Study of the Solubility of Furazolidone from Solid Dispersions with Polyvinylpyrrolidone

Moscow University Chemistry Bulletin - The effect of solid dispersions (SDs) on the solubility of furazolidone is studied. Furazolidone and its SDs with polyvinylpyrrolidone (PVP),...     

Enhancement of solubility, dissolution and bioavailability of ibuprofen in solid dispersion systems

To improve its solubility, dissolution, and bioavailability; Ibuprofen-polyethylene glycol 8000 (PEG 8000) solid dispersions (SDs) with different drug loadings were prepared, characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), and evaluated for solubility, in-vitro release, and oral bioavailability of ibuprofen in rats. Loss of individual surface properties during melting and solidification as revealed by SEM micrographs indicated the formation of effective SDs. Absence or shifting towards the lower melting temperature of the drug peak in SDs and physical mixtures in DSC study indicated the possibilities of drug-polymer interactions. Quicker release of ibuprofen from SDs in rat intestine resulted in a significant increase in AUC and C(max), and a significant decrease in T(max) over pure ibuprofen. Preliminary results of this study suggested that the preparation of ibuprofen SDs using PEG 8000 as a meltable hydrophilic polymer carrier could be a promising approach to improve solubility, dissolution and bioavailability of ibuprofen.     

Solubility and Permeability Enhancement of Oleanolic Acid by Solid Dispersion in Poloxamers and γ-CD

Oleanolic acid (OA) is a pentacyclic triterpenoid widely found in the Oleaceae family, and it represents 3.5% of the dry weight of olive leaves. OA has many pharmacological activities, such as hepatoprotection, anti-inflammatory, anti-oxidant, anti-diabetic, anti-tumor, and anti-microbic activities. Its therapeutic application is limited by its poor water solubility, bioavailability, and permeability. In this study, solid dispersions (SDs) were developed to overcome these OA limitations. Solubility studies were conducted to evaluate different hydrophilic polymers, drug-to-polymer ratios, and preparation methods. Poloxamer 188, Poloxamer 407, and γ-CD exhibited the highest increases in terms of OA solubility, regardless of the method of preparation. Binary systems were characterized using differential scanning calorimetry (DSC), X-ray diffraction (XRPD), and Fourier transform infrared spectroscopy (FTIR). In addition, pure compounds and SDs were analyzed using scanning electron microscopy (SEM) in order to observe both the morphology and the particle surface. In vitro dissolution studies were performed for P407, P188, and γ-CD SDs. Preparation using the solvent evaporation method (SEM) produced the highest increase in the dissolution profiles of all three polymers with respect to the OA solution. Finally, the effect of SDs on OA permeability was evaluated with an in vitro parallel artificial membrane permeability assay (PAMPA). The formulation improved passive permeation across the simulated barrier due to OA increased solubility. The dissolution and PAMPA results indicate that the amorphization of OA by SD preparation could be a useful method to enhance its oral absorption, and it is also applicable on an industrial scale.     

Use of the co-grinding method to enhance the dissolution behavior of a poorly water-soluble drug: generation of solvent-free drug-polymer solid dispersions

The solid dispersion (SD) technique is the most effective method for improving the dissolution rate of poorly water-soluble drugs. In the present work, SDs of the Ca2+ channel blocker dipfluzine (DF) with polyvinylpyrrolidone K30 (PVP) and poloxamer 188 (PLXM) were prepared by the powder solid co-grinding method under a solvent-free condition. The properties of all SDs and physical mixtures were investigated by X-ray diffraction, Fourier-transform infrared, differential scanning calorimetry, scanning electron microscopy, dissolution test, and particles size determination. Eutectic compounds were produced between the DF and PLXM matrix during the co-grinding process, whereas glass suspension formed in the SDs with PVP carrier. Hydrogen bond formation was not observed between DF and carriers and DF was microcrystalline state in the PVP and PLXM matrices. The solubility of DF in different concentration of carriers at 25, 31, and 37°C was investigated; the values obtained were used to calculate the thermodynamic parameters of interaction between DF and carriers. The Gibbs free energy (ΔrGθ) values were negative, indicating the spontaneous nature of dispersing DF into the carriers. Moreover, entropy is the drive force when DF disperses into the matrix of PVP, while, enthalpy-driven dispersing encounters in the PLXM carrier. All the SDs of DF/carriers showed a considerably higher dissolution rate than pure DF and the corresponding physical mixtures. The cumulative dissolution rate at 10?min of the SD with a 1?:?3 DF/carrier ratio increased 5.1-fold for PVP and 5.5-fold for PLXM.     

Solubility of Elemental Sulfur in Water at 298 K

Abstract

The solubility of elemental rhombic sulfur in water is 1.9(±0.6) × 10^?8 mole S₈·kg^?1. This value is in agreement with thermodynamic considerations on the solubility of sulfur and experimental data on sulfur hydrosols.     

Editorial

Abstract

The effect of mono-, di- and trivalent metal salts on the maximum aqueous solubility of β-cyclodextrin (β-CD) has been investigated. The results show the solubility to be highly dependent on the cation charge: M⁺ < M²⁺ < M³⁺. For chloride as the anion, the solubility increases down Group II for a given salt concentration: Mg²⁺ < Ca²⁺ < Sr²⁺ < Ba²⁺. However for nitrate as the anion, solubility is largely cation-independent. The increased solubility allows mediumfield NMR (200 MHz) to be used in the study of the β-CD-thymol inclusion complex.     

Rapid screening and quantification of sulfonate derivatives in white peony root by UHPLC–MS–MS

A rapid ultra-high-performance liquid chromatographic–tandem mass spectrometric (UHPLC–MS–MS) method has been developed for rapid screening and quantitative analysis of sulfonate derivatives (SDs) in commercial white peony root. Separation was performed on an Agilent Zorbax Eclipse Plus-C18 column by gradient elution with acetonitrile–0.1% (v/v) formic acid as the mobile phase. In-source fragmentation was used to generate the characteristic fragment ion at m/z 259 and to screen for nine SDs. Detection of these SDs was further performed in multiple reaction monitoring (MRM) mode to improve sensitivity and to quantify the two SDs paeoniflorin sulfonate and benzoylpaeoniflorin sulfonate. The method was validated for specificity, linearity, limits of detection and quantification, precision, accuracy, and matrix effects. Nine commercial white peony root samples were examined by use of this method, which revealed great variety in the paeoniflorin sulfonate and benzoylpaeoniflorin sulfonate content.     

Radioxenon net count calculations revisited

To obtain the relationship between radon solubility and temperature, salinity, and pH of radon-bearing water in in situ leaching uranium mines, an experimental device for measuring the radon solubility in water was designed and manufactured. According to the range of temperature range, salinity, and pH of radon-containing radioactive water from in situ leaching mines in China, aqueous radon solubilities at different temperatures and salinities were determined using an orthogonal design and, concurrently, radon solubilities at different pH also determined. An empirical equation for estimating the radon solubility in radioactive water containing radon in uranium mining and metallurgy is proposed.

     

Solvent Effects on the Rate of Radiation-Induced Grafting of Vinyl Monomers on Polymeric Films

Earlier work indicated that in the radiation-induced grafting of vinyl monomers on polymeric films, the plasticity of the film being grafted is determined by the Hildebrand solubility parameter of the grafting solution. Film plasticity affects the termination step of the grafting reaction, and thus strongly influences the overall rate of monomer grafting on the polymeric film.

In the grafting of styrene on nylon film, a sequence of irradiation runs was made at selected volume ratios of styrene/benzene/methanol, all grafting solutions having a constant solubility parameter value of 9.5 Under these conditions, a linear plot of grafting rate vs volume percent styrene in the grafting solution was obtained. A similar sequence of runs grafting pentafluorostyrene on nylon film at constant solubility parameter also produced a linear plot of grafting rate vs volume percent PFS.

Styrene was grafted on polyethylene film in a sequence of four runs using styrene dissolved in methanol, ethanol, 1-propanol, and 1-butanol, each solution having the same solubility parameter of 10.4. A straight-line plot of grafting rate vs volume percent styrene was obtained under these conditions.     

THE SYNTHESIS AND PROPERTIES OF DI/1,4 - PHENOTHIAZINE/

Abstract

The structure determination of the poly/1,4- phenothiazine/ is still difficult because of their very slight solubility in the organic solvents and low degree of crystallinity.     

The influence of different evaluation techniques on the results of interlaboratory comparisons

The influence of different evaluation techniques on the results of an interlaboratory comparison for the determination of nutrients in ground- and surface water was investigated. The outlier-test procedure was found to influence the interlaboratory standard deviations (SDs), but not the averages. It was shown that even small differences in the numbers of outliers detected can change the SD severely. Comparing the outlier-test procedures of Hampel, Grubbs and Graf-Henning, it was found that Hampel's test detected the most outliers, thus generally resulting in smaller SDs between interlaboratory comparisons. The Graf-Henning test detected the fewest outliers and its application resulted in the highest SDs of the three test procedures investigated. The comparison of different summarising indices, namely the rescaled sum of z-scores, average of absolute z-scores and average deviation showed no comparability. Possibilities to improve the comparability of interlaboratory comparisons and to minimise misunderstandings are suggested.     

Reversed phase liquid chromatography of PCBs as a basis for the calculation of water solubility and log Kow for polychlorobiphenyls

Summary Water solubility (S _w) and log K _ow values have been determined for 154 possible polychlorobiphenyls using the retention indices obtained by RP-HPLC and structurally selected PCB congeners with known log K _ow values for the regression lines. The water solubility data are melting point corrected.

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Umkehrphasen-Flüssig-Chromatographie von PCBs als Grundlage zur Berechnung der Wasserlöslichkeit und des log K _ow für Polychlorbiphenyle

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 75th birthday     

Die Löslichkeit von Quecksilber in verschiedenen Metallen

Investigations by X-ray analysis proved that V, Nb, Ta, Ti, Zr, Cr, Mo, W, Fe, Ni, Co, Re, Ru, Rh, Os, Ir, Al, Th, and U dissolve only negligible amounts of mercury. The solubility of mercury in platinum up to 250°C is small; at 250°C the solubility increases abruptly to ca. 15.5% and alters little with further temperature increases. The jump at 250°C corresponds to a peritectic reaction in the system Pt–Hg. The data obtained are in good agreement with data in the literature. Manganese dissolves at 500°C ca. 0.3–0.5% Hg; the temperature dependence of the solubility was not examined. Rhenium forms no compounds with Hg, at least at 100–500°C. The metals of the Va and VIa-group of the periodic table do not dissolve any measurable amounts of Zn.

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Nitric acid preparation of cellulose from miscanthus as a nitrocellulose precursor

A nitric acid method for the preparation of cellulose from miscanthus is considered. The method consists in successive treatment of the raw material with nitric acid and sodium hydroxide and affords cellulose with properties suitable for the synthesis of cellulose nitrates. The data on the nitrogen weight fraction, the viscosity, and the solubility of cellulose nitrates from miscanthus in the alcohol-ether medium are given. The miscanthus cellulose was nitrated using an industrial sulfuric-nitric acid mixture to yield cellulose nitrate samples with characteristics close to those of colloxylin.

     

Evaluation of Acidity Constants of Amphoteric Substances by the Corresponding Solubilities Method

Abstract

A simple method for the evaluation of acidity constants of amphoteric substances (HR) is reported in this paper. The method is based on the use of pH values which have corresponding solubilities and has been checked against the p-diethylaminobenzylidenrhodanine system. In order to apply the method it is not necessary to know the intrinsic solubility of HR.     

Phase Solubility Analysis of Some Organophosphate Pesticides

Abstract

Phase solubility analysis (PSA) was applied to the determination of azinphos-ethyl and - methyl standards. The presence of 0.5% purity was detected by the method. A linear cumulative effect was obtained when known amounts of two impurities were added to standards of both organophosphate materials which were then analyzed by the phase solubility method.     

Das Dreistoffsystem Nickel-Kupfer-Bor

The ternary system nickel-copper-boron was established at 700°C by means of X-ray diffraction and metallographic examinations. Confirming the well known binary nickel borides no ternary boride was found.The solubility of boron in the nickel-copper solid solution is very small and has its maximum of about 0.3 at% in the binary system copper-boron.Differential-thermoanalysis shows a quasibinary eutectic between Ni₃B and copper solid solution.

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Quantitation of Carbon Dioxide by High Performance Liquid Chromatography: The Key to Solubility Measurements in Liquefied Gas Solutions

Abstract

A technique is described whereby solubility data may be obtained for systems employing liquefied carbon dioxide as the solvent. Analysis of the solution is effected by the direct injection of an aliquot of pressurized liquid into a modern liquid chromatograph fitted with a reversed-phase C₁₈ column. Detection of the carbon dioxide is accomplished by a differential refractometer. After the appropriate calibrations are performed, data are obtained which compare favourably with the literature value of the solubility of naphthalene in liquid carbon dioxide.     

Soluble,thermally stable,flame retardant quinoline-based poly(ester amide)s

A new diamine was prepared via reaction between 8-hydroxy-5-nitroquinoline and 4-nitrobenzoyl chloride, followed by reduction of the nitro groups of the resulted compound. Novel quinoline-based poly(ester-amide)s were produced through polycondensation reactions of the prepared diamine with different diacid chlorides. The monomer and poly(ester-amide)s were characterized and properties of the polymers including solution viscosity, thermal behavior and stability, solubility, and crystallinity were studied.

High thermal stability and improved solubility was observed for the polymers, indicating successful designing of monomer and related polymers for overcoming the main issue of thermally stable polymers, i.e. the problem of increasing solubility versus high thermal stability.

Also, by changing the diacid chlorides for the preparation of poly(ester-amide)s, the structure-property relations were investigated.