Addition of dexmedetomidine to QX-314 enhances the onset and duration of sciatic nerve block in rats.

An experimental set-up was designed to observe whether adding dexmedetomidine to QX-314 would enhance the onset and duration of sensory and motor function in a rat sciatic nerve block model. Fifty-six Sprague-Dawley rats received unilateral sciatic nerve blocks with 0.2 mL of 35 mmol/L QX-314 alone, dexmedetomidine (5.3 μmol/L (1 μg/kg), 26.4 μmol/L (5 μg/kg), 52.8 μmol/L (10 μg/kg)) alone, or a combination of the two. Thermal nociception and motor function were assessed by an investigator blinded to the drug treatment, and sciatic nerves and perineural tissues were harvested at 14 days after injection. In addition, we examined the effects of these solutions on compound action potentials in isolated frog sciatic nerves. Dexmedetomidine added to QX-314 enhanced the onset and duration of thermal nociception block and motor block (P < 0.05) without aggravating histopathological injuries. Furthermore, 52.8 μmol/L dexmedetomidine added to 35 mmol/L QX-314 showed less inflammation than QX-314 alone at 14 days (P = 0.003). Dexmedetomidine plus QX-314 was shown to dose-dependently reduce the compound action potentials relative to QX-314 alone (P < 0.05). It was concluded that co-administration of QX-314 with a clinical dose of dexmedetomidine produced a synergistic anesthetic effect to enhance the effect of sciatic nerve block.