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溶液的储存条件。采用感觉诱发电位研究了温度、日光或荧光灯在不同贮存条件下对麻醉持续时间的影响。并对肾上腺素和利多卡因的含量及溶液的pH值进行了研究。本研究使用两种局麻溶液：（A）2%利多卡因加1：80，000肾上腺素作为血管收缩剂，甲基苯甲酸酯作为防腐剂，亚硫酸氢钠作为抗氧化剂;（B）2%利多卡因加1：80，000肾上腺素作为血管收缩剂，亚硫酸氢钠作为抗氧化剂。将每种麻醉剂溶液（1）储存在冰箱（4℃）中，（2）储存在30℃的培养箱中，（3）储存在日光下（23 ℃），（4）储存在荧光灯下（23 ℃），（5）储存在暗室（23℃）中1、3、6和12个月。在调节为23℃的室内暴露于日光或荧光灯下时。在30℃保温箱中保存显示保温箱持续时间缩短，显示麻醉持续时间缩短。麻醉液置冰箱（4℃）或暗室（23℃）中保存无明显变化。在23℃暗室中保存时，溶液（B）中的局部麻醉持续时间缩短，与肾上腺素含量降低相关。荧光灯（23℃）保存后，麻醉持续时间也出现类似变化。在整个研究过程中，利多卡因的含量无明显变化，局麻药溶液（A）主要受光照的影响，应在23℃以下避光保存。另一方面，局部麻醉溶液（B）应储存在黑暗和低温下，如冰箱中，因为它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.