Extended duration local anesthetic agent in a rat paw model

Area of Science:

• Biomaterials Science
• Pharmacology
• Neuroscience

Background:

• Extended-release local anesthetics can improve postoperative pain management and reduce complications.
• Developing effective drug delivery systems for sustained anesthesia is crucial for clinical practice.

Purpose of the Study:

• To evaluate the efficacy of an improved extended-duration formulation of 15% bupivacaine encapsulated in poly(DL-lactic acid co castor oil) (p(DLLA-CO)) 3:7.
• To assess the in vivo performance of this bupivacaine-polymer formulation for prolonged local anesthesia.

Main Methods:

• Bupivacaine was encapsulated in p(DLLA-CO) 3:7 via ring-opening polymerization, with in vitro release studies conducted.
• The formulation was administered via sciatic nerve injection in Sprague-Dawley rats, followed by surgical incision in some subjects.
• Sensory and motor block were assessed using Hargreave's hot plate, von Frey filaments, and rearing count.

Main Results:

• In vitro studies showed approximately 70% bupivacaine release from the polymer over 10 days.
• The 15% bupivacaine-polymer formulation significantly extended sensory block duration to at least 48 hours.
• Motor block and reduced rearing were observed for 48 hours post-administration, with no significant changes in mechanical nociceptive response.

Conclusions:

• The optimized bupivacaine-polymer formulation provides a prolonged local anesthetic effect, lasting up to 48 hours in an animal model.
• This extended-duration formulation holds potential for improved postoperative analgesia and reduced complication rates.
• Further research is warranted to translate these findings into clinical applications for enhanced pain management.