Use of the solubility parameter and surface energy concepts in the formulation of solid dosage forms

This review presents some theoretical notions on both the solubility parame ter and surface energy concepts, including the different models and the pow er laws relating them as well as the methods of determination (experimental calculation). Subsequently, we describe the parameters derived from solubi lity parameters and surface energies (interfacial tension, spreading coeffi cient, interaction parameter, strength of interaction). The theoretical pot ential of these parameters is outlined along with practical uses published in the literature. The applications include all the major steps involved in the preparation of solid dosage forms, such as prediction of the organizat ion of powder mixes during blending, estimation of binder efficiency in gra nulation, modification of the powder surface energy to change the tensile s trength of tablets, and optimization of the interaction of plasticizers wit h coating polymers. Finally, a general approach taking particle size into a ccount is proposed, and the consequences for blending (organization, colour and taste) and compactibility are outlined.