European Journal of Biomedical and Pharmaceutical Sciences

COMPARISON OF THE ANALGESIC POTENCY BETWEEN INTRATHECAL ROPIVACAINE AND BUPIVACAINE IN RATS

Tomoki Nishiyama MD, PhD*

ABSTRACT

Background: There is no study to compare analgesic effects of ropivacaine and bupivacaine on different kinds of pain. We compared the effects of intrathecal ropivacaine and bupivacaine for different kinds of pain using acute thermal and formalin induced pain models of rats. Methods: Male Sprague-Dawley rats implanted with lumbar intrathecal catheters were given some different doses of intrathecal ropivacaine or bupivacaine, then tail flick test or formalin test was performed. The 50% effective doses (ED50s) were calculated and compared between ropivacaine and bupivacaine. Behavioral side effects were also checked. Results: The ED50 of bupivacaine was significantly lower than that of ropivacaine in the tail flick test, but it was significantly higher than that of ropivacaine in both phases of the formalin test. ED50s of both bupivacaine and ropivacaine were lower in both phases of the formalin test than those in the tail flick test. Behavioral side effects were observed only with bupivacaine. Conclusions: We suggest that intrathecal analgesia with ropivacaine is better than bupivacaine for inflammatory pain, both acute and chronic phases, but bupivacaine is better for acute thermal pain.

Keywords: Analgesia, Intrathecal, local anesthetic, Ropivacaine, Bupivacaine.