| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
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.
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