• K. Navaneetha
• SK. Sushma Taj
• M. Deepika
• K. Jahnavi
• B. Jeshma Kalyani

This comprehensive review explores the evolution, mechanisms and applications of needle-free injection technology in drug delivery. Beginning with a historical overview, tracing back to 1853 invention of the syringe, it progresses to the present, encompassing various needle-free devices such as skin patches, inhalers and power sprays. The intricate structure of human skin is discussed, emphasizing the importance of understanding its layers for effective drug delivery. The classification of needle-free injection technology is presented based on working principles, type of load, mechanism of drug delivery, and site of delivery. Various technologies, including spring systems, laser-powered devices, energy-propelled systems and shockwaves, are analyzed in detail. The article delves into the challenges associated with gas-propelled systems, emphasizing the need for pressure regulation and innovative solutions. The mechanisms of liquid, powder and projectile/depot delivery methods are elucidated, providing insight into their applications and limitations. Further exploration covers nano-patches, sandpaper-assisted delivery, iontophoresis, and micro-needles, each offering distinct advantages in drug delivery. The review details the working stages of needle-free drug delivery, highlighting the phases of peak pressure, delivery, and drop-off. Components of the injection device, including the injection device, nozzle and pressure source, are dissected, offering a comprehensive understanding of the technology. Examining specific needle-free injection devices such as Serojet, Iject, Injex, and Bioject® Zetajet, the review concludes with a discussion on the advantages and disadvantages of needle-free injection technology. The potential benefits, including painless injections, enhanced patient adherence, and reduced risk of contamination, are weighed against challenges like needle phobia and potential overdose risks, providing a balanced overview of this innovative drug delivery approach.

Needle-free drug delivery, Jet injection, Micro-needle patches, Iontophoresis, Gas-powered injection, Spring-loaded injector

"NEEDLE-FREE INJECTIONS: A GENTLE APPROACH TO HEALTHCARE", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.11, Issue 2, page no.d674-d688, February-2024, Available :http://www.jetir.org/papers/JETIR2402380.pdf

"NEEDLE-FREE INJECTIONS: A GENTLE APPROACH TO HEALTHCARE", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.11, Issue 2, page no. ppd674-d688, February-2024, Available at : http://www.jetir.org/papers/JETIR2402380.pdf