Development of solubility screening methods in drug discovery

We developed two methods for solubility screening of drug candidates in drug discovery. The first is a solution-precipitation (SP) method, in which the sample solutions are prepared by adding the drug solution in dimethylsulfoxide (DMSO) to buffers followed by filtering off the precipitate using 96-well filterplate. The second is a powder-dissolution (PD) method, in which the solid samples are dissolved to the buffer in the HPLC vial equipped with the filter membrane in the HPLC autosampler. An HPLC equipped with a photodiode array detector is used to measure the concentration of the sample solutions in both methods. The SP method was used for high throughput screening the solvating process of the candidates in aqueous solutions with lower sample consumption, and the PD method was used for screening both inter-molecular interaction in solid state and solvation in aqueous solution with more sample amount than that of SP method. Therefore, the solubility screening from early to final stage of lead optimization process would be successfully accomplished by using both methods complementarily.