Solubility and solution thermodynamics of sulfadiazine in polyethylene glycol 400 + water mixtures

Experimental and Theoretical Screening for Green Solvents Improving Sulfamethizole Solubility

Solubility enhancement of poorly soluble active pharmaceutical ingredients is of crucial importance for drug development and processing. Extensive experimental screening is limited due to the vast number of potential solvent combinations. Hence, theoretical models can offer valuable hints for guiding experiments aimed at providing solubility data. In this paper, we explore the possibility of applying quantum-chemistry-derived molecular descriptors, adequate for development of an ensemble of neural networks model (ENNM), for solubility computations of sulfamethizole (SMT) in neat and aqueous binary solvent mixtures. The machine learning procedure utilized information encoded in σ-potential profiles computed using the COSMO-RS approach. The resulting nonlinear model is accurate in backcomputing SMT solubility and allowed for extensive screening of green solvents. Since the experimental characteristics of SMT solubility are limited, the data pool was extended by new solubility measurements in water, five neat organic solvents (acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, and methanol), and their aqueous binary mixtures at 298.15, 303.15, 308.15, and 313.15 K. Experimentally determined order of decreasing SMT solubility in neat solvents is the following: N,N-dimethylformamide > dimethyl sulfoxide > methanol > acetonitrile > 1,4dioxane >> water, in all studied temperatures. Similar trends are observed for aqueous binary mixtures. Since N,N-dimethylformamide is not considered as a green solvent, the more acceptable replacers were searched for using the developed model. This step led to the conclusion that 4-formylmorpholine is a real alternative to N,N-dimethylformamide, fulfilling all requirements of both high dissolution potential and environmental friendliness.

Solubility determination and solution thermodynamics of olmesartan medoxomil in (PEG-400 + water) cosolvent mixtures

The solubility and solution thermodynamic properties of a weakly water-soluble compound olmesartan medoxomil (OLM) in binary 'polyethylene glycol (PEG-400) + water' cosolvent compositions were determined. The 'mole fraction solubility (x _e)' of OLM in binary 'PEG-400 + water' cosolvent compositions and pure solvents (PEG-400 and water) was determined at 'T = 295.15-330.15 K' and 'p = 0.1 MPa'. The Hansen solubility parameter (HSP) of OLM, pure PEG-400, pure water, and binary 'PEG-400 + water' cosolvent compositions free of OLM were also predicted. The obtained x _e values of OLM were correlated using 'van't Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-van't Hoff' computational models with the error values of <4.0%. The maximum and minimum x _e value of OLM was predicted in neat PEG-400 (1.15 × 10^-2 at T = 330.15 K) and neat water (1.90 × 10^-7 at T = 295.15 K), respectively. The OLM HSP was predicted to be more close with that of neat PEG-400. The x _e value of OLM was found increased significantly with increase in temperature and PEG-400 mass fraction in all 'PEG-400 + water' cosolvent compositions including neat PEG-400 and neat water. An 'apparent thermodynamic analysis' studies presented an 'endothermic and entropy-driven dissolution' of OLM in all 'PEG-400 + water' cosolvent compositions including pure PEG-400 and pure water.

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.

Thermodynamic solubility and solvation behavior of ferulic acid in different (PEG-400 + water) binary solvent mixtures

This work was carried out to determine solubility, solution thermodynamics, solvation behavior, and molecular interactions of a natural compound ferulic acid (FLA) in different '[polyethylene glycol-400 (PEG-400) + water]' binary solvent mixtures at 'T = 298.2 K to 318.2 K' and 'p = 0.1 MPa.' The mole fraction solubilities (x_e) of FLA were determined by liquid chromatographic technique using a static equilibrium technique. The obtained solubility data of FLA were regressed using 'Van't Hoff, Apelblat, Yalkowsky-Roseman and Jouyban-Acree models.' The solubility of FLA (expressed in mole fraction) was enhanced with elevation in absolute temperature in each 'PEG-400 + water' binary solvent mixture evaluated. The maximum x_e values of FLA were recorded in neat PEG-400 (1.94 × 10^-1) at 'T = 318.2 K.' While, the minimum one was obtained in neat water (4.90 × 10^-5) at 'T = 298.2 K.' The molecular interactions between FLA-PEG-400 and FLA-water were obtained by determination of activity coefficients of FLA in different 'PEG-400 + water' binary solvent mixtures. The physical data of activity coefficients recorded in this work suggested strong molecular interactions in FLA-PEG-400 in comparison with FLA-water. 'Apparent thermodynamic analysis' suggested an 'endothermic and entropy-driven dissolution' of FLA in each 'PEG-400 + water' binary solvent mixture investigated.

Effects of Hydrogen Bond Acceptor Ability of Solvents on Molecular Self-Assembly of Sulfadiazine Solvates

The solvate formation of sulfadiazine (SDZ) was systematically studied in the 4 selected solvents with the aids of experiment and simulation methods. The intermolecular interactions between solute and solvent molecules in different solid states were analyzed and compared through their single crystal structures, and the solution behavior of SDZ was discussed using molecular dynamics simulations. The results indicated that SDZ was easy to form solvates with the solvents having strong hydrogen bond acceptor ability, which determined the formation of hydrogen bonding synthon. Furthermore, the SDZ molecules conformation and packing were compared in various crystal structures. In addition, the desolvation processes of SDZ solvates were studied to investigate the role of solvent in different solvate structures.

Solubility and Thermodynamics of 6-Phenyl-4,5-dihydropyridazin-3(2H)-one in Various (PEG 400+Water) Mixtures

The aim of this study was to determine the solubility of pyridazinone derivative 6-phenyl-4,5-dihydropyridazin-3(2H)-one (PDP-6) in different “polyethylene glycol 400 (PEG 400)+water” mixtures at temperatures “T=293.2 K to 313.2 K” and pressure “p=0.1 MPa”. The solubilities of PDP-6 were determined using an isothermal method and correlated with Apelblat, van’t Hoff and Yalkowsky–Roseman models. The maximum solubilities of PDP-6 in mole fraction were obtained in neat PEG 400 (8.46×10−2 at T=313.2 K). However, the minimum one was recorded in neat water (7.50×10−7 at T=293.2 K). Apparent thermodynamic analysis showed an endothermic dissolution of PDP-6 in all (PEG 400 water) mixtures. Based on the solubility data of the current study, PDP-6 has been considered as practically insoluble in water and soluble in PEG 400.

Solid state characterization of azelnidipine-oxalic acid co-crystal and co-amorphous complexes: The effect of different azelnidipine polymorphs

In present study, based on the two polymorphs (α and β form) of azelnidipine (AZE), 12 complexes of AZE and oxalic acid (OXA) were prepared by solvent-assisted grinding (SG) and neat powder grinding (NG) methods at the AZE/OXA molar ratios of 2:1, 1:1, and 1:2. The effect of the different polymorphs of AZE on the micro-structure of the complexes were investigated by powder X-ray diffraction (PXRD), tempreture modulated differential scanning calorimetry and thermogravimetric analysis, cryo-field emission scanning electron microscope system, fourier transform infrared (FTIR), and solid-state nuclear magnetic resonance spectroscopy. β-AZE-OXA co-crystal was produced at β-AZE/OXA molar ratio of 2:1 when SG method was used; while α-AZE was used to produce α-AZE-OXA co-crystal at same condition. However, the other 10 combinations were in co-amorphous forms, including the NG samples with α (or β)-AZE/OXA molar ratios of 2:1, 1:1 (SG and NG), and 1:2 (SG and NG). Although the XRD pattern and IR spectra of the two co-crystals showed no difference, the melting enthalpy and specific heat c_p of the β-AZE-OXA co-crystal was higher than that of the α-AZE-OXA co-crystal, indicating that the numbers of solvent molecules which entered the two co-crystal lattices were different. Interestingly, obvious difference occurred in the IR spectra between the α-AZE-OXA and β-AZE-OXA co-amorphous systems. 1745cm^-1 wave-numbers, which were assigned to the free CO groups, appeared in the α-AZE-OXA co-amorphous systems even when just a small amount of OXA was introduced, thereby indicating the presence of different intermolecular forces in the two series of co-amorphous forms. The solubility in different media and the dissolution rate in 0.1molL^-1 HCl of the 12 complexes were determined. The dramatically improved dissolution rates of the α- and β-AZE-OXA 1:2 (NG) combinations in vitro showed potential in improving the physicochemical properties of AZE by co-amorphous complex formation.