Summary
Aim:In this study we investigated the antinociceptive effect of intrathecally administered succinylcholine, a muscle relaxant, and examine its potential interaction with lidocaine.Methods:
Using rats chronically implanted with lumbar intrathecal catheters, the ability of intrathecal succinylcholine and lidocaine, and the mixtures of succinylcholine–lidocaine to alter tail-flick latency was examined. Motor function was assessed using a modified Langerman's scale.
Results:
Intrathecal lidocaine (25–300 μg) alone showed the prolongation of tail-flick latency in a time- and dose-dependent manner. Although intrathecal succinylcholine (50 and 100 μg) alone demonstrated neither sensory nor motor block, the combination of lidocaine (100 or 200 μg) and succinylcholine (100 μg) significantly increased the tail-flick threshold. The combination of succinylcholine (100 μg) and lidocaine (200 μg) did not affect motor function when compared with lidocaine alone.
Conclusion:
These results indicated that the intrathecal succinylcholine potentiates spinal anesthesia with lidocaine.