Lidocaine-loaded dissolving microneedle for safe local anesthesia on oral mucosa for dental procedure.

BACKGROUND: Lidocaine has been widely used as a short-acting local anesthetic agent to reduce the pain caused by needle insertion. Dissolving microneedles (DMNs), which are minimally invasive, can effectively deliver drugs by overcoming the oral mucosal barrier and relieving patient discomfort. METHODS: Lidocaine solution prepared by mixing lidocaine-HCl and hyaluronic acid was used to fabricate oral lidocaine HCl-encapsulated DMNs (oral Li-DMNs) via centrifugal lithography. The dissolution, penetration ability, and local transmucosal drug delivery of oral Li-DMNs into the oral mucosa were evaluated in porcine jaws. Pharmacokinetic analysis and safety assessment were performed using rabbits. RESULTS: The insertion depth of the oral Li-DMNs satisfies the safety standard. The oral Li-DMNs were completely dissolved after 3 min of application. The local transmucosal drug delivery, pharmacokinetic, and safety evaluations showed that the oral Li-DMNs can obtain a local anesthesia effect at a relatively lower dose, and there was no oral mucosal irritation in rabbits. CONCLUSIONS: A novel and safe oral Li-DMNs have potential applications in large animals and clinical trials and would possibly enter the anesthesia market.

Enhanced Micro-Channeling System via Dissolving Microneedle to Improve Transdermal Serum Delivery for Various Clinical Skincare Treatments.

Topical liquid formulations, dissolving microneedles (DMNs), and microscale needles composed of biodegradable materials have been widely used for the transdermal delivery of active compounds for skincare. However, transdermal active compound delivery by topical liquid formulation application is inhibited by skin barriers, and the skincare efficacy of DMNs is restricted by the low encapsulation capacity and incomplete insertion. In this study, topical serum application via a dissolvable micro-channeling system (DMCS) was used to enhance serum delivery through micro-channels embedded with DMNs. Transdermal serum delivery was evaluated after the topical-serum-only application and combinatorial serum application by assessing the intensity of allophycocyanin (APC) loaded with the serum in the porcine skin. APC intensity was significantly higher in the skin layer at a depth of 120-270 µm upon combinatorial serum application as compared to topical-serum-only application. In addition, the combinatorial serum application showed significantly improved efficacy in the clinical assessment of skin hydration, depigmentation, improvement of wrinkles, elasticity, dermal density, skin pores, and skin soothing without any safety issues compared to the serum-only application. The results indicate that combinatorial serum application with DMCS is a promising candidate for improving skincare treatments with optimal transdermal delivery of active compounds.

Development of Lidocaine-Loaded Dissolving Microneedle for Rapid and Efficient Local Anesthesia.

Lidocaine is a local anesthetic agent used in the form of injection and topical cream. However, these formulation types have limitations of being either painful or slow-acting, thereby hindering effective and complete clinical performance of lidocaine. Dissolving microneedles (DMNs) are used to overcome these limitations owing to their fast onset time and minimally invasive administration methods. Using hyaluronic acid and lidocaine to produce the drug solution, a lidocaine HCl encapsulated DMN (Li-DMN) was fabricated by centrifugal lithography. The drug delivery rate and local anesthetic quality of Li-DMNs were evaluated using the pig cadaver insertion test and Von Frey behavior test. Results showed that Li-DMNs could deliver sufficient lidocaine for anesthesia that is required to be utilized for clinical level. Results from the von Frey test showed that the anesthetic effect of Li-DMNs was observed within 10 min after administration, thus confirming fast onset time. A toxicity test for appropriate clinical application standard was conducted with a microbial limit test and an animal skin irritation test, showing absence of skin irritation and irritation-related microorganisms. Overall, Li-DMN is a possible alternative drug delivery method for local anesthesia, meeting the requirements for clinical conditions and overcoming the drawbacks of other conventional lidocaine administration methods.