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 (RAD) and overall root-mean square deviation (104×RMSD) 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 (ΔH0soln>0) and enthalpy driven (ΔS0soln>0). Such solid-liquid equilibrium data of ITC will be of immense help in process and formulation development in pharmaceutical sciences.

Solubilization, Hansen solubility parameters and apparent thermodynamic parameters of Osimertinib in (propylene glycol + water) cosolvent mixtures

The solubilization, Hansen solubility parameters (HSPs) and apparent thermodynamic parameters of a novel anticancer medicine osimertinib (OMT) in binary propylene glycol (P) + water (W) cosolvent mixtures were evaluated. The mole fraction solubility (x e) of OMT in various (P + W) cosolvent mixtures including neat P and neat W was determined at T = 298.2–318.2 K and p = 0.1 MPa by applying a saturation shake flask method. HSPs of OMT, neat P, neat W and (P + W) cosolvent compositions free of OMT were also estimated. The x e values of OMT were regressed with Van’t Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models with an average errors of <3.0 %. The highest and lowest x e value of OMT was estimated in neat P (2.70 × 10−3 at T = 318.2 K) and neat W (1.81 × 10−5 at T = 298.2 K), respectively. Moreover, HSP of OMT was found to be closed with that of neat P. The solubility of OMT was found to be increased significantly with an increase in temperature and P mass fraction in all (P + W) cosolvent compositions including neat P and neat W. The results of activity coefficients suggested higher molecular interactions in OMT-P combination compared with OMT-W combination. The results of thermodynamic studies indicated an endothermic and entropy-driven dissolution of OMT in all (P + W) cosolvent compositions including neat P and neat W.

Solubility Data and Computational Modeling of Baricitinib in Various (DMSO + Water) Mixtures

The solubility and thermodynamic analysis of baricitinib (BNB) in various dimethyl sulfoxide (DMSO) + water mixtures were performed. The “mole fraction solubilities (x_e)” of BNB in DMSO and water mixtures were determined at “T = 298.2–323.2 K” and “p = 0.1 MPa” using an isothermal saturation technique. “Hansen solubility parameters (HSPs)” of BNB, pure DMSO, pure water and “DMSO + water” mixtures free of BNB were also estimated. The x_e data of BNB was regressed well by five different thermodynamics-based co-solvency models, which included “Apelblat, Van’t Hoff, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models” with overall deviations of <5.0%. The highest and lowest x_e value of BNB was computed in pure DMSO (1.69 × 10⁻¹ at T = 323.2 K) and pure water (2.23 × 10⁻⁵ at T = 298.2 K), respectively. The HSP of BNB was found to be closer to that of pure DMSO. Based on activity coefficient data, maximum solute–solvent molecular interactions were observed in BNB-DMSO compared to BNB-water. The results of “apparent thermodynamic analysis” indicated endothermic and entropy-drive dissolution of BNB in all “DMSO + water” combinations including mono-solvents (water and DMSO). “Enthalpy-entropy compensation analysis” showed enthalpy-driven to be the main mechanism of solvation of BNB.

Solubility, Hansen Solubility Parameters and Thermodynamic Behavior of Emtricitabine in Various (Polyethylene Glycol-400 + Water) Mixtures: Computational Modeling and Thermodynamics

This study was aimed to find out the solubility, thermodynamic behavior, Hansen solubility parameters and molecular interactions of an antiviral drug emtricitabine (ECT) in various “[polyethylene glycol-400 (PEG-400) + water]” mixtures. The solubility of ECT in mole fraction was determined at “T = 298.2 to 318.2 K” and “p = 0.1 MPa” using an isothermal method. The experimental solubilities of ECT in mole fraction were validated and correlated using various computational models which includes “Van’t Hoff, Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models”. All the models performed well in terms of model correlation. The solubility of ECT was increased with the raise in temperature in all “PEG-400 + water” mixtures studied. The highest and lowest solubility values of ECT were found in pure PEG-400 (1.45 × 10⁻¹) at “T = 318.2 K” and pure water (7.95 × 10⁻³) at “T = 298.2 K”, respectively. The quantitative values of activity coefficients indicated higher interactions at molecular level in ECT and PEG-400 combination compared with ECT and water combination. “Apparent thermodynamic analysis” showed an “endothermic and entropy-driven dissolution” of ECT in all “PEG-400 + water” combinations studied. The solvation nature of ECT was found an “enthalpy-driven” in each “PEG-400 + water” mixture studied.

Synthesis, Characterization and Solubility Determination of 6-Phenyl-pyridazin-3(2H)-one in Different Pharmaceutical Solvents

The current research work proposed the solubility data and solution thermodynamic properties of the cardiovascular agent 6-phenylpyridazin-3(2H)-one [PPD] in twelve pharmaceutical solvents at "T = 298.2 K to 318.2 K" and "p = 0.1 MPa". The measured solubilities of PPD were regressed well with "van't Hoff and Apelblat models". The solid phases of pure and equilibrated PPD were characterized using differential scanning calorimetry and powder X-ray differactometry, and the results suggested no transformation of PPD into solvates/hydrates/polymorphs after equilibrium. The solubilities of PPD in a mole fraction at "T = 318.2 K" were noted at a maximum in dimethyl sulfoxide (DMSO, 4.73 × 10^-1), followed by polyethylene glycol-400 (PEG-400, 4.12 × 10^-1), Transcutol^® (3.46 × 10^-1), ethyl acetate (EA, 81 × 10^-2), 2-butanol (2.18 × 10^-2), 1-butanol (2.11 × 10^-2), propylene glycol (PG, 1.50 × 10^-2), isopropyl alcohol (IPA, 1.44 × 10^-2), ethylene glycol (EG, 1.27 × 10^-2), ethanol (8.22 × 10^-3), methanol (5.18 × 10^-3) and water (1.26 × 10^-5). Similar tendencies were also noted at other studied temperatures. The results of the "apparent thermodynamic analysis" showed an endothermic and entropy-driven dissolution of PPD in all pharmaceutical solvents. The results of the activity coefficients suggested a maximum interaction at the molecular level in PPD-DMSO, PPD-PEG-400 and PPD-Transcutol, compared with other combination of the solute and solvents.

Solubility and Solution Thermodynamics of Baricitinib in Six Different Pharmaceutically Used Solvents at Different Temperatures

The preset study was undertaken to determine solubility and solution thermodynamics of a novel anticancer drug baricitinib in some pharmaceutically used mono/pure solvents including “water, ethanol, polyethylene glycol-400 (PEG-400), ethyl acetate (EA), dichloromethane (DCM) and dimethyl sulfoxide (DMSO)” at “T = 298.2 K to 323.2 K” and “p = 0.1 MPa”. The solubility of baricitinib after equilibrium (saturation state) was analyzed spectrophotometrically by applying an isothermal technique. Characterization of solid phases of initial and equilibrated baricitinib was confirmed with the help of differential scanning calorimetry (DSC). Measured solubilities of baricitinib were regressed using “van’t Hoff and Apelblat models”. DSC spectra of baricitinib showed no change in physical state of baricitinib after equilibrium. Solubilities of baricitinib (as mole fraction) were estimated highest in DMSO (1.65 × 10−1) followed by PEG-400 (1.42 × 10−1), DCM (1.29 × 10−3), ethanol (7.41 × 10−4), EA (4.74 × 10−4) and water (1.76 × 10−4) at “T = 323.2 K” and same tendencies were also noted at other temperatures studied. With the help of theoretical solubilities of baricitinib, activity coefficients were estimated. The estimated data of activity coefficients indicated higher molecular interactions in baricitinib-DMSO and baricitinib-PEG-400 as compared with baricitinib-water, baricitinib-EA, baricitinib-DCM and baricitinib-ethanol. Thermodynamic treatment of solubility values of baricitinib showed “endothermic and entropy-driven dissolution” of baricitinib in all pharmaceutically used solvents evaluated.