Solubility is a fundamental parameter in the discovery of new drug molecules as well as in their production using crystallization processes. In this work, we experimentally investigate the solubility in different solvents and the density of the anti-cough drug guaifenesin and characterize its solid state via Powder X-Ray Diffraction (PXRD) and thermal analysis. Moreover, a strategy is developed and successfully applied to predict the density and solubility behavior of that pharmaceutical. On the solubility curve concentration and temperature depend on each other for a binary solution at fixed pressure. Therefore, densities of undersaturated aqueous solutions of guaifenesin are measured and used alongside with solubility data to obtain more realistic parameters of thermodynamic model. Perturbed Chain-Statistical Associating Fluid Theory (PC-SAFT) Equation of State (EoS) is used. It was able to successfully represent the solubility curves using a small amount of data for fitting the model parameters. In a second part, the applicability of the model to predict the solubility in various organic solvents of two other pharmaceutically relevant molecules, namely the anti-inflammatory drug ketoprofen and the antimalarial compound artemisinin has been studied.

The results showed that guaifenesin is the most soluble in ethanol and least soluble in ethyl acetate. Its aqueous solubility shows a special behavior with a specific sharp increase with temperature. In all of the solvents, ketoprofen is the highest soluble among the compounds studied followed by guaifenesin and artemisinin. PC-SAFT is able to capture the experimentally observed effects of temperature, and solvent type on the solubility behavior of each of the three solutes.

溶解度是发现新药物分子以及使用结晶过程生产它们的基本参数。在这项工作中，我们通过实验研究了抗咳嗽药物愈创甘油醚在不同溶剂中的溶解度和密度，并通过粉末 X 射线衍射 (PXRD) 和热分析表征了其固态。此外，开发并成功应用了一种策略来预测该药物的密度和溶解度行为。在溶解度曲线上，对于固定压力下的二元溶液，浓度和温度相互依赖。因此，测量愈创甘油醚不饱和水溶液的密度并与溶解度数据一起使用，以获得更真实的热力学模型参数。使用扰动链统计关联流体理论 (PC-SAFT) 状态方程 (EoS)。它能够使用少量数据成功地表示溶解度曲线以拟合模型参数。在第二部分中，研究了该模型在预测其他两种药学相关分子（即抗炎药酮洛芬和抗疟化合物青蒿素）在各种有机溶剂中的溶解度方面的适用性。

结果表明愈创甘油醚在乙醇中的溶解度最大，在乙酸乙酯中的溶解度最低。它的水溶性表现出一种特殊的行为，随着温度的升高而急剧增加。在所有溶剂中，酮洛芬在所研究的化合物中溶解度最高，其次是愈创甘油醚和青蒿素。PC-SAFT 能够捕捉实验观察到的温度和溶剂类型对三种溶质中每一种的溶解度行为的影响。