Shake-Flask Aqueous Solubility assay (Kinetic solubility) v1

Determining compound solubility is an essential tool for the early stages of the drug discovery process, as well as for lead optimization. Low solubility can lead to unpredictable and unreliable results during in vitro testing, thereby increasing the development costs. Solubility issues at the later stages of the drug discovery may lead to poor bioavailability, underestimated toxicity, and other obstacles, lowering the chances of a given drug candidate for success. Typically, for early-stage drug discovery, the kinetic solubility method is used, as it is fast and well-suited for the HTS format. In this case, solid compounds are first dissolved in DMSO, and then linear serial dilutions of each compound are added to an aqueous buffer and observed for precipitate formation when the compound is not completely soluble. For better precision, the solution can be subjected to high-speed centrifugation or filtration using special solubility filter plates and then the compound concentration is measured in the saturated solution directly by UV or LC-MS/MS using separately built calibration curves. Measurements were performed by the shake-flask method with UV-Vis or LC-MS/MS detection.