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The widespread occurrence of sulfonamides (SAs) in the environment water has rasied great concerns about their potential to antibiotics resistance. In this study, the fluorescence behaviors of sulfamethoxazole (SMZ) representing certain properties of the SAs mixed with three different kinds of cyclodextrins (CDs) in water solutions were investigated, respectively. The result reported that the shapes of the fluorescence peak and its position for the SMZ that were mixed with the CDs were almost the same as those of the standard SMZ, respectively. In addition, compared with the identical control sample the fluorescence of SMZ mixed with each of the CD was greatly enhanced. Therefore, a new simple, and sensitive spectrofluorimetric method for the determination of SMZ was established in water solutions. and the dynamic linear ranges varied from 0.01 to 0.7 mg/L with the detection limit of 7.1 ng/L. And the correlation coefficient was more than 99.9%. Significantly, this new method was successfully applied to direct determination of SMZ in pharmaceutical compounds. Moreover, the results showed that the SMZ could separately form the 1:1 supramolecular compound with each of the CD.

Carvedilol is one of the most effective antihypertensive drugs used in the treatment of congestive heart failure. A major disadvantage of this pharmaceutical active substance is its limited solubility in water, gastric and intestinal fluids. One way to overcome this problem is the preparation of inclusion complexes. The aim of this study was to prepare the inclusion complexes of carvedilol with β-cyclodextrin (β-CD) and (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) and to investigate their physical properties. The formation of inclusion complexes with β-CD and HP-β-CD was confirmed using FTIR, 1H-NMR and XRD methods. Phase solubility studies indicate the formation of inclusion complexes in 1:2 molar ratio and the increase of carvedilol solubility. The stability constant (β 2) was found to be 3.4 × 104 and 5.1 × 104 M−2 for inclusion complexes of carvedilol:β-CD and carvedilol:HP-β-CD, respectively. Photostability of carvedilol was increased after preparation of inclusion complexes with β-CD and HP-β-CD. Based on the results of this study, it can be concluded that the prepared complexes of carvedilol improve the solubility and stability of carvedilol and give it an advantage to be applied for the design of new pharmaceutical formulations.

A photochromic system based on dracoflavylium, a natural pigment extracted from Dragon's blood, a resin appearing in the injury parts of the tree Dracaena draco, is studied in water. The photochromism arises from the irradiation of the trans-chalcone, giving a mixture of flavylium cation/quinoidal base as a photoproduct via cis-chalcone and hemiketal. The performance of the photochromic system can be improved in the presence of (2-hydroxypropyl)-β-cyclodextrin. A mathematical model to account for the details of the kinetics and thermodynamics of the system was deduced. The model is general for all the host-guest systems involving the flavylium network of chemical reactions with 1 : 1 stoichiometric association.

Sulfanilamide belongs to the group of drugs that have a bacteriostatic effect on different pathogenic microorganisms. This activity originates from the competitive antagonism with p-aminobenzoic acid, which is an integral part of folic acid. The safe use of sulfanilamide is limited due to poor solubility in the aqueous medium. Therefore, the aim of this paper is the synthesis of sulfanilamide, as well as preparing and structural characterization of its inclusion complexes with cyclodextrins. The crude sulfanilamide was obtained in the synthesis between acetanilide and chlorosulfonic acid according to the standard procedure. The synthesized sulfanilamide was recrystallized from water in order to obtain the satisfactory purity of the substance. Sufanilamide was complexed with beta-cyclodextrin and 2-hydroxypropyl-beta-cyclodextrin by the co-precipitation method. A molecular encapsulation of sulfanilamide was confirmed by using FTIR, H-1-NMR, XRD and DSC methods. Phase-solubility techniques were used to assess the formation of the inclusion complex between sulfanilamide and cyclodextrins. The photostability of sulfanilamide and its inclusion complexes was estimated by UVB irradiation in a photochemical reactor by applying the UV-Vis method. Based on the UV-Vis analysis, sulfanilamide:2-hydroxypropyl-beta-cyclodextrin complex was presented as more photostable than sulfanilamide:beta-cyclodextrin complex and sulfanilamide. The obtained results enable the potential use of these inclusion complexes for the preparation of oral formulations due to the enhanced solubility of sulfanilamide.

In this work, the complex of shikonin-methyl-β-cyclodextrin and shikonin-2-hydroxypropyl-β-cyclodextrin were studied in supercritical carbon dioxide (sc CO2) at moderate pressure and temperature much lower than the melting point of shikonin. For comparing, the complex was also prepared by sealed heating method. Complex efficiency between shikonin and 2-hydroxypropyl-β-cyclodextrin (HPBCD) was quite low. Partly formation of shikonin—methyl-β-cyclodextrin (MBCD) was obtained by sealed heating method. Complete formation of shikonin—MBCD was obtained in sc CO2 media in short reaction time. This complexation was accelerated and enhanced by the rise in both the reaction temperature and carbon dioxide pressure up to 100 °C 100 bar. The physical state of cyclodextrins in complex reaction has remarkable influence on the complex. The aqueous solubility of shikonin could be enhanced about 75 times by complexing with MBCD. In this work, the complex of shikonin-methyl-β-cyclodextrin and shikonin-2-hydroxypropyl-β-cyclodextrin were studied in supercritical carbon dioxide (sc CO2) at moderate pressure and temperature much lower than the melting point of shikonin (SK). For comparing, the complex was also prepared by sealed heating method. Complex efficiency between SK and 2-hydroxypropyl-β-cyclodextrin (HPBCD) was quite low. Partly formation of SK—methyl-β-cyclodextrin (MBCD) complex was obtained by sealed heating method. Complete formation of SK—MBCD was obtained in sc CO2 media in short reaction time. This complexation was accelerated and enhanced by the rise in both the reaction temperature and carbon dioxide pressure. The physical state of cyclodextrins in sc CO2 has remarkable influence on the complex. The aqueous solubility of SK could be enhanced about 75 times by complexing with MBCD.

A capillary electrophoresis method was developed to determine the impurity of etodolac enantiomers. (2-Hydroxypropyl)-beta-cyclodextrin (HP-beta-CD) was used as a chiral selector and ketoprofen as an internal standard to improve the peak area precision. The seperation of the etodolac enantiomers was achived within 35 min at 15 degrees C and its highest resolution was about 4.0 using phosphate buffer (0.1 M, pH 6.0) with 15 mM HP-beta-CD and UV detection at 225 nm with a reference wavelength at 360 nm. This method allowed determination of 0.2% of (R)-(-)-etodolac in (S)-(+)-etodolac and method validation showed adequate linearity over the required range.

To investigate the effect of 2-hydroxypropyl side group substitutions on the structure of beta-cyclodextrin (CD) in water.Molecular dynamics simulations were carried out on four HPBCDs that broadly represent a range of degree of substitutions in order to investigate the effect of substitution of beta-cyclodextrin with 2-hydroxypropyl groups at various O2 and O6 positions of the glucose units.The 2-hydroxypropyl side groups located at the O2 positions widen the cavity entrance at the secondary OH position of the CD molecule. These groups are spatially more spread out but dynamically more restricted, due to the formation of a hydrogen bond network between the hydroxyl groups of the side chains and the glucose units. On the other hand, the 2-hydroxypropyl groups at the O6 positions are dynamically more flexible.The extent and the location of the substitution can affect the cavity structure of the CD molecule, and thus possibly the molecular encapsulation capabilities.

This paper presents the results of precision measurements of isothermal compressibility for aqueous solutions of 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) in the temperature range 10–50°C. The net of hydrogen bonds in water is not radically changed by the incorporation of 2-hydroxypropyl-β-cyclodextrin molecules until the concentration becomes 20.3 wt.%.

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 (2.8×10−8 M in phosphate buffer at 25 °C). In this study, we attempted to improve the solubility of FPFS-410 in water, by means of the complexation with 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD). Further, the interaction of FPFS-410 with HP-β-CyD in 50% v/v methanol/water mixed solution was investigated by ultraviolet and 1H-nuclear magnetic resonance (NMR) spectroscopic methods, because the solubility of FPFS-410 in water was too low to study quantitatively the interaction. The results of the solubility method indicated that HP-β-CyD had a markedly high solubilizing ability to FPFS-410, e.g., the solubility of the compound was increased 200,000-fold by the addition of 40 mM HP-β-CyD. The continuous variation plot of the FPFS-410/HP-β-CyD system in 50% v/v methanol/water solution gave a maximum at a host/guest molar ratio of 1:1. 1H-NMR spectroscopic studies suggested that the stilbene moiety of FPFS-410 is preferably included in the HP-β-CyD cavity to form the 1:1 complex in 50% v/v methanol/water solution. The present results suggest that HP-β-CyD is useful for improvement of the oral bioavailability of FPFS-410.

The effect of 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) on the release of a water-soluble β1-selective adrenoreceptor antagonist, metoprolol (Met), from ternary Met/HP-β-CyD/ethylcellulose (EC) tablets was investigated. The release rate of Met from the ternary tablets was dependent on amounts of HP-β-CyD in the tablets, i.e., the rate decreased when small amounts of HP-β-CyD were added, while large amounts of HP-β-CyD accelerated the rate. The slowest rate was observed for the tablet consisted of a 30/10/60 weight ratio of Met/HP-β-CyD/EC. The analyses of the release rates by the Korsmeyer equation and their temperature dependence suggested that Met is released from the EC matrix containing HP-β-CyD according to the diffusion-controlled mechanism. The water penetration studies and the micro- and macroscopic observations suggested that the retarding effect of HP-β-CyD is attributable to a viscous gel formation in small pores on the surface of the tablets, where HP-β-CyD gels may work as a barrier for the water penetration into the tablets and the release of the drug from the tablets. The in-vitro release property of the ternary tablets was reflected in the in-vivo absorption profile in dogs. The results indicated that a combination of HP-β-CyD and EC is useful for the release control of water-soluble drugs such as Met.

The ability of different cyclodextrins (CDs): γCD, 2-hydroxypropyl βCD to complex drugs like 3-β-hydroxy-11-oxoolean- 12-en-30-oic acid, 2-ethylhexyl-3-(4-methoxyphenyl)-2-propanoate and menthol was compared to that of water-soluble polymers: βCD-co-epichlorhydrin polymer (pβCD/EP) and βCD-co-epichlorhydrin polymer partially modified with trimethylammonium groups (pβCD/EPN+). 3-β-Hydroxy-11-oxoolean-12-en-30-oic acid was poorly solubilized by γCD compared with other CD derivatives, however the determination of the complexation constants was possible for pβCD/EP, K11 = 740, K12 = 4, for pβCD/EPN+, K11 = 681, for γCD, K11 = 16 and for hydroxypropyl βCD, K11 = 114, K12 = 3.4. A significant increase of the solubility was observed for 2-ethylhexyl-3-(4-methoxyphenyl)-2-propanoate with all host molecules, it was 916 times its solubility in pure water with pβCD/EPN+, 1116 and 1300 times with 2-hydroxypropyl βCD and pβCD/EP respectively. The association constants are K11 = 7970, K11 = 4700, K11 = 1470, K11 = 230 and K12 = 200 with pβCD/EP, pβCD/EPN+, γCD, 2-hydroxypropyl βCD respectively. An increase of the solubility of menthol was observed with all CD derivatives, up to 36–37 times, except for γCD. The complexation constants are similar equal to about 200.

Aqueous solutions of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD)at different concentrations of NaCl (0–1.90 mol) were studied by isothermal titration calorimetry (ITC) at 298.15 K. The thermal effects obtained were analysed according to the thermodynamic approach developed by McMillan and Mayer. The calculated enthalpic pair coefficients of HP-β-CD in water and in aqueous solutions of NaCl were analysed taking into consideration electrostatic and structural changes caused by the presence of NaCl in solution.

Pirodavir, 4-[2-[1-(6-Methyl-3-pyridazinyl)-4-piperidinyl]ethoxy]benzoic acid ethyl ester, is an antiviral compound which has low aqueous solubility (

Phase solubility analysis is used to investigate the complex formation of alfaxalone with various cyclodextrins(2-hydroxypropyl-β-cyclodextrine [HPBCD],β-cyclodextrin [BCD] and2-hydroxypropyl-γ-cyclodextrin [HPGCD]).The complexationwith HPBCD was studied in more detail by looking at the effect of temperature on the stability constants using phase solubility analysis. HPLC-analysis was used to measure the dissolved amount of alfaxalone.The solubility of alfaxalone increases linearly with increasing concentration of cyclodextrin, suggesting the formation of a 1 : 1 complex. For the parent BCD the complex starts precipitating out of solution when the solubilizer concentration exceeds 0.25% making the unsubstituted BCD less useful for the preparation of solutions of alfaxalone. Substituted cyclodextrins do not form insoluble complexes with alfaxalone. The complexation constant for BCD and HPBCD are comparable in magnitude, but for HPGCD, the constant is substantially lower.