A semi-interpenetrating network-based microneedle for rapid local anesthesia

Abstract

To improve the mechanical strength of a polyvinylpyrrolidone (PVP K29/32)-derived dissolvable microneedle, a semi-interpenetrating network is developed using covalently crosslinked methacrylated chondroitin sulfate (CS-MA) in combination with PVP K29/32, which is used to successfully load lidocaine hydrochloride (LIDH) and applied as a microneedle patch for rapid local anesthesia. Specifically, CS-MA when mixed with soluble PVP and photo initiators afforded a covalently cross-linked three-dimensional network (CS-MA/PVP MN) after irradiation at 405 nm for 1 min. CS-MA/PVP MNs demonstrated greatly enhanced mechanical strength and reduced moisture absorption rate as compared to PVP MN. The content of LIDH in each microneedle array was determined as 802.8 ± 22.8 μg. The obtained CS-MA/PVP MNs displayed sharp needle edges with a uniform appearance under scanning electron microscope. Penetration studies showed that the prepared microneedles were able to penetrate the skin of experimental animals causing minimum irritation. The biosafety study showed that the trauma to the skin was almost negligible after the application of microneedles. Furthermore, preliminary pharmacodynamic studies in guinea pigs revealed the prepared microneedles achieved a rapid onset of action (<1 min) compared to the commercially available lidocaine cream (about 1 h). Overall, LIDH-loaded semi-interpenetrating network-based microneedles serve as a promising transdermal delivery platform for achieving rapid and efficient local anesthesia.