conjugate (G3, DSM10) has less cytotoxicity and prominent gene transfer activity through not only its serum resistant and endosome-escaping abilities but also nuclear localization ability.

Enhanced bioavailability of a new thiazolidine derivative FPFS-410, an antidiabetic and lipid-lowering drug, after oral administration of its hydroxypropyl-β-cyclodextrin complex to bile duct-cannulated rats

The effect of bile acids on bioavailability of FPFS-410 (2-(N-Cyanoimino)-5-{(E)-4-styrylbenzylidene}-4-oxothiazolidine) after oral administration of the drug and its 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) complex was investigated. The complexation with HP-beta-CyD increased the oral bioavailability of FPFS-410 in normal rats in a HP-beta-CyD concentration-dependent manner, compared with that of drug alone. In bile duct-cannulated rats, bile acid concentrations in pylic serum and biliary were decreased to 18% and 14% of sham-operated rats, respectively. After oral administration of the HP-beta-CyD complex, the plasma levels of FPFS-410 were lower in bile duct-cannulated rats than in sham-operated rats up to 1 h, however, this order reversed from 2 to 12 h. The plasma levels of M1, a dominant metabolite of FPFS-410 in rats, significantly decreased until 2 h after administration of the complex in bile duct-cannulated rats, compared with in sham-operated rats. Bioconversion of FPFS-410 to M1 and CYP3A2 expression in the liver was markedly lowered by bile duct-cannulation. Bile duct-cannulation did not, however, affect the serum levels of estradiol. These results suggest that bile acids have a pivotal role for bioavailability of FPFS-410 after oral administration of the FPFS-410 complex with HP-beta-CyD through CYP3A2 activity in liver of rats.

Effect of 2,6-di-O-methyl-alpha-cyclodextrin on hemolysis and morphological change in rabbit's red blood cells

The effects of 2,6-di-O-methyl-alpha-cyclodextrin (DM-alpha-CyD) on hemolysis and morphological changes in rabbit's red blood cells (RBC) were examined, compared with those of alpha-cyclodextrin (CyD) and 2-hydoxypropyl-alpha-cyclodextrin (HP-alpha-CyD). The hemolytic activity of alpha-CyDs increased in the order of HP-alpha-CyD<alpha-CyD<DM-alpha-CyD. The three alpha-CyDs induced morphological changes of RBC from discocyte to stomatocyte. At the same concentration (3mM) of alpha-CyDs, DM-alpha-CyD and alpha-CyD released phospholipids, rather than cholesterol, and DM-alpha-CyD markedly released proteins from RBC membranes, compared to alpha-CyD and HP-alpha-CyD. The treatment of RBC with DM-alpha-CyD lowered the extent of a fluorescent sphingomyelin analogue from lipid rafts of RBC membranes in a concentration-dependent manner. These results suggest that DM-alpha-CyD has higher hemolytic and morphological change activity than alpha-CyD and HP-alpha-CyD through more extraction of phospholipids including sphingomyelin and proteins, not cholesterol, from RBC membranes than alpha-CyD and HP-alpha-CyD.

Two-dimensional 13C–1H heteronuclear correlation NMR spectroscopic studies for the inclusion complex of cyclomaltoheptaose (β-cyclodextrin) with a new Helicobacter pylori eradicating agent (TG44) in the amorphous state

The interaction of a newly developed Helicobacter pylori eradicating agent (TG44, 4-methylbenzyl-4'-[trans-4-(guanidinomethyl)cyclohexylcarbonyloxy]-biphenyl-4-carboxlylate monohydrochloride) with cyclomaltoheptaose (beta-cyclodextrin, beta-CyD) in the solid state was studied by high-speed frequency-switched Lee-Goldburg (FSLG) (13)C-(1)H heteronuclear correlation (HETCOR) NMR experiments. The TG44/beta-CyD solid complex in a 1:1 stoichiometry was prepared by the grinding method. Powder X-ray diffractometry confirmed that the complex is in an amorphous state. The solid-state (13)C signals of TG44 and beta-CyD were significantly broadened by the complexation. As the temperature increased, the (13)C signals of the aromatic moieties of TG44 were insignificantly influenced, whereas those of the cyclohexyl moiety became sharper. The T1(rho) H values of the aromatic moieties of TG44 were almost the same as those of the beta-CyD carbons, whereas those of other TG44 carbons gave much smaller values. The (13)C-(1)H HETCOR spectra gave the intermolecular correlation peaks between the aromatic carbons of TG44 and the beta-CyD protons or between the biphenyl protons of TG44 and the beta-CyD carbons, when measured using longer contact times (500 and 1500mus). On the basis of these solid NMR spectroscopic data together with aqueous NMR data, we assume that beta-CyD includes predominantly the biphenyl moiety of TG44 in the solid state. (13)C-(1)H HETCOR spectroscopy is particularly useful for the determination of inclusion modes of the complexes that occurring in an amorphous form.

Preparation and Pharmaceutical Evaluation of Liposomes Entrapping Salicylic Acid/.GAMMA.-Cyclodextrin Conjugate

To evaluate the potential use of a drug/cyclodextrin (CyD) conjugate for efficient entrapment in liposomes and prolonged residence of a drug in tissues, we synthesized a salicylic acid (SA) conjugate bound covalently with gamma-cyclodextrin (SA/gamma-CyD conjugate), a model drug/CyD conjugate, and then liposomes entrapping the conjugate (conjugate-in-liposome) were prepared by a freezing-thawing method. The chemical and physicochemical properties of the SA/gamma-CyD conjugate in solution and solid state were investigated and then the physicochemical properties of conjugate-in-liposome, in vitro cellular uptake/release and in vivo disposition of SA/gamma-CyD conjugate after intravenous administration of aqueous suspension containing conjugate-in-liposome in rats, were evaluated, comparing with those of the liposome-entrapped SA alone (SA-in-liposome) or the liposome-entrapped noncovalent SA/gamma-CyD complex (complex-in-liposome). As a result, it was found that the conjugate was amorphous powder and the release of SA from the conjugate in phosphate-buffered saline (PBS) was tolerated to chemical and enzymatic degradation. Meanwhile, the particle sizes and stability of these liposomes were almost identical, and the entrapment ratio of SA/gamma-CyD conjugate in liposomes was higher than those of SA alone and SA/gamma-CyD complex. The cellular uptake of these liposomes was almost equivalent, but the release of SA/gamma-CyD conjugate from RAW264.7 cells was markedly slower, compared with that of SA from cells following cellular uptake of the SA-in-liposome and complex-in-liposome. The disposition of SA or SA/gamma-CyD conjugate following intravenous administration of aqueous suspensions containing each liposome system in rats was comparable, but the residence time of the conjugate in tissues significantly prolonged, compared with that of the SA-in-liposome and complex-in-liposome systems. These results suggest the potential use of SA/gamma-CyD conjugate for efficient entrapment in liposomes as well as of liposomes containing SA/gamma-CyD conjugates for prolonged residence of drugs in tissues.

Improvement of Solubility and Oral Bioavailability of 2-(N-Cyanoimino)-5-{(E)-4-styrylbenzylidene}-4-oxothiazolidine (FPFS-410) with Antidiabetic and Lipid-Lowering Activities in Dogs by 2-Hydroxypropyl-.BETA.-cyclodextrin

2-(N-Cyanoimino)-5-[(E)-4-styrylbenzylidene]-4-oxothiazolidine (FPFS-410) is a newly synthesized thiazolidine derivative having not only antidiabetic but also lipid-lowering activities. However, this compound has an extremely low aqueous solubility (2.8 (+/-0.33) x 10(-8) M (0.0094+/-0.0011 microg/ml) in 1.0 M phosphate buffer (pH 7.0) at 25 degrees C). In this study, we investigated the effect of various hydrophilic cyclodextrins (CyDs) on the solubility of FPFS-410 to select a CyD suitable for formulations of the compound. Among various CyDs, 2-hydroxypropyl-beta-CyD (HP-beta-CyD) had the highest solubilizing ability to FPFS-410, e.g., the solubility of the compound was increased 200000-fold by the addition of 40 mM HP-beta-CyD, which was attributable to the formation of the 1 : 2 (guest : host) inclusion complexes. The interaction of HP-beta-CyD with FPFS-410 was studied using 1H-nuclear magnetic resonance (NMR) spectroscopies including ROESY spectroscopy and a molecular modeling calculation. These results suggested that HP-beta-CyD forms a 1:2 (guest : host) inclusion complex with FPFS-410 by including both the stilbene and thiazolidine moieties. FPFS-410/HP-beta-CyD solid complexes with various stoichiometries were prepared by the spray drying and cogrinding methods, and confirmed by powder X-ray diffractometry that these complexes are in an amorphous state. The dissolution of FPFS-410 in water was significantly accelerated by the complexation with HP-beta-CyD. In vivo studies revealed that HP-beta-CyD markedly increases the bioavailability of FPFS-410 after oral administration in dogs. The present results suggest that HP-beta-CyD is useful for improvement of the extremely low bioavailability of FPFS-410.

Cyclodextrin-based isolation of Ostwald's metastable polymorphs occurring during crystallization

We describe a novel approach for the selective isolation of Ostwald's intermediate metastable polymorphs occurring during an early stage of crystallization, by utilizing the inclusion complex formed with a cyclic oligosaccharide derivative, 2,6-di-O-methyl-beta-cyclodextrin.

Inhibitory effects of dimethylacetyl-beta-cyclodextrin on lipopolysaccharide-induced macrophage activation and endotoxin shock in mice

The potential use of hydrophilic cyclodextrins (CyDs) as an inhibitor for lipopolysaccharide (LPS) was examined. Of the five CyDs used in this study, dimethylacetyl-beta-cyclodextrin (DMA7-beta-CyD) had greater inhibitory activity than other CyDs against the production of nitric oxide (NO) and various proinflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha) in murine macrophages stimulated with two serotypes of LPS and lipid A. The inhibitory effect of DMA7-beta-CyD on NO production was also observed in macrophages stimulated with lipoteichoic acid (LTA), but not peptidoglycan (PGN), polyinosinic-polycytidylic acid (poly I:C) or CpG oligonucleotide (CpG-ODN). Several studies have suggested that the inhibitory effects of DMA7-beta-CyD could be ascribed to the interaction with LPS. Simultaneous administration of DMA7-beta-CyD not only intraperitoneally but also intravenously and intraperitoneal injection of aqueous solution containing LPS and d-galactosamine in murine endotoxin shock model suppressed fatality. Also, DMA7-beta-CyD decreased blood level of TNF-alpha as well as serum levels of aspartate transaminase (AST) and alanine transaminase (ALT) in mice. In conclusion, DMA7-beta-CyD may have promise as a new therapeutic agent for endotoxin shock induced by LPS.

Enhancing effects of galactosylated dendrimer/alpha-cyclodextrin conjugates on gene transfer efficiency

To improve in vitro gene transfer efficiency and/or achieve cell-specific gene delivery of polyamidoamine (PAMAM) starburst dendrimer (generation 2, G2) conjugate with alpha-cyclodextrin (alpha-CDE conjugate (G2)), we prepared alpha-CDE conjugate bearing galactose (Gal-alpha-CDE conjugates) with the various degrees of substitution of the galactose moiety (DSG) as a novel non-viral vector. The agarose gel electrophoretic studies revealed that Gal-alpha-CDE conjugates formed complexes with plasmid DNA (pDNA) and protected the degradation of pDNA by DNase I, but these effects impaired as the DSG value increased. Dendrimer and alpha-CDE conjugate exerted pDNA condensation through the complexation, but Gal-alpha-CDE conjugates did not. Gal-alpha-CDE conjugate (DSG 4) was found to have much higher gene transfer activity than dendrimer, alpha-CDE conjugate and Gal-alpha-CDE conjugates (DSG 8, 15) in HepG2, NIH3T3 and A549 cells, which are independent of the expression of the asialoglycoprotein receptor. Transfection activity of Gal-alpha-CDE conjugate (DSG 4) was insensitive to the existence of competitors (asialofetuin and galactose) and serum. In addition, no cytotoxicity after transfection of the complex of pDNA with Gal-alpha-CDE conjugate (DSG 4) was observed. These results suggest the potential use of Gal-alpha-CDE conjugate (DSG 4) as a non-viral vector in various cells.

Applicability of (SBE)7m-beta-CD in controlled-porosity osmotic pump tablets (OPTs)

The purpose of this study was to investigate the general application of a controlled-porosity osmotic pump tablet (OPT) utilizing (SBE)7m-beta-CD as both a solubilizer and an osmotic agent for drugs with varying physical properties. OPTs utilizing (SBE)7m-beta-CD were prepared for five poorly soluble and two highly water-soluble drugs. The Japanese Pharmacopoeia dissolution method was used to study the drug and (SBE)7m-beta-CD release from the OPTs. The drug concentration in the OPT core after the OPT was placed in the release medium for two hours was assayed gravimetrically and by HPLC. An appropriate composition ratio (ACR) of (SBE)7m-beta-CD to drug at which drug release from the OPT was complete and pH-independent within the physiological pH range of the GI tract was determined for each drug. The ACR values correlate to the drug concentration in the OPT core when the OPTs were placed in the release medium for two hours. The release profiles of prednisolone (a poorly water-soluble drug) and sodium chloride (a water-soluble compound) from the OPTs were almost the same as that of (SBE)7m-beta-CD. Also, the release rate of each drug per unit membrane surface area from the OPTs was similar, regardless of the differences in drug solubility. The present results confirmed that (SBE)7m-beta-CD serves as both a solubility modulator and as an osmotic pumping agent for OPTs, from which the release rate of both water-soluble and poorly water-soluble drugs can be controlled.

Improvement of gene delivery mediated by mannosylated dendrimer/alpha-cyclodextrin conjugates

The purpose of this study is to evaluate in vitro and in vivo gene delivery efficiency of polyamidoamine (PAMAM) starburst dendrimer (generation 2, G2) conjugate with alpha-cyclodextrin (alpha-CDE conjugate (G2)) bearing mannose (Man-alpha-CDE conjugates) with the various degrees of substitution of the mannose moiety (DSM) as a novel non-viral vector in a variety of cells. Man-alpha-CDE conjugates (DSM 3.3 and 4.9) were found to have much higher gene transfer activity than dendrimer, alpha-CDE conjugate and Man-alpha-CDE conjugates (DSM 1.1 and 8.3) in various cells, which are independent of the expression of cell surface mannose receptors. Cellular association of pDNA complexes with dendrimer, alpha-CDE conjugate and Man-alpha-CDE conjugate (DSM 3.3) and their cytotoxic effects differed only very slightly. Surface plasmon resonance study demonstrated that the specific binding activity of Man-alpha-CDE conjugates to concanavalin A was not very strong. Much more conjugation of the mannose moiety to alpha-CDE conjugates provided unfavorable physicochemical properties of pDNA complexes for gene transfer, e.g. the low interaction with pDNA, the low enzymatic stability of pDNA and the lack of pDNA compaction. Man-alpha-CDE conjugate (DSM 3.3) provided gene transfer activity higher than dendrimer and alpha-CDE conjugate in kidney 12 h after intravenous injection in mice. These results suggest the potential use of Man-alpha-CDE conjugate (DSM 3.3) as a non-viral vector.

Design and evaluation of cyclodextrin-based drug formulation

The pharmaceutically useful cyclodextrins (CyDs) are classified into hydrophilic, hydrophobic, and ionic derivatives. Because of the multi-functional characteristics and bioadaptability, these CyDs are capable of alleviating the undesirable properties of drug molecules through the formation of inclusion complexes or the form of CyD/drug conjugates. This review outlines the current application of CyDs in design and evaluation of CyD-based drug formulation, focusing on their ability to enhance the drug absorption across biological barriers, the ability to control the rate and time profiles of drug release, and the ability to deliver a drug to a targeted site.

Involvement of CD14 in the inhibitory effects of dimethyl-α-cyclodextrin on lipopolysaccharide signaling in macrophages

The potential use of alpha-cyclodextrin and its hydrophilic alpha-cyclodextrin derivatives (alpha-CyDs) as antagonists against lipopolysaccharide (LPS), which stimulates the nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production as well as nuclear factor-kappaB (NF-kappaB) activation in macrophages was examined. Of three alpha-CyDs used in the present study, 2,6-di-O-methyl-alpha-CyD (DM-alpha-CyD) had greater inhibitory activity than did the other CyDs against NO and TNF-alpha production through an impairment of gene expression in macrophage cell lines and primary macrophages stimulated with LPS and lipid A in a concentration-dependent manner. Concomitantly, DM-alpha-CyD inhibited NF-kappaB translocation into nucleus. These inhibitory effects of DM-alpha-CyD could be attributed to the release of CD14 from lipid rafts caused by an efflux of phospholipids, but not cholesterol. These results suggest that DM-alpha-CyD may have promise as a potent and unique antagonist for excess activation of macrophages stimulated with LPS.

[Pharmaceutical application of cyclodextrins as multi-functional drug carriers]

Owing to the increasingly globalized nature of the cyclodextrin (CyD)-related science and technology, development of the CyD-based pharmaceutical formulation is rapidly progressing. The pharmaceutically useful CyDs are classified into hydrophilic, hydrophobic, and ionic derivatives. Because of the multi-functional characteristics and bioadaptability, these CyDs are capable of alleviating the undesirable properties of drug molecules through the formation of inclusion complexes or the form of CyD/drug conjugates. This review outlines the current application of CyDs in drug delivery and pharmaceutical formulation, focusing on the following evidences. 1) The hydrophilic CyDs enhance the rate and extent of bioavailability of poorly water-soluble drugs. 2) The amorphous CyDs such as 2-hydroxypropyl-beta-CyD are useful for inhibition of polymorphic transition and crystallization rates of drugs during storage. 3) The delayed release formulation can be obtained by the use of enteric type CyDs such as O-carboxymethyl-O-ethyl-beta-CyD. 4) The hydrophobic CyDs are useful for modification of the release site and/or time profile of water-soluble drugs with prolonged therapeutic effects. 5) The branched CyDs are particularly effective in inhibiting the adsorption to hydrophobic surface of containers and aggregation of polypeptide and protein drugs. 6) The combined use of different CyDs and/or pharmaceutical additives can serve as more functional drug carriers, improving efficacy and reducing side effects. 7) The CyD/drug conjugates may provide a versatile means for the constructions of not only colonic delivery system but also site-specific drug release system, including gene delivery. On the basis of the above-mentioned knowledge, the advantages and limitations of CyDs in the design of advanced dosage forms will be discussed.

Effects of Hydrophilic Cyclodextrins on Aggregation of Recombinant Human Growth Hormone

PURPOSE

To evaluate the effect of hydrophilic cyclodextrins (CyDs) on the aggregation induced by different stresses and on the oxidation and deamidation of recombinant human growth hormone (rhGH).

METHODS

The aggregation of rhGH was induced by three denaturing techniques including chemical (4.5 M guanidine hydrochloride), thermal (differential scanning calorimetry), and interfacial denaturation (vortex agitation). The aggregates were characterized and quantified by UV spectrophotometry and size exclusion chromatography. The effects of hydrophilic CyDs on deamidation and oxidation rates of rhGH were studied by HPLC method.

RESULTS

In both thermally and chemically induced aggregations, branched beta-CyDs significantly inhibited the aggregation of rhGH compared with the other alpha- and gamma-CyDs. This can explain that the beta-CyD cavity with branched sugar moieties may be relatively preferable in preventing the aggregation of rhGH. In contrast, 2-hydroxypropyl beta-CyD with surface activity was found to be effective in reducing the aggregation induced by interfacial denaturation compared with those of branched beta-CyDs. On the other hand, these hydrophilic CyDs showed no noticeable inhibitory effect on the oxidation and deamidation rates of rhGH. The results suggested that CyDs interact preferably with exposed hydrophobic side chains rather than aliphatic side chains of rhGH, resulting in the inhibition of aggregation but not the oxidation and deamidation rates.

CONCLUSIONS

The different inhibitory effect of CyDs is dependent not only on the structure and property of CyD itself but also the nature of the denaturing stimulus. The current results suggested that hydrophilic beta-CyDs can effectively inhibit the aggregation of rhGH. Thus, hydrophilic beta-CyDs may be potentially useful excipients for parenteral preparation of rhGH.

NMR spectroscopic characterization of metoprolol/cyclodextrin complexes in aqueous solution: Cavity size dependency

The inclusion complex formation of a water-soluble beta(1)-selective adrenoreceptor antagonist Metoprolol (Met) with alpha-cyclodextrin (alpha-CyD), beta-cyclodextrin (beta-CyD), gamma-cyclodextrin (gamma-CyD), and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) in aqueous solution was studied by ultraviolet (UV), circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopies and the modes of interaction were assessed. Continuous variation plots revealed that Met forms the inclusion complexes with alpha-CyD, beta-CyD, and HP-beta-CyD in a stoichiometry of 1:1, whereas gamma-CyD forms the 2:1 complex where two Met molecules are included in one gamma-CyD cavity. NMR spectroscopic studies, including ROESY and GROESY techniques, clearly indicated that alpha-CyD with the small cavity includes the methoxyethylbenzene moiety of Met molecule shallowly in the cavity, depositing the benzene and the methoxy moieties around the secondary and primary sides, respectively, of the cavity. In the case of the beta-CyD complex, the methoxyethylbenzene moiety is more deeply included in the cavity, and it is feasible that Met may be able to enter from both primary and secondary hydroxyl sides of the cavity, forming the 1:1 complex. On the other hand, two Met molecules are included probably in an antiparallel orientation in the large gamma-CyD cavity, and the benzene moieties of Met are in contact with each other.

Contribution of Cholesterol and Phospholipids to Inhibitory Effect of Dimethyl-β-Cyclodextrin on Efflux Function of P-Glycoprotein and Multidrug Resistance-Associated Protein 2 in Vinblastine-Resistant Caco-2 Cell Monolayers

PURPOSE

The purpose of this study is to reveal the contribution of membrane components to the inhibitory effect of 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CyD) on P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (MRP2) function in vinblastine-resistant Caco-2 (Caco-2R) cell monolayers.

METHODS

The transport of rhodamine-123 and 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) was studied in Caco-2R cell monolayers. P-gp and MRP2 residing in the monolayers and releasing in cell supernatants were detected by Western blotting. The mRNA levels of MDR1 and MRP2 were detected by reverse transcription-polymerase chain reaction (RT-PCR) method. Cholesterol, phospholipids, and proteins were mainly determined by each assay kit.

RESULTS

Of various beta-cyclodextrin derivatives (beta-CyDs), DM-beta-CyD most significantly impaired the efflux function of P-gp and MRP2 without changing cell viability and membrane integrity. The treatment with CyDs did not change the mRNA levels of MDR1 and MRP2. DM-beta-CyD lowered cholesterol content and P-gp level in caveolar membranes. In addition, DM-beta-CyD released not only cholesterol and phospholipids but also proteins including P-gp and MRP2 from apical membranes of the monolayers.

CONCLUSIONS

DM-beta-CyD may impair P-gp and MRP2 function in Caco-2R cell monolayers, probably, at least in part, through the release of these transporters from the apical membranes of monolayers, and the exertion of the inhibitory effect of DM-beta-CyD may require the extraction of not only cholesterol but also phospholipids from the monolayers.

Inhibitory Effect of Sulfobutyl Ether β‐cyclodextrin on DY‐9760e‐Induced Cellular Damage: In vitro and in vivo Studies

The effects of water-soluble beta-cyclodextrin derivatives (beta-CyDs), such as 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) and sulfobutyl ether beta-cyclodextrin (SBE7-beta-CyD) on cytotoxicity of DY-9760e (3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate) toward human umbilical vein endothelial cells (HUVECs) in vitro and vascular damage of the auricular vein of rabbits by DY-9760e in vivo were investigated. The spectroscopic study revealed that of the four beta-CyDs SBE7-beta-CyD forms the most stable inclusion complex in phosphate-buffered saline, probably because of a synergetic effect of hydrophobic and electrostatic interactions. beta-CyDs inhibited DY-9760e-induced cell death toward HUVECs in an order of G(2)-beta-CyD < beta-CyD < HP-beta-CyD < SBE7-beta-CyD, which was consistent with the order of the magnitude of stability constants. When the DY-9760e solution was infused into the auricular vein of rabbits for 24 h, SBE7-beta-CyD suppressed a DY-9760e-induced irritation such as thrombus, desquamation of the endothelium vasculitis, and perivasculitis. The present data indicated that SBE7-beta-CyD formed an inclusion complex with DY-9760e in a buffer solution and possessed the protective effect on DY-9760e-induced cytotoxicity toward HUVECs and vascular damage in rabbits. These results suggested potential use of SBE7-beta-CyD as a parenteral carrier for DY-9760e.

In vitro and in vivo gene transfer by an optimized alpha-cyclodextrin conjugate with polyamidoamine dendrimer

The purpose of the present study is to optimize the structure of the polyamidoamine starburst dendrimer (dendrimer) conjugate with alpha-cyclodextrin (alpha-CDE conjugate) as a nonviral vector. alpha-CDE conjugates of dendrimer (generation 3, G3) with various average degrees of substitution (DS) of alpha-CyD of 1.1, 2.4, and 5.4 were prepared. alpha-CDE conjugates formed the complexes with pDNA, resulting in a change of the particle sizes of pDNA complexes, but the distinction of physicochemical properties among their vector/pDNA complexes was only very slight. The membrane-disruptive ability of alpha-CDE conjugates on liposomes encapsulating calcein and their cytotoxicity to NIH3T3 and HepG2 increased with an increase in the DS value of alpha-CyD. In vitro gene transfer activity of alpha-CDE conjugates in both NIH3T3 and HepG2 cells augmented as the charge ratio (vector/pDNA) increased, and the activity of alpha-CDE conjugate (DS 2.4) was the highest at higher charge ratios among dendrimer (G3), the three alpha-CDE conjugates, and TransFast. After intravenous administration of pDNA complexes in mice, alpha-CDE conjugate (DS 2.4) delivered pDNA more efficiently in spleen, liver, and kidney, compared with dendrimer and other alpha-CDE conjugates (DS 1.1 and 5.4). The potential use of alpha-CDE conjugate (G3, DS 2.4) could be expected as a nonviral vector in vitro and in vivo, and these data may be useful for design of alpha-CyD conjugates with other nonviral vectors.

Involvement of cholesterol in the inhibitory effect of dimethyl-beta-cyclodextrin on P-glycoprotein and MRP2 function in Caco-2 cells

We compared the inhibitory effect of various cyclodextrins (CyDs) on P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (MRP2) function and examined the contribution of cholesterol to the inhibitory effect of 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CyD) on the efflux activity of the function in Caco-2 cell monolayers. Of various CyDs, DM-beta-CyD significantly impaired the efflux activity of P-gp and MRP2. DM-beta-CyD released P-gp and MRP2 from the monolayers in the apical side's transport buffer and decreased the extent of cholesterol as well as P-gp and MRP2 in caveolae of Caco-2 cell monolayers, but not caveolin and flotillin-1. On the other hand, DM-beta-CyD did not change MDR1 and MRP2 mRNA levels. Therefore, these results suggest that the inhibitory effect of DM-beta-CyD on P-gp and MRP2 function, at least in part, could be attributed to the release of these transporters from the apical membranes into the medium as secondary effects through cholesterol-depletion in caveolae after treatment of Caco-2 cell monolayers with DM-beta-CyD.

6-O-alpha-(4-O-alpha-D-glucuronyl)-D-glucosyl-beta-cyclodextrin: solubilizing ability and some cellular effects

Some physicochemical and biopharmaceutical properties of a new branched cyclodextrin, 6-O-alpha-(4-O-alpha-D-glucuronyl)-D-glucosyl-beta-cyclodextrin (GUG-beta-CyD), were investigated. The interaction of GUG-beta-CyD with drugs was studied by spectroscopic and solubility methods, and compared with those of parent beta-CyD and 6-O-alpha-maltosyl-beta-CyD (G(2)-beta-CyD). The hemolytic activity of GUG-beta-CyD on rabbit erythrocytes was lower than those of beta-CyD and G(2)-beta-CyD. GUG-beta-CyD and G(2)-beta-CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG-beta-CyD to neutral and acidic drugs was comparable to or slightly smaller than those of beta-CyD and G(2)-beta-CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG-beta-CyD showed greater affinity for the basic drugs, compared with beta-CyD and G(2)-beta-CyD, owing to an electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus, GUG-beta-CyD may be useful as a safe solubilizing agent particularly for basic drugs.

Inclusion complex formation of captopril with alpha- and beta-cyclodextrins in aqueous solution: NMR spectroscopic and molecular dynamic studies

The inclusion complex formation of alpha-cyclodextrin (alpha-CyD), beta-cyclodextrin (beta-CyD), and 2-hydroxylpropyl-beta-cyclodextrin (HP-beta-CyD) with an angiotensin converting enzyme inhibitor, captopril, in aqueous solution was studied by (1)H- and (13)C-nuclear magnetic resonance spectroscopies, including ROESY and GROESY techniques, by kinetic methods and by molecular dynamic calculations. The oxidative degradation of captopril was markedly suppressed in alpha-CyD solutions, whereas beta-CyD and HP-beta-CyD had negligible stabilizing effects. These NMR and kinetic results suggested that alpha-CyD includes preferably the propyl thioalcohol moiety of captopril, depositing the proline moiety outside the cavity. On the other hand, beta-CyD includes a whole molecule of captopril in the cavity, locating the carboxylic acid within the cavity and the terminal thiol moiety outside the cavity. These inclusion structures were supported by molecular dynamic studies.

Protective effect of sulfobutyl ether beta-cyclodextrin on DY-9760e-induced hemolysis in vitro

The hemolytic behavior of a novel cytoprotective agent, DY-9760e (3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate) was investigated using rabbit erythrocytes. Further, the effects of water-soluble cyclodextrin derivatives, such as 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) and sulfobutyl ether of beta-cyclodextrin (SBE-beta-CyD), on the hemolytic activity of DY-9760e were studied. DY-9760e induced hemolysis at concentrations >0.2-0.3 mM in phosphate buffered saline (PBS) of pH 4.0 and 6.0, where DY-9760e is predominantly in dicationic and monocationic forms, respectively. The hemolytic activity of the monocationic DY-9760e was higher than that of the dicationic species, and the hemolysis at pH 4.0 involved the formation of methemoglobin. DY9760e induced the morphological change of erythrocytes towards membrane invagination at both pH 4.0 and 6.0. SBE7-beta-CyD significantly suppressed the DY-9760e-induced hemolysis and morphological change at both pH 4.0 and 6.0, as well as the formation of methemoglobin at pH 4.0. On the other hand, HP-beta-CyD suppressed only the hemolysis, but neither the morphological change nor the formation of methemoglobin. In addition, the inhibitory effect of SBE7-beta-CyD on the hemolysis was greater than that of HP-beta-CyD. The superior inhibitory effect of SBE7-beta-CyD on the DY-9760-induced hemolysis, the morphological change, and the formation of methemoglobin may be attributable to the formation of a stable inclusion complex with DY-9760e and to the weaker hemolytic activity of SBE7beta-CyD than HP-beta-CyD. These results suggest potential use of SBE7-beta-CyD as a parenteral carrier for DY-9760e.

Effects of structure of polyamidoamine dendrimer on gene transfer efficiency of the dendrimer conjugate with alpha-cyclodextrin

To improve gene transfer activity of a new nonviral vector, a polyamidoamine dendrimer (G2) conjugate with alpha-cyclodextrin (alpha-CDE conjugate (G2)), we prepared alpha-CDE conjugates with dendrimer having different generations (G3 and G4), and their gene transfer activities were compared with those of alpha-CDE conjugate (G2) and TransFast, a novel transfection reagent. alpha-CDE conjugates (G2, G3, and G4) formed the complexes with pDNA, changing the zeta-potential and particle size of pDNA complexes and the protection of pDNA from DNase I in a charge ratio-dependent manner, although their differences at higher charge ratios (vector/pDNA) were small. The gene transfer activity of alpha-CDE conjugates (G2, G3, and G4) was higher than that of the corresponding dendrimer alone in NIH3T3 and RAW264.7 cells. Of these CDE conjugates, alpha-CDE conjugate (G3) had a superior gene transfer activity which was comparable to that of TransFast in NIH3T3 cells. The intracellular distribution of pDNA after application of the pDNA complex with alpha-CDE conjugate (G3) to NIH3T3 cells was different from that with dendrimer alone (G3), although the cellular association of pDNA was almost comparable among all vectors. alpha-CDE conjugate (G3) strongly interacted with a fluorescence probe, 2-(p-toluidinyl)-naphthalene-6-sulfonate (TNS), suggesting that the conjugate possesses the inclusion ability with biomembrane constituents such as phospholipids after transfection. These results suggest that alpha-CDE conjugates, particularly the G3 conjugate, could be novel nonviral gene transfer agents.

Cyclodextrin conjugate-based controlled release system: repeated- and prolonged-releases of ketoprofen after oral administration in rats

6(A)-O-[2-(3-Benzoylphenyl)propinoyl]-alpha-cyclodextrin (KP-alpha-CyD conjugate), in which an anti-inflammatory drug, ketoprofen (KP), is covalently bound to one of the primary hydroxyl groups of alpha-cyclodextrin, was prepared, and its release behavior in vitro and in vivo was investigated. Further, the CyD conjugate-based repeated- and prolonged-release systems were designed by combining the conjugate (used as a delayed-release fraction) with the KP-2-hydroxypropyl-beta-CyD (HP-beta-CyD) complex (used as a fast-release fraction) or with KP-ethylcellulose (EC) solid dispersion (used as a slow-release fraction), respectively. The conjugate released KP only in rat cecum and colonic contents, whereas it was stable in other biological fluids of rats. The conjugate showed a typical delayed-release pattern after oral administration to rats, i.e., plasma levels of KP increased after a lag time of about 3 h and reached a maximum concentration at about 7 h. On the other hand, the non-covalent inclusion complex of KP with HP-beta-CyD gave a rapid increase in plasma drug levels, and the KP-EC solid dispersion retarded slightly the increase of plasma levels. The co-administration of the conjugate and the HP-beta-CyD complex gave a typical repeated release profile, i.e., double peaks were observed at about 1-2 and 8-12 h in plasma KP levels. On the other hand, the co-administration of the conjugate and the EC solid dispersion gave a typical sustained-release pattern of KP, i.e., a constant plasma KP level was maintained for at least 24 h. These repeated or long circulating release patterns in plasma KP levels after oral administration were clearly reflected in the anti-inflammatory effect using rats with carageenan-induced acute edema in paw. The results suggest that various release-controlled preparations can be designed by employing CyD conjugates in combination with other carriers with different releasing properties.

Colon-specific delivery of prednisolone-appended alpha-cyclodextrin conjugate: alleviation of systemic side effect after oral administration

Prednisolone (PD), a typical glucocorticoid, has been widely used for the treatment of inflammatory bowel disease (IBD). However, when PD is administered orally, a large amount of the drug is absorbed from the upper gastrointestinal (GI) tract and causes systemic side effects. In this study, the anti-inflammatory effect and systemic side effect of the PD succinate/alpha-cyclodextrin (PDsuc/alpha-CyD) ester conjugate after oral administration were studied using IBD model rats. The anti-inflammatory effect of the PDsuc/alpha-CyD conjugate was comparable to those of PD alone. On the other hand, the systemic side effect of the PDsuc/alpha-CyD conjugate was much lower than that of PD alone when administered orally. The lower side effect of the conjugate was attributable to passage of the conjugate through the stomach and small intestine without significant degradation or absorption, followed by the degradation of the conjugate site-specifically in the large intestine. The oral administration of PD alone gave higher plasma concentrations of PD, giving the significant systemic side effect. The results suggested that the PDsuc/alpha-CyD conjugate is useful as a delayed-release type prodrug of PD for colon-specific delivery, owing to alleviation of the systemic side effect, while maintaining the therapeutic effect.