Effect of oral tizanidine on local-anesthetic infiltration pain during epidural catheterization.

PURPOSE Tizanidine is a clonidine derivative and has the same effects, such as sedation, anxiolysis and analgesic response. We evaluated the effect of tizanidine on infiltration pain during epidural catheterization. METHODS Forty patients scheduled to undergo epidural anesthesia in elective surgery were randomly allocated into two groups. The control group received placebo 60 minutes before arrival in the operating room, and the tizanidine group received 3 mg of oral tizanidine as premedication 60 minutes before arrival in the operating room. Every patient was measured heart rate and blood pressure before receiving placebo or premedication and after arrival in the operating room. After an epidural catheter was indwelled, the patients were questioned about the infiltrating pain of local anesthetic, and the degree was assessed by means of visual analog scale score (VAS score, 0 to approximately 100 mm). RESULTS Blood pressure in the operating room was significantly attenuated in the tizanidine group compared to the control group (148 +/- 21 mmHg vs 130 +/- 15 mmHg). Heart rate was not significantly different between the two groups. Rate-pressure product was significantly lower in the tizanidine group (11282 +/- 2960 vs 9592 +/- 2632). VAS score in the tizanidine group was significantly lower than that in the control group (P <0.001). CONCLUSION It was possible to reduce the infiltration pain of local anesthetic during epidural catheterization by oral administration of 3 mg of tizanidine as premedication. Blood pressure and rate-pressure product in the operating room were also attenuated by receiving tizanidine. Therefore, we recommend premedication with tizanidine for patients undergoing epidural catheterization.