Enhancement of norfloxacin solubility via inclusion complexation with β-cyclodextrin and its derivative hydroxypropyl-β-cyclodextrin

The objectives of the study were to investigate the effects of β-cyclodextrin(βCD) and hydroxypropyl-β-cyclodextrin(HPβCD) on the solubility and dissolution rate of norfloxacin prepared using three different methods, at drug to cyclodextrin weight ratios of 1:1, 1:2, 1:4 and 1:8. All the methods increased the solubility and dissolution rate of norfloxacin via inclusion complexation with βCD and HPβCD. Norfloxacin was converted from crystalline to amorphous form through inclusion complexation. Solvent evaporation method was the most effective method in terms of norfloxacin solubilisation, while inclusion complex of HPβCD has higher solubility than βCD complex when prepared using the same procedure.

Inclusion complexes of cefuroxime axetil with β-cyclodextrin:Physicochemical characterization, molecular modeling and effect of Larginine on complexation

The inclusion complexes of poorly water-soluble cephalosporin, cefuroxime axetil(CFA), were prepared with β-cyclodextrin(βCD) with or without addition of L-arginine(ARG) to improve its physicochemical properties. We also investigated the effect of ARG on complexation efficiency(CE) of βCD towards CFA in an aqueous medium through phase solubility behaviour according to Higuchi and Connors. Although phase solubility studies showed AL(linear) type of solubility curve in presence and absence of ARG, the CE and association constant(Ks) of βCD towards CFA were significantly promoted in presence of ARG,justifying its use as a ternary component. The solid systems of CFA with βCD were obtained by spray drying technique with or without incorporation of ARG and characterized by differential scanning calorimetry(DSC), X-ray powder diffractometry(XRPD), scanning electron microscopy(SEM), and saturation solubility and dissolution studies. The molecular modeling studies provided a better insight into geometry and inclusion mode of CFA inside βCD cavity. The solubility and dissolution rate of CFA were significantly improved upon complexation with βCD as compared to CFA alone. However, ternary system incorporated with ARG performed better than binary system in physicochemical evaluation. In conclusion, ARG could be exploited as a ternary component to improve the physicochemical properties of CFA via βCD complexation.

Study on the Structure of Supramolecular Inclusion Complex of β-Cyclodextrin with Retinoic Acid

Inclusion compound of retinoic acid with (-cyclodextrin was prepared by coprecipitating method, the structure of resulting product was studied by elemental analysis, differential scanning caloriemetry(DSC) analysis, FT-IR spectroscopy and X-ray diffractometry, and the formed supramolecule self-assembles in aqueous solution according to molar ratio 2:1 of host-guest.

Structural Study of Inclusion Complex of Andrographolide with β-Cyclodextrin Prepared under Microwave Irradiation

An inclusion complex of b-cyclodextrin with andrographolide (Andro) was prepared by using a convenient method of microwave irradiation. The structure of the inclusion complex was determined by the 1H NMR, 2D NMR spectroscopy as well as the elemental analysis.

Formation of the Inclusion Complex of Orange Ⅱ with β-Cyclodextrin and Its Photostability

Inclusion complex of Orange II with β-Cyclodextrin (β-CD) and the anti-photolysis effect under UV-light were investigated. The molar ratio of inclusion complex of β-Cyclodextrin and Orange Ⅱ is 1∶1. The formation constant K=1.236×10 3 L/mol was determined by the UV and Fluorescence spectra respectively, which was quite in accordance with the calculation with a modified Benesi-Hildbrand equation. The inclusion complex was characterized by the IR spectra and the molar ratio of inclusion complex is 1∶1 too. The formation constant K=1.266×10 3 L/mol was determined by 1 H NMR analysis and was nearly the same by UV and fluorescence spectra. The photocatalytic decolorization rate of Orange Ⅱ solutions containing β-CD and TiO_ 2 was smaller by 51.9% than that of the Orange Ⅱ solutions only containing TiO_ 2 , while in the case of direct photolysis of Orange Ⅱ solutions, β-CD can lower the photolysis rate by 48.1% under UV-light. This result indicates β-CD can inhibit the photolysis and photocatalytic decolorization of Orange Ⅱ under UV-light. The β-CD inclusion complex was found to be persistent to UV-light photolysis.

Mechanism and Kinetics of Thermal Dissociation of Inclusion Complex of β-Cyclodextrin and 1-Methylcyclopropene

The inclusion-complex of CD-MCP （β-cyclodextrin （β-CD） including 1-methylcyclopropene （1-MCP）） was prepared and characterized. Basing on programmed-heating procedure and weight-temperature analysis, as well as the application of Satava-Sestak＇s, Ozawa＇s and Kissinger＇s methods, the mechanism and kinetics of thermal dissociation of this inclusion complex were studied. An additional mass loss is found at 170-180℃. The mechanism of thermal dissociation of CD-MCP is dominated by a one-dimensional random nucleation and subsequent growth process （A2/3）. The activation energy Es and the pre-exponential factor AS for the process are 102.14 kJ/mol and 3.63×10^10s^-1, respectively. This ES value shows that there is no strong chemical intere, ctions between β-CD and 1-MC;P,

FORMATION OF THE CRYSTALLINE INCLUSION COMPLEX BETWEEN β-CYCLODEXTRIN AND POLYPROPYLENE

PP can be included in the cavities of cyclodextrin (CD). The crystalline inclusion complex between β-CD and lowmolecular weight polypropylene (PP) was obtained and investigated. α-CD and γ-CD did not form crystalline inclusioncomplexes with PP. The FTIR spectra, TGA, X-ray diffraction spectra were studied, ~1H-NMR spectra and ^(13)C CP/MAS NMR spectra were used to characterize the crystalline inclusion complexes.

A Study of the Driving Force for Inclusion Complexation of α- and β- Cyclodextrin with Substituted Benzene

The driving force for inclusion complexation of α and β CD with substituted benzene(PhX) was studied by means of step wise regression analysis. A set of multiple regression equations was established with correlation coefficients 0 96 and 0 94 for the individual complexation of α CD and β CD with PhX. The ln K a(calc.) values calculated with the aid of the regression equations were close to those determined experimentally. The inclusion complexation is dominantly driven by van der Waals force and hydrophobic interactions.

Inclusion complexes between sildenafil citrate and cyclodextrins enhance drug solubility

Sildenafil citrate is a potent and selective phosphodiesterase-5inhibitor. It is effectively used in the treatment of erectile dysfunction and pulmonary arterial hypertension. The drug is rapidly absorbed and pharmacologically acts within30 min to 1 h after oral administration. However, it has a relatively low absolute bioavailability of 41%because its limited solubility in water is the major problem (1)To improve the oral bioavailability of poorly water-soluble drugs.

Synthesis of a Novel Aromatic Diamino-bridged Bis(β-cyclodextrin) and its Inclusion Complexation with Dyes Molecules

A novel brideed bis（β-cvclodextrin）, 4, 4＇-diaminodiphenyl ether-bfiged-bis （6-aimino-6-deoxv-β-cyclodextrin） 3, has been synthesized and its inclusion complexation behavior with three linear＇guest dyes （AR, NR and MB ） has been investigated by. means of fluorescence spectrometry. The-result obtained demonstrated that the novel bridged bis（β-cyclodextnn） showed much higher affinities towards guest dyes than native β-cyclodextrin.

Inclusion Complex of Paclitaxel in Hydroxypropyl-β-cyclodextrin

Introduction Paclitaxel （as Taxol） is a kind of diterpenoid natural product extracted from Chinese yew. It has been reported to have high anti-tumor effects, such as the activity against oophorama, mammary cancer, encephaloma, cervical carcinoma, and non- small-cell lung carcinoma. One of the major problems of paclitaxel applied to therapy is its extremely low solubility in water. In addition, paclitaxel is administered as a slow infusion in a vehicle consisting of Cremophor EL （ polyoxyethylated castor oil ）. However, Cremophor has been observed to cause severe, occasionally fatal hypersensitivity reactions in animals and humans. Therefore, paclitaxel therapy includes a prophylactic regimen of antihistamines and corticosteroids , along with a prolonged infusion time to reduce the severity and incidence of hypersensitivity reactions. Because of the reasons mentioned above, currently its preparation needs to be improved further.

PREPARATION AND CHARACTERIZATION OF INCLUSION COMPLEXES OF TWO-ARM LINEAR AND FOUR-ARM STAR-SHAPED POLY(ε-CAPROLACTONE)S WITHα-CYCLODEXTRIN

Both four-ann star-shaped poly（ε-caprolactone） （4sPCL） and two-ann linear PCL （2LPCL） were synthesized and their inclusion complexation with α-cyclodextrin （α-CD） were studied. The inclusion complexes （ICs） formed between the PCL polymers and α-CD were characterized by ^1H-NMR, DSC, TGA, WAXD, and FT-1R, respectively. Both branch ann number and molecular weight of the PCL polymers have apparent effect on the stoichiometry （CL：CD, mol：mol） of these ICs. All these analytical results indicate that the branch arms of the PCL polymers are incorporated into the hydrophobic α-CD cavities and their original crystalline properties are completely suppressed. Moreover, the inclusion complexation between two-ann linear or four-ann star-shaped PCL polymers and α-CD not only enhances the thermal stability of the guest PCL polymers but also improves that of α-CD.

Preparation and Spectroscopic Study of Different Stoichiometric Solid Supramolecular Inclusion Complexes of β-Cyclodextrin with Short Chain Aliphatic Amines

The solid Supramolecular complexes of β-cyclodextrin （β-CD） with ethylenediamine 1, diethylenetriamine 2 and triethylamine 3 were obtained and characterized using elemental analysis, powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and ^1H nuclear magnetic resonance spectroscopy. Based on the results of elemental analysis and ^1H NMR, the guest-host stoichiometries of the three solid complexes were determined to be 5：2 for 1-β-CD, hl for 2-β-CD, and 1：3 for 3-β-CD. The yields were relative to the molar volume ratio of guest to β-CD cavity, and increased in the order： 1-β-CD〈2-3-CD〈3-β-CD. X-ray diffraction patterns of the inclusion complexes gave very good exhibitions not only in location of diffraction peaks but also in shape and diffraction intensity of the peaks due to the intermolecular complexations between β-CD and the guests. The formation of host-guest inclusion complexes exhibited obviously enhanced phase change temperatures of the complexed guests such as 1 and 3. The H-5 protons located at the narrower rim inside the CD cavity experienced a higher shift upon inclusion while all other protons experienced lower shifts.

Preparation and Action Mechanism of Inclusion Complex of β-cyclodextrin and Sulfurized Isobutylene as Additives in Solution of Polyethylene Glycol-600

The inclusion complex of β-cyclodextrin (β-CD) and sulfurized isobutylene (T321) was prepared with a co-precipitation method. The tribological properties of the complex with different concentrations were investigated by a four-ball tester in the solution of polyethylene glycol-600 (PEG-600). The experimental results suggest that the complex exhibits better anti-friction and anti-wear properties than β-CD under different load conditions. The tribo-system shows the least friction coefficient when the concentration of the complex is 0.8%. During the friction process, the complex was decomposed into various molecular fragments and the T321 molecules were released onto the friction interface to provide effective lubrication. The XPS analytical results on the worn surfaces reveal that sulfide film formed by the released T321 plays a major role, and the iron alkoxide and carbon deposition films formed by the β-CD fragments have better anti-friction effect on the sulfide film surface. The interactions of different films result in the formation of a mixed boundary lubrication film.

Crystal Structure of a Novel Sandwich Inclusion Complex of β-Cyclodextrin with α-Naphthylacetic Acid

A supramolecular inclusion complex between β-cyclodextrin（β-CD） and α-naphthylacetic acid was prepared, and its crystal structure was investigated by single-crystal X-ray crystallography. The complex contains two β-CD molecules, one α-naphthylacetic acid, two ethanols and twenty-eight water molecules in the asymmetric unit, which could be formulated as [（C42H70O35）2·（C12H10O2）·（C2H5OH）2·28H2O]. Two β-CD molecules constitute a dimer by face-to-face contact of their secondary hydroxyl sides. At the interface of the dimer, one α-naphthylacetic acid molecule is sandwiched between two β-CD molecules. Each β-CD unit of the dimer includes one ethanol molecule in its cavity. The β-CD dimers are linked together via hydrogen bonding to form layers that are stacked in a brickwork-like pattern. The comparative study of some sandwich complexes elucidates that the interface of the β-CD dimer has a stronger inclusion capacity than the cavity of β-CD for some suitable planar guest molecules. The novel inclusion structure results from the competitive inclusion of α-naphthylacetic acid and ethanol.

Studies on the Inclusion Complex Reaction and Fluorescent Analytical Application of β- cyclodextrin with Hymecromone

The inclusion complex reaction condition and the mechanism of β cyclodextrin with hymecromone have been studied by fluorescent spectrum. The fluorescent intensity and the stability of the system can be qreatly increased in qiven condition, and the formation constant of the inclusion complex reaction has been determined too. The system can be applied to the determination of trace amounts of hymecromone, the maximum fluorescent intensity is obtained with excitation and emission wavelength at 362 nm and 452 nm, respectively. The linear range for hymecromone is 8.0×10 -9 mol·L -1 to 1.0×10 -5 mol·L -1 . The detection limit is 1.8×10 -9 mol·L -1 . A simple, rapid and highly sensitive fluorimetric method is proposed for the determination of hymecromone. The results obtained are in agreement with those given by an official method.

Intramolecular Charge Transfer Dual Fluorescence pH Sensing using p-Dibutylaminobenzoic Acid-β-cyclodextrin Inclusion Complex

The intramolecular charge transfer dual fluorescence of p-dibutylaminobenzoic acid-b-cyclodextrin inclusion complex showed a substantially higher sensitivity toward aqueous solution pH variation when compared with that of p-dibutylaminobenzoic acid alone, which established a new principle for direct CT fluorescence sensing in aqueous solution by using the CT fluorophore-cyclodextrin inclusion complex.

Studies on the Stability and Structure of β-cyclodextrin Vitamin D_2 Inclusion Complex

The inclusion complex of β\|cyclodextrin (βCD) with Vitamin D 2 (VD 2 ) was prepared in 60% ethanol aqueous solution. The accelerated tests of the inclusion complex βCD\|VD 2 were performed under strong light, high temperature and high humidity. The results showed that the content of VD 2 in the inclusion complex was still kept 85%~95% after two years, while that in the βCD and VD 2 mixture was just 17%~22%. It indicated that VD 2 in inclusion complex was much more stable than pure VD 2. Therefore, adding the inclusion complex βCD\|VD 2 into “Longmu” Zhuanggu Chongji, a medicine for children to prevent and cure rickets, can not only decrease the expense of VD 2, but also enhance the stability of the products. IR, X\|ray, DTA and UV techniques were used to characterize the structures of the inclusion complex. The results indicated that intermolecular hydrogen bonds formed in the βCD\|VD 2 inclusion complex.

DSC and NMR Study on the Inclusion Complex of Lappaconitine with b-Cyclodextrin

The inclusion complex of lappaconitine (Lap) with b-cyclodextrin (b-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR, 2D-NMR spectroscopy. The structure of the complex has been deduced.