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.

Co-administration of Intravenous Drugs: Rapidly Troubleshooting the Solid Form Composition of a Precipitate in a Multi-drug Mixture Using On-Site Raman Spectroscopy

Intravenous drugs are often co-administrated in the same intravenous catheter line due to which compatibility issues, such as complex precipitation processes in the catheter line, may occur. A well-known example that led to several neonatal deaths is the precipitation due to co-administration of ceftriaxone- and calcium-containing solutions. The current study is exploring the applicability of Raman spectroscopy for testing intravenous drug compatibility in hospital settings. The precipitation of ceftriaxone calcium was used as a model system and explored in several multi-drug mixtures containing both structurally similar and clinically relevant drugs for co-infusion. Equal molar concentrations of solutions containing ceftriaxone and calcium chloride dihydrate were mixed with solutions of cefotaxime, ampicillin, paracetamol, and metoclopramide. The precipitate formed was collected as an "unknown" material, dried, and analyzed. Several solid-state analytical methods, including X-ray powder diffraction, Raman spectroscopy, and thermogravimetric analysis, were used to characterize the precipitate. Raman microscopy was used to investigate the identity of single sub-visual particles precipitated from a mixture of ceftriaxone, cefotaxime, and calcium chloride. X-ray powder diffraction suggested that the precipitate was partially crystalline; however, the identity of the solid form of the precipitate could not be confirmed with this standard method. Raman spectroscopy combined with multi-variate analyses (principal component analysis and soft independent modelling class analogy) enabled the correct detection and identification of the precipitate as ceftriaxone calcium. Raman microscopy enabled the identification of ceftriaxone calcium single particles of sub-visual size (around 25 μm), which is in the size range that may occlude capillaries. This study indicates that Raman spectroscopy is a promising approach for supporting clinical decisions and especially for compatibility assessments of drug infusions in hospital settings.

Parenteral Nutrition Overview

Parenteral nutrition (PN) is a life-saving intervention for patients where oral or enteral nutrition (EN) cannot be achieved or is not acceptable. The essential components of PN are carbohydrates, lipids, amino acids, vitamins, trace elements, electrolytes and water. PN should be provided via a central line because of its hypertonicity. However, peripheral PN (with lower nutrient content and larger volume) can be administered via an appropriate non-central line. There are alternatives for the compounding process also, including hospital pharmacy compounded bags and commercial multichamber bags. PN is a costly therapy and has been associated with complications. Metabolic complications related to macro and micronutrient disturbances, such as hyperglycemia, hypertriglyceridemia, and electrolyte imbalance, may occur at any time during PN therapy, as well as infectious complications, mostly related to venous access. Long-term complications, such as hepatobiliary and bone disease are associated with longer PN therapy and home-PN. To prevent and mitigate potential complications, the optimal monitoring and early management of imbalances is required. PN should be prescribed for malnourished patients or high-risk patients with malnutrition where the feasibility of full EN is in question. Several factors should be considered when providing PN, including timing of initiation, clinical status, and risk of complications.

Parenteral nutrition compatibility and stability: A comprehensive review

Several guidance documents support best practices across the stages of the parenteral nutrition (PN)-use process to optimize patient safety. The critical step of PN order verification and review by the pharmacist requires a contextual assessment of the compatibility and stability implications of the ordered PN prescription. This article will provide working definitions, describe PN component characteristics, and present a wide-ranging representation of compatibility and stability concerns that need to be considered prior to preparing a PN admixture. This paper has been approved by the ASPEN Board of Directors. This article is protected by copyright. All rights reserved.

High particle counts in neonatal parenteral nutrition solutions with added cysteine: Relationship to crystal formation and effect of filtration on cysteine content

BACKGROUND

Parenteral nutrition(PN) solutions containing calcium gluconate and cysteine have elevated particle counts when analyzed using laser light obscuration (LO) as recommended by the United States Pharmacopeia. It is unclear whether increased particle formation in these solutions results in decreased availability of cysteine to neonatal patients due to filtration.

OBJECTIVE

The purpose of this study was to measure cysteine concentrations in neonatal PN solutions before and after filtration as well as analyze precipitates on filters.

METHODS

Solutions of PN containing amino acids with and without cysteine that were compounded with calcium chloride or calcium gluconate plus potassium phosphate were analyzed using LO. Concentrations of cysteine were measured before and after filtration. The effect on particle formation of magnesium sulfate (MgSO₄ ) and D70 was also evaluated.

RESULTS

Multiple additives including the specific calcium or D70 additive, cysteine, and MgSO₄ influenced particle formation of particles detected using LO. There was no significant decrease in cysteine concentration because of filtering and there was no difference in the amount of calcium on filters of various solutions after filtration regardless of LO particle counts. Scanning electron micrographic (SEM) analysis found no significant differences in crystal composition. Light microscopic and SEM examination did not show evidence of high particle counts on filters.

CONCLUSION

The increased particle counts detected in neonatal PN solutions containing cysteine added at the time of compounding does not appear to result in increased precipitate or crystal formation. It is not associated witha decrease in cysteine delivery to patients.

WoCoVA consensus on the clinical use of in-line filtration during intravenous infusions: Current evidence and recommendations for future research

The need for filtering intravenous infusions has long been recognized in the field of venous access, though hard scientific evidence about the actual indications for in-line filters has been scarce. In the last few years, several papers and a few clinical studies have raised again this issue, suggesting that the time has come for a proper definition of the type of filtration, of its potential benefit, and of its proper indications in clinical practice. The WoCoVA Foundation, whose goal is to increase the global awareness on the risk of intravenous access and on patients' safety, developed the project of a consensus on intravenous filtration. A panel of experts in different aspects of intravenous infusion was chosen to express the current state of knowledge about filtration and to indicate the direction of future research in this field. The present document reports the final conclusions of the panel.

Use of sodium glycerophosphate in neonatal parenteral nutrition solutions to increase calcium and phosphate compatibility for preterm infants

BACKGROUND

Preterm infants require higher calcium and phosphate intake than term infants to facilitate adequate bone growth, but this is rarely met in parenteral nutrition (PN) solution because of the limited solubility of calcium and phosphate. This study aimed to evaluate the solubility of organic phosphate with calcium gluconate in neonatal PN solutions, simulating its clinical use.

METHODS

PN solutions were composed of calcium gluconate at 50 mEq/L and sodium glycerophosphate (NaGP) at 25 mmol/L. Another component included 1% or 4% amino acid and 10% or 20% dextrose. For comparison, PN solution composed of potassium phosphate was also evaluated. Each solution was evaluated using the following methods: visual inspection, light obscuration particle count test, and pH measurement. To simulate the clinical condition, the solution was tested after compounding, after being stored at 25 °C for 24 h, and after being stored at 2°C-8°C for 2 or 9 days and subsequently at 25 °C for 24 h.

RESULTS

There was no visual deposition in PN solution using NaGP in any of the concentrations and under any stored condition. The solution fulfilled the criteria of physical compatibility as < 25 particles/mL measuring ≥10 μm in diameter and <3 particles/mL measuring ≥25 μm in diameter. On the contrary, visual deposition was evidently noted in PN solution using potassium phosphate after its formulation, and the particle count significantly exceeded the range of physical compatibility.

CONCLUSION

NaGP and calcium gluconate have significantly good compatibility in PN solution. The use of NaGP in neonatal PN prevents calcium and phosphorus precipitation, hence increasing their supply to preterm infants in meeting their growth requirement.

Sodium glycerophosphate and prescribed calcium concentrations in pediatric parenteral nutrition: a retrospective observational study and economic evaluation

Background

The risk of precipitation limits calcium and phosphate concentrations that can be administered parenterally to pediatric patients. As an alternative to dipotassium phosphate, sodium glycerophosphate (NaGlyP) is claimed to reduce the risk of precipitation in solutions for parenteral administration.

Objectives

To determine the calcium concentrations, NaGlyP, and dipotassium phosphate prescribed in pediatric parenteral nutrition orders and the cost–benefit of the organic phosphate.

Methods

We retrospectively collected cross-sectional data for parenteral nutrition orders from September 2014 to August 2015 for pediatric patients including neonates and children aged <18 years who were admitted to King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Calcium concentration, calcium concentration adjustments, and costs of phosphate used per bag were analyzed.

Results

Of 2,192 parenteral nutrition orders, NaGlyP was used in 2,128 (97.1%) with calcium concentrations in the range of 0.84–139.91 mmol/L, which were significantly higher than calcium concentrations used with dipotassium phosphate (0.00–12.21 mmol/L, P < 0.001). There was no report of visible precipitation. Median costs of NaGlyP and dipotassium phosphate used per unit bag were not significantly different (35.88 and 41.25 Thai baht [THB] or 1.04 and 1.20 USD per bag, respectively, P>0.99; (1 USD equivalent to 34.241 THB U.S. Federal Reserve Bank G5.A annual average rate 2015).

Conclusions

Higher calcium concentrations could be achieved without increasing the direct cost per unit bag significantly as a result of using NaGlyP, an alternative to dipotassium phosphate as a source of phosphate for patients who require high amounts of calcium in parenteral nutrition.

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.

Avoidance of Overt Precipitation and Patient Harm Following Errant Y-Site Administration of Calcium Chloride and Parenteral Nutrition Compounded With Sodium Glycerophosphate

Calcium phosphate precipitates present 1 of many challenges associated with parenteral nutrition (PN) compounding. Extensive research has led to the establishment of solubility curves to guide practitioners in the prescription and preparation of stable PN. Concurrent dosing of intravenous products via y-site administration with PN can alter the chemical balance of the solution and modify solubility. Medications containing calcium or phosphate should not be administered in the same line as PN, due to the high potential for precipitation. Herein a case is reported from a pediatric cardiac intensive care unit where a physician ordered the administration of calcium chloride. The bedside nurse added the calcium chloride intermittent infusion as a y-site administration with the patient's PN. The patient's PN had been compounded with sodium glycerophosphate, temporarily available in the United States during a sodium phosphate shortage. The patient did not experience any observable adverse effects from the y-site administration with PN. Following this event, the scenario was replicated to investigate any precipitation risk associated with the y-site administration. Additionally, a separate PN solution containing sodium phosphate rather than glycerophosphate was compounded and used in a laboratory setting to demonstrate the potential for harm had the patient's PN been compounded with an inorganic phosphate source. This replication of the error demonstrates the additional safety gained in relation to precipitation risk when PN solutions are compounded with sodium glycerophosphate in place of sodium phosphate.

Significant Published Articles for Pharmacy Nutrition Support Practice in 2016

Purpose: To assist the pharmacist engaged in nutrition support therapy in staying current with pertinent literature. Methods: Several clinical pharmacists engaged in nutrition support therapy compiled a list of articles published in 2016 considered important to their clinical practice. The citation list was compiled into a single spreadsheet where the author participants were asked to assess whether the paper was considered important to nutrition support pharmacy practice. A culled list of publications was then identified whereby the majority of author participants (at least 5 out of 8) considered the paper to be important. Guideline and consensus papers from professional organizations, important to practice but not scored, were also included. Results: A total of 103 articles were identified; 10 from the primary literature were voted by the group to be of high importance. An additional 11 organizational guidelines, position, recommendation, or consensus papers were also identified. The top-ranked articles from the primary literature were reviewed. Conclusion: It is recommended that pharmacists, engaged in nutrition support therapy, be familiar with the majority of these articles as it pertains to their practice.

Calcium chloride in neonatal parenteral nutrition: A 15 year experience

OBJECTIVE

The objective of this study was to determine if outcomes at our neonatal intensive care units (NICUs) since we began using calcium chloride (CaCl2) as our preferred calcium additive in order to reduce aluminum (Al) exposure are within expected outcome ranges for NICUs in the U.S. where calcium gluconate in glass vials (CaGlu-Gl) has been the preferred additive.

STUDY DESIGN

A retrospective study of very low birth weight infants born between January 1, 2000 and December 31, 2014. Outcomes in two intensive care units (NICUs) using CaCl2 were compared to all U.S. NICUs in the Vermont Oxford Network. Primary outcomes were chronic lung disease (CLD), percent requiring supplemental oxygen at 28 days, and mortality excluding early deaths (MEED). The incidence of IV infiltrates of all admissions to the study NICUs in 2013-2014 was compared to the literature.

RESULTS

The incidence of CLD and those requiring oxygen at 28 days were 24.0% vs 28.6% and 46.2% vs 51.8% for the study NICUs compared to all U.S. NICUs, respectively (both p < 0.0001). The MEED was 8.7% vs 10.3% (p < 0.002). All major morbidities were lower at the study NICUs. The incidence of infiltrates was lower than that in the literature.

CONCLUSION

The use of CaCl2 was not associated with any detectable adverse effects. Calcium chloride appears to be a safe alternative to the use of CaGlu-Gl based upon studies of clinical outcomes.