Rapid solubility determination using vapor-phase osmometry

Because of the need for resource-sparing assays of the solubility of new dr ug candidates, we sought to develop and validate a rapid method for determi ning the solubility of nonvolatile: pharmaceutical solids in water. Vapor-p hase osmometry was used to determine the concentration of drugs in saturate d solutions prepared by a rapid ultrasound-mediated dissolution protocol. T he osmolality of saturated solutions as measured by the vapor-phase osmomet er is an excellent predictor of the solubility of pharmaceutical solids in water. Each osmolality measurement requires less than 10 mu l of saturated solution and takes less than 2 minto complete. For small-molecule drugs wit h solubilities greater than 10 g/kg, osmometry may prove to be a rapid and accurate method for determining the water solubilities of drugs.