Topical use of Xylocaine for relieving vasospasm: effect of concentration.

The spasmolytic and antispasmodic effects of Xylocaine in different concentrations were studied. Twenty-five Wistar rats were divided into five groups according to the concentrations of Xylocaine used (2 percent, 4 percent, 10 percent, 20 percent, and 40 percent). The diameters of rat femoral arteries were measured with vernier calipers under the microscope. Effects were evaluated by the percentage of the test arterial diameter compared with that of the control contralateral artery. Vasospasm of both femoral arteries was produced by administration of the fresh blood of other rats. After immersion in the blood for 10 min. Xylocaine was administered into the right femoral artery for 10 min to examine its spasmolytic effect. The effects of the concentrations shown by the percent diameter were 106 percent, 108 percent, 107 percent, 111 percent, and 106 percent, respectively. There was no significant statistical difference between each agent and its control. Thirty minutes after removal of the agent, 2 percent Xylocaine failed to maintain its spasmolytic effect, while 4 percent, 10 percent, 20 percent, and 40 percent Xylocaine did maintain it. Next, blood was again administered after vessel immersion in the agent to examine its antispasmodic effect. The effects of the concentrations were 100 percent, 114 percent, 124 percent, 152 percent, and 146 percent. There were statistically significant differences, except in the case of 2 percent Xylocaine. Twenty-percent Xylocaine demonstrated a superior antispasmodic effect. The duration of the spasmolytic effect and the antispasmodic effect were concentration-dependent, up to approximately 20 percent.