In vitro oxidation of i.v. lipid emulsions in different all-in-one admixture bags assessed by an iodometric assay and gas-liquid chromatography

Use of Total Parenteral Nutrition (TPN) as a Vehicle for Drug Delivery

Total Parenteral Nutrition (TPN) is a method of providing nutrients directly into the bloodstream for individuals who are unable to meet their nutritional needs through the normal digestive process or gastrointestinal system. It provides macronutrients and micronutrients in a single container, reducing handling and contamination risks and making it more cost-effective. TPN has the potential to be used as a drug delivery system, with applications in combination therapies, personalized medicine, and integrating advanced technologies. It can enhance drug dosage precision and provide nutritional assistance, potentially reducing hospitalization and improving patient outcomes. However, implementing new applications requires thorough testing and regulatory approval. TPN could be particularly useful in pediatric and geriatric care and could also contribute to global health by combating malnutrition in areas with limited medical resources. Healthcare professionals prepare a sterile solution tailored to each patient's nutritional needs, and administration involves a central venous catheter. However, the simultaneous administration of medications with PN admixtures can result in pharmacological incompatibility, which can impact the stability of the oil-in-water system. The European Society for Clinical Nutrition and Metabolism and the American Society for Parenteral and Enteral Nutrition recommendations advise against including non-nutrient drugs in PN admixtures due to safety concerns. This review focuses on the utilization of Total Parenteral Nutrition (TPN) as a method for delivering drugs. It discusses the benefits and difficulties associated with its commercial application and offers suggestions for future research endeavors.

Stability and compatibility of parenteral nutrition solutions; a review of influencing factors

Both stability and compatibility of parenteral nutrition solutions (PNS) with drug products are major concerns for clinicians and clinical pharmacists, especially when concurrent administration of PNS with intravenous medications (IVM) is unavoidable. Since the same physicochemical principles apply to both adult's and paediatrics' PNS, concerns about stability and compatibility may still apply to both. However, these concerns are relatively more common in paediatrics and neonatal clinical settings, where limited vascular access can be problematic and the coadministration of PNS and drugs is more common. In neonatal and paediatric populations, there have been few experimental studies and comprehensive evaluations looking at medication compatibility with frequently used PNS. This work is part of a larger research project concerned for compatibility of PNS with commonly used intravenous medication in paediatric and neonates. This paper captures and reviews published data on factors influencing stability and compatibility of parenteral nutrition solutions. This information will help clinicians and clinical pharmacists to understand the principals of the stability and compatibility of PNS, furthermore, it will inform better design of future compatibility studies, as it highlights the complexity of PNS and the multiple factors influencing the stability of PNS, and hence its compatibility with IVM. When preparing, prescribing, and administering the PNS, especially when co-administration with IVM is unavoidable, it is important to take into account the physicochemical properties of the PNS components and IVM as well as administration conditions and environmental factors. These factors should also be considered in the design of the compatibility studies of the PNS with the IVM.

Spectrophotometric determination of hydrogen peroxide in water with peroxidase-catalyzed oxidation of potassium iodide and its applications to hydroxylamine-involved Fenton and Fenton-like systems

A spectrophotometric method for the rapid measurement of hydrogen peroxide (H₂O₂) in aqueous solutions was developed in this study. This method is based on a reaction catalyzed by peroxidase (POD) in which potassium iodide (KI) is oxidized to generate the stable yellow-colored I₃^- within 15 s. The absorbance of the generated I₃^- at both 350 nm and 400 nm had good linear relationships with H₂O₂ concentration in the range of 0-70 μM (R² > 0.999) with sensitivities of 2.34 × 10⁴ M^-1 cm^-1 and 5.30 × 10³ M^-1 cm^-1 respectively. Meanwhile, through calculation, the detection limits of the proposed POD-KI method at 350 nm and 400 nm were 0.09 μM and 0.33 μM, respectively. Even when the concentration of H₂O₂ was up to 350 μM, the absorbance of the generated I₃^- at 350 nm did not decrease observably. The generated I₃^- was found to be stable enough in ultrapure water, underground water, reservoir water and samples containing the strong reducing agent hydroxylamine. Moreover, the proposed POD-KI method was successfully used to analyze trace H₂O₂ in rainwater, and to monitor the change of H₂O₂ concentration in the Fenton, hydroxylamine/Fenton and hydroxylamine/Cu(II)/H₂O₂ systems. Overall, the POD-KI method could be adopted as a candidate method to determine H₂O₂ in Fenton and Fenton-like systems, and especially in those involving hydroxylamine.

Multi-wavelength spectrophotometric determination of hydrogen peroxide in water by oxidative coloration of ABTS via Fenton reaction

In this study, a sensitive and low-cost multi-wavelength spectrophotometric method for the determination of hydrogen peroxide (H₂O₂) in water was established. The method was based on the oxidative coloration of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) via Fenton reaction, which resulted in the formation of green radical (ABTS^•+) with absorbance at four different wavelengths (i.e., 415 nm, 650 nm, 732 nm, and 820 nm). Under the optimized conditions (C_ABTS = 2.0 mM, C_Fe²⁺ = 1.0 mM, pH = 2.60 ± 0.02, and reaction time (t) = 1 min), the absorbance of the generated ABTS^•+ at 415 nm, 650 nm, 732 nm, and 820 nm were well linear with H₂O₂ concentrations in the range of 0-40 μM (R² > 0.999) and the sensitivities of the proposed Fenton-ABTS method were calculated as 4.19 × 10⁴ M^-1 cm^-1,1.73 × 10⁴ M^-1 cm^-1, 2.18 × 10⁴ M^-1 cm^-1, and 1.96 × 10⁴ M^-1 cm^-1, respectively. Meanwhile, the detection limits of the Fenton-ABTS method at 415 nm, 650 nm, 732 nm, and 820 nm were respectively calculated to be 0.18 μM, 0.12 μM, 0.10 μM, and 0.11 μM. The absorbance of the generated ABTS^•+ in ultrapure water, underground water, and reservoir water was quite stable within 30 min. Moreover, the proposed Fenton-ABTS method could be used for monitoring the variations of H₂O₂ concentration during the oxidative decolorization of RhB in alkali-activated H₂O₂ system.

Emulsion Stability of Different Intravenous Propofol Formulations in Simulated Co-Administration with Remifentanil Hydrochloride

Background

Propofol and remifentanil often need to be co-administered via the same intravenous catheter line, which predisposes to potential compatibility issues. Our aim was to determine and compare the emulsion stability of three propofol formulations, two with medium chain triglycerides and one with long chain triglycerides, when administered together with remifentanil hydrochloride.

Methods

Remifentanil hydrochloride (Ultiva ® ) 50 µg/mL was mixed with two concentrations (10 and 20 mg/mL) of each propofol formulation in mixing ratios 10+1, 20+1, 1+1 and 1+20. Emulsion stability was assessed immediately after mixing and 4 hours later by measurements of pH, mean droplet diameter, polydispersity index, and calculating percentage of fat residing in globules>5 µm (PFAT5).

Results

High PFAT5 values were observed in certain mixing ratios. The correlation between elevated PFAT5 and high propofol concentration (20 mg/mL), when remifentanil was in abundance and for long contact time indicated that these factors influenced the stability of the propofol emulsions.

Conclusions

Stability differences between the propofol formulations were identified under extreme test conditions. Co-administration of remifentanil and propofol in the same i.v. line is safe when propofol is in abundance. Caution is advised when remifentanil is present in equal parts or in abundance when co-administered with propofol 20 mg/mL.

New Parenteral Lipid Emulsions for Clinical Use

Routine use of parenteral lipid emulsions (LE) in clinical practice began in 1961, with the development of soybean oil (SO) - based LE. Although clinically safe, experimental reports indicated that SO-based LE could exert a negative influence on immunological functions. Those findings were related to its absolute and relative excess of omega-6 polyunsaturated fatty acids (PUFA) and the low amount of omega-3 PUFA and also to its high PUFA content with an increased peroxidation risk. This motivated the development of new LE basically designed along the reduction of omega-6 PUFA and the omega-3 PUFA addition in order to obtain balanced levels of the omega-6/omega-3 ratio. The new LE for clinical use (available in Europe and South America) are differentiated by their content in polyunsaturated (omega-6 and omega-3), monounsaturated, and saturated fatty acids (FA), as well as FA source of their origin, including soy, coconut, olive, and fish oil. This article presents the new LE nutrition and energy functions but also its biochemical, metabolic, and immunomodulating aspects, according to their FA content. LE at 20% when infused from 1.0 to 2.0 g/kg body weight/day rates, either alone or in association with amino acids and glucose, are safe and well tolerated in routine clinical practice. LE combining SO with medium-chain triglycerides and/or olive oil have less omega-6 PUFA and are better metabolized, with less inflammatory and immunosuppressive effects than in relation to pure SO-based LE. The omega-3 PUFA used alone or as component of a new and complex LE (soy, MCT, olive and fish oil) has demonstrated anti-inflammatory and immunomodulatory effects.

Evolution of Fatty Acid Profile and Lipid Oxidation During Enteral Formula Storage

BACKGROUND

Enteral formulas can be stored for up to 2 years. Fat oxidation during storage can lead to the loss of nutritive value and generation of toxic products such as lipid peroxides.

METHODS

Two standard enteral formulas were stored for short periods at high temperatures (1-4 weeks at 32-55 degrees C) or for long periods at low temperatures (12-36 weeks at 4 degrees C, 20 degrees C, or 30 degrees C). The present study included the assessment of lipid oxidation by measuring related fluorescent compounds and the evolution of fatty acids profile.

RESULTS

Enteral formula fat was oxidized under all assayed conditions, including storage at 4 degrees C. The loss of essential fatty acids (linoleic and linolenic acids) was always higher when time and temperature were increased. The omega6/omega3 ratio was increased by storage from 5.6 to 7.8, which could exacerbate the inflammatory response in critically ill patients. Fluorescence intensity increased with time and temperature of storage and was correlated with the decrease in essential fatty acids (lineal correlation between -0.9416 and -0.9996).

CONCLUSIONS

Enteral formula fat was oxidized during storage, leading to a loss of nutritional value. These formulas should be stored under refrigeration to minimize this loss. Finally, fluorescence measurement proved to be a fast and easy method to assess fat oxidation status.

Kinetic stability of all-in-one parenteral nutrition admixtures in the presence of high dose Ca2+ additive under clinical application circumstances

Background

TPN infusions are usually administered during a treatment period of 10–24 hours per day due to the metabolic capacity of the liver. During this time interval physicochemically stable TPN solution (emulsion) is needed for the treatment. The purpose of the present study was to examine how the kinetic stability features of ready-made total parenteral nutrition admixtures containing olive oil and soybean oil will change under the usage-modeling 24-hour application with and without overdose Ca²⁺.

Methods

Particle size analysis and zeta potential measurements were carried out to evaluate the possible changes in the kinetic stability of the emulsions.

Results

Our results indicate that in two of the four mixtures bimodal droplet-size distribution figures were detected and appearance of fat particles over 5 μm can not be disclosed. The tendency for separation of large diameter droplets in the two types of oil-based emulsion systems was different. In case of soybean containing emulsion second peak of droplets appeared in the bottom of the container in contrast to the olive oil containing emulsions where the second peak appeared in the surface layer. Interestingly this phenomenon is independent of calcium-content.

Conclusions

From therapeutic point the emulsions of the bigger droplets containing upper layer are safer because the potentially dangerous big droplets could remain in the infusion bag after the administration.

Practical handling of AIO admixtures - Guidelines on Parenteral Nutrition, Chapter 10

All-in-one admixtures (AIO-admixtures) provide safe, effective and low-risk PN (parenteral nutrition) for practically all indications and applications. Water, energy (carbohydrates and lipids), amino acids, vitamins and trace elements are infused together with PN either as industrially-manufactured AIO admixtures provided as two- or three-chamber bags (shelf life usually more than 12 months) completed with electrolytes and micronutrients where appropriate or as individually compounded ready-to-use AIO admixtures (compounding, usually prepared by a pharmacy on either a daily or weekly basis and stored at 2–8°C). Physico-chemical and microbial stability of an AIO admixture is essential for the safety and effectiveness of patient-specific PN, and its assurance requires specialist pharmaceutical knowledge. The stability should be documented for an application period of 24 (–48) hours. It is advisable to offer a limited selection of different PN regimes in each hospital. For reasons of drug and medication safety, PN admixtures prepared for individual patients must be correctly labelled and specifications for storage conditions must also be followed during transport. Monitoring is required where applicable. Micronutrients are usually administered separately to AIO admixtures. In case compatibility and stability have been well documented trace elements and/or combination preparations including water-soluble or water-soluble/fat soluble vitamin supplements can be added to PN admixtures under strict aseptic conditions. AIO admixtures are usually not used as vehicles for drugs (incompatibilities).

Influence of the calcium concentration in the presence of organic phosphorus on the physicochemical compatibility and stability of all-in-one admixtures for neonatal use

BACKGROUND

Preterm infants need high amounts of calcium and phosphorus for bone mineralization, which is difficult to obtain with parenteral feeding due to the low solubility of these salts. The objective of this study was to evaluate the physicochemical compatibility of high concentrations of calcium associated with organic phosphate and its influence on the stability of AIO admixtures for neonatal use.

METHODS

Three TPN admixture formulas were prepared in multilayered bags. The calcium content of the admixtures was adjusted to 0, 46.5 or 93 mg/100 ml in the presence of a fixed organic phosphate concentration as well as lipids, amino acids, inorganic salts, glucose, vitamins and oligoelements at pH 5.5. Each admixture was stored at 4 degrees C, 25 degrees C or 37 degrees C and evaluated over a period of 7 days. The physicochemical stability parameters evaluated were visual aspect, pH, sterility, osmolality, peroxide formation, precipitation, and the size of lipid globules.

RESULTS

Color alterations occurred from the first day on, and reversible lipid film formation from the third day of study for the admixtures stored at 25 degrees C and 37 degrees C. According to the parameters evaluated, the admixtures were stable at 4 degrees C; and none of them presented precipitated particles due to calcium/phosphate incompatibility or lipid globules larger than 5 mum, which is the main parameter currently used to evaluate lipid emulsion stability. The admixtures maintained low peroxide levels and osmolarity was appropriate for parenteral administration.

CONCLUSION

The total calcium and calcium/phosphorus ratios studied appeared not to influence the physicochemical compatibility and stability of AIO admixtures.

A randomized controlled trial on parenteral nutrition, oxidative stress, and chronic lung diseases in preterm infants

OBJECTIVES

To evaluate the effect of trace elements (TEs), when added to total parenteral nutrition (TPN) solutions, on peroxides load, and to test the hypothesis that protection of TPN from light can decrease peroxides load and is associated with improvement in oxidant-related clinical outcomes in preterm infants.

SUBJECTS AND METHODS

A total of 80 preterm infants were randomized to 1 of 4 groups (n=20 each): group 1 received a mixture of dextrose and amino acids; group 2 received a mixture of dextrose, amino acids, and lipid emulsion; group 3 received dextrose, amino acids, lipid emulsion, and multivitamins (MVP); and group 4 received dextrose, amino acids, lipid emulsion, MVP, and TEs. Each group was subdivided into photo-protected and photo-exposed subgroups (n=10 each). Using ferrous oxidation of xylenol orange technique, we measured the baseline level of excreted urinary peroxides before and 48 hours after starting TPN. We examined the association among light protection, urinary peroxides, and clinical outcomes of these infants.

RESULTS

Baseline urinary peroxides ranged between 5.5 and 24.8 micromol/L. A significant increase in urinary peroxides was observed in all groups after receiving TPN. The use of TEs did not affect peroxide production. In regression analysis, the addition of MVP (P<0.0001) and the exposure to light (P=0.02) were significantly associated with increased urinary peroxides. In the overall population, light exposure was associated with a significant increase in the incidence of chronic lung disease (adjusted OR 9.26, confidence interval 1.2-73; P=0.03) but had no effect on mortality, necrotizing enterocolitis, or sepsis.

CONCLUSIONS

TEs in TPN solutions have no effect on the production of urinary peroxides. Addition of MVP and exposure of TPN to light are the 2 major sources of peroxides in TPN. Protection from ambient light is associated with a decrease in chronic lung disease.

Practical aspects of multichamber bags for total parenteral nutrition

PURPOSE OF REVIEW

Ready-to-use all-in-one admixtures are standards for short and long-term parenteral nutrition. Their limited stability does not allow storage over prolonged periods of time. Multichamber bags represent industrially manufactured near complete standard parenteral nutrition premixes with extended shelf lives. This review focuses on the characterization of multichamber bags, their influence on parenteral nutrition practice, the need for individual parenteral nutrition compounding, and the role of the pharmacist in the nutrition team.

RECENT FINDINGS

The all-in-one admixture concept, its correlation with parenteral nutrition effectiveness, safety, and pharmaceutical issues are reviewed. Multichamber bags, the bag material, their use and practical handling are addressed.

SUMMARY

Newly developed container materials are mainly responsible for the increased stability of multichamber bag parenteral nutrition premixes. Multichamber bags are used for (standard) parenteral nutrition in adults. Multichamber bags cannot eliminate individualized all-in-one parenteral nutrition compounding. Pharmaceutical assistance with expertise in compatibility and stability is mandatory for the nutrition team to implement and control good parenteral nutrition practices, e.g. to convert multichamber bags into complete ready-to-use all-in-one admixtures or to compound individualized regimens. The incorporation of additional components into parenteral nutrition admixtures (pharmaconutrients, drugs) must rely on documented compatibility with the parenteral nutrition admixtures. Multichamber bags have their advantages and limitations. Studies on the effectiveness and costs of multichamber bags are needed to meet the expectations of pharmacists, physicians, nurses, and industry for optimal parenteral nutrition in patients.

Peroxidation potential of lipid emulsions after compounding in all-in-one solutions

OBJECTIVES

We investigated the peroxidation potential of fat emulsions in all-in-one solutions (AIOs).

METHODS

Three 20% emulsions were compared: soybean oil (SO; 60% polyunsaturated fatty acids [PUFAs], alpha-tocopherol:PUFAs = 0.44), soybean plus medium-chain triacylglycerol (SO-MCT; 31% PUFAs, alpha-tocopherol:PUFAs = 0.35), and olive oil (OO; 21% PUFAs, alpha-tocopherol:PUFAs = 1.42). For each emulsion, six AIO solutions were prepared by adding 250 mL of emulsion to a lipid-free solution. Lipid peroxide (LPX) and malondialdehyde (MDA) concentrations were evaluated in fat emulsions, lipid-free solutions, and AIOs immediately (T0) and 24 h (T24) after lipid addition. Statistical analysis was done with analysis of variance.

RESULTS

Fat emulsion LPX in SO-MCT was lower than that in SO (P = 0.015) and OO (P = 0.024); LPX in SO was greater than that in OO (P = 0.013); MDA in SO was greater than that in SO-MCT (P = 0.001) and OO (P = 0.013); and MDA in SO-MCT was greater than that in OO (P = 0.001). In comparison with MDA at AIO-T0, MDA at AIO-T24 increased in SO (P = 0.005) and SO-MCT (P < 0.001) and decreased in OO (P = 0.003); at AIO-T24, LPX was greater in SO, but not significantly.

CONCLUSIONS

In AIO bags, LPX occurred within 24 h after the addition of the lipid emulsion and seemed to be directly related to the PUFA content and inversely related to the alpha-tocopherol:PUFA ratio of the emulsion.

Lipid metabolism of the micropremie

Intravenous lipid emulsions often provide substance for the very low-birth weight or extremely low-birth weight infant that need total parenteral nutrition. The process used in this type of treatment as well as the effects of such treatment are discussed at length in this article. Some of the main compounds of representative lipid emulsions are listed and evaluated and the benefits and consequences of their use are presented.

Lipid peroxidation of intravenous lipid emulsions and all-in-one admixtures in total parenteral nutrition bags: the influence of trace elements

An iodometric titration was used to assess the influence of a daily portion of trace elements on lipid peroxidation of pure lipid emulsions and lipid-containing all-in-one (AIO) admixtures by measuring the peroxide value (PV; mmol peroxides/L). A pure lipid emulsion (Intralipid 20%; Pharmacia & Upjohn, Dubendorf, Switzerland) was stored in ethylvinylacetate bags under light protection (LP) at 40 degrees C with and without trace elements. In absence of trace elements the PV of Intralipid 20% was significantly lower (day 14: 2.77 vs 18.04; p < .001). After the same time period with the same storage conditions the drop in pH was two times higher in presence of trace elements (1.54 vs 0.77). In an AIO admixture with LP stored at 2 degrees C to 8 degrees C, trace elements increased the PV from 0.04 to 0.19 mmol/L (day 29; p < .01). The drop in pH was 0.01 and 0.02 units, respectively. When stored at 20 degrees C to 30 degrees C and exposed to daylight, the PV of the AIO admixture containing trace elements reached 1.92 compared with 0.52 in their absence (day 19; p < .001) with a pH drop of 0.03 and 0.11, respectively (day 29). Although trace elements led to a much higher drop in pH in pure lipid emulsions, no obvious influence on the pH of AIO admixtures was demonstrated. To minimize lipid peroxidation, AIO admixtures should be stored light-protected and refrigerated without trace elements. The latter should be added immediately before administration or should be given separately.

Phagocyte-induced lipid peroxidation of different intravenous fat emulsions and counteractive effect of vitamin E

Unsaturated fatty acids, a major component of fat emulsions used in parenteral nutrition, are prone to peroxidation which is an important feature of oxygen-associated tissue damage. We used the nitroblue tetrazolium (NBT) reduction test to measure the production of superoxide radicals by stimulated polymorphonuclear neutrophils (PMN) in the presence of different fat emulsions: Intralipid (containing 100% long-chain triacylglycerols, LCT), Vasolipid (a physical mixture of 50% LCT and 50% medium-chain triacylglycerols, MCT) and Structolipid (structured triacylglycerols containing 63% LCT and 37% MCT). We measured the amount of malonaldehyde (MDA) and 4-hydroxyalkenal to determine the lipid peroxidation of the three fat emulsions in the presence of stimulated neutrophils. Further, we investigated the role of vitamin E (alpha-tocopherol) in preventing lipid peroxidation in vitro. The results showed that the values of NBT reduction of PMN were significantly decreased in each of the three fat emulsions and that increasing concentrations of fat emulsions were associated with decreased values of NBT reductions, in a dose-dependent way (P<0.001). There were, however, no statistically significant differences between the values of the three different types of fat emulsions (P>0.05). Lipid peroxidation increased significantly in the presence of all three types of fat emulsions, and was more pronounced for Intralipid than for Vasolipid and Structolipid after 1 and 2 h of incubation with resting as well as with stimulated phagocytes. The increased lipid peroxidation of the fat emulsions was markedly reduced by vitamin E, and the inhibition was concentration dependent. In conclusion, lipid peroxidation in vitro is more pronounced when PMNs are incubated with fat emulsions. This increase in lipid peroxidation can be reduced by adding vitamin E to the fat emulsions.

Stability issues in home parenteral nutrition

Home parenteral nutrition (HPN) is a method of providing nutrients, fluid and electrolytes intravenously to patients with a malfunctioning gastrointestinal tract, at home. Parenteral nutrition (PN) formulations are checked carefully for stability by the hospital pharmacist before the bags are made. However, there are many differences between supplying PN regimens to in-patients on the ward and to patients at home. Transportation between the hospital and home may be prolonged if the patient lives a long way from the hospital and may not be straight-forward. A number of factors can adversely affect the stability of the PN, which in turn can cause complications such as line blockage; or even life-threatening events, such as pulmonary embolism. The hospital team caring for HPN patients needs to be aware of these stability issues if complications resulting from incompatibilities of the solutions in the bags or the infusion line are to be avoided.

Basic principles for compounding all-in-one parenteral nutrition admixtures

Parenteral nutrition admixtures are complex pharmaceutical entities. The more closely they are examined, the more physico-chemical interactions emerge that could potentially affect stability. The move towards large scale hospital or commercial preparation, with a requirement for extended shelf life, and the increasing use of admixtures as vehicles for drugs and pharmaconutrients have created new formulation challenges for pharmaceutical scientists.

Lipid peroxidation of i.v. lipid emulsions in TPN bags: the influence of tocopherols

Four commercial i.v. lipid emulsions containing soybean oil were investigated to determine the tocopherol content. A sensitive high-performance liquid chromatography (HPLC) on a diol column was established to quantitate the tocopherol isomers in lipid emulsions. A previously described iodometric titration was used to assess the peroxide value (mmol peroxides/L). The pH was measured also. The initial tocopherol concentration ranges in three of the four commercial soybean oil-based 20% lipid emulsions studied were compared ([mg/L]: alpha: 17-23, beta: 4, gamma: 88-129, delta: 40-44). One product showed an increased alpha-tocopherol content (172 mg/L) due to supplementation during manufacture. During storage in an ethylvinyl acetate (EVA) bag at 40 degrees C under light-protection (LP) for 34 d, a lipid emulsion 20% with a natural alpha-tocopherol content showed a peroxide value (PV) of 9.18 (about 450 times the value of controls in glass bottles) with a concomittant reduction of the tocopherol isomers to 61.6% (alpha), 86.5% (gamma), and 88.9% (delta) compared to the initial values. Comparison of two lipid emulsions with different amounts of alpha-tocopherol (Lipidem 20%, B. Braun, Switzerland: 156.29 mg/L vs. Intralipid 20%, Pharmacia Upjohn, Switzerland: 8.75 mg/L) for their antioxidative capacity using the same stress conditions revealed for the emulsion with the high alpha-tocopherol content a significantly higher PV over the whole test period (after 5 wk: 33.63 vs. 6.23; P < 0.001) and an increased alpha-tocopherol decomposition (51.6% vs. 8.7%). The drop in pH was higher, also (1.9 vs. 1.0 pH units). In contrast to ordinary concentrations of about 20 mg/L, alpha-tocopherol in 20% lipid emulsions showing antioxidative properties, a supplementation with about 160 mg/L showed a prooxidative effect when exposed to ambient atmosphere in an EVA bag.