Khan K, Elia M
Dunn Clinical Centre, 100 Tennis Court Road, Cambridge CB2 1QL, UK.
Clin Nutr. 1991 Aug;10(4):186-92. doi: 10.1016/0261-5614(91)90037-d.
The degradation rate of L-glutamine in water, various buffers, and intravenous solutions was assessed over a period of 2 weeks. Measurements were made at various temperatures (22-24 degrees C, and 4 degrees C and -80 degrees C) and pH, and also in the presence and absence of light and oxygen (intravenous solutions only). At 22-24 degrees C, the degradation rate of glutamine was variable depending on the type of solution used (0.23% in water pH 6.5; 0.22% in dextrose/water [15% w/v]; 0.8% in mixed total parenteral nutrition (TPN) solution), and on the pH, molarity and type of buffer used. The degradation rate was essentially unaffected by light and O(2). The degradation rate of L-glutamine in the intravenous solutions was less than 0.15%/day at 4 degrees C, minimal at -20 degrees C (<0.03%/day), and undetectable at -80 degrees C. Glutamine degradation resulted in the equimolar formation of ammonia and no associated formation of glutamate. It is concluded that (a) glutamine degradation in solution is variable due to the effect of physico-chemical factors, and (b) glutamine degradation in TPN solutions is sufficiently slow, especially during storage at 4 degrees C or below, to consider its inclusion in such solutions, for clinical use.
在两周的时间内评估了L-谷氨酰胺在水、各种缓冲液和静脉注射液中的降解率。在不同温度（22 - 24摄氏度、4摄氏度和 - 80摄氏度）和pH值下进行测量，并且还分别在有光和无氧（仅针对静脉注射液）以及无光和有氧的条件下进行测量。在22 - 24摄氏度时，谷氨酰胺的降解率因所用溶液类型而异（在pH 6.5的水中为0.23%；在葡萄糖/水[15% w/v]中为0.22%；在混合全胃肠外营养（TPN）溶液中为0.8%），并且还受所用缓冲液的pH值、摩尔浓度和类型的影响。降解率基本上不受光和氧气的影响。L-谷氨酰胺在静脉注射液中的降解率在4摄氏度时小于0.15%/天，在 - 20摄氏度时最小（<0.03%/天），在 - 80摄氏度时无法检测到。谷氨酰胺降解导致等摩尔量的氨生成，且没有相关的谷氨酸生成。得出的结论是：（a）由于物理化学因素的影响，溶液中谷氨酰胺的降解是可变的；（b）TPN溶液中谷氨酰胺的降解足够缓慢，特别是在4摄氏度或更低温度下储存时，因此可考虑将其加入此类溶液中以供临床使用。
