Nahata M C, Morosco R S, Hipple T F
College of Pharmacy, Ohio State University, Columbus 43210.
J Clin Pharm Ther. 1993 Feb;18(1):69-71. doi: 10.1111/j.1365-2710.1993.tb00570.x.
Lorazepam is commonly used to produce sedation in infants. As errors may occur with the measurement of small volumes of concentrated drugs, we studied the stability of lorazepam diluted from 4 mg/ml to 1 mg/ml in bacteriostatic water for injection at two temperatures. The diluted lorazepam was stored in 10 glass vials (five at 22 degrees C and five at 4 degrees C). Samples were collected at 0, 7, 14, 28, 42, 56, 70 and 91 days after storage at each temperature. Lorazepam was measured in duplicate from each of five vials (n = 10) at each temperature by a specific and stability-indicating high-performance liquid chromatographic (HPLC) method. After 7 days' storage, the mean lorazepam concentration was 88% of the original concentration at 22 degrees C, and 90% of the original concentration at 4 degrees C. After 2 weeks of storage, the mean lorazepam concentration was 42% of the original concentration at 22 degrees C, and 1.5% of the original concentration at 4 degrees C. Crystals appeared after 4 weeks of storage at 22 degrees C and after 2 weeks of storage at 4 degrees C. At 3 months the mean lorazepam concentration was 6.1% and 7.5% of the original concentration at 22 degrees C and 4 degrees C, respectively. Thus, lorazepam diluted in bacteriostatic water for injection and stored in glass vials is stable for less than 7 days at 22 degrees C and for 7 days at 4 degrees C.
劳拉西泮常用于使婴儿镇静。由于在测量小体积浓缩药物时可能会出现误差，我们研究了劳拉西泮在两种温度下于注射用抑菌水中从4毫克/毫升稀释至1毫克/毫升后的稳定性。稀释后的劳拉西泮储存在10个玻璃小瓶中（5个在22摄氏度，5个在4摄氏度）。在每个温度下储存0、7、14、28、42、56、70和91天后采集样本。通过一种特定的、能指示稳定性的高效液相色谱（HPLC）方法，在每个温度下从5个小瓶（n = 10）中的每一个中对劳拉西泮进行一式两份测量。储存7天后，22摄氏度时劳拉西泮的平均浓度为原始浓度的88%，4摄氏度时为原始浓度的90%。储存2周后，22摄氏度时劳拉西泮的平均浓度为原始浓度的42%，4摄氏度时为原始浓度的1.5%。在22摄氏度储存4周后以及在4摄氏度储存2周后出现了晶体。3个月时，22摄氏度和4摄氏度下劳拉西泮的平均浓度分别为原始浓度的6.1%和7.5%。因此，在注射用抑菌水中稀释并储存在玻璃小瓶中的劳拉西泮在22摄氏度下稳定时间少于7天，在4摄氏度下稳定7天。
