We aimed to investigate the local anesthetic effect of 2-adamantanamine in spinal anesthesia. The dose-response curves were constructed after intrathecally injecting the rats with five doses of 2-adamantanamine and a common local anesthetic mepivacaine. The quality and duration of 2-adamantanamine at producing spinal nociceptive, proprioceptive and motor block were compared with that of mepivacaine. We revealed that 2-adamantanamine provoked spinal nociceptive, proprioceptive and motor block dose-dependently. On the 50% effective dose (ED50) basis, the rank of potency was mepivacaine >2-adamantanamine at producing spinal nociceptive, proprioceptive and motor block (p<0.05 for the differences). 2-Adamantanamine, but not mepivacaine produced more nociceptive block than motor block (p<0.05). At the equianesthetic doses (ED75, ED50, and ED25), the nociceptive block duration caused by 2-adamantanamine was greater than that caused by mepivacaine (p<0.01 for the differences). These preclinical data showed that 2-adamantanamine is less potent than mepivacaine, while 2-adamantanamine provokes greater duration of spinal nociceptive block than mepivacaine. Furthermore, 2-adamantanamine demonstrates a more nociceptive-selective action over motor block.
Keywords: 2-adamantanamine; Intrathecal injection; Mepivacaine; Motor function; Nociception; Proprioception.
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