• J Boogaerts, N Lafont, M Donnay, H Luo, and F J Legros.
• Laboratory of Physiopathology, Free University of Brussels.
• Acta Anaesthesiol Belg. 1995 Jan 1;46(1):19-24.

AbstractBupivacaine has been encapsulated into multilameller liposomes in order to reduce its systemic toxicity and to lengthen its action. Low, constant and sustained plasma levels have been observed after epidural injection and brachial plexus administration to rabbits. The present experiment was performed in order to study the motor block effect and the possible neurotoxicity of bupivacaine encapsulated in multilamellar liposomes applied in vivo to intact peripheral nerve bundles. Five milliliters of sterile solutions containing 0.75% bupivacaine encapsulated in 42.5 and 85 mg of lipids (phosphatidylcholine and cholesterol in a molar ratio 4:3) were administered to 4 rabbits at the level of the brachial plexus. A motor blockade of the forelimb lasting for 10 hours was measured immediately after injection of the liposomal drug. Light microscopic analyses of the nerves after 2 and 7 days revealed weak inflammatory perineural infiltration. Electron microscopy showed no changes of the myelin sheaths and no alteration of unmyelinated fibers. It may be concluded that the pharmacologically active liposomal formulation of bupivacaine did not induce alterations of the nerve tissues.

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