An evaluation of the analgesic effect of AnestaGel™ on mechanical allodynia in a rat model of postoperative incisional pain

Abstract

Purpose

Sustained release hydrogel with bupivacaine (AnestaGel^™) is a novel formulation of extended release bupivacaine in a biohydrogel Matrix^™. We sought to compare the analgesic effects via mechanical allodynia, the pharmacokinetic characteristics via serum blood levels, and the local tissue effects via pathology, following injection of either sustained release hydrogel with bupivacaine, liposome bupivacaine, or hydrogel only (negative control group).

Materials and methods

Ninety rats (30 in each group) were randomized to receive a sciatic nerve block injection of either sustained release hydrogel with bupivacaine, liposome bupivacaine (Exparel^®), or a biohydrogel matrix. The total force generated was obtained at varying time points. Pathologic analysis was undertaken on days 5 and 42 of the study. Six additional rats (two in each group) were randomized to receive a sciatic nerve block injection of either sustained release hydrogel with bupivacaine, liposome bupivacaine, or bupivacaine and pharmacokinetic data were obtained for up to 120 hours.

Results

The sustained release hydrogel with bupivacaine group had significantly better response to mechanical allodynia compared to the other two groups. The pathology showed no significant adverse events at 42 days in any group. Finally, bupivacaine was present longer in the serum of sustained release hydrogel with bupivacaine group than the other two groups.

Conclusion

The sustained release hydrogel with bupivacaine achieved longer lasting analgesia with no significant findings on pathology at 42 days when compared to both positive and negative controls.

Keywords:

• mechanical allodynia
• local anesthetics
• extended release
• nerve block

Acknowledgments

The authors would like to acknowledge Technomics Research, LLC, for their assistance with statistical analysis for this manuscript and NAMSA for their assistance with the GLP and pharmacokinetic portion of the study. This study was funded by InSitu Biologics, LLC.

Disclosure

Dr Hutchins is a consultant and owns stock with InSitu Biologics, LLC. William Taylor is an employee and owns stock with InSitu Biologics, LLC. The authors report no other conflicts of interest in this work.