The effects of storage conditions of dental local anesthetic solution on the duration of anesthesia

本研究的目的是探讨牙科局部麻醉液的储存条件。用感觉诱发电位研究了不同储存条件下温度、日光或荧光灯对麻醉持续时间的影响。并对溶液中肾上腺素和利多卡因的含量及pH值进行了研究。本研究使用两种局麻液：(A)2%利多卡因+1：8万肾上腺素为血管收缩药，甲基对苯甲酸为防腐剂+亚硫酸钠为抗氧化剂，(B)2%利多卡因+1：8万肾上腺素为血管收缩药，亚硫酸氢钠为抗氧化剂。每种麻醉液分别在冰箱(4℃)、保温箱(2)30℃、日光(23℃)、荧光灯(23℃)、暗室(23℃)中保存1、3、6、12个月。在23℃的日光或荧光灯下，肾上腺素水平和麻醉持续时间(A)均减少。在孵箱中保存30℃，表明孵箱的持续时间缩短，表明麻醉持续时间缩短。麻醉液放置在冰箱(4℃)和暗室(23℃)中无明显变化。在暗室保存23℃时，B液的局部麻醉持续时间缩短，肾上腺素含量降低。在荧光灯下保存(23℃)后，麻醉持续时间也有类似的变化。在整个研究过程中，利多卡因的含量没有明显变化，局麻溶液(A)应保存在黑暗中，且应在23℃以下，因为该溶液主要受光照影响。另一方面，局麻药溶液(B)应在黑暗和低温下储存，例如在冰箱中，因为它很容易受到光线和温度的影响。

The purpose of this study was to investigate the storage condition of choice for dental local anesthetic solution. The effects of temperature and daylight or fluorescent light under various storage conditions on the duration of anesthesia were studied using sensory evoked potential. The content of epinephrine and lidocaine and pH of the solution were also studied. Two kinds of local anesthetic solution were used in this study; (A) 2% lidocaine with 1 : 80, 000 epinephrine as a vasoconstrictor, methyhydrobenzoate as a preservative and sodium phrosulfite as an antioxidant, (B) 2% lidocane with 1 : 80, 000 epinephrine as a vasoconstrictor and sodium bisulfite as antioxidant. Each anesthetic solution was stored (1) in a refrigerator (4℃), (2) at 30℃ in a incubator, (3) under daylight (23℃), (4) under fluorescent light (23℃), (5) in a dark room (23℃) for 1, 3, 6 and 12 months.The level of epinephrine and the duration of anesthesia in the solution (A) were decreased, when exposed to daylight or fluorescent light in a room regulated at 23℃. Preservation at 30℃ in an incubator showed a shortening of the duration of an incubator showed a shortening of the duration of anesthesia. There were no remarkable changes when anesthetic solution was stored in a refrigerator (4℃) or a dark room (23℃). The duration of local anesthesia in the solution (B) was shortened in association with the decrease of epinephrine content, when stored at 23℃ in darkroom. Similar changes in the duration of anesthesia was also shown after the preservation under fluorescent light (23℃). There were no significant changes in the content of lidocaine throughout the study.The local anesthetic solution (A) should be stored in dark and at less than 23℃ because this solution was mainly affected by light. On the other hand, the local anesthetic solution (B) should be stored in dark and in low temperature, such as in a refrigerator because it is easily affected by both light and temperature.