The interaction between a medical device and a pharmaceutical solution it contacts may dictate solution safety and/or efficacy. Of specific concern is the ability of device components to leach into the contacting solution. As pharmaceutical solutions containing surfactants, co-solvents and solubilizing agents become more common, method's for assessing the extent of leaching are needed. In this manuscript, a model is developed which relates a solution's polarity to its ability to interact with a plastic material. The validity of the developed model is examined via direct analysis of several pharmaceutically relevant solutions.