Session: 05-06-01 Biomedical Devices I

Paper Number: 66422

Start Time: Friday, 11:25 AM

66422 - Effects of Nozzle Diameter and Injection Volume of Drug on Performance of a Needle-Free Injector 

Among the techniques of subcutaneous drug delivery, the needle-free injection is relatively new. Compared to the hypodermic syringe, the needle-free injector has several advantages such as convenient usage and simple operation. Furthermore, the needle-free injection avoids accidental stabbing and cross-infection. A typical needle-free injection system is mainly composed of an injection chamber, a nozzle and a pressure source. The injection chamber accommodates the drug to be injected via the nozzle. The pressure source assumes the function of providing energy for the drug. Release of compressed gas can impose a transient force on a piston, which then propels the drug towards the nozzle outlet. Consequently, a high-velocity tiny liquid jet is issued from the nozzle and the stagnation pressure as the jet arrives at the skin is high enough to puncture the skin. Then the drug is rapidly delivered into the resultant hole and diffuses in the tissue. Although the needle-free injection technique has been exercised, the knowledge about the mechanism of the drug flow is insufficient. Particularly, instantaneous behaviors of the drug during the injection process have not been clarified.

The present study aims to reveal drug flow characteristics of the needle-free injection. The effects of major operational parameters were investigated as well. An experimental work incorporating the measurement of instantaneous stagnation pressure and the visualization of drug diffusion beneath the skin was conducted. High-sensitivity pressure transducers and a high-speed camera were used. Pure water serves as the liquid medium. Regarding the visualization of liquid diffusion, a specifically prepared gel was used to mimic the tissue. The nozzle diameters of 0.14 mm, 0.25 mm and 0.32 mm were selected. The volumes of injection range from 0.1 ml to 0.3 ml. The results show that the needle-free injection process is characterized by time-varying stagnation pressure. The peak stagnation pressure at the initial stage of injection is an important indicator of the aggressivity of the drug. The peak stagnation pressure decreases linearly with the increase of the nozzle diameter or the volume of injection. Nonetheless, the time required to reach the peak stagnation pressure varies insignificantly with the jet pressure and the nozzle diameter. It is evidenced that the increase in the volume of injection causes an enlargement of the diffusion area of ​​the liquid in the gel, which implies that the drug absorption rate is improved accordingly. Furthermore, with large nozzle diameter, the power consumption is high. Therefore, the maximum penetration depth of the liquid in the gel increases with the nozzle diameter. However, the attainable lateral distance of the liquid is nearly insensitive to the nozzle diameter. It is noteworthy that an oversized nozzle could result in severe bleeding and skin damage during the needle-free injection process.

Presenting Author: Can Kang Jiangsu University

Authors:

Yang Zhu Jiangsu University
Can Kang Jiangsu University
Chunli Zhang Jiangsu Poke Medical Technology Co., Ltd.
Haifei Li Jiangsu Poke Medical Technology Co., Ltd