Purpose: The skin permeation enhancement of local anesthetics by newer innovative nanotechnologies has been an appealing field recently. However, which nanocarrier is better for drug loading and has better stability? Therefore, the aim of our study was to compare two kinds of nanocarriers: liposomes and lipid-polymer hybrid nanoparticles (LPNs) for lidocaine (LA) delivery. Methods: LA-loaded liposomes (LA-LPs) and LPNs (LA-LPNs) were prepared. Two kinds of nanocarriers were characterized in terms of particle size, zeta potential, drug encapsulation efficiency (EE), drug release, and stability. Their in vitro skin permeation was studied using a Franz diffusion cell mounted with depilated mouse skin in vitro. In vivo local anesthetic effects of LA containing formulations were evaluated by tail flick latency (TFL) test using a tail-flick measuring device. Results: Compared with LA-LPs, LA-LPNs showed significantly better in vitro skin permeation ability and in vivo local anesthetic effects. Conclusion:The results demonstrated that LPNs could improve the efficacy of drugs to higher levels than LPs and free drugs, thus could serve as an effective drug system for LA loading for local anesthetic therapy.

Context: Transdermal local anesthesia is one of the most applied strategies to avoid systemic adverse effects; there is an appealing need for a prolonged local anesthetic that would provide better bioavailability and longer pain relief with a single administration. Objective: Layer-by-layer (LBL) technique was used in this study to explore a nanosized drug delivery system for local anesthetic therapy. Materials and methods: LBL-coated lidocaine-loaded nanostructured lipid nanoparticles (LBL-LA/ NLCs) were prepared and characterized in terms of particle size (PS), zeta potential, drug encapsulation efficiency (EE), in vitro skin permeation and in vivo local anesthetic studies. Results: Evaluation of the in vitro skin permeation and in vivo anesthesia effect illustrated that LBL-LA/NLCs can enhance and prolong the anesthetic effect of LA. Discussion and conclusion: LBL-LA/NLCs could function as a promising drug delivery strategy for overcoming the barrier function of the skin and could deliver anesthetic through the skin with sustained release behavior for local anesthetic therapy.