Prolonged local anesthetic action through slow release from poly(lactic acid co castor oil)

Marina Sokolsky-Papkov, Ludmila Golovanevski, Abraham J. Domb, Carolyn F. Weiniger

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Purpose. To evaluate a new formulation of bupivacaine loaded in an injectable fatty acid based biodegradable polymer poly(lactic acid co castor oil) in prolonging motor and sensory block when injected locally. Materials and methods. The polyesters were synthesized from dl-lactic acid and castor oil with feed ratio of 4:6 and 3:7 w/w. Bupivacaine was dispersed in poly(fatty ester) liquid and tested for drug release in vitro. The polymer p(DLLA:CO) 3:7 loaded with 10% bupivacaine was injected through a 22G needle close to the sciatic nerve of ICR mice and the duration of sensory and motor nerve blockade was measured. Results. The dl-lactic acid co castor oil p(DLLA:CO) 3:7 released 65% of the incorporated bupivacaine during 1 week in vitro. Single injection of 10% bupivacaine loaded into this polymer caused motor block that lasted 24 h and sensory block that lasted 48 h. Conclusion. Previously we developed a ricinoleic acid based polymer with incorporated bupivacaine which prolonged anesthesia to 30 h. The new polymer poly(lactic acid co castor oil) 3:7 provides slow release of effective doses of the incorporated local anesthetic agent and prolongs anesthesia to 48 h.

Original languageEnglish
Pages (from-to)32-39
Number of pages8
JournalPharmaceutical Research
Issue number1
StatePublished - Jan 2009
Externally publishedYes

Bibliographical note

Funding Information:
This research was supported in part by grant no. 5868 from the Chief Scientist Office of the Ministry of Health, Israel and in part by a grant from the Joint Research Fund of the Hebrew University and Hadassah Medical Organization, Jerusalem, Israel. We are grateful to Professor Michael Tal, Department of Anatomy and Cell Biology, Hadassah Hebrew University School of Medicine, for use of his Hargreaves Hot Plate.


  • Analgesia
  • Local anesthetic
  • Long-acting
  • Mice
  • Polymer-bupivacaine


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