Study for levobupivacaine

市售的布比卡因是S(-)-和R(+)-对映体的外消旋混合物。虽然s(-)-对构象左旋布比卡因和罗哌卡因对心血管和中枢神经系统的毒性比布比卡因小，但它们的相对疗效尚未确定。本研究直接比较了左旋布比卡因、罗哌卡因、布比卡因或R(+)-布比卡因的剂量反应。以0.1 Hz或5 Hz的刺激频率灌注0.2、0.4和0.8 mM的局麻溶液，比较左旋布比卡因、罗哌卡因和R(+)-布比卡因的麻醉作用。大鼠坐骨神经在5 Hz 0.8 mM局麻作用下，R(+)-布比卡因对复合动作电位振幅的抑制作用明显大于左旋布比卡因和罗哌卡因。三种局麻药在0.2和0.4 mM的0.1和5 Hz，以及0.8 mM的0.1 Hz下均无差异。在硬膜外或鞘内分别给予0.25%、0.5%和0.75%左布比卡因、罗哌卡因或布比卡因后，以盲、随机方式研究大鼠甩尾潜伏期和定性运动功能的时间变化过程。在硬膜外和鞘内给药后，与所有浓度的罗哌卡因相比，左布比卡因和布比卡因产生了相当且显著持久的抗痛觉作用。低局部麻醉浓度（硬膜外和鞘内）的运动阻滞时间与左布比卡因和罗哌卡因相当，但明显短于布比卡因。硬膜外0.75%左布比卡因和布比卡因表现出比罗哌卡因更持久的运动阻滞。在硬膜外或鞘内给予左布比卡因，在相同浓度下比罗哌卡因产生更持久的抗伤害作用，并且在硬膜外和鞘内给予较低浓度时产生类似的运动阻断作用。

Commercially available bupivacaine is a racemic mixture of S(-)- and R(+)-enantiomers. Although the s(-)-enantionmers levobupivacaine and ropivacaine are less toxic to the cardiovascular and central nervous systems than bupivacaine, their relative efficacy has not been determined. This study directly compares the dose response of levobupivacaine, ropivacaine, and bupivacaine or R(+)-bupivacaine.Desheathed rat sciatic nerve was perfused with 0.2, 0.4 and 0.8 mM local anesthetic solution at a stimulation frequency of either 0.1 or 5 Hz, to compare the anesthetic action of levobupivacaine, ropivacaine, and R(+)-bupivacaine. In rat sciatic nerve exposed to 0.8 mM local anesthetic at 5 Hz, the depression of compound action potential amplitude was significantly greater with R(+)-bupivacaine than levobupivacaine and ropivacaine. No differences were observed among three local anesthetics at 0.2 and 0.4 mM by 0.1 and 5 Hz, and at 0.8 mM by 0.1 Hz.The time course of change in tail-flick latency and qualitative motor function was studied in rats following epidural or intrathecal administration of 0.25%, 0.5%, and 0.75% levobupivacaine, ropivacaine, or bupivacaine in blind, randomized fashion. Levobupivacaine and bupivacaine produced comparable and significantly enduring antinociceptive effects compared with ropivacaine at all concentrations following both epidural and intrathecal administrations. During of motor block at lower local anesthetic concentrations (epidurally and intrathecally) was comparable with levobupivacaine and ropivacaine but significantly shorter than with bupivacaine. Epidural 0.75% levobupivacaine and bupivacaine showed more enduring motor block than ropivacaine.Levobupivacaine, given epidurally or intrathecally, produces longer lasting antinociceptive action than ropivacaine at equivalent concentrations and similar motor blocking effect at lower concentrations in both epidural and intrathecal administrations.