The design of injection devices, including prefilled syringes (PFSs) and autoinjectors, requires an understanding of the optimization of injection conditions. The injection of highly concentrated biopharmaceuticals can lead to exceptionally high injection forces, due to their high viscosity. To overcome this challenge, a tapered needle has been recently developed by Terumo Corporation. In the present study, we measured the injection forces in PFSs equipped with 24G-29G tapered needle (29G TNN), 27G thin-wall needle (27G TW), and 29G TW using several model and pharmaceutical protein solutions. The injection forces measured in the 29G TNN PFSs were lower than those in 29G TW for all solutions, similar to those in 27G TW PFSs for Newtonian solutions, and were lower than those in the 27G TW PFSs for non-Newtonian solutions which demonstrated shear-thinning behavior. No significant changes in aggregates or micron-size particle concentrations were observed upon injection, regardless of the needle type. Mathematical modeling supported the experimental findings that under similar flow rate conditions injection pressure in a tapered needle is lower than that in a cylindrical needle. Our results indicate that there are advantages of using tapered needles for the injection of biopharmaceutical formulations particularly those showing shear-thinning behavior.
Krayukhina E, et al. J Pharm Sci 2020;109;1:515-523.