Relative Contribution of Adjuvants to Local Anesthetic for Prolonging the Duration of Peripheral Nerve Blocks in Rats.

Background and Objectives: A chemically compatible, safe 4-drug multimodal formulation of bupivacaine combined with 3 adjuvants (clonidine, buprenorphine, and dexamethasone) has been proposed for long-lasting single-injection peripheral nerve blocks in patients. However, the relative importance of each of the adjuvants of the 4-drug formulation in producing long-lasting nerve blocks has not been determined. The aim of this study in rats was to determine which adjuvants (clonidine, buprenorphine, or dexamethasone) are essential for producing a long-lasting nerve block. Methods: After baseline sensory and motor responses were recorded, 0.1 mL of drug solution was injected into the sciatic notch of rats. Animals were reevaluated at 10-minute intervals after injection for the absence or presence of sensory and motor response in the sciatic nerve. The 4-drug formulation of 0.25% bupivacaine plus all 3 adjuvants (clonidine, buprenorphine, and dexamethasone), 0.25% bupivacaine with 1 or 2 of the adjuvants added separately, and 0.25% bupivacaine alone were compared for duration of nerve block. Results: The 4-drug multimodal solution produced a longer duration of sensory and motor nerve block than 0.25% bupivacaine alone (P

from Anaesthesiology via xlomafota13 on Inoreader http://ift.tt/2ahfePf
via IFTTT