Characterization of needle-assisted jet injections

Area of Science:

• Biomedical Engineering
• Drug Delivery Systems
• Medical Device Technology

Background:

• Traditional hypodermic injections face challenges with patient compliance due to pain and needle-stick injury risks.
• Needle-free jet injections (NFJI) aim to overcome these issues but suffer from limited control over dose and depth, and require high pressures (>20MPa).
• Variability in skin properties further complicates NFJI reliability and necessitates bulky, expensive devices.

Purpose of the Study:

• To characterize needle-assisted jet injections (NAJI) using a short needle (<5mm) for improved transcutaneous drug delivery.
• To evaluate the effect of needle gauge size on jet parameters and injection performance.
• To assess the feasibility of NAJI for reliable, low-pressure drug delivery into subcutaneous tissue.

Main Methods:

• A voice-coil actuated jet injector was modified with 30G, 31G, and 32G needles.
• Pulse tests were conducted to measure jet velocity and injection volume for each needle size.
• Injection studies were performed in porcine skin to evaluate penetration depth and injectate volume at reduced pressures (0.8–1.4MPa).

Main Results:

• Jet velocity and volume were slightly reduced with smaller gauge needles (32G vs. 30G), but 30G and 31G showed minimal differences.
• NAJI achieved substantial injectate penetration (~10mm) and delivery (~100μL) into porcine subcutaneous fat within 40ms.
• The required injection pressures were an order of magnitude lower than NFJI, achieving a delivery rate of 2.25mL/s.

Conclusions:

• Needle-assisted jet injections offer a promising alternative for transcutaneous drug delivery, enhancing reliability and control.
• The reduced pressure requirements of NAJI enable smaller, more cost-effective devices and minimize shear stress on sensitive biologics.
• NAJI technology has the potential to improve patient compliance and expand therapeutic options for various injectable drugs and vaccines.