Assessment of Ascorbic Acid Stability in Different Multilayered Parenteral Nutrition Bags: Critical Influence of the Bag Wall Material

Background: The recent development of multilayered bags has minimized ascorbic acid oxidation in parenteral nutrition (PN) admixtures. However, the gas-barrier property of multilayered bags depends on their plastic material. This study compared ascorbic acid stability in different multilayered bags under experimental conditions. Methods: Oxygen permeability of a newly developed 6-layered bag (6-L) was compared with a highly mechanical-resistant 3-layered bag (3-LR) and a highly flexible 3-layered bag (3-LF) using gas chromatography. Ascorbic acid stability was assessed by iodine titration in bags filled with 2.5 L H2O and 40 g carbohydrates after setting residual O2 content at ≤1 or ≥5 ppm. The effect of storage at 4°C, 21°C, and 40°C on ascorbic acid stability was assessed over 48 hours in a complete PN admixture (ie, 330 g carbohydrates, 100 g lipids, 96 g amino acids and trace elements) using high-pressure liquid chromatography. Results: Oxygen permeability was markedly reduced in 6-L bags (0.5 mL O2 /m2/d) compared with 3-LR (150 mL O2 /m2/d) and 3-LR (1500 mL O2/m2/d). Accordingly, ascorbic acid was more stable in 6-L bags (half-life [T1/2] = 16 days up to 40°C) than in 3-LR (T1/2 = 9 days at 4°C, 47 hours at 21°C and 29 hours at 40°C) and 3-LF (T1/2 = 15 hours at 4°C, 10 hours at 21°C, and 6 hours at 40°C). During the first 6 hours after PN admixture compounding, an additive ascorbic acid loss of 4.6 ± 0.5 mg/L/ppm O2 occurred because of residual O2 in the bag. Conclusions: The new combination of plastic layers and careful O2 monitoring during the filling process allowed near to complete prevention of ascorbic acid degradation in multilayered PN bags during 48 hours, regardless of the storage temperature. Comparisons between different multilayered parenteral nutrition bags showed that the gas permeability of the bag wall material is the main limiting factor for ascorbic acid stability. Near to complete prevention of ascorbic acid oxidation in the parenteral nutrition bags was only possible in a newly developed 6-layered bag.