Biodistribution of liposome-associated bupivacaine after extradural administration to rabbits

• Published in: British journal of anaesthesia : BJA Vol. 75; no. 3; p. 319
• Main Authors: Boogaerts, J G, Lafont, N D, Carlino, S, Noel, E, Raynal, P, Goffinet, G, Legros, F J
• Format: Journal Article
• Language: English
• Published: England 01-09-1995
• Subjects: Anesthetics, Local - administration & dosage; Anesthetics, Local - blood; Anesthetics, Local - pharmacokinetics; Animals; Bupivacaine - administration & dosage; Bupivacaine - blood; Bupivacaine - pharmacokinetics; Drug Carriers; Injections, Epidural; Liposomes; Liver - metabolism; Rabbits; Spinal Cord - metabolism; Spinal Nerves - metabolism; Time Factors; Tissue Distribution; Tritium
• ISSN: 0007-0912
• DOI: 10.1093/bja/75.3.319

After one extradural injection of 0.25% bupivacaine 0.3 ml and 3H-bupivacaine 0.005 mCi in multilamellar liposomes, no systemic radioactivity (plasma, liver, heart muscle) was obtained for 1 h, and the labelling was less than that of systemic distribution of plain bupivacaine for the following 3 h. In contrast, radioactivity in the lumbar spinal nerves peaked in the first hour and remained higher than that of plain bupivacaine for 4 h. No radioactivity was measured in cerebrospinal fluid. Small unilamellar vesicles incorporating 3H-cholesterol did not significantly label spinal nerves and central nervous structures indicating that the mode of action of liposomal bupivacaine did not involve uptake by nerve structures. Rapid uptake of radioactivity by spinal nerves suggested exchange of bupivacaine between liposomes and nerve sheaths.