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

本研究的目的是探讨口腔局部麻醉溶液的储存条件选择。用感觉诱发电位法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。研究了溶液中肾上腺素和利多卡因的含量及pH值。本研究采用两种局麻溶液；(A) 2%利多卡因加1:8万肾上腺素作血管收缩剂，苯甲酸甲酯作防腐剂，亚硫酸氢钠作抗氧化剂，(B) 2%利多卡因加1:8万肾上腺素作血管收缩剂，亚硫酸氢钠作抗氧化剂。每种麻醉溶液分别保存(1)冰箱（4℃），(2)培养箱（30℃），(3)日光（23℃），(4)荧光灯（23℃），(5)暗室（23℃）1、3、6、12个月。在23℃室温下，暴露于日光或荧光灯下，麻醉溶液(A)的肾上腺素水平和麻醉时间均降低。在30℃的培养箱中保存显示出培养箱时间的缩短显示出麻醉时间的缩短。麻醉溶液在冰箱（4℃）和暗室（23℃）中均无明显变化。在23℃暗室保存时，局部麻醉时间(B)随着肾上腺素含量的降低而缩短。在荧光灯（23℃）下保存后，麻醉时间也发生了类似的变化。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)主要受光照影响，应避光保存，保存温度应低于23℃。另一方面，局部麻醉溶液(B)应在黑暗和低温下保存，如在冰箱中，因为它很容易受到光和温度的影响。

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.