Dissolving Microneedles for Rapid and Painless Local Anesthesia

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Nanotechnology

Background:

• Microneedles offer a promising alternative to traditional injections for drug delivery.
• Lidocaine is a widely used local anesthetic, but conventional delivery methods can be painful.
• Developing painless and effective local anesthesia delivery is crucial for patient comfort and compliance.

Purpose of the Study:

• To evaluate the efficacy and safety of dissolving microneedles loaded with lidocaine (Li-DMN) for local anesthesia.
• To assess the physical properties, biocompatibility, and anesthetic performance of the Li-DMN patch.
• To confirm the potential of carboxymethyl cellulose-based microneedles for painless transdermal drug delivery.

Main Methods:

• Fabrication of Li-DMN patches using centrifugal lithography with carboxymethyl cellulose.
• Assessment of physical properties (rigidity, fracture force) and lidocaine-HCl capacity.
• In vitro evaluation of cytotoxicity on neuronal cells and electrophysiological recordings.
• In vivo assessment of biocompatibility (histology, edema test) and anesthetic efficacy (von Frey test) in rats.

Main Results:

• The Li-DMN patches exhibited sufficient rigidity for skin penetration.
• The maximum lidocaine-HCl load was 331.20 ± 6.30 µg per patch.
• Negligible cytotoxicity and minimal skin irritation were observed in vitro and in vivo.
• Electrophysiological studies confirmed lidocaine's effect on sodium channels, and rats showed immediate reduction in pain behavior.

Conclusions:

• Dissolving microneedles fabricated with carboxymethyl cellulose are a viable platform for lidocaine delivery.
• The Li-DMN patch provides effective and painless local anesthesia with excellent biocompatibility.
• This technology represents a significant advancement in transdermal drug delivery for pain management.