Extended release formulations for local anaesthetic agents

Anaesthesia. 2012 Aug;67(8):906-16. doi: 10.1111/j.1365-2044.2012.07168.x. Epub 2012 May 18.


Systemic toxicity through overdose of local anaesthetic agents is a real concern. By encapsulating local anaesthetics in biodegradable carriers to produce a system for prolonged release, their duration of action can be extended. This encapsulation should also improve the safety profile of the local anaesthetic as it is released at a slower rate. Work with naturally occurring local anaestheticss has also shown promise in the area of reducing systemic and neurotoxicity. Extended duration local anaesthetic formulations in current development or clinical use include liposomes, hydrophobic based polymer particles such as Poly(lactic-co-glycolic acid) microspheres, pasty injectable and solid polymers like Poly(sebacic-co-ricinoleic acid) P(SA:RA) and their combination with synthetic and natural local anaesthetic. Their duration of action, rationale and limitations are reviewed. Direct comparison of the different agents is limited by their chemical properties, the drug doses encapsulated and the details of in vivo models described.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Anesthetics, Local / administration & dosage*
  • Chemistry, Pharmaceutical
  • Clinical Trials as Topic
  • Delayed-Action Preparations
  • Injections
  • Lactic Acid / administration & dosage
  • Liposomes
  • Microspheres
  • Polyglycolic Acid / administration & dosage
  • Polylactic Acid-Polyglycolic Acid Copolymer
  • Polymers


  • Anesthetics, Local
  • Delayed-Action Preparations
  • Liposomes
  • Polymers
  • Polylactic Acid-Polyglycolic Acid Copolymer
  • Polyglycolic Acid
  • Lactic Acid