Formation Of Eutectic Mixture Research Articles

Agglomeration behaviour of various biomass fuels under different air staging conditions in fluidised bed technology for renewable energy applications

The most common technology for thermochemical conversion of solid fuel through the process of gasification, such as coal, varieties of residues from biomass and agriculture are the bubbling fluidised bed or fluidised bed systems. However, there are some disadvantages within these systems including the formation of eutectic mixtures, increased process of melting and bed agglomeration. Hence, the current study aimed to evaluate the agglomeration behaviour of various biomass fuels. Characteristics of five biomass fuels (miscanthus, peanut, straw, domestic wood and industrial wood) in a bubbling fluidised bed (BFB) combustor were studied by SEM-EDX, XRD and XRF analysis of bed materials and ash samples. The influence of bed temperatures on the fuel ash composition and bed particles was evaluated, as well as fuel ash components, their interaction with the particles from the bed sand and morphology of the bed material. The combustion efficiency ranged from 95.5 to 99.5% with the highest value obtained for miscanthus under SA conditions. The peanut and straw had the highest K content, whereas the industrial wood ash contained the highest Ca content compared to other biomasses. The XRF results showed that most of the potassium (K) from the wheat straw biomass was converted to K2O with 19%. No bed agglomeration was noticed without staging-air (WSA) and with staging-air (SA) combustion conditions, even with temperatures up to 850 °C during the testing period. Overall obtained results demonstrated that agglomeration is unlikely expected to be a major problem during fluidised bed combustion of tested biomass fuels.

Effect of SiO2/CaO on the viscosity and structure of yellow phosphorus slag in the electric furnace

Slag within suitable viscosity range is important for well controlled slag tapping of phosphorus reduction process in electrical furnace. The suitable slag viscosity depends on the adjustment of SiO2/CaO by adding silica. However, the influence of SiO2/CaO on slag viscosity and structure at slag tapping condition is still unknown. In this work, it is found that the slag viscosity increased slightly with increasing SiO2/CaO above the liquidus temperature. This is because the reduction of free oxygen ions (O2–) leads to an increase of the polymerization degree. However, the slag viscosity decreased as the SiO2/CaO ratio increased below the liquidus temperature. The weakening of the crystallization tendency, the formation of eutectic mixtures, and the reduction of Si-O-Ca-O units with larger ionic radii improve the fluidity of the slag. In addition, the presence of phosphorus slightly promoted the polymerization of the silicate network with increasing SiO2/CaO. This is caused by the increasing proportion of modified cations released by phosphorus from the silicate network. Meanwhile, the increasing SiO2/CaO decreased the polymerization degree of the aluminate structure due to the transition of [AlO4] to [AlO5]. The optimal slag discharge temperature range for the slag with a composition of 85 wt% (SiO2 + CaO) and a SiO2/CaO ratio of 0.9 was 1252 °C-1285 °C.

Three pesticide-pesticide eutectic systems of boscalid: Mechanochemical preparation, characterization and mechanism analysis

Preparation of eutectic mixture is considered to be an efficient means to improve physical and chemical properties in many fields. In this work, three pesticide-pesticide eutectic systems of boscalid with diniconazole, uniconazole and 3,6-dichloropicolinic acid were prepared by mechanochemical method. The formation of eutectic mixtures was identified by differential scanning calorimetry and powder X-ray diffraction characterizations. From the constructed solid–liquid phase diagrams, it is discovered that these eutectic systems could form a eutectic when the molar fraction of boscalid is 0.500. In addition, all eutectic temperatures are more than 29 K lower than the higher melting points of the constituents in the systems, which eliminates the issue of the poor thermal stability of constituents and enables the treatment of them using melting-based operations. Ideal model and COSMO-RS theory also calculate these solid–liquid phase diagrams relatively accurately, and the calculated activity coefficient values prove that these systems do not deviate significantly from the ideal state. The distinct non-ideality at the eutectic composition of the three systems also suggests that the interactions of the three coformers and the boscalid differ. The formation of eutectic mixtures was further confirmed by other solid state characterizations including mid-infrared spectroscopy, Raman spectroscopy and etc. The accelerated stability test indicates the good stability of the three eutectic mixtures. Furthermore, the water solubility study suggests the boscalid in the eutectic systems has a higher solubility than raw boscalid. By using COSMO-RS modelling, the most typical homo/hetero-molecular complexes of these pesticides were obtained and analyzed. Based on the trend of affinity characterized by the Gibbs free energy of the generation of molecular complexes, it could be inferred that eutectic point could be viewed as the state for which affinity of hetero-molecular complexes is greatest. The affinity of hetero-molecular complexes also presents the interaction between boscalid and 3,6-dichloropicolinic acid is greater than the other two pesticides at the eutectic point. Furthermore, the calculated solvation free energies document the intermolecular interaction plays an important role in stabilizing the three eutectic systems. These eutectic systems solve the problem that the three coformers are unsuitable for melting-based procedures and improve the solubility, making them potential options for future pesticide formulation development.

Saquinavir-Piperine Eutectic Mixture: Preparation, Characterization, and Dissolution Profile.

The dissolution rate of the anti-HIV drug saquinavir base (SQV), a poorly water-soluble and extremely low absolute bioavailability drug, was improved through a eutectic mixture formation approach. A screening based on a liquid-assisted grinding technique was performed using a 1:1 molar ratio of the drug and the coformers sodium saccharinate, theobromine, nicotinic acid, nicotinamide, vanillin, vanillic acid, and piperine (PIP), followed by differential scanning calorimetry (DSC). Given that SQV-PIP was the only resulting eutectic system from the screening, both the binary phase and the Tammann diagrams were adapted to this system using DSC data of mixtures prepared from 0.1 to 1.0 molar ratios in order to determine the exact eutectic composition. The SQV-PIP system formed a eutectic at a composition of 0.6 and 0.40, respectively. Then, a solid-state characterization through DSC, powder X-ray diffraction (PXRD), including small-angle X-ray scattering (SAXS) measurements to explore the small-angle region in detail, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a powder dissolution test were performed. The conventional PXRD analyses suggested that the eutectic mixture did not exhibit structural changes; however, the small-angle region explored through the SAXS instrument revealed a change in the crystal structure of one of their components. FT-IR spectra showed no molecular interaction in the solid state. Finally, the dissolution profile of SQV in the eutectic mixture was different from the dissolution of pure SQV. After 45 min, approximately 55% of the drug in the eutectic mixture was dissolved, while, for pure SQV, 42% dissolved within this time. Hence, this study concludes that the dissolution rate of SQV can be effectively improved through the approach of using PIP as a coformer.

Sustainable Setups for the Biocatalytic Production and Scale-Up of Panthenyl Monoacyl Esters under Solvent-Free Conditions.

A sustainable scaling-up process for the biocatalytic production of new bioactive provitamin-B5 monoacyl esters has been demonstrated. A solvent-free reaction protocol, based on the formation of eutectic mixtures between neat substrates, renders highly efficient direct esterification of free fatty acids (i.e., from C6 to C18 alkyl-chain length) with panthenol catalyzed by lipase. The scale-up from 0.5 to 500 g was evaluated by means of using several reaction systems (i.e., ultrasound assistance, orbital shaking, rotary evaporator, and mechanical stirring coupled to vacuum). For all reactor systems, the yield in panthenyl monoacyl esters was improved by increasing the length of the alkyl chain of the fatty acid (i.e., from 63% yield for panthenyl butyrate to 83% yield for panthenyl myristate). The best results (87-95% product yield, for all cases) were obtained upon a scale-up (50-500 g size) and when a vacuum system was coupled to the biocatalytic reaction unit. Under the optimized conditions, a 5-fold reduction of the amount of biocatalysts with respect to reactors without vacuum was achieved. The recovery and reuse of the immobilized enzyme for five operation cycles were also demonstrated. Finally, different metrics have been applied to assess the greenness of the solvent-free biocatalytic synthesis of panthenyl monoesters here reported.

Eco-friendly and economical preparation of permanent ferrite magnet with ultrapure magnetite concentrate: Focus on the action mechanism of silicon and aluminum impurities

In this study, ultrapure magnetite concentrate (UMC) was used to replace high-quality iron oxide red (IOR) for permanent ferrite magnet (PFM) preparation. UMC needs to be pre-oxidized to eliminate FeO which easily generates nonmagnetic phases in PFM. The magnetic powder and PFM products prepared with UMC and IOR had close magnetic properties, but the calcination temperature was lower and calcination time was shorter with UMC. Si and Al impurities in UMC could not only form eutectic compounds but also dissolve into the ferrite grain by substituting Fe. Those eutectic compounds benefited uniformity of grains by inhibiting grain overgrowth but decreased the purity of PFM because they were non-magnetic substances. Mn impurity in IOR entered into the ferrite grain by replacing Fe instead of participating in the formation of eutectic mixtures, while Cl impurity was evaporated during calcination, causing equipment erosion and environment pollution. UMC has the advantages of low raw material cost, good product property and non-pollution, and thus it has a broad application prospect in PFM preparation.

Eutectic Mixture Formation and Relaxation Dynamics of Coamorphous Mixtures of Two Benzodiazepine Drugs

The formation of coamorphous mixtures of pharmaceuticals is an interesting strategy to improve the solubility and bioavailability of drugs, while at the same time enhancing the kinetic stability of the resulting binary glass and allowing the simultaneous administration of two active principles. In this contribution, we describe kinetically stable amorphous binary mixtures of two commercial active pharmaceutical ingredients, diazepam and nordazepam, of which the latter, besides being administered as a drug on its own, is also the main active metabolite of the other in the human body. We report the eutectic equilibrium-phase diagram of the binary mixture, which is found to be characterized by an experimental eutectic composition of 0.18 molar fraction of nordazepam, with a eutectic melting point of Te = 395.4 ± 1.2 K. The two compounds are barely miscible in the crystalline phase. The mechanically obtained mixtures were melted and supercooled to study the glass-transition and molecular-relaxation dynamics of amorphous mixtures at the corresponding concentration. The glass-transition temperature was always higher than room temperature and varied linearly with composition. The Te was lower than the onset of thermal decomposition of either compound (pure nordazepam decomposes upon melting and pure diazepam well above its melting point), thus implying that the eutectic liquid and glass can be obtained without any degradation of the drugs. The eutectic glass was kinetically stable against crystallization for at least a few months. The relaxation processes of the amorphous mixtures were studied by dielectric spectroscopy, which provided evidence for a single structural (α) relaxation, a single Johari-Goldstein (β) relaxation, and a ring-inversion conformational relaxation of the diazepinic ring, occurring on the same timescale in both drugs. We further characterized both the binary mixtures and pure compounds by FTIR spectroscopy and first-principles density functional theory (DFT) simulations to analyze intermolecular interactions. The DFT calculations confirm the presence of strong attractive forces within the heteromolecular dimer, leading to large dimer interaction energies of the order of -0.1 eV.

Glibenclamide–malonic acid cocrystal with an enhanced solubility and bioavailability

Objective The objective of the work is to enhance the solubility, dissolution, and pharmacokinetic properties of glibenclamide (GLB) via cocrystallization technique. Significance Glibenclamide is an oral hypoglycemic agent used for treating non-insulin-dependent (type II) diabetes mellitus. It exhibits poor aqueous solubility and oral bioavailability, thereby compromising its therapeutic effect. Therefore, utilizing cocrystal approach for enhancing the solubility will modulate the physicochemical properties of GLB without altering its molecular structure. Methods Cocrystal was prepared by solution crystallization method using coformer malonic acid. The cocrystal was characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared (FT-IR) studies. The prepared cocrystal was subjected to solubility, in vitro dissolution, and pharmacokinetic studies. Results The DSC endotherms, PXRD patterns, and the FT-IR spectra of the cocrystal established the formation of a cocrystal. The formation of eutectic mixture was refuted upon comparing the DSC endotherm and PXRD pattern of the cocrystal with that of the physical mixture. GLB showed a twofold enhancement in solubility and a significant improvement in the rate of dissolution (p < 0.05, independent t-test) after cocrystallization. The pharmacokinetic parameters on male Sprague Drawly rats showed 1.45 enhancement in AUC0–24 and 1.36-fold enhancement in the C max of GLB as compared to the pure drug. Conclusion These findings demonstrate that cocrystallization technique was able to tailor the solubility and dissolution profile of GLB leading to an enhanced pharmacokinetic property.

Understanding the phase and solvation behavior of fluorinated ionic liquids

• Effect of perfluoroalkyl chains on the properties and phase equilibria of FILs. • VLE of FILs show the need of optimal fluorine density to enhance gas absorption. • LLE of FILs reveal high surfactant behavior in water and improved PFCs solubility. • SLE of FILs uncover formation of eutectic mixtures with complex phase behavior. • FILs show huge relevance in GHGs capturing processes and biomedical applications. Fluorinated ionic liquids (FILs) are defined as molecules having fluorinated tags equal to or longer than 4 carbon atoms in the anion and/or cation structures. They present nanosegregated domains making them 3-in-1 solvents with exceptional properties, including an attractive solubility power. This work is an important contribution towards understanding the current research on the phase behavior of FILs, which may be used as task-specific materials for industrial applications. An overview of the main works published in the last two decades is presented, concerning gas solubility in FILs, the application of membranes to improve the gas absorption in FILs, and the use of modeling approaches to ease the application of FILs in gas capture and separation processes, with emphasis on the relationship between the structural properties and their performance. Contributions concerning the liquid-liquid and solid-liquid equilibria behavior of FILs, including the liquid-liquid equilibria (LLE) of FILs in water and perfluoroalkanes, and the solid-liquid equilibria (SLE) of solid FILs in water and mixtures of FILs are also presented. Regarding the absorption of gases in FILs, a careful analysis of the published works reveals that: (1) an optimal density of fluorine atoms in FILs structure is required to positively impact the absorption of different gases, (2) the functionalization of membranes can be also a useful method to improve the performance in separation processes, and (3) modeling tools can ease the screening of the features that promote the absorption of gases by FILs. The study of FILs LLE showed a rich phase behavior with water and perfluoroalkanes and the enhanced surfactant power of FILs, which is highly dependent on the length of the hydrogenated and fluorinated side chains. Finally, studying the SLE of FILs mixtures allowed the formation of deep eutectic systems that enlarges the applicability of FILs.

DFT calculations, molecular docking and SAR investigation for the formation of eutectic mixture using thiourea and salicylic acid

The eutectic mixture is a mixture of two or more components and freezes congruently and helpful for many applications. In this work, we have designed the eutectic mixture using thiourea and salicylic acid in the different equivalent ratios (1:1, 1:2, 1:3, 1:4, 2:1; 3:1 and 4:1); were studied with the help of density functional theory (DFT) calculations using Gaussian 16. Depending on the optimization energies and free energy of the eutectic mixture, we came to know that formation of all the eutectic mixtures is feasible but the Change in free energy (ΔG) for the formation of T4S1 is minimum (equivalent of thiourea: salicylic acid is 4:1); that is −0.07856 Hartree/ particle or −47.6052 kcal/mol. Further, a work done by Jakob et al is referred and a theoretical model was developed to get the eutectic mixture; T1S1 has the minimum melting temperature. Further, the potential of the molecules was studied against the Mpro of nCoV using molecular docking. An interesting observation is found that the T1S4 showed good inhibition against Mpro of nCoV based on the binding energy. Further, the authors investigated the information through the regression and correlation, that is, structure–activity relationship(SAR). Authors have correlated the optimization energies of the molecules and performed the multiple regression with the binding energy, energy of HOMO and LUMO to get the equation to calculate predicted optimization energy. The plot was calculated and predicted optimization energies were drawn and the value of the R2 is 0.998, confirming the validity of the equation obtained through regression.

Mechanosynthesis of Eutectics of Anti‐Inflammatory Drug Ethenzamide – A Comparison with Analogous Cocrystals

AbstractMechanochemical milling of ethenzamide (ETZ), a nonsteroidal anti‐inflammatory drug, with substituted aromatic carboxylic acids as well as anti‐tuberculosis drug pyrazinamide (PZA) resulted in the formation of eutectics. Although a large number of cocrystals as well as polymorphic cocrystals are reported for ETZ, for the first time we have synthesized six eutectics including an instance of a drug‐drug eutectic system. Supramolecular synthon energy calculations validate the formation of eutectic mixtures over cocrystals with coformers considered in our study.

Formulation of Eutectic mixture of Curcumin with Salicylic Acid for improving its Dissolution Profile

Background: Eutectics are basically multi-component crystalline solids closely related to solid solutions. However, the structural organization of eutectics has not been studied in as much detail as solid solutions, which are defined based on the arrangement of a major (solvent) and a minor (solute) component in the crystal lattice. Purpose: The goal of this study is basically improvement in aqueous solubility of poorly water soluble drug i.e curcumin via its eutectic formation by using salicylic acid as coformer. Material and Method: Here the eutectic mixture of curcumin and salicylic acid was prepared by solvent evaporation technique for improving the dissolution behaviour of curcumin. DSC and FT-IR spectroscopy were used as analytical techniques for characterization of eutectic mixture. Result: The DSC and FT-IR spectroscopy conformed the formation of eutectic mixture and In-Vitro dissolution studies revealed an improved dissolution behaviour for eutectic mixture (69.38 %) as compared to the pure curcumin (40.53%). Conclusion: The study conclude that binary systems improved the dissolution behaviour of poorly water soluble drugs without changing the physiochemical and pharmacological properties of concerned API.

Studies on fatty acid profile and microstructure of butter, dairy fat spreads and blended spreads produced in Russia

This paper examines the features of the production of butter and spreads in the Russian Federation. It was found that the fatty acid profile of the cows' milk of the Yaroslavl breed does not differ significantly in comparison with the milk of the more widespread breeds in the world. It is shown that when using different methods of butter production, there are differences in the butter microstructure. It is noted that the use of the concentration and phase reversal method for the production of butter and spreads can be accompanied by the formation of eutectic mixtures of fatty acids.

The study of structure and interactions of glucose-based natural deep eutectic solvents by molecular dynamics simulation

In the current study, molecular dynamics simulations were conducted to investigate the structural and dynamical properties of glucose-based Deep Eutectic Solvents (DESs) at different molar ratios (the mixture of glucose and choline chloride with the molar ratios of 1:3, 1:1 and 3:1). Accordingly, the interaction energies of different species and structural properties such as atom–atom radial distribution functions (RDFs), the hydrogen-bonding network between species, and spatial distribution functions (SDFs) were computed to understand effective interactions in the eutectic mixture formation. It was found that the insertion of glucose molecules reduced the accumulation of chloride anions around choline cations, eventually decreasing the interaction between the choline chloride ion pairs. Moreover, the possible explanations for the thermos-physical properties of DESs, such as the shear viscosity and density, have been provided. Dynamical properties of DES were evaluated by calculating the mean-square displacement (MSD) and the velocity autocorrelation function (VACF) for the centers of the mass of the ions and glucose molecules. MSD analysis results were then used to calculate the self-diffusion parameter by applying the Einstein relation. The simulation results indicated that increasing the temperature led to easing the migration of the molecules and decreasing the dependence of the movement of the molecules on each other. This growing trend of migration may lead to an increase in the self-diffusion coefficient of molecules. Structural analysis revealed that a ratio of 1:1 of glucose: choline chloride could provide the best condition to maintain the low melting point of the mixture due to the strong hydrogen-bonded network between the two species.

Physical properties and solid-liquid equilibria for hexafluorophosphate-based ionic liquid ternary mixtures and their corresponding subsystems

Mixing ionic liquids is a simple and economical method of exploiting their tunability and allows to use ionic liquids with high melting temperatures for low-temperature applications through the formation of eutectic mixtures. In this study, the phase diagrams of the [C4mpy][PF6]-[C4mpip][PF6]-[C4mpyrr][PF6] ternary system (where [C4mpyrr] = 1-butyl-1-methylpyrrolidinium; [C4mpy] = 1-butyl-3-methylpyridinium; [C4mpip] = 1-butyl-1-methyl-piperidinium) and all of its unary and binary subsystems were measured and modelled using the Modified Quasichemical Model and the Compound Energy Formalism for the liquid and relevant solid solutions, respectively. The phase diagram determination allowed for density and viscosity measurements over the entire composition range, from temperatures close to the liquidus up to about 110 °C. In addition, the thermal and physical properties of the ionic liquid [C4mim][PF6] ([C4mim] = 1-butyl-3-methylimidazolium) were measured. A new viscosity model was proposed to describe mixtures and was compared to the Grunberg-Nissan mixing law. The proposed model exhibited a better predictive ability for the viscosity data of ternary mixtures compared to the Grunberg-Nissan mixing law with the same number of adjustable parameters. The limits of the proposed viscosity model were analyzed in light of the Gibbs-Adam theory, using viscosity and configurational entropy data for [C4mim][PF6].

NADES as potential solvents for anthocyanin and pectin extraction from Myrciaria cauliflora fruit by-product: In silico and experimental approaches for solvent selection

In this work, in silico and experimental approaches were combined for the selection of starting compounds of NADES (Natural Deep Eutectic Solvents) aiming a selective and sequential extraction of anthocyanin and pectin from Myrciaria cauliflora by-product. Six NADES were prepared and characterized by DSC, pH, and rheological analysis. COSMO-RS was used to study the molecular contributions that confer affinity between NADES and target molecules. Besides, experimental solubility, extraction ability, and NADES cost were evaluated. DSC confirmed the formation of eutectic mixtures, which presented low pH values (0.77 to 4.01) and a wide range of apparent viscosity (0.070 to 36.922 Pa·s). The σ-profile [p(σ)], obtained by COSMO-RS, provided information on the polarity distribution of molecules and σ-potential [μ(σ)] curves was indicative of affinity between solute and solvent. According to in silico evaluation, both NADES and target compounds exhibit amphoteric character, indicating affinities between them. Acid-based NADES showed the highest affinity in the H-bond acceptor region while NADES content betaine and water presented the best affinities in the H-bond donor region. However, all NADES presented a low affinity for non-polar compounds. Choline chloride (ChCl):propylene glycol (Pro) were the most promising NADES for anthocyanin extraction and citric acid (Ca):glucose (Glu):water (Wa), for pectin. The proposed approach established a wise way to select NADES:water solutions as low-cost green solvents, aiming to achieve selective recoveries of value-added compounds.

Modulating the crystallization of phytosterols with monoglycerides in the binary mixture systems: mixing behavior and eutectic formation

Phytosterols (PSs) are insoluble in water and poorly soluble in oil, which hampers their potential as cholesterol level regulator in human. To mitigate this problem, monoglycerides (MGs) were used to modulates the crystallization behavior of PSs. Therefore, the understanding on mixing behavior provides the insight into different aspects of crystallization and the resultant effects. The effects on thermal, morphology, diffraction, and spectroscopy behavior were investigated for binary mixtures of 11 different ratios (100:0 to 0:100 MGs:PSs). The phase behavior of binary mixtures of commercial MGs and PSs exhibited complexity with the formation of eutectic mixtures at 90:10 and 80:20 (MGs:PSs) combinations. These combinations revealed a single melting profile and reduced melting enthalpy, though after a month of storage at 5 °C. Conversely, two separate melting regions were observed in others. Furthermore, powder X-ray diffraction (PXRD) analysis of selected combinations revealed a change in crystalline forms with changes in the peaks located between 18-19° (2θ) and 25-26° (2θ). Accordingly, Raman spectroscopy results revealed changes in intensities and peak shape. Therefore, the change in crystalline forms or behavior correlated well to the change in thermal properties. Overall, the characterizations revealed the formation of eutectic mixtures between MGs and PSs at 90:10 and 80:20 (MGs:PSs) in which MGs modified the crystallization of PSs and changed the crystal forms thus, thermal behaviors. This study provides new insight into the mixing behavior of MGs and PSs which supports other research. Therefore, the results of this study are beneficial for the improvement of formulation of phytosterols in food and pharmaceutical products. Nonetheless, this study reveals a simple technique to alter crystal forms of phytosterols through simple complexation with monoglycerides.

Preparation and characterization of glimepiride eutectic mixture with l-arginine for improvement of dissolution rate.

In this study, glimepiride and l-arginine (GA) binary mixtures at various molar ratios were prepared to evaluate whether they could improve the poor water solubility and dissolution characteristics of glimepiride. It was shown that glimepiride and arginine form a eutectic mixture, a type of crystalline solid dispersions, at a 1:1M ratio and eutectic temperature of 426.9K using a phase diagram constructed using differential scanning calorimetry (DSC) and thermo-microscopy. The preserved characteristic powder X-ray diffraction (PXRD) patterns and infrared (IR) spectra of each material in those of GA binary mixtures confirmed the formation of eutectic mixture without molecular interaction in solid state. The formation of GA eutectic mixture (GAEM) resulted in the improvement of solubility through pH modification and the intermolecular interaction of glimepiride and l-arginine in aqueous mediums, thereby wettability and dissolution rate of glimepiride were also enhanced. The intermolecular interaction between glimepiride and l-arginine at a 1:1 stoichiometry of the complex in solution state was identified by phase solubility, stoichiometric determination, and solution state nuclear magnetic resonance (NMR) spectroscopy. Specific molecular interactions such as hydrogen bonding and hydrophobic interaction were suggested as main mechanisms of GA complexation in solution. Therefore, this study concludes that the GAEM could be an effective way to improve the solubility and dissolution rate of glimepiride.

Formation of Diacerein − fumaric acid eutectic as a multi-component system for the functionality enhancement

The present study aimed to enhance physico-mechanical properties of poorly soluble drug Diacerein (DIA) using crystal engineering approach. Fumaric acid (FMA) was competent enough to generate a novel solid form of DIA by acetone assisted grinding method and was fully characterized. A lower melting depression and maximum enthalpy of fusion resulted from phase diagram and Tammann's triangle of binary system revealed the formation of eutectic mixture with molar ratio of 1: 2 (DIA: FMA). It was further confirmed by PXRD and FT-IR spectra. The topographical differences were observed in case of eutectic by SEM analysis imparting its better flow and packability. Pharmaceutical behaviors in terms of solubility, dissolution, tabletability, compressibility and stability suggested superior functionality of eutectic compared to DIA alone. Pharmacokinetic study of eutectic demonstrated 1.77 times greater bioavailability. Thus, the concept of crystal engineering was successful to prepare DIA-FMA eutectic as a potential way for improving material functionality.

Characterization of Thermal Fraction of Clarified Butter and its Applicability to Improve Bioavailability of Rosuvastatin

Abstract: Aim: The present investigation shows confirmatory evidence for the complex formation of Rosuvastatin with a fraction of Clarified Butter. Material and Methods: Fractions of Clarified Butter prepared according to thermal behavior at different temperatures (30°C, 40°C, 50°C). Rosuvastatin biform complex with Clarified Butter in the ratio (1:1) and (1:2) w/w was prepared. Physicochemical properties of all fractions of Clarified Butter had determined as per Indian Pharmacopoeia. The fractions were subject to Fouriertransform Infrared spectroscopy (FTIR), Differential Scanning Calorimeters (DSC) and in-vitro release studies (Simulated gastric fluid, pH 1.2 for 2 h and simulated intestinal fluid, pH 6.8 for 6 h). Results: Based on these investigations; the optimized ratio (1:1) w/w were further characterized for DSC and FTIR studies. Where Rosuvastatin showed a strong carbonyl band at 1543.05 cm−1 , all fractions showed the disappearance of strong carbonyl band at 1543.05 cm−1, spectra of biform complex shifted to higher frequency 1747.51 cm−1 (13.29 % increase), that show carboxylic and hydroxyl group of both saturated and unsaturated fatty acid present in Clarified Butter. From in vitro release study the highest percent release i.e. 99.23±0.08% of Rosuvastatin was obtained from 1:1 biform complex. DSC thermogram confirming the formation of eutectic mixture by lowering the peak of pure Clarified Butter (67.4°C) to 58.10°C by the formation of biform complex with the drug Rosuvastatin. Conclusion: Thus, Clarified Butter and its fraction are prominent in improving the bioavailability of Rosuvastatin. Key words: Rosuvastatin, Clarified Butter, Peroxide value, Thermal oxidation, Bioavailability.