Se investigó la solubilidad de sulfadiazina (SD), sulfamerazina (SMR) y sulfametazina (SMT) en mezclas codisolventes de octanol + metanol a 278,15 K, 298,15 y 313,15 K. En todos los casos, la solubilidad más baja de cada fármaco se obtuvo en octanol puro a 278,15 K. La solubilidad máxima depende de la polaridad del fármaco, por lo que SMR y SMT alcanzaron su máxima solubilidad en mezclas cosolventes ricas en metanol. Las funciones termodinámicas de solución se calcularon a partir de los datos experimentales de solubilidad, utilizando las ecuaciones de van’t Hoff y Gibbs, siguiendo el enfoque propuesto por Krug et al. La entalpía de la solución es positiva en todos los casos, lo cual es una indicación del proceso endotérmico con un marcado favorecimiento entrópico. La solubilidad teórica y la concentración letal media se calcularon utilizando el modelo de Abraham.

Equilibrium solubility of triclocarban (TCC) expressed in mole fraction in 1,4-dioxane and cyclohexane, as well, as in 19 {cyclohexane (1) + 1,4-dioxane (2)} mixtures, was determined at seven temperatures fromT = (288.15 to 318.15) K. Logarithmic TCC solubility in these cosolvent mixtures was adequately correlated with a lineal bivariate equation as function of both the mixtures composition and temperature. Apparent thermodynamic quantities for the dissolution and mixing processes were computed by means of the van’t Hoff and Gibbs equations observing endothermal and entropy-driven dissolution processes in all cases. The enthalpy–entropy compensation plot of apparent enthalpyvs.apparent Gibbs energy was linear exhibiting positive slope implying enthalpy-driving for TCC transfer from cyclohexane to 1,4-dioxane. Ultimately, by using the inverse Kirkwood–Buff integrals it is observed that TCC is preferentially solvated by cyclohexane molecules in 1,4-dioxane-rich mixtures but preferentially solvated by 1,4-dioxane molecules in cyclohexane-rich mixtures.

Solubility is one of the most important physicochemical properties, because it is related to some industrial processes such as: formulation, preformulation, purification and quantification. The experimental determination of solubility requires rigorous processes that involve a significant amount of resources. In this context, mathematical models allow estimating solubility under conditions different from the experimental ones from a limited number of data. The objective of this research was to evaluate the pertinence of 10 mathematical models (Extended Hildebrand, van’t Hoff, Two-parameter Weibull, Buchowski–Ksiazczak $$\lambda h$$ λ h , van’t Hoff-Yaws, Apelblat, Wilson, NRTL, Modified Wilson and van’t Hoff-Modified Wilson) in the calculation of the solubility of isoniazid in PEG 200 (1) + Water (2) cosolvent mixtures, the parameters of each model were calculated using Python, Pandas and the NumPy and SciPy library. Once each model was evaluated, two models were defined as the best alternatives based on their predictive power and mathematical simplicity. Thus, the van’t Hoff and Modified Wilson models were combined to obtain an equation that allows the calculation of solubility as a function of temperature and cosolvent composition, obtaining MRD% less than 3.0. In conclusion, mathematical models represent a good prediction tool being a potential alternative in relation to the optimization of some industrial processes related to solubility.

Solubility studies are essential for developing more efficient dosing processes and systems. The solubility of INH in a mixture of PEG 300 (1) + water (2) was evaluated at various temperatures using UV/Vis spectrophotometry and the shaking flask method. Solubility increased by 150% at 288.15 K and 298% at 318.15 K, reflecting the temperature dependence of solubility when transitioning from pure water to pure PEG 300. Generally, the solubility of INH is an endothermic process favoured by entropy. Its affinity increases with PEG 300 proportion in the mixtures, transitioning from an enthalpic to an entropic mechanism as it approaches the pure solvent. Ultimately, it is concluded that PEG 300 acts as an excellent, eco-friendly cosolvent that could help to optimise more sustainable pharmaceutical systems.