Effect of the Intravenous Lipid Emulsions on the Availability of Calcium when using Organic Phosphate in TPN Admixtures

Optical Microscopy as a Tool for Assessing Parenteral Nutrition Solution Stability: A Proof of Concept

Background/Objectives: Parenteral nutrition (PN) is used when enteral feeding is not possible. It is a complex mixture of nutrients that must meet a patient's needs but can face stability issues, such as lipid emulsion destabilisation and precipitate formation. Stability studies are complex, and the methodologies used are very varied in the literature. In addition, many studies are outdated and use outdated components. This study conducts a stability analysis of PN solutions using optical microscopy. Methods: Samples were prepared according to clinical practice standards and previous studies. We used a counting chamber for optical microscopic observations and different storage conditions (RT, 4 °C 1-14 days). Results: Precipitates larger than 5 µm were found in 8 out of 14 samples after 14 days of storage at room temperature, and none were observed in refrigerated samples. More lipid globules larger than 5 µm were detected in samples stored at room temperature than in those stored in a refrigerator after 14 days. Additionally, the number of large globules generally increased from day 1 to day 14 in most samples. Conclusions: The observed precipitates were probably calcium oxalate crystals, the formation of which is possible in PN but is not expected under the usual storage conditions in a hospital environment. Prolonged storage time and storage at room temperature increases the formation of these precipitates. These findings highlight the importance of using filters during both the preparation and administration of PN to prevent large particles from reaching patients.

Electron Microscopy for the Stability Assessment of Parenteral Nutrition Admixtures: Focus on Precipitation

(1) Background: parenteral nutrition (PN) is indispensable for patients unable to receive oral or enteral feeding. However, the complexity of PN solutions presents challenges regarding stability and compatibility. Precipitation reactions may occur. The most frequent is the formation of calcium phosphate (Ca-P). The different factors influencing these reactions must be considered to ensure patient safety. (2) Methods: eight paediatric PN solutions were prepared, following standard protocols. Samples were stored at room temperature and in a refrigerator. Electron microscopy, coupled with energy dispersive X-ray spectroscopy (EDS), was employed. Precipitates were analysed for composition and morphology. (3) Results: precipitates were observed in all samples, even at day 0. Crystalline structures, predominantly composed of calcium or magnesium, sometimes associated with chlorine or phosphorus, were detected. Additionally, amorphous precipitates, contained heterogeneous compositions, including unexpected elements, were identified. (4) Conclusions: various precipitates, primarily calcium- or magnesium-based, can form in PN solutions, although it is not expected that they can form under the real conditions of use. Calcium oxalate precipitation has been characterised, but the use of organic calcium and phosphate salts appears to mitigate calcium phosphate precipitation. Electron microscopy provides interesting results on NP precipitation, but sample preparation may present technical limitations that affect the interpretation of the results.

Physicochemical Stability of Hospital Parenteral Nutrition Solutions: Effect of Changes in Composition and Storage Protocol

(1) Background: Parenteral nutrition (PN) is a technique used for the administration of nutrients to patients for whom traditional routes cannot be used. It is performed using solutions with extremely complex compositions, which can give rise to a large number of interactions. These interactions can impact their stability and put the patient's life at risk. The aim of this study is to determine how changes in composition and storage protocol affect the stability of NP solutions. (2) Methods: Twenty-three samples were prepared according to routine clinical practice, with modifications to the concentration of some components. The samples were stored at room temperature (RT) and refrigerated (4 °C). Measurements of the droplet diameter, pH, density and viscosity were performed for both storage protocols on days 1, 3, 10 and 14. (3) Results: The samples with the lowest concentration of lipids (PN13-17) and proteins (PN18-22) showed a larger droplet diameter than the rest of the samples throughout the experiments. The USP limits were exceeded for some of the measurements of these sample groups. The pH density and viscosity remained relatively constant under the conditions studied. (4) Conclusions: The PN samples were considered stable and safe for administration under real-world conditions, but the samples with the lowest concentrations of lipids and proteins showed a tendency towards emulsion instability.

Stability of lipid emulsion in total parenteral nutrition: An overview of literature

BACKGOUND AND AIMS

Total parenteral nutrition (TPN) is an extremely complex mixture. The multitude of chemical compounds involved can give rise to numerous reactions that condition its stability. We set out to review the existing literature on different issues related to stability, and which are still of concern in the hospital environment; such as the stability of the lipid emulsion. In addition, we analyse other related factors and parameters that allow us to predict the stability of TPN based on the composition.

MATERIAL AND METHODS

we searched PubMed and Google Scholar, over the date range 1995-2019 for relevant studies about TPN stability. We included experimental studies where the physical stability of the lipid emulsion in TPN had been analysed. We applied specific exclusion criteria.

RESULTS

we included 20 papers in this review of TPN stability. The studies combined different analytical techniques to assess the stability. In all the studies, the mean droplet diameter (MDD) is measured and the stability analysis is completed with other measurements. Temperature and components concentration are also considered.

CONCLUSIONS

studies on the stability of TPN used differing components with different chemical characteristics and their results can be difficult to extrapolate. There is no clear consensus about the composition of the mixtures and there is also great variety in the analytical techniques that were used to analyse stability. It is necessary to conduct new studies to update information on TPN stability.

Compatibility of Maximum Inorganic and Organic Calcium and Phosphate Content in Neonatal Parenteral Solutions

The purpose of the study was to determine the maximum safe concentration of calcium and phosphate in neonatal parenteral nutrition (PN) solutions when various combinations of inorganic and organic salts are applied. Twelve PN solutions for neonatal use were aseptically prepared. Increasing concentrations of inorganic and organic calcium and phosphate were added to the standard formulas. Each admixture was separately tested according to the following conditions; after mixing, at 37 °C for 24 hr, and the maximum safe combination of calcium and phosphate were stored at 4 °C for 30 days and followed by 24 hr at 37 °C. Visual inspections and microscopic observation of undiluted PN solutions as well as the membrane filter after filtration of the PN solution, pH evaluation, and absorbance were examined. The safe maximum concentration of organic and inorganic calcium and phosphate were proposed individually for each composition of parenteral nutrition solutions. Surprisingly, organic calcium with organic phosphate showed precipitation but over the therapeutic range. The protective effect of amino acid was observed and higher concentrations of calcium and phosphate were free of precipitation. This work is valuable in daily practice as it allows an increase in the limits of calcium and phosphate in PN solutions for infants.

Maximization of calcium and phosphate in neonatal total parenteral nutrition

BACKGROUND

Appropriate calcium and phosphate supplementation is essential for bone growth in preterm infants. Using Rehabix-K2™ (AY Pharmaceuticals, Tokyo, Japan) and Pleamin-P Injection™ (Fuso Pharmaceutical Industries, Osaka, Japan) as the total parenteral nutrition (TPN) and amino acid solution, respectively, we investigated ways of maximizing calcium and phosphate in the TPN solution.

METHODS

Rehabix-K2, Pleamin-P, calcium gluconate, sodium phosphate, 50% glucose, and water were mixed in varying proportions to create 16 formulations. Precipitation assessment was done three times for each of the 16 formulations, and was based on the Japanese Pharmacopeia.

RESULT

Precipitation was observed 24 h after mixing when the calcium and phosphate were 60 mEq/L and 30 mmol/L or 80 mEq/L and 40 mmol/L, respectively. No precipitation was observed when the calcium and phosphate were 20 mEq/L and 10 mmol/L, respectively. Precipitation was observed once out of three times, when the calcium and phosphate were 40 mEq/L and 20 mmol/L, respectively, and the amino acids were 2% and 3% (mean pH, 6.13 and 6.26, respectively). No precipitation was observed, however, when the calcium and phosphate were 40 mEq/L and 20 mmol/L, respectively, and the amino acids were 0% and 1% (mean pH, 5.88 and 6.05, respectively).

CONCLUSION

Not only the concentration of calcium and phosphate, but also the pH of the TPN solution, are crucial factors for precipitation. Based on these results, a well-balanced TPN solution maximizing calcium and phosphate availability will be able to be formulated.