Fabrication of lidocaine-loaded polymer dissolving microneedles for rapid and prolonged local anesthesia

Abstract There is an urgent need for research on effective interventions for pain management to improve their life quality. Traditional needle and syringe injection were used to administer the local anesthesia. However, it causes various discomforts, ranging from brief stings to trypanophobia and denial of medical operations. In this study, a dissolving microneedles (MNs) system made of composite matrix materials of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and sodium hyaluronate (HA) was successfully developed for the loading of lidocaine hydrochloride (LidH). The morphology, size and mechanical properties of the MNs were also investigated. After the insertion of MNs into the skin, the matrix at the tip of the MNs was rapidly dissolved, releasing the loaded LidH to diffuse into deeper skin tissue through microchannels formed by MNs insertion. The back patching of MNs could be acted as a drug reservoir to form a prolonged local anesthesia effect due to the swelling and dissolving of MNs by absorption of interstitial fluid. The results showed that LidH MNs provided a superior analgesia up to 8 h, exhibiting a rapid and long-lasting analgesic effects. Additionally, tissue sectioning and in vitro cytotoxicity tests indicated that the MNs patch we developed had a favorable biosafety profile.