Several computational approaches have been applied in order to study the interactions between Active Pharmaceutical Ingredients and the surrounding solvents. Most of them are using Molecular Dynamics simulations and GROMACS software. Even though some significant results have been observed by several groups of researches, there is currently no universal protocol for solubility predictions of API's in various solvents. In this project we are aiming to study the interactions of few API molecules (felodipine, fenofibrate, danazol) with solvents consisting of water, taurocholate and phospholipids molecules at different ratios. We will study the formation of micelles and the impact of their presence and structure on the free energy difference while inserting/deleting the API molecule into/from the simulation box. This is a starting point for a bigger project, where a number of techniques will be applied to a prediction of solubilities in a multidimensional parametric field.