A Novel Controllable Pneumatic Needle-Free Injection System for Larger-Volume Drug Delivery.

Hypodermic needles and syringes are currently the main route of the transdermal administration. Many complaints associated with needle-stick injuries, needle phobia, and needle abuse have motivated the development of alternative drug delivery strategies. Pneumatic needle-free injections stand out from various alternative strategies because of the convenience in adjusting the driving pressure and the injection volume. This study proposed a novel control method of the pneumatic needle-free injection for delivering larger volume drugs to the target sites at desired rates and time by controlling the driving pressure. The dynamic characteristics of this injection mode were evaluated in the impact experiments and the results confirmed the reliability of this controllable system in controlling the outlet pressure and jet velocity. The injection performances of it were compared with that of other injection modes through in vivo and in vitro experiments. This controllable system was able to control the injection depth and it was more conducive to the lateral diffusion of the liquid jets in gelatin. Moreover, it could not only enlarge the diffusion of diclofenac solution in rats, but also accelerate the metabolism of diclofenac solution in rats. All experimental results confirmed the reliability of this controllable injection system.