A high-dosage microneedle for programmable lidocaine delivery and enhanced local long-lasting analgesia

Considering the staggering global prevalence of local pain affecting hundreds of million individuals, it is of great sig-nificance to develop advanced dosage forms or delivery systems for analgesic therapy to fulfill clinical applicability. In this study, a hydrogel microneedles (MNs) system made out of gelatin-methacryloyl (GelMA) was designed to deliver lidocaine hydrochloride (LiH) ina sustained manner, and the drug loading capacity of the GelMA MNs was increased considerably by using the backing layer reservoir. The in vitro and in vivo tests showed that the fabricated GelMA MNs are strong enough for reliable skin application, and achieve high drug delivery efficiency as compared with the com-mercial lidocaine patches. The Spared-nerve injury (SNI) model of rats was also prepared to test behavioral pain sen-sitivity in response to mechanical stimuli, which proved that the LiH/GelMA MNs can enhance and prolong the anesthetic effect of LiH. In addition, with biosafety evaluation in rats, the MNs treated site restored to normal appear-ance within several hours of application and no dermatosis-related side effects or behavior disorders were observed during the experiment. Together these results indicated that the use of GelMA MNs for transdermal delivery of LiH is an effective, safe and simple treatment method to provide a better choice for local long-lasting analgesia.

Automated summary

Considering the global prevalence of local pain, this study developed a GelMA MNs system for sustained delivery of lidocaine hydrochloride. Results showed that the system was reliable and efficient, enhancing and prolonging the anesthetic effect in a rat model. Biosafety evaluation confirmed the absence of side effects.