Objective: Autoinjectors are a convenient and efficient way to self-administer subcutaneous injections of biopharmaceuticals. Differences in device mechanical design can affect the autoinjector functionality and performance. This study investigates the performance differences of two single-spring-actuated autoinjectors. Methods: We compare the performance between Emgality (120 mg/mL) and Aimovig (140 mg/mL) autoinjector devices from an engineering point of view at two test conditions: room (25 C $°$) and storage (5 C $°$) temperatures. We employ a novel experimental procedure to simultaneously acquire the force and acoustic signals during operation, and high-speed imaging during the needle insertion and drug injection. Results: We perform 18 quantitative comparisons between Emgality and Aimovig, and we observe that 14 of these have statistically significant differences. For both test conditions, Emgality requires an 8 N activation force while Aimovig requires 14 N activation force, and the needle of Emgality has an insertion depth of 5 mm while Aimovig has an insertion depth of 7 mm. The injection speeds are significantly affected by temperature. Emgality has an injection speed of 0.40 mL/s and 0.28 mL/s at room and storage temperature condition, respectively; while Aimovig has an injection speed of 0.24 mL/s and 0.16 mL/s at those conditions. Lastly, confirmation “click” sound of Emgality occurs 0.75–1.53 s after dose completion, while in Aimovig, the confirmation “click” sound occurs 0.26-0.46 s before dose completion. Conclusions: This study revealed performance differences between Emgality and Aimovig autoinjector devices, despite the fact that the delivery principle of these single-spring-actuated autoinjectors are the same. These differences may result in different risk of intramuscular injection and premature device removal, both of which need to be further verified in clinical trials.

A detailed numerical investigation of the flow behind a square cylinder at a Reynolds number of 21,400 is conducted to assess the ability of the delayed detached-eddy simulation (DDES) modeling approach to accurately predict the velocity recovery in the wake of a bluff body. Three-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) and DDES simulations making use of the Spalart–Allmaras turbulence model are carried out using the open-source computational fluid dynamics (CFD) toolbox OpenFOAM-2.1.x, and are compared with available experimental velocity measurements. It is found that the DDES simulation tends to overestimate the averaged streamwise velocity component, especially in the near wake, but a better agreement with the experimental data is observed further downstream of the body. The velocity fluctuations also match reasonably well with the experimental data. Moreover, it is found that the spanwise domain length has a significant impact on the flow, especially regarding the fluctuations of the drag coefficient. Nonetheless, for both the averaged and fluctuating velocity components, the DDES approach is shown to be superior to the URANS approach. Therefore, for engineering purposes, it is found that the DDES approach is a suitable choice to simulate and characterize the velocity recovery in a wake.