Towards the understanding of complex fluids in pharmaceutical sciences

Macromolecular substances are included in most pharmaceutical dosage forms. Their physicochemical properties are important for the performance of the end product, and thus rheological behavior becomes a critical quality attribute. Rheology is a well-known method in the food industry and the characterization of various drug delivery systems by the utilization of rheology could also be beneficial. Additionally, the complexity of the body fluids that the dosage forms come in contact with, e.g. the physicochemical properties like rheological parameters, will affect the therapeutic outcome. This review provides a brief introduction to rheology as a characterization tool and gives examples of the utilization of rheology within the characterization of biological fluids, solid dosage forms and protein formulations. In all those examples rheology has shown to give additional useful information on the conditions experienced by the active pharmaceutical ingredient.