Calculating the Solubilities of Drugs and Drug-Like Compounds in Octanol

Experimental Examination of Solubility and Lipophilicity as Pharmaceutically Relevant Points of Novel Bioactive Hybrid Compounds

The important physicochemical properties of three novel bioactive hybrid compounds with different groups (-CH₃, -F and -Cl) were studied, including kinetic and thermodynamic solubility in pharmaceutically relevant solvents (buffer solutions and 1-octanol) as well as partition coefficient in system 1-octanol/buffer pH 7.4. The aqueous solubility of these chemicals is poor and ranged from 0.67 × 10^-4 to 1.98 × 10^-3 mol·L^-1. The compounds studied are more soluble in the buffer pH 2.0, simulating the gastrointestinal tract environment (by an order of magnitude) than in the buffer pH 7.4 modelling plasma of blood. The solubility in 1-octanol is significantly higher; that is because of the specific interactions of the compounds with the solvent. The prediction solubility behaviour of the hybrid compounds using Hansen's three-parameter approach showed acceptable results. The experimental solubility of potential drugs was successfully correlated by means of two commonly known equations: modified Apelblat and van't Hoff. The temperature dependencies of partition coefficients of new hybrids in the model system 1-octanol/buffer pH 7.4 as a surrogate lipophilicity were measured by the shake flask method. It was found that compounds demonstrated a lipophilic nature and have optimal values of partition coefficients for oral absorption. Bioactive assay manifested that prepared compounds showed antifungal activities equal to or greater than fluconazole. In addition, the thermodynamic aspects of dissolution and partition processes have been examined. Bioactive assay manifested that prepared compounds showed antifungal activities equal to or greater than the reference drug.

Application of PC-SAFT EOS for Pharmaceuticals: Solubility, Co-Crystal, and Thermodynamic Modeling

In this study, the applicability of the perturbed chain statistical associating fluid theory (PC-SAFT) was evaluated for pharmaceutical compounds. For this purpose, the parameters of the PC-SAFT equation of state (EOS) were regressed by applying the experimental solubility data of 54 pharmaceuticals in pure solvents. The reported errors for train and test data show the suitability of the PC-SAFT EOS. The applicability of the PC-SAFT EOS was explored by its prediction accuracy for the ternary system of medicine in solvent mixtures. The model errors were 23 and 26% for two ternary systems of salicylic acid and lidocaine HCl in solvent mixtures of ethanol and water, respectively. The co-crystal formation of salicylic acid-sulfamethazine in methanol was investigated by the PC-SAFT EOS. Finally, the reaction and crystallization sections for acetaminophen production from p-aminophenol were simulated by accompanying the PC-SAFT EOS and equilibrium assumption. The purification efficiencies for acetaminophen were obtained to be 93-98% for different temperatures.

From Micelles to Vesicle and Membrane Structures of Double-Strand Ionic Liquids in Water: Molecular Dynamics Simulation

The structures of novel double-strand imidazolium iodide ionic liquids (ILs)-based lipid in the water phase have been studied in this research. We report the effect of alkyl chain length of 1,3-dimethyl-4,5-dialkyl-imidazolium iodide([2(Me)2(C _n)im]I, n = 7, 11, 15) ILs on their structures in the aqueous solution by molecular dynamics simulation. The structure details of IL clusters lead to the various aggregation forms by increasing the alkyl chain length of ILs. The ILs with n = 7 and 11 can help develop micelle structures of different sizes, and the IL with n = 15, the benign IL, feasible to develop lipidlike vesicle. To obtain more details about bilayer properties, [2(Me)2(C₁₅)im]I IL is investigated by different IL/water ratios in this study exclusively. The [2(Me)2(C₁₅)im]I IL bilayer thickness and deuterium order parameters are compared with lipid membrane, and they reveal a small difference. The energies, radial distribution functions, spatial distribution function, cluster size, number density, and membrane properties all prove that the stable IL vesicle is formed in the dilute solution but the membrane is formed in the concentrated aqueous solution of [2(Me)2(C₁₅)im]I.

Solubility of organic compounds in octanol: Improved predictions based on the geometrical fragment approach

Two new models are introduced to predict the solubility of chemicals in octanol (S_oct), taking advantage of the extensive character of log(S_oct) through a decomposition of molecules into so-called geometrical fragments (GF). They are extensively validated and their compliance with regulatory requirements is demonstrated. The first model requires just a molecular formula as input. Despite an extreme simplicity, it performs as well as an advanced random forest model involving 86 descriptors, with a root mean square error (RMSE) of 0.64 log units for an external test set of 100 molecules. For the second one, which requires the melting point T_m as input, introducing GF descriptors reduces the RMSE from about 0.7 to <0.5 log units, a performance that could previously be obtained only through the use of Abraham descriptors. A script is provided for easy application of the models, taking into account the limits of their applicability domains.