Stability after dilution of an oral L-glutamine preparation

Objective: Glutamine is a conditionally essential amino acid. Attention has been focusing recently on the potential non-nutritional effects of Glutamine including gut protection, enhancement of cell-mediated immunity, cell-volume regulation, synthesis of heat-shock proteins, and incretinsecretagogue action, which may play a crucial role in the regulation of glucose metabolism. However, the relative instability of Glutamine in water may reduce the effectiveness of oral preparations of Glutamine and/or decrease patient compliance. Design: The aim of this study was to investigate the stability of an oral L-Glutamine preparation. Materials and methods: An oral Glutamine powder preparation (Adamin-G, SHS International Ltd, UK, kindly provided by Nutricia Italy) was tested. One sachet (containing 5 g of L-Glutamine, as indicated by the producer) was diluted in 200 mL of water to obtain a solution with a nominal concentration of 170 μmol/mL. Samples were obtained at 0, 2, 6, 12, and 24 hours after dilution and analyzed by highperformance liquid chromatography. Results: The mean measured concentrations of Glutamine (g/200 mL) in the samples were as follows: 0h: 5.095±0.17; 2h: 5.098±0.06; 6h: 5.090±0.09; 12h: 5.103±0.07; 24h: 5.007±0.01 (p=ns at ANOVA). Conclusion: These results show that a commercially available oral L-Glutamine preparation is stable for at least 24 hours after dilution in water. This may have critical clinical relevance in patients unable to comply with fast oral intake of supplements, allowing day-long administration and improving patient compliance. Oral L-Glutamine supplements may prove beneficial in a number of clinical conditions and thus represent an emerging tool for metabolic support. © 2010 SINPE-GASAPE.