Dissolution Thermodynamics Research Articles

Increasing the Equilibrium Solubility of Meloxicam in Aqueous Media by Using Dimethyl Sulfoxide as a Cosolvent: Correlation, Dissolution Thermodynamics and Preferential Solvation

Meloxicam is widely prescribed as an analgesic and anti-inflammatory drug in human therapeutics. Owing the very low aqueous solubility of meloxicam, this property has been studied in dimethyl sulfoxide (DMSO)-aqueous solvent systems at several temperatures from 273.15 to 313.15 K to expand the solubility database about analgesic drugs in mixed solvents. The flask shake method followed by ultraviolet-visible (UV-vis) spectrophotometry analysis were used for meloxicam solubility determinations. A number of cosolvency models, including the Jouyban–Acree model, were challenged for solubility correlation/prediction of this drug in these mixtures. The van’t Hoff and Gibbs equations were employed to calculate the apparent standard thermodynamic quantities relative to dissolution and mixing processes. The inverse Kirkwood–Buff integral method was employed for calculating the preferential solvation parameters of meloxicam by DMSO in the mixtures. Meloxicam solubility increases with increasing temperature and maximum solubilities are observed in neat DMSO at all temperatures studied. Dissolution processes were endothermic in all cases and entropy-driven in the composition interval of 0.40 ≤ x1 ≤ 1.00. A nonlinear enthalpy–entropy relationship was observed in the plot of enthalpy vs. Gibbs energy for drug transfer processes. Meloxicam is preferentially solvated by water in water-rich mixtures but preferentially solvated by DMSO in the composition interval of 0.21 < x1 < 1.00.

Enhancement of clozapine solubility in three aqueous choline chloride-based deep eutectic solvents: Experimental and COSMO-RS prediction

• Solubility behaviors of clozapine in aqueous DESs solutions were revealed by COSMO-RS. • Solubility of clozapine in aqueous DESs solutions was measured. • Solubility of clozapine was enhanced by increasing weight fraction of DES and temperature. • Dissolution thermodynamics of clozapine was calculated via van't Hoff equation. The clozapine (CLZ) solubility (molar fraction) in three aqueous choline chloride (ChCl) based deep eutectic solvents (DESs) with urea (U), glycerol (G) and ethylene glycol (EG) was determined at T = (293.15 to 313.15) K under an atmospheric pressure. As neoteric green co-solvents, DESs can apparently enhance the CLZ solubility more than 550-fold than that in pure water at T = 293.15 K, especially in ChCl/G. At the same DESs proportion (weight fraction) and same temperature, the CLZ solubility in aqueous DESs solutions is ranked as ChCl/G > ChCl/EG > ChCl/U. Furthermore, the experimental solubility of CLZ in aqueous DES solutions has been correlated by NRTL, three-Suffix Margules, UNIQUAC and Wilson models, suggesting NRTL model to be the best correlation. In addition, the SLE CLZ solubility data was also predicted by reference solubility method using COSMO-RS model, and the predicted results are consistent with the experiment data. The basic mechanism of the solubility behavior of CLZ and solvent molecules was analyzed by studying σ profiles of DESs as well as the molecular interaction energies, implying that the CLZ dissolution is a complex process affected by the synergy of molecular interactions. Based on van’t Hoff equation, the solution thermodynamic properties (Δ G dis o , Δ H dis o and Δ S dis o ) have been estimated, indicating the dissolution process of CLZ in aqueous DES solutions is endothermic and entropy-driven. The improved solubility of CLZ in aqueous DES solutions provides reference for its application in novel crystallization development for the CLZ manufacture.

Solubility measurement, correlation and dissolution thermodynamics properties of marbofloxacin in binary solvents

Marbofloxacin (MAB) is a broad-spectrum veterinary antibacterial drug with the great application prospects. The solid-liquid equilibrium solubility of MAB in three kinds of aqueous binary solvent systems (ethanol + water, acetonitrile + water, and methanol + water) was determined between 283.15 and 323.15 K using a dynamic laser-monitoring method at atmospheric pressure. The experimental results revealed that the solubility of MAB increased with increasing temperature and mole fraction of water in the three binary solvent systems. The modified Apelblat, λh, and (non-random two-liquid) NRTL models were used to correlate the experimental data. For the ethanol + water system, the modified Apelblat model provided a better correlation with the experimental results than the other two models. However, for the acetonitrile + water and methanol + water systems, the most favorable correlation was obtained using the NRTL model. Furthermore, the van’t Hoff equation was used to study the thermodynamic properties of MAB. The obtained solubility data and thermodynamic properties of MAB can provide theoretical guidance for selecting the appropriate solvent system for the reaction, crystallization, and purification of MAB.

Equilibrium solubility of trans-resveratrol in {acetone (1) + water (2)} mixtures: Correlation, dissolution thermodynamics and preferential solvation

ABSTRACT Reported mole fraction solubilities of trans-resveratrol in aqueous mixtures of acetone in the temperature interval from (273.2 to 313.2) K were correlated by means of some cosolvency models, like multi-linear models of Jouyban-Acree and Jouyban-Acree-van’t Hoff and non-linear models of the modified Wilson and CNIBS/R-K model. Apparent thermodynamic quantities of the dissolution processes were computed using the van’t Hoff and Gibbs equations. Gibbs energies and enthalpies were positive in all cases, while negative and positive entropies were observed. The plot of enthalpy vs. Gibbs energy of dissolution was non-linear with negative slopes in the region of 0.00 ≤ x 1 ≤ 0.70 but positive slopes in the region of 0.70 ≤ x 1 ≤ 1.00. Further, by means of the inverse Kirkwood-Buff integrals is observed that trans-resveratrol is preferentially solvated by water in water-rich and acetone-rich mixtures but preferentially solvated by acetone in the composition interval of 0.21 < x 1 < 0.77.

Solubility of Sulfamethazine in the Binary Mixture of Acetonitrile + Methanol from 278.15 to 318.15 K: Measurement, Dissolution Thermodynamics, Preferential Solvation, and Correlation

Solubility of sulfamethazine (SMT) in acetonitrile (MeCN) + methanol (MeOH) cosolvents was determined at nine temperatures between 278.15 and 318.15 K. From the solubility data expressed in molar fraction, the thermodynamic functions of solution, transfer and mixing were calculated using the Gibbs and van ’t Hoff equations; on the other hand, the solubility data were modeled according to the Wilson models and NRTL. The solubility of SMT is thermo-dependent and is influenced by the solubility parameter of the cosolvent mixtures. In this case, the maximum solubility was achieved in the cosolvent mixture at 318.15 K and the minimum in pure MeOH at 278.15 K. According to the thermodynamic functions, the SMT solution process is endothermic in addition to being favored by the entropic factor, and as for the preferential solvation parameter, SMT tends to be preferentially solvated by MeOH in all cosolvent systems; however, , so the results are not conclusive. Finally, according to mean relative deviations (MRD%), the two models could be very useful tools for calculating the solubility of SMT in cosolvent mixtures and temperatures different from those reported in this research.

Solubility, correlation, dissolution thermodynamics and preferential solvation of meloxicam in aqueous mixtures of 2-propanol

Background: Meloxicam is a powerful analgesic and anti-inflammatory drug widely prescribed by physicians in current therapeutics. Because of the very low aqueous equilibrium solubility of meloxicam, this property has been studied in {2-propanol + water} mixtures from (293.15 to 313.15) K to expand the solubility database about pharmaceutical compounds in mixed solvents useful for homogeneous liquid dosage forms design. Methods: Flask shaken method and UV-vis spectrophotometry were used for meloxicam solubility determinations. Jouyban-Acree model was challenged for solubility correlation. The van’t Hoff and Gibbs equations were employed here to calculate the respective apparent standard thermodynamic quantities for the dissolution and mixing processes, namely Gibbs energy, enthalpy, and entropy. In addition, the inverse Kirkwood-Buff integrals were employed to compute the preferential solvation parameters of meloxicam by 2-propanol in the mixtures. Results: Meloxicam solubility increases with temperature arising and maximum solubilities are observed in the mixture of x1 = 0.70 at all temperatures. Jouyban-Acree model correlates the meloxicam solubility very well. Dissolution processes were endothermic in all cases and entropy-driven in the interval 0.20 ≤ x1 ≤ 1.00. Non-linear enthalpy–entropy relationship was observed in the plot of enthalpy vs. Gibbs energy exhibiting negative but variant slopes in the composition region 0.00 &lt; x1 &lt; 0.40 and variant negative and positive slopes in the other mixtures. Meloxicam is preferentially solvated by water in water-rich mixtures, it is apparently solvated by water in 2-propanol-rich mixtures, but it is preferentially solvated by 2-propanol in the composition interval of 0.19 &lt; x1 &lt; 0.78. Conclusion: Solid-liquid equilibrium of meloxicam in {2-propanol + water} mixtures has been studied at several temperatures as a contribution to preformulation studies of homogeneous liquid pharmaceutical dosage forms based on this drug.

Solubility of trans-resveratrol in {ethanol (1) + water (2)} mixtures revisited: Correlation, dissolution thermodynamics and preferential solvation

ABSTRACT Reported equilibrium mole fraction solubility values of trans-resveratrol in some aqueous-ethanolic mixtures in the temperature interval from (273.2 to 323.2) K were correlated by means of some cosolvency models, like multi-linear models of Jouyban-Acree and Jouyban-Acree-van’t Hoff and non-linear models of the modified Wilson and Buchowski-Ksiazczak. Apparent thermodynamic functions of the dissolution processes were computed using the van’t Hoff and Gibbs equations. Gibbs energy and enthalpy were positive in all cases, while negative and positive entropies were observed. The plot of enthalpy vs. Gibbs energy of dissolution was non-linear with negative slopes in the region of 0.00 ≤ x 1 ≤ 0.60 but positive slope in the region of 0.60 ≤ x 1 ≤ 0.90. Further, by means of the inverse Kirkwood-Buff integrals is observed that trans-resveratrol is preferentially solvated by water in water-rich mixtures but preferentially solvated by ethanol in the composition interval of 0.24 < x 1 < 1.00.

A Combined Experimental and Theoretical Study of Nitrofuran Antibiotics: Crystal Structures, DFT Computations, Sublimation and Solution Thermodynamics.

Single crystal of furazolidone (FZL) has been successfully obtained, and its crystal structure has been determined. Common and distinctive features of furazolidone and nitrofurantoin (NFT) crystal packing have been discussed. Combined use of QTAIMC and Hirshfeld surface analysis allowed characterizing the non-covalent interactions in both crystals. Thermophysical characteristics and decomposition of NFT and FZL have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and mass-spectrometry. The saturated vapor pressures of the compounds have been measured using the transpiration method, and the standard thermodynamic functions of sublimation were calculated. It was revealed that the sublimation enthalpy and Gibbs energy of NFT are both higher than those for FZL, but a gain in the crystal lattice energy of NFT is leveled by an entropy increase. The solubility processes of the studied compounds in buffer solutions with pH 2.0, 7.4 and in 1-octanol was investigated at four temperatures from 298.15 to 313.15 K by the saturation shake-flask method. The thermodynamic functions of the dissolution and solvation processes of the studied compounds have been calculated based on the experimental data. Due to the fact that NFT is unstable in buffer solutions and undergoes a solution-mediated transformation from an anhydrate form to monohydrate in the solid state, the thermophysical characteristics and dissolution thermodynamics of the monohydrate were also investigated. It was demonstrated that a combination of experimental and theoretical methods allows performing an in-depth study of the relationships between the molecular and crystal structure and pharmaceutically relevant properties of nitrofuran antibiotics.

Solubility and thermodynamic aspects of etonogestrel in several aqueous co-solvent solutions

The current work was devoted to the investigation on equilibrium solubility, Hansen solubility parameter, solvation performance and dissolution thermodynamics of etonogestrel in binary aqueous blends of the cosolvents {n-propanol, N,N-dimethylformamide (DMF), ethanol or isopropanol} by experimentation and several mathematical relationships. The solubility determination was conducted under atmospheric pressure (101.2 kPa) from 278.15 to 323.15 K through the common shake-flask method. The maxima of etonogestrel solubility expressed in mole fraction scale at 323.2 K were observed as 8.713 × 10−3 for ethanol, 16.81 × 10−3 for n-propanol, 19.52 × 10−3 for isopropanol and 121.4 × 10−3 for DMF; while the minimum was 0.01477 × 10−3 for pure water at 278.15 K. The solubility performance of etonogestrel was deeply considered by means of Hansen solubility parameter concept. The obtained equilibrium solubility was computationally expressed by modified Jouyban–Acree–van’t Hoff model, mixture response surface (MRS) model, modified Wilson model and Jouyban–Acree model with the relative average deviations of no higher than 7.12%. The relative prominence of solvent–solvent and solute–solvent molecule interactions on etonogestrel solubility variation specified the dipolarity-polarizability and solubility parameter of solution descriptors that was studied in terms of the linear solvation energy relationships. The extended Hildebrand solubility approach was used to inspect the solubility data at 298.15 K acquiring the correlation coefficient of >0.9999. The quantitative investigation on preferential solvation of etonogestrel by solvent species in different solutions was made by the inverse Kirkwood–Buff integrals technique in terms of numerous solution properties. Positive preferential solvation parameters for cosolvents of isopropanol, DMF, ethanol and n-propanol in aqueous solutions with cosolvent-rich and intermediate scopes suggested the preferential solvation of etonogestrel by the cosolvents (isopropanol/DMF/ethanol/n-propanol). It was assumed that etonogestrel acted as a Lewis acid in these composition ranges with the isopropanol/DMF/ethanol/n-propanol molecules. Thermodynamic analysis of dissolution properties and enthalpy–entropy compensation demonstrated an entropy-driven mechanism and endothermic process for etonogestrel dissolved in different blended solvents.

Solubility of sulfamerazine in (ethylene glycol + water) mixtures: Measurement, correlation, dissolution thermodynamics and preferential solvation

The equilibrium solubility of sulfamerazine (SMR) in neat ethylene glycol (EG) and nineteen {(EG) (1) + water (2)} mixtures is reported at temperatures from (278.15 to 318.15) K. Mole fraction solubility of SMR (x3) increases with temperature arising and also increases with the EG proportion increasing. It varies from 1.71 × 10−5 in neat water to 7.78 × 10−4 in neat EG at 298.15 K. Solubility behavior was correlated by the extended log-linear model of Yalkowsky, the Jouyban-Acree model, and Jouyban-Acree-van’t Hoff model and the obtained mean percentage deviations are 80.1%, 6.7% and 6.6%, respectively. From the variation of solubility with temperature, the apparent thermodynamic analysis of dissolution and mixing processes was performed in all the mixtures and neat solvents. From inverse Kirkwood-Buff integrals (IKBI) calculations is observed that SMR exhibits low negative preferential solvation parameters by EG in water-rich mixtures. Otherwise, SMR is preferentially solvated by EG in the interval (0.24 < x1 < 1.00).

Solubility, Dissolution Thermodynamics and Preferential Solvation of Meloxicam in (Methanol + Water) Mixtures

Solubility, Dissolution Thermodynamics and Preferential Solvation of Meloxicam in (Methanol + Water) Mixtures

Solubility of fluconazole in (ethanol + water) mixtures: Determination, correlation, dissolution thermodynamics and preferential solvation

In this research, the equilibrium mole fraction solubility of fluconazole (FLC) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy–entropy relationship for FLC was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition regions of 0.00 ≤ w1 ≤ 0.40 and 0.70 ≤ w1 ≤ 1.00. Thus, the driving mechanism for FLC transfer processes in water-rich mixtures is the entropy. In addition, by means of the inverse Kirkwood-Buff integrals is observed that FLC is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in the mixtures of 0.23 < x1 < 1.00.

Comments regarding “Solid-liquid equilibrium and dissolution thermodynamics of 4-Methylumbelliferon in different solvents”

An argument is aroused for the thermodynamics-related characteristics suggested within the published study. Ouyang and colleagues made a mistake that the determined data pertaining to dissolution thermodynamics-related characteristics of 4-Methylumbelliferon suggested within Table 3 are inconsistent with the Wilson equation curve-fit coefficients.

Solubility, dissolution thermodynamics and preferential solvation of sulfadiazine in (N-methyl-2-pyrrolidone + water) mixtures

Solubility of sulfadiazine in {N-methyl-2-pyrrolidone (NMP) + water} mixtures from 278.15 K to 313.15 K has been determined and correlated by means of the Jouyban-Acree model. Discontinuous solubility trends are observed in NMP-rich mixtures at low temperatures. By using the van't Hoff and Gibbs equations the respective apparent thermodynamic quantities for the dissolution and mixing processes, namely Gibbs energy, enthalpy, and entropy, were calculated. Non-linear enthalpy–entropy relationships were observed in the plot of enthalpy vs. Gibbs energy exhibiting negative but variant slopes in the composition region 0.00 < w1 < 0.60 and variant negative and positive slopes in the other mixtures for the first case. Otherwise, a variant negative slope from neat water to w1 = 0.80 but a positive slope from this mixture to neat NMP were observed for the second case. Based on the inverse Kirkwood-Buff integrals it follows that sulfadiazine is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by NMP molecules in mixtures 0.17 < x1 < 1.00 at 313.15 K.

Experimental measurement – correlation of solubility and dissolution thermodynamics study of itraconazole in pure monosolvents at various temperatures

The information about the solubility and thermodynamic properties of solution is important for pharmaceutically important processes, formulation development, and further theoretical studies. In the present study, the solid–liquid equilibrium (solubility) for itraconazole (ITC) was determined experimentally in 14 monosolvents at temperatures between 293.15 K and 318.15 K under pressure of 0.1 MPa. The mole fraction solubilities were found to increase with increasing temperatures and followed inverse trend with the polarity of selected solvents. Besides, KAT-LSER analysis was performed to study the effect of solvent. The results revealed that the solute–solvent interaction (43.94%) was much higher than that of solvent–solvent interaction (16.59%). Thermodynamic based models like van’t Hoff equation, modified Apelblat equation, Buchowski–Ksiazaczak equation, and polynomial empirical equation were applied to fit and correlate the experimental solubilities. Overall relative average deviation and overall root-mean square deviation () were observed to be minimum with the empirical polynomial equation and attained the values of 0.0033 and 0.0047, respectively. Furthermore, theoretical ideal solubilities, activity coefficients, and thermodynamic properties of dissolution including molar enthalpy, molar entropy, molar Gibbs free energy, and excess enthalpy were estimated. Ideal solubilities were projected considerably higher than experimental solubilities at each studied temperature. Thermodynamic properties of dissolution indicated that the dissolution was not a spontaneous process; observed to be endothermic ( and enthalpy driven Such solid–liquid equilibrium data of ITC will be of immense help in process and formulation development in pharmaceutical sciences.

Solubility Determination of c-Met Inhibitor in Solvent Mixtures and Mathematical Modeling to Develop Nanosuspension Formulation.

The solubility and dissolution thermodynamics of new c-Met inhibitor, ABN401, were determined in eleven solvents and Transcutol® HP–water mixture (TWM) from 298.15 to 318.15 K. The experimental solubilities were validated using five mathematical models, namely modified Apelblat, van’t Hoff, Buchowski–Ksiazaczak λh, Yalkowsky, and Jouyban–Acree van’t Hoff models. The experimental results were correlated and utilized further to investigate the feasibility of nanosuspension formation using liquid anti-solvent precipitation. Thermodynamic solubility of ABN401 increased significantly with the increase in temperature and maximum solubility was obtained with Transcutol® HP while low solubility in was obtained water. An activity coefficient study indicated that high molecular interaction was observed in ABN401–Transcutol® HP (THP). The solubility increased proportionately as the mole fraction of Transcutol® HP increased in TWM, which was also supported by a solvent effect study. The result suggested endothermic and entropy-driven dissolution. Based on the solubility, nanosuspension was designed with Transcutol® HP as solvent, and water as anti-solvent. The mean particle size of nanosuspension decreased to 43.05 nm when the mole fraction of ABN401 in THP, and mole fraction of ABN401 in TWM mixture were decreased to 0.04 and 0.1. The ultrasonicated nanosuspension appeared to give comparatively higher dissolution than micronized nanosuspension and provide a candidate formulation for in vivo purposes.

Solubility and Dissolution Thermodynamics of 1,1-Bis(3-methyl-4-hydroxyphenyl)cyclohexane (MeBZ) in Different Pure Organic Solvents in the Temperature Range from 299.15 to 328.15 K

The solubility of 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane (MeBZ) in different pure organic solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, 1,4-dioxane, ethylacetate, and tetrahydrofuran over a temperature range from 299.15 to 328.15 K at atmospheric pressure were measured by gravimetric method. The solubility increased significantly with increase in temperature in all studied solvents. Among the studied solvents, tetrahydrofuran showed the highest solubility at 328.15 K. The experimental solubilities were corelated with the modified Apelbalt equation and Buchowski–Ksiazczak (λh) equation.The thermodynamic parameters such as enthalpies of solution ( $$\Delta H_{{{\text{sol}}}}^{^\circ }$$ ), Gibbs energy of dissolution ( $$\Delta G_{{{\text{sol}}}}^{^\circ }$$ ), isobaric heat capacity( $$\Delta C_{{p\;{\text{sol}}}}^{^\circ }$$ ), and entropy of solutions ( $$\Delta S_{{{\text{sol}}}}^{^\circ }$$ ) were calculated using Clark and Glew equation.

Solubility of sulfadiazine in (acetonitrile + methanol) mixtures: Determination, correlation, dissolution thermodynamics and preferential solvation

The equilibrium solubility of sulfadiazine (SD, 3) in {acetonitrile (MeCN, 1) + methanol (MeOH, 2)} mixtures at nine temperatures from 278.15 K to 318.15 K has been determined and correlated by means of some well-known thermodynamic correlation models. Five models including van't Hoff, the mixture response surface (MRS), Jouyban-Acree, Jouyban-Acree-van't Hoff and the modified Wilson models were applied to mathematical solubility data modelling. The accuracy of each model is investigated by the mean relative deviations (MRD%) of the back-calculated solubility. All used models show a low MRD% values (< 8.0%) for the calculated data indicating a good correlation of sulfadiazine solubility data with the given mathematical models. By using the van't Hoff and Gibbs equations the respective apparent thermodynamic quantities of the dissolution and mixing processes, namely Gibbs energy, enthalpy, and entropy, were calculated. Non-linear enthalpy–entropy relationship was observed for SD in the plot of enthalpy vs. Gibbs energy exhibiting negative slope in the composition region 0.00 < w1 < 0.05 indicating entropy-driving mechanism for this transfer process, and variant but mainly positive slopes in the composition interval 0.05 < w1 < 0.30, indicating enthalpy-driving mechanism for these transfer processes. From w1 = 0.30 to neat MeCN a slope near zero is observed. Furthermore, the preferential solvation of SD by MeCN or MeOH was analysed by using the inverse Kirkwood-Buff integrals. Thus, SD is preferentially solvated by MeOH molecules in MeOH-rich mixtures.

Solubility of Hydroxytyrosol in binary mixture of ethanol + water from (293.15 to 318.15) K: Measurement, correlation, dissolution thermodynamics and preferential solvation

Hydroxytyrosol (HXT) (also known as 3,4-dihydroxyphényléthanol,) is a biophenol extracted from olive. HXT is known for its high antioxidant significance effect. In this work, we focused on the study of the behavior of the solubility of HXT in binary solvent mixtures (ethanol + water) as well as the thermodynamic proprieties. The solubility of HXT in water, ethanol and in binary solvent mixtures (ethanol + water) was measured at five different temperatures from (293.15 to 318.15) K. The enthalpy of fusion and the melting point of HXT were experimentally determined since they are essential for the study of the of solubility and crystallization process. Thermodynamic properties of dissolution of the HXT (Gibbs energy (ΔsolG°), molar enthalpy of dissolution (ΔsolH°), and molar entropy of dissolution (ΔsolS°)) are predicted using the van’t Hoff analysis, the Gibbs equation, and the measured solubilities data. The preferential solvation has been determined using the inverse Kirkwood–Buff integral (IKBI) theory.

Dissolution thermodynamics and preferential solvation of meloxicam in (acetonitrile + water) mixtures

ABSTRACT Solubility of meloxicam in {acetonitrile + water} mixtures at five temperatures from 293.15 K to 313.15 K has been determined and correlated by means of the Jouyban-Acree model. By using the van’t Hoff and Gibbs equations the respective apparent thermodynamic quantities for the dissolution and mixing processes, namely Gibbs energy, enthalpy, and entropy, were calculated. Non-linear enthalpy–entropy relationship was observed in the plot of enthalpy vs. Gibbs energy exhibiting negative slope in the composition region 0.00 < x 1 < 0.20 and variant slopes in the other mixtures. Based on the inverse Kirkwood-Buff integrals it follows that meloxicam is preferentially solvated by water molecules in water-rich and acetonitrile-rich mixtures but preferentially solvated by acetonitrile molecules in mixtures 0.26 < x 1 < 0.60.