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Prolongation of Epidural Analgesia Using Solid Lipid Nanoparticles as Drug Carrier for Lidocaine
  1. Fujian Leng, MD*,,,
  2. Jiangling Wan, PhD*,,
  3. Wei Liu, PhD*,,
  4. Bo Tao, MS*, and
  5. Xuehong Chen, MS*,
  1. From the *National Engineering Research Center for Nanomedicine and
  2. College of Life Science and Technology, Huazhong University of Science and Technology; and
  3. Department of Anesthesiology, Hubei Women and Children’s Hospital, Wuhan, China.
  1. Address correspondence to: Wei Liu, PhD, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Rd, Wuhan 430074, China (e-mail: wliu{at}


Background and Objectives Solid lipid nanoparticles (SLNs), as a drug carrier, are a very attractive strategy for sustained and controlled drug release. In this study, we investigated the feasibility of SLNs to prolong the action of lidocaine for potential application in epidural anesthesia and analgesia.

Methods Lidocaine-loaded SLNs were prepared with different lipids, including monostearin (MS), glyceryl palmitostearate (GP), and stearic acid (SA). The morphology and crystallinity were characterized with transmission electron microscopy and powder x-ray diffraction. In vitro release studies were carried in phosphate buffer solution of pH 7.4 using cellulose dialysis membrane. The in vivo efficacy of epidural anesthesia was evaluated in rats.

Results Lidocaine was successfully incorporated in SLNs prepared with MS, GP, and SA, respectively. The particle sizes of lidocaine-loaded SLNs were 143 to 388 nm with polydispersity index of 0.29 to 0.45. Powder x-ray diffraction analysis showed that lidocaine was mainly dispersed in SLNs in an amorphous state. The in vitro release within 48 hrs showed that lidocaine released from SLNs was 80% with MS SLNs, 69% with GP SLNs, and 89% with SA SLNs. The epidural efficacy was compared with that of aqueous lidocaine HCl. Single injection of lidocaine SLN suspension produced epidural block for more than 8 hrs with MS SLNs, 12 hrs with GP SLNs, and 4 hrs with SA SLNs. ]The same dose of lidocaine in aqueous solution lasted for less than 2 hrs.

Conclusions Solid lipid nanoparticles can be exploited as a promising drug carrier for extending the action of lidocaine.

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  • This work was supported by National Basic Research Program of China (2011CB933103, 2007CB935800) and Natural Science Foundation of China (31170960). All the funds were to Professor Wei Liu.

  • The authors declare no conflict of interest.