Lipid emulsions in parenteral nutrition: current applications and future developments

The Advances in Phospholipids-Based Phase Separation Gels for the Sustained Release of Peptides, Proteins, and Chemotherapeutics

Implantable drug delivery systems formed upon injection offer a host of advantages, including localized drug administration, sustained release, minimized side effects, and enhanced patient compliance. Among the various techniques utilized for the development of in situ forming drug implants, solvent-induced phase inversion emerges as a particularly promising approach. However, synthetic polymer-based implants have been associated with undesirable effects arising from polymer degradation. In response to this challenge, a novel category of drug delivery systems, known as phospholipids-based phase separation gels (PPSGs), has emerged. These gels, characterized by their low initial viscosity, exhibit injectability and undergo rapid transformation into in situ implants when exposed to an aqueous environment. A typical PPSG formulation comprises biodegradable components, such as phospholipids, pharmaceutical oil, and a minimal amount of ethanol. The minimized organic solvents in the composition show good biocompatibility. And the relatively simple composition holds promise for industrial-scale manufacturing. This comprehensive review provides an overview of the principles and advancements in PPSG systems, with specific emphasis on their suitability as drug delivery systems for a wide range of active pharmaceutical ingredients (APIs), spanning from small molecules to peptides and proteins. Additionally, we explore the critical parameters and underlying principles governing the formulation of PPSG-based drug delivery strategies, offering valuable insights on optimization strategies.

Impact of lipid emulsions in parenteral nutrition on platelets: a literature review

Lipid emulsions are essential components of parenteral nutrition solutions that provide energy and essential fatty acids. The complexity of the formulations of lipid emulsions may lead to adverse outcomes such as platelet reactivity and changes in platelet aggregation and related coagulation. Platelets are responsible for haemostasis; they activate and demonstrate morphological changes upon extracellular factors to maintain blood fluidity and vascular integrity. Although parenteral nutrition lipid emulsions are generally found safe with regard to modulation of platelet activity, studies are still accumulating. Thus, this review aims to investigate platelet-related changes by parenteral nutrition lipid emulsions in human studies. Studies have pointed out patients at risk of bleeding and increased platelet aggregation responses due to the administration of lipid emulsions. Lipid emulsions may further benefit patients at high risk of thrombosis due to anti-thrombotic effects and should be cautiously used in patients with thrombocytopenia. The reported platelet-related changes might be associated with the fatty acid change in the plasma membranes of platelets following changes in platelet synthesis and plasma levels of eicosanoids. In conclusion, studies investigating platelets and parenteral nutrition should be supported to minimize the adverse effects and to benefit from the potential protective effects of parenteral nutrition lipid emulsions.

Construction and evaluation of a phospholipid-based phase transition in situ gel system for brexpiprazole

The objective of this study was to develop phospholipid-based injectable phase transition in situ gels (PTIGs) for the sustained release of Brexpiprazole (Brex). Phospholipid (Lipoid S100, S100) and stearic acid (SA) were used as the gel matrix which was dissolved in biocompatible solvent medium-chain triglyceride (MCT), N-methyl pyrrolidone (NMP), and ethanol to obtain PTIGs solution. The Brex PTIG showed a solution condition of low viscosity in vitro and was gelatinized in situ in vivo after subcutaneous injection. Both in vitro release assay and in vivo pharmacokinetics study in SD rats displayed that Brex in PTIGs could achieve a sustained release, compared with brexpiprazole solution (Brex-Sol) or brexpiprazole suspension (Brex-Sus). The Brex-PTIGs had good degradability and biocompatibility in vivo with rare inflammation at the injection site. Among the three Brex-PTIG formulations, Brex-PTIG-3 with the SA in the formulation had the greatest gelation viscosity, the lowest initial release rate, and the most stable release profile with sustained release of up to 60 days. The above results indicated that, as a novel drug delivery system, the Brex-PTIGs offered a new option for the clinical treatment of patients with schizophrenia.

Simultaneous determination of 22 fatty acids in total parenteral nutrition (TPN) components by gas chromatography-mass spectrometry (GC-MS)

Evaluating total parenteral nutrition (TPN) products for quality assurance and quality control is crucial due to the chemical complexity of its components. With the advent of exploring different approaches for analysing TPN components using tandem mass spectrometry techniques, there is still a need for a robust and reproducible method for industrial routine analyses. This study allows simple, simultaneous determination of 22 fatty acids (FAs) commonly found in TPN components using gas chromatography-mass spectrometry (GC-MS). Five different transesterification techniques were applied for the FA standards and the sodium methoxide in methanol-dimethyl carbonate method was selected due to its good methylation efficiency. Fatty acid methyl esters (FAMEs) were separated in gas chromatography using an HP-5MS UI column with helium as the carrier gas. Mass spectrometry was used to fragment and quantify FAMEs using electron ionization (EI) and selected ion monitoring (SIM) mode. The analytical method was evaluated using the guidelines from the US Food and Drug Agency (FDA) and European Medicines Agency (EMA) in compliance with the International Council for Harmonization (ICH) document Q2(R2). Correlation coefficients (R²) of the calibration curves for FAMEs were 0.99, except for C24:1 n-9 and C24:0, both R² = 0.98. The limits of detection (LOD) and quantification (LOQ) were found to be 1.69 μg mL^-1 and 5.14 μg mL^-1, respectively. The linear range was from 3.10-179.9 μg mL^-1 for most FAMEs, except for C18:1 n-7 (3.96-224.9 μg mL^-1) and C18:1 n-9 (6.30-349.57 μg mL^-1). The intra-day and inter-day precision coefficients of variance (CV) of the method were less than 11.10% and 11.30%, respectively. Freeze-thaw cycles and ambient temperature measurements were performed for assessing sample stability. The validated method was applied to analyse major TPN components-fish and olive oils, and an unidentified lipid sample. The presented GC-MS method is simple and robust in the identification and quantification of 22 fatty acids simultaneously in the tested TPN components.

The Metabolic Impact of Two Different Parenteral Nutrition Lipid Emulsions in Children after Hematopoietic Stem Cell Transplantation: A Lipidomics Investigation

Hematopoietic stem cell transplantation (HSCT) involves the infusion of either bone marrow or blood cells preceded by toxic chemotherapy. However, there is little knowledge about the clinical benefits of parenteral nutrition (PN) in patients receiving high-dose chemotherapy during HSCT. We investigated the lipidomic profile of plasma and the targeted fatty acid profiles of plasma and erythrocytes in children after HSCT using PN with either a fish oil-based lipid emulsion or a classic soybean oil emulsion. An untargeted liquid chromatography high-resolution mass spectrometry platform connected with a novel in silico annotation algorithm was utilized to determine the most relevant chemical subclasses affected. In addition, we explored the interrelation between the lipidomics profile in plasma, the targeted fatty acid profile in plasma and erythrocytes, several biomarkers of inflammation, and antioxidant defense using an innovative data integration analysis based on Latent Components. We observed that the fish oil-based lipid emulsion had an impact in several lipid subclasses, mainly glycerophosphocholines (PC), glycerophosphoserines (PS), glycerophosphoethanolamines (PE), oxidized PE (O-PE), 1-alkyl,2-acyl PS, lysophosphatidylethanolamines (LPE), oxidized PS (O-PS) and dicarboxylic acids. In contrast, the classic soybean oil emulsion did not. Several connections across the different blocks of data were found and aid in interpreting the impact of the lipid emulsions on metabolic health.

Polyphenolic Antioxidants in Lipid Emulsions: Partitioning Effects and Interfacial Phenomena

The autoxidation of lipids in complex systems such as emulsions or biological membranes, although known to occur readily and to be associated with important pathological events, is lacking in quantitative data in spite of the huge efforts that have been made in attempting to unravel the complex mechanisms of lipid oxidation and its inhibition by antioxidants. Lipids are present as oil-in-water emulsions in many foods and pharmaceutical formulations, and the prevalent role of the interfacial region is critical to understand the antioxidant behavior and to correctly interpret antioxidant efficiencies. The aim of this review is to summarize the current knowledge on the chemical fate of antioxidants before they react with peroxyl radicals. Many researchers highlighted the predominant role of interfaces, and although some attempts have been made to understand their role, in most instances, they were essentially qualitative and based on putative hypotheses. It is only recently that quantitative reports have been published. Indeed, knowledge on the effects of relevant experimental variables on the effective concentrations of antioxidants is necessary for a successful design of alternate, effective antioxidative solutions.

New-generation intravenous fat emulsions and bronchopulmonary dysplasia in preterm infants: a systematic review and meta-analysis

BACKGROUND

Fat emulsion is an important component of parenteral nutrition in premature infants. However, intravenous fat emulsions (IVFE) was reported to be associated with some serious complications, such as bronchopulmonary dysplasia (BPD). Compared to conventional soybean oil-based IVFE, new-generation IVFE may protect against BPD but the results are conflicting.

METHODS

Relevant literatures search was conducted and the summary effect estimates of odds ratio (OR) and 95% confidence interval (CI) were calculated with fixed-effects models.

RESULTS

Of 22 studies involving 3781 infants were selected in this study and BPD was reported as part of the included studies. The pooled estimate for 13 studies, comparing administration of new-generation IVFE with conventional IVFE, indicated that new-generation IVFE was not associated with a reduced risk of BPD in preterm infants, compared with conventional IVFE (OR 0.96; 95% CI 0.80-1.14); the pooled estimate for 18 studies, comparing administration of fish oil-containing IVFE with non-fish oil IVFE, indicated that fish oil-containing IVFE has no protective effect against the occurrence of BPD in preterm infants (OR 0.88; 95% CI 0.71-1.08).

CONCLUSIONS

There is no evidence to support that the new-generation IVFEs could prevent the incidence of BPD or fish oil-containing IVFEs could show a beneficial effect to BPD in premature infants.

The ω-3 Polyunsaturated Fatty Acids and Oxidative Stress in Long-Term Parenteral Nutrition Dependent Adult Patients: Functional Lipidomics Approach

Omega-3 polyunsaturated fatty acids (ω-3PUFAs) are introduced into parenteral nutrition (PN) as hepatoprotective but may be susceptible to the lipid peroxidation while olive oil (OO) is declared more peroxidation resistant. We aimed to estimate how the lipid composition of PN mixture affects plasma and erythrocyte lipidome and the propensity of oxidative stress. A cross-sectional comparative study was performed in a cohort of adult patients who were long-term parenterally administered ω-3 PUFAs without (FO/–, n = 9) or with (FO/OO, n = 13) olive oil and healthy age- and sex-matched controls, (n = 30). Lipoperoxidation assessed as plasma and erythrocyte malondialdehyde content was increased in both FO/– and FO/OO groups but protein oxidative stress (protein carbonyls in plasma) and low redox status (GSH/GSSG in erythrocytes) was detected only in the FO/– subcohort. The lipidome of all subjects receiving ω-3 PUFAs was enriched with lipid species containing ω-3 PUFAs (FO/–˃FO/OO). Common characteristic of all PN-dependent patients was high content of fatty acyl-esters of hydroxy-fatty acids (FAHFAs) in plasma while acylcarnitines and ceramides were enriched in erythrocytes. Plasma and erythrocyte concentrations of plasmanyls and plasmalogens (endogenous antioxidants) were decreased in both patient groups with a significantly more pronounced effect in FO/–. We confirmed the protective effect of OO in PN mixtures containing ω-3 PUFAs.

Novel Strategies to Prevent Total Parenteral Nutrition-Induced Gut and Liver Inflammation, and Adverse Metabolic Outcomes

Total parenteral nutrition (TPN) is a life-saving therapy administered to millions of patients. However, it is associated with significant adverse effects, namely liver injury, risk of infections, and metabolic derangements. In this review, the underlying causes of TPN-associated adverse effects, specifically gut atrophy, dysbiosis of the intestinal microbiome, leakage of the epithelial barrier with bacterial invasion, and inflammation are first described. The role of the bile acid receptors farnesoid X receptor and Takeda G protein-coupled receptor, of pleiotropic hormones, and growth factors is highlighted, and the mechanisms of insulin resistance, namely the lack of insulinotropic and insulinomimetic signaling of gut-originating incretins as well as the potentially toxicity of phytosterols and pro-inflammatory fatty acids mainly released from soybean oil-based lipid emulsions, are discussed. Finally, novel approaches in the design of next generation lipid delivery systems are proposed. Propositions include modifying the physicochemical properties of lipid emulsions, the use of lipid emulsions generated from sustainable oils with favorable ratios of anti-inflammatory n-3 to pro-inflammatory n-6 fatty acids, beneficial adjuncts to TPN, and concomitant pharmacotherapies to mitigate TPN-associated adverse effects.

The effect of ω-3 polyunsaturated fatty acids on the liver lipidome, proteome and bile acid profile: parenteral versus enteral administration

Parenteral nutrition (PN) is often associated with the deterioration of liver functions (PNALD). Omega-3 polyunsaturated fatty acids (PUFA) were reported to alleviate PNALD but the underlying mechanisms have not been fully unraveled yet. Using omics´ approach, we determined serum and liver lipidome, liver proteome, and liver bile acid profile as well as markers of inflammation and oxidative stress in rats administered either ω-6 PUFA based lipid emulsion (Intralipid) or ω-6/ω-3 PUFA blend (Intralipid/Omegaven) via the enteral or parenteral route. In general, we found that enteral administration of both lipid emulsions has less impact on the liver than the parenteral route. Compared with parenterally administered Intralipid, PN administration of ω-3 PUFA was associated with 1. increased content of eicosapentaenoic (EPA)- and docosahexaenoic (DHA) acids-containing lipid species; 2. higher abundance of CYP4A isoenzymes capable of bioactive lipid synthesis and the increased content of their potential products (oxidized EPA and DHA); 3. downregulation of enzymes involved CYP450 drug metabolism what may represent an adaptive mechanism counteracting the potential negative effects (enhanced ROS production) of PUFA metabolism; 4. normalized anti-oxidative capacity and 5. physiological BAs spectrum. All these findings may contribute to the explanation of ω-3 PUFA protective effects in the context of PN.

A new alternative for intravenous lipid emulsion 20% w/w from superolein oil and its effect on lipid and liver profiles in an animal model

PURPOSE

Intravenous lipid emulsion (IVLE) was first used to prevent essential fatty acids deficiency. IVLE with α-tocopherol was reported to provide protection against parenteral nutrition-associated liver disease. This study aims to determine the optimal parameters and conditions in developing a physically stable IVLE from superolein palm oil (SoLE 20%) and its effect on lipid and liver profiles in an animal model.

METHODS

SoLE 20% was prepared using superolein oil and MCT oil (1:1), stabilized with egg lecithin and homogenized using a high pressure homogenizer. Mean droplet size was used as the response variable and was measured using laser diffraction and dynamic light scattering method. Physical stability at 4 °C, 25 °C and 40 °C storage temperatures were determined based on particle size and distribution, polydispersity index, zeta potential, viscosity, vitamin E contents and pH. Sterility and pyrogenicity were also investigated. Rabbits were administered with 1.0 g/kg SoLE 20% for 5 h and repeated daily for 3 days to investigate its effect on blood lipid and liver enzymes profile.

RESULTS

SoLE 20% was succesfully prepared using the optimized parameters of 800 psi, 7 cycles and 1.2 g lecithin. The IVLE prepared had a particle size of 252.60 ± 4.88 nm and was physically stable for 4 weeks at different storage temperatures. SoLE 20% had a high content of natural vitamin E, remained sterile and pyrogen free. It was also safe for intravenous administration and did not alter the blood lipid (p > 0.05) and liver enzymes profiles (p > 0.05) of the rabbits.

CONCLUSION

The optimal parameters to develop a stable superolein based IVLE are 800 psi homogenization pressure, 7 homogenization cycles and using 1.2 g lecithin as the emulsifier. SoLE 20% is safe for intravenous administration and does not significantly alter lipid and liver enzymes profiles of the rabbits.

Lipid Emulsion Enriched in Omega-3 PUFA Accelerates Wound Healing: A Placebo-Controlled Animal Study

BACKGROUND

The Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) generate bioactive lipid mediators that reduce inflammation. The present study evaluated the effect of SMOFlipid containing ω-3 PUFAs on wound healing.

METHODS

Rats were divided into a SMOFlipid (SMOF) group and a 0.9% saline (placebo) group, with eight rats in each group. Wound excision was performed on the dorsal surface of each rat. In the SMOF group, 1 gm/kg SMOFlipid was dissolved in 3 mL saline as a treatment; in the placebo group, 3 mL saline was prepared as a treatment. The treatments were administered intravenously at an initial rate of 0.2 mL/kg body weight/h immediately after wounding, for 72 h. Blood samples were collected for white blood cell, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 measurements at the baseline and at 1, 6, 12, 24, 48, and 72 h after intervention. Wound areas were measured over a 2-week period after excision, and a histological examination was performed.

RESULTS

Compared with the placebo group, SMOFlipid supplementation engendered significant decreases in the wound area on day 3 (78.28 ± 5.25 vs. 105.86 ± 8.89%), day 5 (72.20 ± 4.31 vs. 96.39 ± 4.72%), day 10 (20.78 ± 1.28 vs. 39.80 ± 10.38%), and day 14 (7.56 ± 0.61 vs. 15.10 ± 2.42%). The placebo group had a higher TNF-α level than the SMOF group at 72 h. The IL-10 level was higher in the SMOF group than in the placebo group at 48 h. Histological analysis revealed a higher rate of fibroblast distribution and collagen fiber organization in the SMOF group (P = 0.01).

CONCLUSION

SMOFlipid enriched in ω-3 PUFA accelerates wound healing.

Medium-chain fatty acids decrease serum cholesterol via reduction of intestinal bile acid reabsorption in C57BL/6J mice

Background

Bile acids play a pivotal role in cholesterol metabolism via the enterohepatic circulation. This study investigated the effects of medium-chain triglycerides (MCTs)/medium-chain fatty acids (MCFAs) on the reduction of bile acid absorption in the small intestine and the mechanisms of action in vivo and partially verified in vitro.

Methods

Thirty-six C57BL/6 J mice with hypercholesterolaemia were randomly divided into 3 groups: fed a cholesterol-rich diet (CR group), fed a cholesterol-rich and medium-chain triglyceride diet (CR-MCT group) and fed a cholesterol-rich and long-chain triglyceride diet (CR-LCT group). Body weights and blood lipid profiles were measured in all groups after 16 weeks of treatment. The concentrations of bile acids in bile and faeces were analysed using HPLC-MS (high-performance liquid chromatography-mass spectrometry). Gene transcription and the expression levels associated with bile acid absorption in the small intestines were determined using real-time PCR and Western blot. Ileal bile acid binding protein (I-BABP) was analysed using immunofluorescence. The effects of MCFAs on the permeability of bile acid (cholic acid, CA) in Caco-2 cell monolayers and I-BABP expression levels in Caco-2 cells treated with caprylic acid (C8:0), capric acid (C10:0), stearic acid (C18:0) and oleic acid (C18:1) were determined.

Results

Mice in the CR-MCT group exhibited lower body weights and serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels and a higher HDL-C/LDL-C ratio than the CR-LCT group (P < 0.05). The concentrations of primary bile acids (primarily CA) and secondary bile acids in faeces and secondary bile acids in bile in the CR-MCT group were significantly higher than in the CR-LCT group (P < 0.05). C8:0 and C10:0 decreased the permeability of CA in Caco-2 cell monolayers. MCT/MCFAs (C8:0 and C10:0) inhibited I-BABP gene expression in the small intestines and Caco-2 cells (P < 0.05).

Conclusions

MCT slowed the body weight increase and promoted the excretion of bile acids. MCT lowered serum cholesterol levels at least partially via reduction of bile acid absorption in the small intestine by inhibition of I-BABP expression. Our results provide the basis for clinical trials of MCT as a dietary supplement for lowering plasma cholesterol and reducing risk of CHD.

Prescribed hypocaloric nutrition support for critically-ill adults

BACKGROUND

There are controversies about the amount of calories and the type of nutritional support that should be given to critically-ill people. Several authors advocate the potential benefits of hypocaloric nutrition support, but the evidence is inconclusive.

OBJECTIVES

To assess the effects of prescribed hypocaloric nutrition support in comparison with standard nutrition support for critically-ill adults SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, Embase and LILACS (from inception to 20 June 2017) with a specific strategy for each database. We also assessed three websites, conference proceedings and reference lists, and contacted leaders in the field and the pharmaceutical industry for undetected/unpublished studies. There was no restriction by date, language or publication status.

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials comparing hypocaloric nutrition support to normo- or hypercaloric nutrition support or no nutrition support (e.g. fasting) in adults hospitalized in intensive care units (ICUs).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We meta-analysed data for comparisons in which clinical heterogeneity was low. We conducted prespecified subgroup and sensitivity analyses, and post hoc analyses, including meta-regression. Our primary outcomes were: mortality (death occurred during the ICU and hospital stay, or 28- to 30-day all-cause mortality); length of stay (days stayed in the ICU and in the hospital); and Infectious complications. Secondary outcomes included: length of mechanical ventilation. We assessed the quality of evidence with GRADE.

MAIN RESULTS

We identified 15 trials, with a total of 3129 ICU participants from university-associated hospitals in the USA, Colombia, Saudi Arabia, Canada, Greece, Germany and Iran. There are two ongoing studies. Participants suffered from medical and surgical conditions, with a variety of inclusion criteria. Four studies used parenteral nutrition and nine studies used only enteral nutrition; it was unclear whether the remaining two used parenteral nutrition. Most of them could not achieve the proposed caloric targets, resulting in small differences in the administered calories between intervention and control groups. Most studies were funded by the US government or non-governmental associations, but three studies received funding from industry. Five studies did not specify their funding sources.The included studies suffered from important clinical and statistical heterogeneity. This heterogeneity did not allow us to report pooled estimates of the primary and secondary outcomes, so we have described them narratively.When comparing hypocaloric nutrition support with a control nutrition support, for hospital mortality (9 studies, 1775 participants), the risk ratios ranged from 0.23 to 5.54; for ICU mortality (4 studies, 1291 participants) the risk ratios ranged from 0.81 to 5.54, and for mortality at 30 days (7 studies, 2611 participants) the risk ratios ranged from 0.79 to 3.00. Most of these estimates included the null value. The quality of the evidence was very low due to unclear or high risk of bias, inconsistency and imprecision.Participants who received hypocaloric nutrition support compared to control nutrition support had a range of mean hospital lengths of stay of 15.70 days lower to 10.70 days higher (10 studies, 1677 participants), a range of mean ICU lengths of stay 11.00 days lower to 5.40 days higher (11 studies, 2942 participants) and a range of mean lengths of mechanical ventilation of 13.20 days lower to 8.36 days higher (12 studies, 3000 participants). The quality of the evidence for this outcome was very low due to unclear or high risk of bias in most studies, inconsistency and imprecision.The risk ratios for infectious complications (10 studies, 2804 participants) of each individual study ranged from 0.54 to 2.54. The quality of the evidence for this outcome was very low due to unclear or high risk of bias, inconsistency and imprecisionWe were not able to explain the causes of the observed heterogeneity using subgroup and sensitivity analyses or meta-regression.

AUTHORS' CONCLUSIONS

The included studies had substantial clinical heterogeneity. We found very low-quality evidence about the effects of prescribed hypocaloric nutrition support on mortality in hospital, in the ICU and at 30 days, as well as in length of hospital and ICU stay, infectious complications and the length of mechanical ventilation. For these outcomes there is uncertainty about the effects of prescribed hypocaloric nutrition, since the range of estimates includes both appreciable benefits and harms.Given these limitations, results must be interpreted with caution in the clinical field, considering the unclear balance of the risks and harms of this intervention. Future research addressing the clinical heterogeneity of participants and interventions, study limitations and sample size could clarify the effects of this intervention.

An in situ-forming phospholipid-based phase transition gel prolongs the duration of local anesthesia for ropivacaine with minimal toxicity

An injectable, phospholipid-based phase transition gel (PPTG) has been developed for prolonging the release of ropivacaine (RO) for local anesthesia. PPTG was prepared by mixing phospholipids, medium-chain triglyceride and ethanol. Prior to injection, the PPTG is in a sol state with low viscosity. After subcutaneous injection, the PPTG rapidly forms a gel in situ, which acts as a drug release depot as verified by in vitro release profiles and in vivo pharmacokinetics. Administering RO-PPTG to rats led to a significantly smaller initial burst release than administering RO solution or RO base suspension. Nerve blockade in guinea pigs lasted 3-fold longer after injection of RO-PPTG than after injection of RO solution. RO-PPTG showed good biocompatibility and excellent degradability in vivo. These results suggest that this PPTG-based depot system may be useful for sustained release of local anesthetics to prolong analgesia without causing systemic toxicity.

STATEMENT OF SIGNIFICANCE

The sustained release of local anesthetics at the surgical site after a single injection is the optimal method to control post-surgical pain. In situ forming implant is an attractive alternative for the sustained release of local anesthetics. However, its practical use is highly limited by certain drawbacks including high viscosity, involved toxic organic solvents and fast drug release. To date, phospholipids-based phase transition gel (PPTG) is emerging for clinical development because of the non-toxicity, biocompatibility and ready availability of phospholipids in body. Thus, we present a novel strategy for sustained release of local anesthetics to control post-surgical pain based on PPTG, which showed a prolonged duration of nerve blockade and excellent biocompatibility.

Comparison of Formulas Based on Lipid Emulsions of Olive Oil, Soybean Oil, or Several Oils for Parenteral Nutrition: A Systematic Review and Meta-Analysis

Many studies have reported that olive oil-based lipid emulsion (LE) formulas of soybean oil, medium-chain triglycerides, olive oil, and fish oil (SMOF) may be a viable alternative for parenteral nutrition. However, some randomized controlled clinical trials (RCTs) have raised concerns regarding the nutritional benefits and safety of SMOFs. We searched principally the MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Scopus, EMBASE, and Cochrane Central Register of Controlled Trials databases from inception to March 2014 for the relevant literature and conducted a meta-analysis of 15 selected RCTs that 1) compared either olive oil- or SMOF-based LEs with soybean oil-based LEs and 2) reported plasma concentrations of α-tocopherol, oleic acid, and ω-6 (n-6) and ω-3 (n-3) long-chain polyunsaturated fatty acids (PUFAs) and liver concentrations of total bilirubin and the enzymes alanine transaminase, aspartate transaminase, alkaline phosphatase, and γ-glutamyl transferase. The meta-analysis suggested that SMOF-based LEs were associated with higher plasma concentrations of plasma α-tocopherol, oleic acid, and the ω-3 PUFAs eicosapentaenoic and docosahexaenoic acid. Olive oil- and SMOF-based LEs correlated with lower plasma concentrations of long-chain ω-6 PUFAs and were similar to soybean oil-based LEs with regard to their effects on liver function indicators. In summary, olive oil- and SMOF-based LEs have nutritional advantages over soybean oil-based LEs and are similarly safe. However, their performance in clinical settings requires further investigation.

[Fish oil containing lipid emulsions in critically ill patients: Critical analysis and future perspectives]

Third-generation lipid emulsions (LE) are soybean oil sparing strategies with immunomodulatory and antiinflammatory effects. Current evidence supporting the use of intravenous (i.v) fish oil (FO) LE in critically ill patients requiring parenteral nutrition or receiving enteral nutrition (pharmaconutrient strategy) mainly derives from small phase ii clinical trials in heterogenous intensive care unit patient's population. Over the last three years, there have been published different systematic reviews and meta-analyses evaluating the effects of FO containing LE in the critically ill. Recently, it has been demonstrated that i.v FO based LE may be able to significantly reduce the incidence of infections as well as mechanical ventilation days and hospital length of stay. Nonetheless, more robust evidence is required before giving a definitive recommendation. Finally, we strongly believe that a dosing study is required before new phase iii clinical trials comparing i.v FO containing emulsions versus other soybean oil strategies can be conducted.

Changes in Antioxidant Defense System Using Different Lipid Emulsions in Parenteral Nutrition in Children after Hematopoietic Stem Cell Transplantation

Background: Traditionally, lipids used in parenteral nutrition (PN) are based on ω-6 fatty acid-rich vegetable oils, such as soybean oil, with potential adverse effects involving oxidative stress. Methods: We evaluated the antioxidant defense system in children, after hematopoietic stem cell transplantation (HSCT), who were randomized to use a lipid emulsion with fish oil or soybean oil. Blood samples at baseline, at 10 days, and at the end of the PN were taken to analyze plasma retinol, α-tocopherol, β-carotene, coenzyme Q9 and coenzyme Q10 levels, and catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPOX), and superoxide dismutase (SOD) levels in lysed erythrocytes. Results: An increase in plasma α-tocopherol levels in the group of patients receiving the fish oil-containing emulsion (FO) compared with the group receiving the soybean emulsion was observed at day 10 of PN. Concurrently, plasma α-tocopherol increased in the FO group and β-carotene decreased in both groups at day 10 compared with baseline levels, being more significant in the group receiving the FO emulsion. Conclusion: FO-containing emulsions in PN could improve the antioxidant profile by increasing levels of α-tocopherol in children after HSCT who are at higher risk of suffering oxidative stress and metabolic disorders.

Synthesis, Characterization, and Nanoencapsulation of Tetrathiatriarylmethyl and Tetrachlorotriarylmethyl (Trityl) Radical Derivatives—A Study To Advance Their Applicability as in Vivo EPR Oxygen Sensors

Tissue oxygenation plays an important role in the pathophysiology of various diseases and is often a marker of prognosis and therapeutic response. EPR (ESR) is a suitable noninvasive oximetry technique. However, to reliably deploy soluble EPR probes as oxygen sensors in complex biological systems, there is still a need to investigate and improve their specificity, sensitivity, and stability. We reproducibly synthesized various derivatives of tetrathiatriarylmethyl and tetrachlorotriarylmethyl (trityl) radicals. Hydrophilic radicals were investigated in aqueous solution mimicking physiological conditions by, e.g., variation of viscosity and ionic strength. Their specificity was satisfactory, but the oxygen sensitivity was low. To enhance the capability of trityl radicals as oxygen sensors, encapsulation into oily core nanocapsules was performed. Thus, different lipophilic triesters were prepared and characterized in oily solution employing oils typically used in drug formulations, i.e., middle-chain triglycerides and isopropyl myristate. Our screening identified the deuterated ethyl ester of D-TAM (radical 13) to be suitable. It had an extremely narrow single EPR line under anoxic conditions and excellent oxygen sensitivity. After encapsulation, it retained its oxygen responsiveness and was protected against reduction by ascorbic acid. These biocompatible and highly sensitive nanosensors offer great potential for future EPR oximetry applications in preclinical research.

Intravenous fish oil lipid emulsions in critically ill patients: an updated systematic review and meta-analysis

INTRODUCTION

Intravenous fish oil (FO) lipid emulsions (LEs) are rich in ω-3 polyunsaturated fatty acids, which exhibit anti-inflammatory and immunomodulatory effects. We previously demonstrated that FO-containing LEs may be able to decrease mortality and ventilation days in patients who are critically ill. Since 2014, several additional randomized controlled trials (RCTs) of FO-containing LEs have been published. Therefore, the purpose of this systematic review was to update our previous systematic review with the aim of elucidating the efficacy of FO-containing LEs on clinical outcomes of patients who are critically ill.

METHODS

We searched electronic databases from 1980 to 2014. We included four new RCTs conducted in critically ill adult patients in which researchers evaluated FO-containing LEs in parenterally or enterally fed patients.

RESULTS

A total of 10 RCTs (n = 733) met inclusion criteria. The mean methodological score was 8 (range, 3 to 12). No effect on overall mortality was found. When we aggregated the results of five RCTs in which infections were reported, we found that FO-containing LEs significantly reduced infections (risk ratio (RR) = 0.64; 95% confidence interval (CI), 0.44 to 0.92; P = 0.02; heterogeneity I (2) = 0%). Subgroup analysis demonstrated that predominantly enteral nutrition-based trials showed a tendency toward a reduction in mortality (RR = 0.69; 95% CI, 0.40 to 1.18; P =0.18; heterogeneity I (2) =35%). High-quality trials showed a significant reduction in hospital length of stay (LOS) (weighted mean difference = -7.42; 95% CI, -11.89 to -2.94; P = 0.001), whereas low-quality trials had no effect (P = 0.45). The results of the test for subgroup differences in hospital LOS was significant (P = 0.001).

CONCLUSION

FO-containing LEs may be associated with a reduction in infections and also could be associated with a reduction in duration of ventilation and hospital LOS. Further large-scale RCTs are warranted and should be aimed at consolidating potential positive treatment effects.

Mixed nanomicelles as potential carriers for systemic delivery of Z-GP-Dox, an FAPα-based doxorubicin prodrug: formulation and pharmacokinetic evaluation

Z-GP-Dox, the FAPα (fibroblast activation protein-α)-based doxorubicin prodrug, demonstrates excellent tumor targeting effects and a favorable toxicokinetic profile. However, the insoluble nature of Z-GP-Dox becomes a significant barrier to drug administration, particularly when it comes to the clinical stage. Here we developed a nanomicelle system to facilitate the systemic delivery of Z-GP-Dox, and evaluated its disposition in rats following administration of the micelles using a physiologically-based pharmacokinetic model. Z-GP-Dox-loaded mixed nanomicelles (ZGD-MNs) were prepared by dispersion of an ethanol solution of Z-GP-Dox, lecithin, and sodium oleate in water. The obtained ZGD-MNs were 86.6 nm in size with a drug loading of 14.03%. ZGD-MNs were fairly stable in phosphate-buffered saline and showed satisfactory physical and chemical stability over a 2-week observation period. Accumulative drug release was more than 56% within 24 hours. Further, the physiologically-based pharmacokinetic rat model consisting of various organs (ie, heart, liver, spleen, lung, kidney, and intestine) was fitted to the experimental data following administration of ZGD-loaded cosolvent (control) or micelles. Derived partition coefficient values revealed that the nanomicelles significantly altered the biodistribution of Z-GP-Dox. Of note, drug distribution to the lung, liver, and spleen was greatly enhanced and the fold change ranged from 2.4 to 33. In conclusion, this is the first report of a mixed micelle system being a viable carrier for delivery of Z-GP-Dox. Also, the pharmacokinetic behavior of Z-GP-Dox was satisfactorily described by the physiologically-based pharmacokinetic model.

Feeding the gut: how, when and with what -- the metabolic issue

PURPOSE OF REVIEW

To review the literature on feeding critically ill patients with special emphasis on the intestine.

RECENT FINDINGS

Many dogmas have been questioned in the past few years. In particular, the absence of evidence for impact on outcomes in critically ill patients has been highlighted. So 'early enteral feeding', the trophic effect on intestinal mucosa in humans, 'pharmaco-nutrition', postpyloric feeding and prokinetic drugs have all been found to lack proper evidence to affect outcomes.

SUMMARY

The use of gastric feeding in critical illness is recommended. Successful gastric feeding is indicative of a functional gastrointestinal tract. Pharmacological effects of nutrients are questionable, but supplementation of deficits (glutamine, selenium, etc.) may be in the patient's best interest. A more individualized prescription of nutrition in the critically ill is advocated.

Lipemia: causes, interference mechanisms, detection and management

In the clinical laboratory setting, interferences can be a significant source of laboratory errors with potential to cause serious harm for the patient. After hemolysis, lipemia is the most frequent endogenous interference that can influence results of various laboratory methods by several mechanisms. The most common preanalytical cause of lipemic samples is inadequate time of blood sampling after the meal or parenteral administration of synthetic lipid emulsions. Although the best way of detecting the degree of lipemia is measuring lipemic index on analytical platforms, laboratory experts should be aware of its problems, like false positive results and lack of standardization between manufacturers. Unlike for other interferences, lipemia can be removed and measurement can be done in a clear sample. However, a protocol for removing lipids from the sample has to be chosen carefully, since it is dependent on the analytes that have to be determined. Investigation of lipemia interference is an obligation of manufacturers of laboratory reagents; however, several literature findings report lack of verification of the declared data. Moreover, the acceptance criteria currently used by the most manufacturers are not based on biological variation and need to be revised. Written procedures for detection of lipemia, removing lipemia interference and reporting results from lipemic samples should be available to laboratory staff in order to standardize the procedure, reduce errors and increase patient safety.