Adequate aqueous solubility of new chemical entities (NCEs) is one of the key properties required for successful pharmaceutical formulation development. Solubility is generally defi ned as the concentration of the compound in a solution which is in contact with an excess amount of the solid compound when the concentration and the solid form do not change over time (Sugano et al. 2007 ) . Solubility is closely related to dissolution which is a kinetic process that involves the detachment of drug molecules from the solid surface and subsequent diffusion across the diffusion layer surrounding the solid surface. The relationship of solubility and dissolution rate is described by the.
