Hyaluronic acid modified nanostructured lipid carriers for transdermal bupivacaine delivery: In vitro and in vivo anesthesia evaluation

For effective transdermal local anesthetic therapy, to reduce the barrier of stratum corneum and improve the antinociceptive effect, hyaluronic acid (HA) modified, bupivacaine (BPV) loaded nanostructured lipid carriers (NLCs) were designed. HA and linoleic acid (LOA) conjugated propylene glycol (PEG) was synthesized (HA-PEG-LOA). HA-PEG-LOA was added during the preparation process of NLCs, thus LOA was inserted into the NLCs, The physicochemical properties of NLCs, particle size, zeta potential, drug loading capacity, in vitro skin permeation, drug release profiles and in vivo therapeutic effect were evaluated. HA-BPV/NLCs have small particle size of 150 nm, with a zeta potential of - 40 mV. Nearly 90% high drug encapsulation efficiency and good stability were also observed. In vitro release rate of BPV from HA-BPV/NLCs was complying with a sustained behavior until 72 h of study. HA-BPV/NLCs and BPV/NLCs exhibited 2.5 and 1.6 fold of percutaneous penetration improvement than free BPV. BPV loaded NLCs produced a more prolonged antinociceptive effect when compared with free BPV. In vitro and in vivo results pointed out HA modified NLCs have the capability to act as effective drug carriers, thus prolonging and enhancing the anesthetic effect of BPV. The NLCs developed in this study might provide a useful platform for developing a sophisticated dermal delivery system for analgesic.