Local anesthetic effects of bupivacaine loaded lipid-polymer hybrid nanoparticles: In vitro and in vivo evaluation

PurposeThere is a compelling need for prolonged local anesthetic that would be used for analgesia with a single administration. However, due to the low molecular weight of local anesthetics (LA) (lidocaine, bupivacaine, procaine, dibucaine, etc), they present fast systemic absorption.MethodsThe aim of the present study was to develop and evaluate bupivacaine lipid-polymer hybrid nanoparticles (BVC LPNs), and compared with BVC loaded PLGA nanoparticles (BVC NPs). Their morphology, particle size, zeta potential and drug loading capacity were evaluated. In vitro release study, stability and cytotoxicity were studied. In vivo evaluation of anesthetic effects was performed on animal models.ResultsA facile nanoprecipitation and self-assembly method was optimized to obtain BVC LPNs, composed of PLGA, lecithin and DSPE-PEG2000, of ∼175 nm particle size. Compared to BVC NPs, BVC LPNs exhibited prolonged in vitro release in phosphate-buffered saline (pH = 7.4). Further, BVC LPNs displayed enhanced in vitro stability in 10% FBS and lower cytotoxicity (the concentration of BVC ranging from 1.0 μM to 20 μM). In addition, BVC LPNs exhibited significantly prolonged analgesic duration.ConclusionThese results demonstrate that the LPNs could function as promising drug delivery system for overcoming the drawbacks of poor stability and rapid drug leakage, and prolonging the anesthetic effect with slight toxicity.