The project was to develop and evaluate biorelevant in vitro methods and to use computer simulations to predict the oral performance of different commercial products based on in vitro data.Glyburide was chosen as a model drug.Computer simulations using GastroPlusTM based on the Advanced Compartmental and Transit model (ACAT) were used to assess if in vitro/in vivo correlations (IVIVCs) can be established.Material characterization indicated that all five glyburide Active Pharmaceutical Ingredients (APIs) had similar crystal structures,however,significant differences in surface area,particle size and distribution were observed.Solubility studies demonstrated that the solubility of glyburide was low and pH-dependent.Dissolution tests of the glyburide products were performed in Fasted State Simulated Intestinal Fluid (FaSSIF) using conventional and dynamic pH change protocols.A permeability study using the Caco-2 model showed that glyburide is a highly permeable drug.Computer simulations using the physicochemical data were able to predict the oral absorption of four glyburide products.An IVIVC was established.