Viscosity is an important fluid property that can be used to predict performance in real world applications. One of the most common uses of viscosity is to assess the ability to deliver pharmaceutical formulations to the patient by injection. A significant component of formulation research and development is rheology modification to ensure that therapeutics can be delivered without an excessive injection force. This concern is especially important when developing high concentration antibody formulations, which can have a broad range of viscosities depending on the specific protein-protein interactions. To tackle the problem of relating viscosity to injection force, we turn to fluid mechanics for pressure driven flow through a circular cross section.
This application note lays the theoretical foundation for future tutorials on experimental design and data analysis. In this application note we cover general syringe geometry and the equations required to calculate injection force of Newtonian, power-law, and general non-Newtonian fluids.